The foundation of best practice in health promotion is a robust theoretical base that informs design, implementation, and evaluation of interventions that promote the public’s health. This study provides a novel contribution to health promotion through the adaptation of the agenda-setting approach in response to the contribution of social media. This exploration and proposed adaptation is derived from a study that examined the effectiveness of Twitter in influencing agenda setting among users in relation to road traffic accidents in Saudi Arabia.The proposed adaptations to the agenda-setting model to be explored reflect two levels of engagement: agenda setting within the social media sphere and the position of social media within classic agenda setting. This exploratory research aims to assess the veracity of the proposed adaptations on the basis of the hypotheses developed to test these two levels of engagement.To validate the hypotheses, we collected and analyzed data from two primary sources: Twitter activities and Saudi national newspapers. Keyword mentions served as indicators of agenda promotion; for Twitter, interactions were used to measure the process of agenda setting within the platform. The Twitter final dataset comprised 59,046 tweets and 38,066 users who contributed by tweeting, replying, or retweeting. Variables were collected for each tweet and user. In addition, 518 keyword mentions were recorded from six popular Saudi national newspapers.The results showed significant ratification of the study hypotheses at both levels of engagement that framed the proposed adaptions. The results indicate that social media facilitates the contribution of individuals in influencing agendas , a component missing from traditional constructions of agenda-setting models. The influence of organizations on agenda setting is also highlighted . In addition, 13 striking similarities showed the relationship between newspapers and Twitter on the mentions trends line.The effective use of social media platforms in health promotion intervention programs requires new strategies that consider the limitations of traditional communication channels. Conducting research is vital to establishing a strong basis for modifying, designing, and developing new health promotion strategies and approaches. Communication is a core component of many effective health promotion interventions and change processes at individual and community levels . In the Globally, road traffic accidents result in 1.24 million deaths and 20 to 50 million injuries per year, many of which cause permanent disabilities . The WorMaximizing the effectiveness of social media for the promotion and protection of health necessitates intervention programs based on a thorough scientific understanding of how communication and media action theories and models are prioritized ,9. AgendAccording to Kaplan and Haenlein, social media is “a group of Internet-based applications that build on the ideological and technological foundations of Web 2.0, and that allow the creation and exchange of User Generated Content” . This deThe development of social media has been recognized as an opportunity for the promotion of the public’s health demonstrated through the concept of infodemiology, a term coined by Eysenbach . InfodemInfodemiology is based on the idea that the vast quantities of communication data generated by social media can be used for public health . We liveThese data provide a new level of information that was not measurable before this era . CurrentTwitter is “an information network made up of 140-character messages called Tweets” . It is aLippman  first exAs indicated in the model, media agenda setting refers to traditional media organization decisions on which issues to discuss through their channels. Public agenda setting revolves around the issues that are considered important to the general public. Policy agenda setting involves official organizations or government agencies that determine which issues are important and worthy of discussion .Kozel et al  developeIn addition to the work by Kozel and colleagues on the development and application of health promotion agenda-setting, the concept and components of agenda setting have been used in public health and health promotion in a range of areas -42. UndeAgenda-setting initiatives have been extensively studied and developed by researchers and practitioners. New frames and models have been proposed with emphasis placed on the ideal match between changes people and societies are undergoing in the social media era and agenda setting for public health . Given tSimple application of agenda setting in the era of social media does not reflect the complex process of communication resulting from the use of social media platforms . We arguAs proposed by Dearing and Rogers , agenda Social media offers numerous platforms where people can communicate and interact. One of the most important changes in agenda setting within the social media realm is the shift in power towards the public in terms of control over communication; this shift was triggered by the fact that with social media technologies, individuals become active producers instead of functioning merely as receivers of information. Bekkers et al  argue thFurthermore, individuals differ significantly in how they respond to the media agenda . The powSocial media has also redistributed the power to control communication at the organizational level. The nature of social media has allowed many types of organizations—not only media and policy institutions—to contribute to agenda setting. Similar to the shift in power at the public and individual level, changes at the organizational level have translated to organizational influence over and interaction with various agendas.The effect of the presence of health organizations on these platforms has been explored in recent studies ,53. ThesThe organizational agenda is not a new concept. Berger  pointed The authors propose to regard organizations as essential stakeholders in agenda setting because they can interact with different community actors, including the public, media, and policy makers.As previously stated, the nature of social media with its two-way communication platforms and channels differs completely from that of traditional one-way mass communication channels. The social media age has driven changes in the manner by which information is disseminated. This era has decentralized traditional communication, thereby diminishing its power in shaping the issues that people think about . ResearcMcCombs  and MeraCollectively, the aforementioned studies focused not only on the discrepancy between traditional and social media in their effectiveness as communication tools but also on the independence of social media as an agenda-setting channel. Their findings suggest that studying social media as part of traditional media in the agenda-setting context is an unsuitable framework from which to understand the complexity of the agenda-setting process within the arena occupied by modern media innovations. About 70% of journal articles that explored agenda setting in the social media age are concentrated in intermedia agenda setting between new and traditional media . Yet, thHypothesis 1 (H1) revolves around the agenda-setting process within social media and suggests a new model fitted to the uniqueness of agenda setting under a social media interface. H1 maintains that individual and organizational agendas constitute a new body of plans and schemes instead of falling within the category of media and policy agendas see .To validate H1, we put forward the following subhypotheses:H1-1a: Individual accounts are the most dominant accounts.H1-1b: Organizational accounts are more dominant than media and policy accounts.We used three measures to determine the validity of H1-1a and H1-1b: rank scale measures for retweet impressions, total impressions, and total amplification multipliers  and retweet impressions and that between impressions and the amplification multiplier.Hypothesis 2 (H2) is related to the position of the social media agenda within classic agenda-setting theory. The theory posits that social media are new components incorporated into the three main elements of the classic agenda setting proposed by Rogers and Dearing  Figure .Determining the validity of H2 necessitates an investigation into the relationship between the social media agenda and the three other agenda types . However, the data collected in this study are useful only in exploring the relationship between Twitter as a social media platform and newspapers as traditional media channels. The collected data also lack many of the characteristics required from evidentiary sources . Despite these limitations, the data can provide valuable insights into the interaction between Twitter and newspaper agendas.H2 is articulated thus:H2: The trend of social media mentions is similar to that of newspaper mentions.This study is part of exploratory research aimed at testing the capability of traditional communication theories in understanding social media platforms related to health promotion practice.Exploratory research is preliminary research that contributes to the formulation and identification of hypotheses that show some merit in being followed up by confirmatory research ,59. The The study used an important concern of public health, that of road traffic accidents. Based on the conceptual frames ,62 and tImmediately after completion of this Twitter intervention, a national campaign on road safety was run through various traditional and social media channels. The campaign enhanced the dynamics of mentioning the keywords of the study. Such enhancement does not bias the study as it reflects the normal dynamic of interactions targeted by the study to be examined. Furthermore, the collected data covered the periods before and after the campaign. Intervention tweets:Good health is a major resource for social, economic, and personal development and an important dimension of quality of life.81% of all deaths in Ministry of Health hospitals are due to road traffic accidents.Road safety is a public health issue which involves health as well as other sectors that have the responsibility to be engaged in road traffic accident prevention.Tweets by other users:Your life is a candle; do not extinguish it. Stats: it is estimated that the number of traffic accidents will reach 1 million in the next 8 years.Traffic accidents cost SR 1.9 trillion (US $518 billion) globally each year.Did you know that in Saudi Arabia one person every hour is killed in a traffic accident?!!Twitter data can be accessed directly from service profiles. Many third-party providers also offer Twitter statistics and analysis services. For instance, Tweetreach offers licensed access to the full Twitter “firehose” through Gnip, a licensed data reseller . IncreasTo validate the hypotheses, we collected data from two primary sources: Twitter activities and Saudi newspapers. As previously stated, keyword mentions served as indicators of agenda promotion; for Twitter, interactions were used to measure the process of agenda setting within the platform. Data from both sources were collected in a 90-day period from January 1 to March 31, 2014. Three Arabic keywords that are highly associated with road traffic accidents were considered in the analysis. The English translations of these keywords are “traffic accidents,” “the traffic accidents,” and “road accidents.” Tracking mentions of predefined keywords have been used in previous studies although for different research purposes ,73,74.In collecting the Twitter data, we used the Tweetreach service to collect all tweets that contained the keywords. Many researchers have used this tool. For example, it has been employed in examining the use of Twitter as a platform for sharing information about medical events ,76 and aIn this study, we set up operators to filter tweets: only those expressed in the Arabic language were included, and tweets to and from Arab states other than Saudi Arabia were excluded. The final dataset comprised 59,046 tweets  and 38,066 contributors. For each tweet and contributor, variables were collected. A total of three datasets were obtained from Twitter trackers: tweet data, retweet data, and contributor data.Al-riyadh, Okaz, Al-Madina, Al-Yaum, Al-Watan, and Al-Jazirah. Across these newspapers, 518 keyword mentions were recorded. All the datasets were extracted and prepared using Excel spreadsheets (Microsoft Corp).In collecting the newspaper data, we used Google Advanced Search to gather information on six popular Saudi national newspapers: The classification of data from social media, particularly Twitter, is coherent with the concept of infodemiology as described by Eysenbach ,17 withiFor H1, we developed a classification to code the 2364 filtered users into four types of accounts. Individual accounts refer to any account owned by one person. Organizational accounts are those owned by a group or organization but not by media or policy organizations. Media accounts are accounts related to the media, including traditional media (programs or organizations) or news. Policy accounts are nonindividual accounts created for policy purposes or owned by political organizations.Most of the accounts were classified in a straightforward manner as one of the authors is familiar with the Saudi environment; however, we needed to check profiles and tweets for some accounts. To validate the classification, an external observer independently classified 20% of the sample, made up of randomly chosen users from the list. The kappa  indicatiFrom the 59,046 Twitter activities, we obtained data on 16,073 regular tweets (not retweets or replies) that mentioned any of the three Arabic keywords. Each tweet was linked to user name, time, and variables listed in To isolate the influential tweets, tweets with no retweets were excluded (2895 tweets). From the dataset, we extracted the account users. A retweet impression indicates the ability of a user to reach audiences that extend beyond his/her direct followers. For users with more than one tweet we selected the tweet with the highest retweet impressions (1818 tweets). By manually checking the Twitter profiles of users, we filtered out all but user accounts owned by Saudi individuals or organizations with mainly Saudi audiences. Users on the list of 1115 were classified into the four account types.The first step in the analysis was determining the degree of influence of the groups by calculating the total impressions for each classification type. Total impressions can be an informative measure of reach, which includes all the times at which a tweet was received (including receipt by the user’s followers). Users with numerous followers can be influential in the Twitter community because of previously built influence. These users can be called Twitter influentials. To evaluate the ability of ordinary users to influence other users, we also analyzed retweet impressions, which show the total number of times a tweet was indirectly received. This is a strong measure of degree of influence, even among users with a limited number of followers.Subsequently, a simple rank scaling measure was applied to all the users on the list. We summed the total values of all the account types. For each of the three statistics , we calculated the percentage of the classification types and determined the average of the retweet impressions for these classifications. This multiple test technique allows more accurate assessment in examining the study hypotheses.From the primary Twitter dataset, we obtained a list of 38,066 contributors who mentioned the keywords during the 90-day data collection period. For each contributor, we used multiple variables, including the number of retweets by user, number of impressions, and amplification multipliers. Tweetreach defines impressions as the “number of timelines that received the tweet directly from the user” and the amplification multiplier as the “rate of amplification, based on how far that contributor’s tweets spread due to the retweets and replies.” The amplification rate is calculated as follows :[ / impressions] + 1Users with amplification multipliers below 1.2x were filtered out in accordance with the Tweetreach evaluation : “anyoneEysenbach , in relaBased on total delivery ranks, we used the data on 40,193 retweets to extract data on 2665 retweets. These were all retweets over the average of deliveries, which was 2888.5. For each retweet, we identified users who retweeted a message and those who created the retweeted message. After filtering for both lists of users, 1951 unique users were classified. Type codes were used to identify 1382 users who interacted with one another.Using R open source statistical computing and graphics software  we perfoFrom the Twitter and newspaper data, we extracted two lists: total number of mentions in the examined newspapers and total number of mentions on Twitter. To normalize the data, all the values were divided by the maximum value in each data column, after which the data were plotted on a simple line graph. Visually, similar spikes  were identified in the trend mentions of the newspapers and Twitter.Among the 1115 users who posted regular tweets, the number of individual accounts was considerably higher than the number of other accounts. On the basis of the total of the three measures, individual users accounted for 76.29%, 67.79%, and 96.16% of retweet impressions, total impressions, and total amplification multipliers, respectively, as shown in As determined from the three measures, the organizational accounts dominated the media and policy accounts in terms of retweet impressions and total impressions but not in total amplification multipliers. This result indicates that policy accounts are more influential than organizational accounts based on the amplification multiplier measure.The average of the three totals ; the impressions and amplification multipliers showed a strong correlation (r=.01).The line graph that represents the mention trends in Twitter and newspapers  shows thAvailable evidence reflects the importance of communication technologies and the Internet in daily life and social interaction ,46. The Among the many effective features of social media, user-generated content is critical to the positioning of new channels within the agenda-setting process. Other social media functions that influence agenda-setting dynamics are the sharing of content and the selection of the type of information that users want to receive .Based on a simple classification scheme, Twitter accounts can be either personal or organizational.. This study suggests that in many cases, the emergence of agenda setting among social media users  occurs through the advocacy of individual personal agendas. On social media platforms, individuals can influence the public and organizations through their own agenda. In other words, individuals can function as independent actors in agenda setting. In a similar vein, social media platforms enable organizations and the public to influence individual perceptions and behaviors through their agendas.From the viewpoint of health promotion, agenda setting is an effective approach to achieving best practice aims and objectives ,11,12. AThis exploratory study centers on the importance of a comprehensive understanding of best practices for health promotion. It does so by suggesting a novel contribution to health promotion through the development of an adapted agenda-setting approach in the social media era and within its platforms.Health promotion needs a more creative approach to research and practice in using the agenda-setting function . This isUnlike classic agenda setting, agenda setting as a process of interaction within the social media sphere involves different actors. With evolving tools and powerful features, social media provides a unique social space characterized by rich platforms where community members can communicate and interact. Agenda setting in the context of social media remains a communication process, but it differs from traditional communication  in that Given this backdrop, we suggest two levels of understanding in exploring agenda setting in the social media era. First, we propose social media as an independent agenda-formulating body within the agenda-setting process. Second, we recommend the exploration of agenda setting within social media. We argue that within Twitter, agenda-setting participants can change, unlike the fixed nature of participants in classic agenda setting. This variability is attributed to the power shift towards new actors, such as individuals and organizations, as indicated in previous research ,48,49. WThe results suggest that the individual agenda dominated over the other agenda types and that organizations exhibited stronger influence than that wielded by media and policy groups. Although the data of amplification multiplier measure showed that policy accounts are more influential than organizational accounts, this influence is limited to retweets of other accounts only, which means policy accounts hold more ability to enhance the diffusion of tweets by influencing nonfollower users. In spite of this, each of the three measures used to evaluate the influence of the account types presented analogous results from various calculation methods and different variables. We believe this feature strengthens the evidence supporting the formulated hypotheses because it rectifies the limitations of one indicator or its measures.For the individual agenda, the analysis derived different statistics which confirm that power is not restricted to the public agenda but extends to individual personal agendas. The averages of the total impressions and amplification multipliers suggest the influence of the personal agenda. The contributor interactions also support this finding, as indicated by the strong influence of the individual agenda as a target. The findings of the data analyses also highlight the influence of the public agenda, but the statistical results do not demonstrate specific differences between personal and public agendas. Agenda melding among individuals was reflected by the data on contributor interactions (672 interactions recorded).This study aimed to examine the effectiveness of agenda setting as a theory in the social media era. Therefore, a critical requirement was to consider the influence of agenda with reference to the type of account rather than account influence. The dynamics of interactions on Twitter are affected by many factors and will be/are reflected in the data . A highlAlthough influentials or opinion leaders are beyond the scope of this work, they remain essential participants in any social communication process, including agenda setting . In earlWe hypothesized a relationship between newspapers and Twitter and illustrated this association via a line graph of mention trends over the platform. Nevertheless, the collected data cannot illuminate a clear direction for this relationship and do not exclude external factors that can affect the trends. This hypothesis was intended as a starting point in exploring the incorporation of the social media agenda in the classic agenda-setting process. This relationship has been studied and validated through various analysis techniques and methodologies ,49,55,91Nonetheless, this relationship is only part of the model proposed in this work and therefore requires further examination ,83. PartWe have proposed an alternative perspective from which to understand agenda setting in the social media age. Supported by the data collected, we adopted well-defined measures that reflected a positive evaluation of the study’s hypotheses. We have applied multiple hypothesis testing methods which can support authenticity of the study as is recommended for any exploratory research . NonetheThe nature of data on social media results in limitations which can affect any infodemiology study. These include, for example, the lack of strong representation of the population and the lack of accuracy of some information provided on such platforms .Furthermore, the statistical procedures and measures used require replication and/or repetition to establish a solid foundation for the implications of the results. As indicated by McCombs , such stMany factors and variables must be considered, guided by a more in-depth understanding of the process of agenda setting in relation to its possible applications . This wiFor the public health and health promotion domain, further research may include different health topics with larger data samples and modified methods. At the organizational level, the findings suggest more dominance for health organizations in the agenda-setting process within social media. Further research related to strategies and best practices is required for such organizations to close the gap that has already been identified . MoreoveThe results indicate that media platforms are a promising avenue that can enhance the efficacy of intervention programs. However, the effective use of such platforms will necessitate new strategies that address the limitations of traditional communication channels. More efforts towards modifying health promotion strategies and developing new approaches should be initiated. For such development, conducting research is vital to establishing a strong basis for the design, formulation, and implementation of agendas. Social media augments the effectiveness of this approach by shifting power towards reachable individual participants. In turn, agendas become more accessible and more easily used as tools or targets of influence. Finally, organizations that promote the public’s health will benefit considerably from actively participating in the agenda-setting process through the formulation of the organizational agenda.


Dengue fever epidemic dynamics are driven by complex interactions between hosts, vectors and viruses. Associations between climate and dengue have been studied around the world, but the results have shown that the impact of the climate can vary widely from one study site to another. In French Guiana, climate-based models are not available to assist in developing an early warning system. This study aims to evaluate the potential of using oceanic and atmospheric conditions to help predict dengue fever outbreaks in French Guiana.Lagged correlations and composite analyses were performed to identify the climatic conditions that characterized a typical epidemic year and to define the best indices for predicting dengue fever outbreaks during the period 1991–2013. A logistic regression was then performed to build a forecast model. We demonstrate that a model based on summer Equatorial Pacific Ocean sea surface temperatures and Azores High sea-level pressure had predictive value and was able to predict 80% of the outbreaks while incorrectly predicting only 15% of the non-epidemic years. Predictions for 2014–2015 were consistent with the observed non-epidemic conditions, and an outbreak in early 2016 was predicted.These findings indicate that outbreak resurgence can be modeled using a simple combination of climate indicators. This might be useful for anticipating public health actions to mitigate the effects of major outbreaks, particularly in areas where resources are limited and medical infrastructures are generally insufficient. Aedes aegypti is well established, experiences an epidemic cycle of dengue with large and prolonged epidemics occurring approximately every 3 years. Dengue is one of the most prioritized infectious diseases, and it requires an intense mobilization of local public health authorities, health services, and health professional and vector control services. A specific surveillance, preparedness and response plan has been developed based upon these needs. Gaining an accurate understanding of the drivers of dengue transmission is required to develop a model to predict the risk of an epidemic and to plan activities aimed at controlling it. Here, we assessed the effects of climatic factors on dengue spread to develop a predictive model of the epidemics in French Guiana on a country-wide scale. The goal of the model is to anticipate and plan both preventive and control activities. Given climate conditions, the model predicts that a dengue epidemic is likely to occur in early 2016. These conditions, which are favorable for Aedes mosquito proliferation, could also enhance the diffusion of other arboviruses, such as the Zika virus, in northeastern South America.Climatic determinants are amongst the most frequently cited in studies aimed at understanding and explaining the dynamics of vector-borne infections, and dengue in particular. French Guiana, a French overseas territory in which the vector  Aedes sp. mosquitos. Infection produces a spectrum of illnesses that range from indiscernible or mildly nonspecific febrile syndrome to severe disease forms, including dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Currently, there are no specific dengue therapeutics, and prevention strategies are limited to vector control measures  warming in the Equatorial Pacific Ocean and [ii] northward displacement of the Azores High, which causes a rainfall deficit at the end of the dry season. This work refines the results of Gagnon et al. , who usea priori hypothesis derived from the work of Gagnon et al. [Warming events in the Equatorial Pacific Ocean are known to modify the mean climate over South America. During a warming phase, the northern region of the continent experiences drought conditions because the eastern subsidence of the Walker circulation is reinforced, which weakens convection and precipitation . These rn et al. , which iIn northern South America, rainfall is associated with water vapor that is transported from the north Atlantic via the northeasterly trade winds and thus from the SLP gradients. At the end of the dry season (October–November), the convergence of trade winds transports moisture over French Guiana, which fuels convection and precipitation. Positive SLP anomalies over the Azores High favor a northward position of the ITCZ over the Atlantic. Precipitation consequently decreases over the north part of South America in November.nd tercile) that corroborated our results. Specifically, the two identified false alarms (1994 and 1999) showed relatively high incidence rates for non-epidemic years. In addition, one of the two unpredicted epidemic years (2001) was associated with lower incidence rates than the other epidemic years.Not all El Niño events are the same, and their effects on weather/climate may therefore differ. In 1994 and 1999, the model predicted an epidemic year would result from the high SLP and SST indices. However, the observed dry season rainfall patterns  were inconsistent with the usual occurrences, and this may explain the lack of an epidemic situation. In addition, 2001 and 2005 were epidemic years that were not predicted by the model. In these two years, dry season rainfall showed no positive or negative specific anomalies. For 2005, these observations were consistent . However, in 2001, given the low SST and SLP indices, a wetter dry season was expected than was observed. Thus, if a large part of the dry season rainfall variability in French Guiana is driven by the SST and SLP of the targeted areas, it is not always the case. These data highlight the complexity of predicting epidemiological patterns for non-climate-contrasted years and suggests that rainfall variability is not driven only by the two large scale indicators that were identified in the present study. Nevertheless, global predictions for the 1991–2013 period were better when the SST and SLP indices were used than when the dry season rainfall index was used . InteresAe. aegypti, which is the only urban vector for DF in French Guiana, are known to be able to resist desiccation and to thereby survive dry episodes [Ae. aegypti can maintain significant background densities during the dry season. As a consequence, the virus can remain in the area during the dry season, leading to a higher potential of an epidemic when the wet season returns. Further entomological field investigations should be performed to test these hypotheses. The evolution of the surveillance system that was used for data collection beginning in 2006, following the introduction of new laboratories and new methods of diagnosis, increased the difficulty of performing meaningful comparisons of the scope of epidemics, particularly those that occurred before 2006. It is also important to take the circulating serotypes into consideration to enhance the assessment of the model’s predictions. Circulating serotypes that have affected only a small portion of the population before the predicted year could play a role by increasing the transmission risk, given the size of the susceptible population. Conversely, serotypes that have recently caused epidemics could limit the transmission risk despite propitious climatic conditions. In this study, we explored the reason that the model wrongly predicted certain epidemiological situations looking at the predominant serotypes. Two of the four years that were wrongly predicted could be explained by the serotypes circulating during the previous year. In 1999, for which the model erroneously predicted an epidemic, both circulating serotypes (DENV1 and DENV4) had already caused epidemics in 1997 and 1998. In addition, the 2001 epidemic, which was not predicted by the model, was caused by DENV3, which had not caused an epidemic in the ten previous years. Other well-known factors that might play a key role in transmission, including the immune status of the host population or the presence of outbreaks in neighboring countries, were not included in the present analysis. Finally, considering the potential competitive viral suppression in vectors that can be caused by co-infections, the emergence of new viruses that can also be transmitted by Aedes mosquitoes in French Guiana, such as the Zika virus, could limit the transmission of dengue fever. It will be interesting to see how the emergence of the Zika virus in 2016 may interacts with dengue fever transmission in a propitious climatic context.Our findings indicate that an important rainfall deficit at the end of the dry season enhances the risk of epidemic in the following year, and these types of conditions are likely to impact the vector population. Two non-exclusive main hypotheses related to mosquito densities can be stated. First, the eggs of episodes . During Future studies should attempt to validate hypotheses regarding the impact of the identified climate factors and associated meteorological patterns  on direct measurements of vector behavior and breeding sites. Among other possible future developments, we plan to take into account the sub-country incidence of dengue to model the propagation of epidemics within the country.Among the wide panel of factors that can influence DF outbreaks, these results suggest that large-scale climate factors play an important role. We found that the climatic indices that were assessed in this study were important for DF monitoring and for predicting outbreaks in French Guiana over a period of 2–3 months. This delay may give public health authorities the ability to anticipate outbreaks and implement social communication and vector control measures, and to adapt healthcare capacity and increase preparedness in a timely manner. Importantly, this model could be easily and regularly updated using newly collected data that was retrieved from the ongoing dengue surveillance system. Because the identified climate indicators are simple and easy to access, they could be used to estimate the probability of future epidemics occurring according to climate change simulations and help to evaluate the effectiveness of potential intervention strategies.S1 FigThe gray lines represent each individual forecast produced during the cross-validation process.(TIFF)Click here for additional data file.


Demographic change and policy changes in social care provision can affect the type of social care support received by older people, whether through informal, formal state or formal paid-for sources. This paper analyses the English Longitudinal Study of Ageing data (wave 4) in order to examine the relationship between demographic and socio-economic characteristics, and the receipt of support from different sources by older people who report difficulty with daily activities. The research outlines three key results with implications for the future organisation of social care for older people. Firstly, the number of instrumental activities of daily living (IADLs) an older person reports having difficulty with, followed by the number of activities of daily living (ADLs) are the strongest determinants of receiving support from any source. Secondly, there are significant gender differences in the factors associated with receiving support from different sources; for example, physical health is a strong determinant of informal support receipt by men, while mental health status is a strong determinant of informal support receipt by women. Finally, the research shows that different kinds of impediments in everyday life are associated with receiving support from different sources. This ‘link’ between particular types of difficulties and support receipt from particular sources raises questions about the way social care provision can or should be organised in the future. The need for support in later life for individuals living in the community can be met through a combination of contributions from the informal, formal state and formal paid-for sector, however, informal networks of family and friends constitute the cornerstone of care provision for older people, and a more common source of support for those who have children compared to formal state or formal paid-for sources of care (Grundy and Read i.e. 70 years and over), when men are more likely to care for their spouses largely as a result of gender differences in men's and women's marital status in later life  for such support  the growth in the number of the ‘oldest old’ is often cited as an indicator of the increase in high-support needs among the older population, and the concomitant increase in demand on support services , which is a longitudinal survey of people aged 50 and over, who live in private households in England. The ELSA sample has been drawn from respondents to the Health Survey for England (HSE), which is an annual cross-sectional household survey which collects a wide range of health data and biometric measures. Each HSE sample is drawn using a two-stage sampling strategy, which involves a selection based on postcodes selected from the Postcode Address File and a random selection of households from a fixed number of addresses covering each postcode sector. As a result, the HSE is nationally representative of private households. There is a potential loss of representativeness before the ELSA data are drawn from HSE data due to non-response to HSE, refusal to be re-contacted, attrition between HSE and ELSA, and the exclusion of individuals living in institutions such as residential and nursing homes. However, such factors have been partly mitigated by weights in the ELSA.e.g. dressing), instrumental activity of daily living  or mobility , totalling 3,395 individuals. The tool of ADLs was developed in the 1960s, and is used in order to evaluate an individual's ability to perform functional activities independently ; socio-economic variablesphysical health variables ; mental health variables ; disability/functional limitations variables ; environment/technology variables .The seven categories include: The paper first presents results of the bivariate analysis, followed by results of the multivariate analysis. Among older people who report a difficulty and receive support, The next part of this section turns to explore the determinants of receiving support from informal, state or paid-for sources, first discussing the development of the model and then the results of the analysis. The receipt of informal support for men is associated with higher age, having a partner/spouse, reporting a lung disease, reporting difficulties with mobility, ADLs, IADLs, reporting a LLSI, using a walking stick and using an occupational therapist. Reporting difficulty with a high number of IADLs is the strongest predictor of receiving informal support for men; the odds of receiving informal support amongst men experiencing difficulty with between five and nine IADLs are 31 times the odds of men who report experiencing no difficulty in performing IADLs . On the Among women, the strongest independent determinants of receiving informal support include marital status, whether or not children are living in the household, the household wealth, as well as the report of difficulty with cognitive, mobility or IADL tasks, and the receipt of professional support. Being married among women shows the strongest association with being in receipt of informal support compared to other groups of marital status, and living in households in the lowest wealth quintile is a stronger predictor of receiving informal support than living in households in the fourth wealth quintile . SimilarThe receipt of paid-for support by older men and women is associated most strongly with the number of IADLs a person had difficulty with. For example, the odds of receiving ‘privately paid-for support’ for a person who reports having difficulty with one IADL are almost 42 times those of a person who reports having no difficulty with IADLs , althouget al.To date, the academic literature has often discussed the relationship between an individual's health status, reflected in the report of difficulty with different activities, and the amount of support received in later life  rather than a gradient of difficulty (e.g. a little or a lot of difficulty). To some extent, this weakness is mediated by our derived variables adding the number of difficulties reported within the ADL, IADL and mobility categories. The third relates to attrition and the ways in which it has affected our analytical sample. The ELSA team's research showed that non-respondents were different to respondents in terms of their housing tenure, ethnicity, highest educational qualification and marital status


N = 55) and providers of health services (N = 34) to such women and focus groups [2 with WID (N = 15) and 2 with health service providers (N = 12)]. The resulting comprehensive women-centered intervention, RBT+WC, was then pretested and further refined in a sample of 20 WID. Results indicated positive pre-post changes in urine screening results and perceived needs for both RBT+WC and a case management control condition. The approach to treatment adaptation and the revised elements of RBT+WC are presented and discussed.Women who inject drugs (WID) are highly marginalized and stigmatized and experience ongoing discrimination in Georgia. Few opportunities exist for WID to receive publicly funded treatment for substance use disorders. The IMEDI  project was developed in response to the need for women-specific and women-centered treatment services. This paper described our approach to understanding the Georgian culture—and WID within that culture—so that we could integrate two interventions for substance use found effective in other Western and non-Western cultures and to outline how we refined and adapted our integrated intervention to yield a comprehensive women-centered intervention for substance use. Reinforcement Based Treatment (RBT) and the Women's CoOp (WC) were adapted and refined based on in-depth interviews with WID ( Injection-drug-using individuals are highly marginalized, highly stigmatized, and are at increased risk for STIs, HCV, and HIV worldwide . Women wWomen in Georgia who use illicit substances commonly experience emotional abuse, physical aggression, and sexual violence . Such viWID are at high risk for contracting and spreading HIV . InjectiThere are few opportunities for women to receive publicly funded substance use disorder treatment in Georgia. Given that drug treatment has been designed to serve male beneficiaries—when treatment is available—it lacks sensitivity to the unique needs and challenges that WID face in their daily lives , 13.The purpose of the present paper is to present the methods and findings of a study whose purpose was the development and pilot testing of a culturally sensitive, women-centered intervention for WID in Georgia. This section introduces the overall project and describes our first two studies, which represent our approach to understanding the Georgian culture—and WID within that culture—in order that we could integrate two interventions for substance use found effective in other Western and non-Western cultures. The Materials and Methods section then outlines the general methodological approach of the project and how we refined and adapted our integrated intervention to yield a comprehensive women-centered intervention for substance use. Results present a summary of qualitative and quantitative findings from the pilot projects, while Discussion reviews the “lessons learned” from the pilot study.The IMEDI  project was developed in response to the need for women-specific and women-centered treatment services. IMEDI is the Georgian word for “hope”, the feeling we aimed to give women participating in the project. The IMEDI project has two goals: first, to gain the necessary knowledge from WID and treatment providers about drug use, HIV risk behaviors, and the current drug treatment in Georgia, second, use this information to adapt, integrate, and implement a comprehensive treatment program to slow HIV and HCV transmission in Georgia.The overall IMEDI Project design is depicted in n study, with n corresponding to the particular aim. Aims 1 and 2 involved the conduct of two separate qualitative interview studies of WID and the health care providers. The results of these analyses were reviewed by our Advisory Boards, which then fed into the initial development of our culturally sensitive, comprehensive, women-centered intervention for substance use. The Aim 3 study involved the cyclical refinement and adaption of this intervention, and findings from this study are the primary foci of the present paper.In-depth semistructured interviews 60–120 minutes in length were conducted with 55 WID [In-depth semistructured interviews 60–120 minutes in length were completed with 34 health service providers who had previously provided services to a WID one or more times in the two months prior to the interview . ResultsBecause of their importance, both to the overall project and to our Aim 3 study, this section describes our Community Advisory Board and our Beneficiary Advisory Board, prior to a discussion of the Aim 3 study methods. Moreover, general issues germane to Aim 1 and/or Aim 2 studies and to our Aim 3 study are described in this section.All three studies were approved by the Office of Research Protection Institutional Review Board (IRB) at RTI International, USA, and the IRB at the Maternal and Child Care Union, Georgia.N = 11).Our CAB, chaired by our Georgian principal investigator (IK), met 2 times per year during the intervention development phases. The CAB assisted the investigative team in several ways, most notably in understanding stigma and barriers to treatment and then developing an infrastructure of organizations that would serve as a lasting and sustainable contribution to improving the network of services provided to WID in Georgia. CAB members include local experts in women's health and services that are provided to WID, drug treatment providers, professionals working in prisons and law enforcement, women's violence intervention, providers of family planning and other aspects of women's reproductive health, counselors that provide HIV and STI counseling, HIV prevention services, women in the Global Fund's Country Coordinating Mechanism who oversee HIV and tuberculosis prevention and treatment programs in Georgia, and a methadone maintenance treatment facility director  were facilitated by a senior project researcher (IK), who had considerable prior experience in conducting focus groups for research purposes and was extremely knowledgeable regarding qualitative research methods. All interviews were audio-recorded, with the prior written consent of participants.http://www.qsrinternational.com/products_nvivo.aspx) qualitative analysis software. Content and thematic analyses were then conducted under the direction of IK. Two coders independently coded relevant textual material from the recordings. nVivo was used to search the text for themes that were then coded, examined, and collated to form subcategories and categories. The general focus of the analysis in each study was on the opinions, attitudes, beliefs, and/or behavior of the participants, which varied by study.Qualitative analyses for Aims 1, 2, and 3 studies followed the same general procedure. Audio recordings were transcribed directly into Georgian in Unicode text format. Transcripts of these text files were exported into PDF files, which were then imported into nVivo 9 (N = 20) who met eligibility criteria  and who were seeking treatment were recruited to participate in drug treatment research, with block randomization of each successive pair of participants to either one or the other treatment condition, such that n = 10 in each condition.WID  adapting the US based case management manual and materials; (2) integrating the modules from the original Women's CoOp and other editions such as the Women's Health CoOp South Africa and the Russian Women's CoOp [n's CoOp , 16 inton's CoOp  to creatBased on findings from the Aims 1 and 2 studies , 14, 18,Case Management Condition. Development of a case management condition was necessary because there were no available active control conditions in Georgia for substance-using women against which RBT+WC could be compared.The general focus of the case managers in the case management condition was to first identify the needs and severity and acuity of the needs women have using a standardized needs assessment instrument. Next, the case manager worked with the participant using a comprehensive resource guide developed with the input of our CAB and BAB that identified services and programs where the participant might be eligible to receive services. The case manager then provided instructions about how to contact those resources. The case manager role-played with the participant about how to contact the service and what to say and what not to say. The case manager also worked with the participant on determining the barriers the participant might face in accessing that service and how to minimize or overcome such barriers. At each meeting, the case manager and the participant reviewed the progress that had been made in accessing the service and the need for reprioritizing the plan for service access . A plan was then made in terms of the order in which the services would be contacted and sought. A phone was provided and minimal funds for transportation were given on specified days to support the participant in accessing services.Development of RBT+WC. In reviewing the available behavioral interventions that have been tested with women, Reinforcement Based Treatment (RBT) appeared to be a promising intervention to adapt for women living in Georgia. RBT reduces drug use and related injection-drug-use risk behaviors in both men and women [nd women , 19. RBTnd women . Other sLike many substance abuse treatments, RBT effectively reduces injection drug use and related risk behaviors but not sexual risk behaviors. This lack of effect may be in part because it does not include specific skills to promote condom competence or communication skills to negotiate condom protection. Thus, incorporated into RBT was a component to address women-centered sexual risk behaviors based upon selected treatment modules from the Russian Women's CoOp intervention (WC) , and adaWC is considered a best-evidence intervention and has been adapted in other countries and found efficaious . Based iRBT and WC have complementary strengths that had the potential to yield a comprehensive, women-centered intervention. However, it was necessary to revise both RBT and WC to produce an intervention that would be sensitive to the values and context found in the Georgian culture. Both the BAB and CAB reviewed the treatment manuals. Important feedback common to both groups included a greater focus on communication skills-building, the need to build a trusting relationship with the women, and a greater focus on the employment and financial needs and empowerment of the women.N = 15 total) and two with health care providers  participants, respectively. In each focus group, the materials related to the RBT+WC and case management condition were reviewed for accuracy and appeal of content and presentation and lack of stigmatizing language. Participants reacted to and commented upon both strengths and weaknesses of the materials. For the providers, we sought to examine to what extent these materials would be practical and useful for them to use in the future and what changes would need to be made to achieve that goal. The order of discussion of the two models was counterbalanced across the respective types of groups. The goal of these focus groups was to inform further refinement and adaptation of the two interventions to better address the needs of Georgian WID.Prior to conducting our pilot feasibility study, we conducted four focus groups, two with active WID  developed for research in Russia served as the primary outcome measure . The RRBBased on findings from our Aim 1 and Aim 3 studies, the RRBA was supplemented with a time-line follow back (TLFB) procedure to assess both substance use and sex-risk behaviors. The TLFB procedure was intended to provide information of drug use and sexual activity weekly throughout the participant's enrollment in the study, rather than simply at the beginning and end of treatment. We modified the TLFB , 30 for The RRBA has been used in international WC outcome research for more than 10 years and has been translated from English into several other languages, including Russian. Moreover, three members of the investigative team were responsible for the earlier pilot research in Georgia and were familiar with issues regarding cultural sensitivity of the measures and their translation and back-translation. Two members of the investigative team were from Georgia and were fluent in reading and writing both Georgian and English, as were the project manager and research staff. Thus, the RRBA was reviewed in English and revised in English in a series of meetings with project staff in English so the English phrasing of the measure could be accurately translated into Georgian so that it would accurately assess substance use and risky behavior in our population. The RRBA was then translated into Georgian, back-translated, and then reviewed by Georgian staff for accuracy and completeness in translation.Both baseline and post-treatment-completion data were collected. Each participant was intensively interviewed according to an adaptation and refinement process that proceeded in three cycles. After each cycle, the RBT and case management interventions were refined as necessary, and the respective interventions provided to the next cycle . The first two cycles involved 3 participants from each of the two treatments, while the last cycle involved 4 participants from each of the two treatments. In each cycle, one participant was interviewed after each week of treatment, one was interviewed after each 4 weeks of treatment, and one was interviewed only at the conclusion of treatment; in the final cycle, there was an additional participant in each treatment who was interviewed only at the conclusion of treatment. The goal of this interview schedule was to obtain a “snapshot” of participants' views of treatment and the treatment process at different points in treatment. Although it might be argued that all participants should be interviewed weekly, such frequent interviews “sensitize” participants to treatment and the treatment components. Thus feedback from such participants would be unrepresentative of how the treatment would be viewed by someone who was provided the treatment without such interview schedule. Therefore, we designed our interview schedule to minimize the possibility by interviewing participants at various points in treatment.Quantitative data were collected as part of the Aim 3 study to determine possible issues with measures and to assess the need to make changes in the treatment process. As with Aims 1 and 2 studies, findings from the focus groups were reviewed by our CAB and BAB. The two groups met separately and first reviewed a summary of qualitative findings from Aims 1 and 2 studies. This was followed by discussion of recreational activities to be offered to study participants. CAB and BAB members proposed a wide range of both recreational and skills-building activities, such as swimming, manicure/pedicure, hair cutting/dyeing and skin care courses, automobile driving schools (few women in Georgia have driver's licenses), and pastry cooking courses. Based on these recommendations and discussion within the project team, two activities—beads working and felt making—were selected for the project. Moreover, both the CAB and BAB provided important feedback regarding the order of topics for intervention modules to be delivered to participants see .Participants in the Aim 3 study were all Georgian citizens, one native Russian and another native Chechen, the remaining were native Georgian. Two variables that we thought would be informative regarding the efficacy of the intervention were chosen as primary outcomes. The first is the results of the weekly urine screening test illicit drugs. Given the small sample size and the sparseness of the data on weekly evaluation of each drug under assay, we chose to examine this outcome at baseline (prior to the beginning of the intervention) and at the end of the intervention, as a dichotomous variable, with yes for a positive result for any illicit drug and no otherwise. The second outcome was the results of a needs assessment that is part of the RRBA, and so needs assessment data were collected at baseline and at 12 weeks at the end of the intervention, thus matching with the assessment time points for the first outcome. The needs assessment asks the participant to indicate whether she felt she needed help with any of the 20 issues . Again, due to the sparseness of responding to each question, a single needs assessment score was determined by summing the yes responses to the 20 questions.Both outcomes were examined with generalized estimating equations (GEE) models, with the between-subjects effect of intervention condition, the within-subjects effect of assessment time point, and their interaction, with biological assay for illicit drugs assumed to be a binary variable following a binomial distribution, and the needs assessment assumed to be a count variable following a Poisson distribution.P < 0.04 and P < 0.001, resp.), with positive urine screening test results declining by 50% and the number of perceived needs on the part of the participants declining more than 60%. Neither the main effect for intervention condition nor the interaction effect was significant for either outcome .We were gratified to find that our participants reported constructive change in their lives as a function of treatment, at least in terms of the two outcomes we examined. Although we might have hoped to find a significant interaction that favored RBT, we doubted that we had any reasonable power to detect an interaction effect in a pilot study whose primary goals were to establish feasibility and acceptance of treatment on the part of the participant population. In that regard, we did conclude that our pilot study was a success, with only one participant dropping out of treatment prior to session 12, from the RBT condition.Moreover, we did reach a number of conclusions from this study that we will apply to the Aim 4 study. First, in terms of measures, the TLFB did not seem to be informative above and beyond the information collected by the RRBA, so we have decided to omit it from use in study 4. Second, many items on the RRBA had a low frequency of responding , so the RRBA was streamlined in order to assess outcomes directly relevant to the intervention conditions. Third, in order to maximize continuing contact with participants, rather than offering the intervention once per week over a 12-week period, it was decided to offer it twice per week for 6 weeks in our ongoing Aim 4 study.Finally, the incentive structure for participation was substantially revised. The amount and form of incentives were discussed with the CAB and BAB and with focus groups during interviews and at the initial stage of the research. Based on these discussions participants were offered the cash-equivalent of 15 USD in local currency (Georgian GEL) for every visit and the equivalent of 10 USD for every breath and urine sample provided. In addition, in the case of RBT condition, in order to encourage abstinence, these samples had to be negative for monitored substances. However, feedback from study participants in this regard was critical, based on the perceived inequality between the two conditions. Thus, provision of monetary incentives for participation in the study was revised such that participants received the equivalent of 20 USD for completing the baseline and end-of-treatment interviews and 10 USD for each completed interview following sessions 1–12, with an additional 5 USD for providing breath and urine samples at each of these visits. Therefore, participants were able to receive a maximum of 220 USD (362 GEL) in incentives for participation, and payment in the RBT+WC was not contingent on provision of a negative urine sample. We stress that payment to participants were for their participation in the study and not as motivation for behavior change. It may be of considerable interest to pair RBT+WC with contingency management in future research.Limitations. As with any small-scale pilot study, the present study has several notable limitations. The first limitation is that the study was not powered to detect differences between the treatment conditions, and so any conclusions reached in regard to the relative efficacy of either treatment cannot yet be drawn. Second, the extent to which the sample reflects the larger population of WID in Georgia is unknown. Clearly, the sample is reasonably well educated, and most appeared to be in stable relationships. However, the extent to which such circumstances are unrepresentative of WID in Georgia needs further research. Third, although participants completed the RRBA at baseline and after treatment, they were interviewed at various points during treatment, as noted above. They were specifically asked for their comments on the RRBA after the baseline assessment. Therefore, we believe that the responses to the follow-up measures have been contaminated to some degree by the interview process, which may have attuned participants to attend to the assessment measures and process. Fourth, our choice to discontinue use of the TLFB may have been premature and may reflect more on the specifics of the current sample and the participants' limited range of sexual activity. It may be that the TLFB would be quite informative, particularly if we would have put greater emphasis on obtaining information regarding unprotected sex. Finally, although Aim 3 study focused on the development of a comprehensive, culturally sensitive, and women-centered intervention, we understand that such an intervention may be necessary but not sufficient to effect behavior change in WID in Georgia. There are likewise changes that need to be effected in the larger treatment system, including policies of the Ministry of Health. Otiashvili et al. view the treatment system in Georgia from a policy perspective and detail the changes that need to be undertaken by the larger treatment system for any treatment of WID in Georgia to optimally effect change [t change .This series of studies is the first of its kind for reaching substance-using women in Georgia. It was an iterative process with many partners who all offered important additions that helped create a more comprehensive and culturally congruent intervention. One vitally important lesson that we had learned in our previous pilot study delivering treatment services to males , 33 was A second lesson that this project taught us about treatment adaptation is the vital role that mixed methods research plays. The qualitative research conducted in studies 1 and 2 allowed for a greater understanding of the relationship of substance-using women to their Georgia culture, their substance use and sexual practices that put them at risk, and the lack of fit between their treatment needs and the services that were available to them. Findings from these two studies allowed for an integrative RBT+WC approach to treatment that was much more aligned with the needs of the population. Moreover, data from both the qualitative and quantitative interviews with participants in Aim 3 study allowed for a deeper understanding of what outcomes were important to measure and how best to deliver the treatment so that it would have the promise of meaningfully impacting their lives.Our Aim 4 study now holds the promise of providing meaningful findings regarding feasibility and initial efficacy of a culturally sensitive, women-centered, and comprehensive treatment approach that is aligned with the needs of the intended population. It will represent only the first step in further developing and refining such an approach so that it will prove impactful for substance-abusing women in Georgia.


Gymnocephalus cernuus), killer shrimp (Dikerogammarus villosus), and golden mussel (Limnoperna fortunei), respectively. Model predictions for Eurasian Ruffe have been used to direct surveillance efforts within the Great Lakes and DNA evidence of ruffe presence was recently reported from one of three high risk port localities identified by our model. Predictions made for killer shrimp and golden mussel suggest that these two species have the potential to become rapidly widespread if introduced to the Great Lakes, reinforcing the need for proactive ballast water management. The model used here is flexible enough to be applied to any species capable of being spread by ballast water in marine or freshwater ecosystems.Ballast water in ships is an important contributor to the secondary spread of invasive species in the Laurentian Great Lakes. Here, we use a model previously created to determine the role ballast water management has played in the secondary spread of viral hemorrhagic septicemia virus (VHSV) to identify the future spread of one current and two potential invasive species in the Great Lakes, the Eurasian Ruffe ( Gymnocephalus cernuus), and two predicted future invaders . These three species were prioritized by Great Lakes resource managers and scientists as species whose spread around the Great Lakes may be enhanced by movement of ballast water. The species chosen are representative of probable future invasion management challenges in the region, but our approach may be applied to any species that may be moved via ballast water and to any ecosystem that may experience invasions due to commercial shipping.Invasive species have been identified as one of the major threats to the biodiversity of freshwater ecosystems, including the Laurentian Great Lakes Dreissena polymorpha), which is already widespread in the Great Lakes  spread in Ohio due to both natural and human-mediated vectors Diabrotica virgifera ssp. virgifera) in Austria Predictive models are increasingly being used to identify how human-mediated vectors spread invasive species. For instance, Schneider et al. (1998) and Bossenbroek et al. (2007) used gravity models to identify lakes that were most at risk for future invasion of zebra mussels Ballast water discharge data has been used before to conduct risk assessments for ports in the Great Lakes and throughout North America. For example, Ruiz et al. (2013) used the number of ship trips and amount of ballast water discharged at U.S. ports to determine if nonnative species richness is related to shipping activity For this study, we adapt our dynamic spatial model to predict the future spread of Eurasian Ruffe, golden mussel, and killer shrimp. We used backcasting of the historic invasion pattern of zebra mussels and ruffe to identify the most important parameters and values that predicted their spread. We then predicted localities most at risk of future invasion by ruffe using the best parameter values that backcast historic ruffe spread, and those parameters that backcast historic zebra mussel dispersal were used to forecast the spread of golden mussel and killer shrimp. Based on the results of our models, we make recommendations for the future management of invasive species and ballast water in the Great Lakes.The Great Lakes and St. Lawrence Seaway were the water bodies of interest for this study. The St. Lawrence Seaway was defined as the portion of the St. Lawrence River from Lake Ontario downstream to the western tip of Anticosti Island. The study area included Lake St. Clair and Niagara, Detroit, St. Clair, and St. Marys Rivers, as well. Despite water in the St. Lawrence Seaway flowing eastward towards the Atlantic Ocean, the trend of ballast water movement is westward, with Duluth-Superior Harbors, Minnesota-Wisconsin, USA receiving the most ballast water each year . As idenWe parameterized our models by backcasting the spread of two invasive species that already occur in the Great Lakes, zebra mussel and Eurasian Ruffe. Zebra mussel was backcast as a surrogate for golden mussel and killer shrimp, because golden mussel have life history traits and use habitats similar to zebra mussel In order to determine if ballast water was contributing to species spread we compared the location model with a random model. The random model acts as the null model, and the location model needed to perform better than the random model in order to be able attribute spread to ballast water movement. The random model does not take into consideration other invasion pathways  that also contribute to spread in the Great Lakes. Both the random and location models selected the number of new annual infestations by randomly selecting from a Poisson distribution. The means and variances (λ) for the distributions were set equal to the mean number of new invasions potentially due to ballast water. For zebra mussel, λ was calculated as the mean number of occurrences per year for 1986 to 1992 as identified from records in the Nonindigenous Aquatic Species (NAS) database, thus λ = 4 Upon determining if past infestations were correlated with ballast water discharge locations, the third model, the “propagule pressure” model, was used to determine if infestation locations could better be identified if ship trip information was included. First, ballast water source locations that occurred within an infested area were identified. Next, locations that received ballast water from those infested locations were selected. To determine if the selected discharge locations actually became infested upon receiving ballast water from infested sources, the potential invasion result was selected from a binomial distribution. A result of 0 meant a trip did not end in infestation, and a result of 1 meant a trip did lead to infestation. The number of trials, n, was equal to the number of trips made to a discharge location that year by ships carrying infested ballast water. The probability of infestation for each day of the trip was varied for each species to identify the best value for the parameter. Probabilities of 0.000001, 0.0001, and 0.01 were tested for Eurasian Ruffe, and 0.05, 0.25, 0.50, and 0.75 for zebra mussels . A singlOnce infestation locations were selected for a year, the dispersal of the species from the initial invasion point was then identified for all models. First, an infestation area was identified from the new invasive species occurrence. Coordinates for ballast water discharge and source locations in the National Ballast Information Clearinghouse (NBIC) were recorded with a precision no less than one one-hundredths of a degree. We calculated that in the Great Lakes, the difference between two points that were one one-hundredths of a degree apart was approximately 1.4-km. This was identified as the estimated difference that could occur between the actual and recorded discharge locations due to rounding error, and was used as the radius of the area of infestation, since the species could have potentially been discharged anywhere within that circle. To identify the rate of natural spread that could occur upon being introduced to a new location, a second radius was used to expand the area of infestation. For ruffe, the natural spread distance was identified from the rate of secondary spread along the south shore of Lake Superior that was most likely due to fish dispersal. As identified from the occurrences recorded in the NAS database, the dispersal distance was most commonly ∼25-km along the south shore of Lake Superior Invasive species occurrences were required to run all three models, and ballast water data were needed for the “location” and “propagule pressure” models. Zebra mussel and Eurasian Ruffe presence locations for 1986 to 1992 and 1986 to 2011 respectively were obtained from the NAS Database The models were developed in Python to be run in ArcGIS see . ScriptiThe model results were analyzed by calculating the overall, presence, and absence accuracies for each iteration of the model Additionally, the length of time that would be required to spread the full extent of the current area invaded by each species if only natural spread is considered was identified. This was done by applying the largest spread distances tested above, 20-km for zebra mussel and 25-km for ruffe, to the initial introduction locations detected in 1986 for each species. The invasion front was identified for each year and was limited to the areas identified as being inhabitable by the species of interest.Upon identifying the best fit model, the next step was to predict the future secondary spread of invasive species that either already occur in the Great Lakes or may occur in the Great Lakes in the future. The three species that predictions were simulated for were the Eurasian Ruffe, golden mussel, and killer shrimp.Prediction models differed from the backcasting models in that the current Great Lakes distribution or possible initial introduction locations were used as the initial sources of infestation for each species. Also, instead of comparing the final distributions of the model predictions to the actual occurrences of the invasive species, the total number of model iterations a port was predicted to be invaded in the future was calculated. For each model iteration, once a port was identified as invaded in a given year, it continued to be invaded for all subsequent years. Each model simulated 10 time-steps of future invasion, and each simulation was run for 100 iterations. Time-steps were used in lieu of years, as the lag between a species introduction, establishment and potential for spread is uncertain. That uncertainty is also compounded by ballast water best management practices, recently required by the U.S. Coast Guard  and U.S. Environmental Protection Agency's (USEPA) General Vessel Permit (2013), that are thought to reduce the likelihood of uptake and secondary spread within the basin The initial introduction locations, natural spread distances, and probability of infestation were different for each species. Unlike the other two species being modeled, Eurasian Ruffe already occurs in the Great Lakes. The actual occurrences of this species were used as the initial starting locations for future secondary spread. The best fit values for natural spread distance and probability of infestation were identified from the results of the backcasting exercise described above. For golden mussel and killer shrimp, the potential initial invasion locations were identified as those Great Lakes ports that received ballast water from international ports within the species' known current distribution. International ballast water source-discharge patterns were identified from the NBIC for 2004 to 2010  [36]. PrResults of the Eurasian Ruffe backcasting identified the propagule pressure models as performing best overall, with mean overall accuracies between 0.69 and 0.72 . DespiteThe propagule pressure models were also the best performing in backcasting the spread of zebra mussel. Overall, the random and location models performed as well or nearly as well as the best performing propagule pressure models ; howeverIn order to capture a range of possible outcomes for the future spread of Eurasian Ruffe, both models identified by Eurasian Ruffe backcasting above (10-km 0.01 probability and 25-km 0.001 probability) were used to forecast future secondary spread. The predictions made based on the two models depict relatively similar patterns of spread . Both moIn order to forecast the secondary spread of golden mussel and killer shrimp, the best performing model and parameters identified by backcasting zebra mussel were used. Since none of the models were found to over-predict zebra mussel occurrences, the model with the highest presence accuracy, the 20-km propagule pressure model with a probability of infestation of 0.75, was chosen. This model also had one of the highest overall accuracies.Our analysis of the NBIC 2004–2010 data indicated seven ports historically received shipping from the global range of killer shrimp. Forecasting results predict that killer shrimp could become widespread within three to four time-steps of invasion. If the species invades Duluth, Minnesota, USA first, it is predicted to most likely spread to Two Harbors (100 out of 100 model iterations) and Silver Bay (100), Minnesota, USA, Marquette (98) and Alpena (100), Michigan, USA, Indiana Harbor (93), Indiana, USA, and Ashtabula (85), Ohio, USA next . By the Results of golden mussel forecasting indicate that regardless of whether Duluth, Minnesota, USA or Bay City, Michigan, USA  are invaded first, this invasive species will spread rapidly throughout the Great Lakes, much as zebra mussel did . By the Our ballast water model simulates the potential spread of invasive species once they become established in the Great Lakes; whereas, previous assessments have focused on identifying the first ports of introduction to the basin. By applying source- and species-specific data to generate spread predictions, we were able to attribute ballast water as a vector of spread. Ruiz et al. (2013) previously found that there was no relationship between nonnative species richness and ballast water volume and number of ship arrivals at U.S. ports when data on ballast source locations were not considered The inclusion of source information in predicting the spread of invasive species was important in identifying ports that may become invaded in the future. For instance, despite not being amongst the top 25 ports receiving the most visits by discharging ships , both SaThe ability to predict the future spread of invasive species is an important part of any biosecurity surveillance and response program. Although prevention of new species invasions is expected to be the least expensive option for managing invasive species, early detection, containment, and eradication is the next best option when prevention has failed The importance of prediction as part of a surveillance and response program is best illustrated by our predicted spread of Eurasian Ruffe across the remaining parts of the Great Lakes basin, namely southern Lakes Michigan and Huron, and Lakes Erie and Ontario. Our predictions identified three locations at high risk for invasion, and six additional sites with lower invasion risk based on current ballast water movement patterns . These oUnlike Eurasian Ruffe, killer shrimp and golden mussels have not been detected in the Great Lakes; however, if they are introduced, they are predicted to spread rapidly. Golden mussel has life history traits similar to zebra mussel Shipping is the most important pathway of introduction and spread of invasive species in marine, freshwater, and estuarine environments A further limitation to the model we have described here is the lack of rigorous occurrence data for invasive species. There is a tendency for aquatic species occurrence records to only be collected in port and marina locations; however, the spread of occurrences that we obtained from the NAS database are not limited to these areas, though some port bias may exist  and 2 [3The creation of a dynamic, spatial model simulating the secondary spread of invasive species due to ballast water in the Great Lakes has allowed us to identify the links between ballast water source and discharge locations. This information is already informing invasive species managers and policy-makers, motivating surveillance efforts, and illustrating the need to proactively manage ballast water to prevent or slow the spread of current and future invaders. With the model predictions for Eurasian Ruffe, we were able to identify the most likely locations where this invasive fish will invade next. For golden mussel and killer shrimp, we show that prevention is still the best policy for these species, as they both are expected to spread rapidly upon invasion. Also, given surveillance limitations, proactive management of intra-basin movement of ballast water is advisable if there is to be any hope that a new invader can be contained and eradicated.Information S1Model Code. Included is the Python code for the models used to backcast the spread of Eurasian Ruffe and zebra mussel and to forecast the spread of Eurasian Ruffe, killer shrimp, and golden mussel. The code has been modified so as to include generic file names. The random and location models both include code from a random selection tool (RandomSelection.tbx) that was downloaded from the ESRI website: http://arcscripts.esri.com/details.asp?dbid=15441 (last accessed: 3/29/2011) and modified.(PDF)Click here for additional data file.Information S2Prediction Maps. Included are the resulting predictions modeled for Eurasian Ruffe, killer shrimp, and golden mussel. Ten time-steps were modeled from each of the invasion start locations for each species. Results are also included for both sets of parameter values used to predict the future spread of Eurasian Ruffe. Killer shrimp spread predictions were not modeled from Superior, Wisconsin, USA due to its proximity to Duluth, Minnesota, USA.(PDF)Click here for additional data file.