The impact of active surveillance and health education on an Ebola virus disease cluster - Kono District, Sierra Leone, 2014-2015.
BACKGROUND
During December 2014-February 2015, an Ebola outbreak in a village in Kono district, Sierra Leone, began following unsafe funeral practices after the death of a person later confirmed to be infected with Ebola virus. In response, disease surveillance officers and community health workers, in collaboration with local leadership and international partners, conducted 1 day of active surveillance and health education for all households in the village followed by ongoing outreach. This study investigated the impact of these interventions on the outbreak.


METHODS
Fifty confirmed Ebola cases were identified in the village between December 1, 2014 and February 28, 2015. Data from case investigations, treatment facility and laboratory records were analyzed to characterize the outbreak. The reproduction number (R) was estimated by fitting to the observed distribution of secondary cases. The impact of the active surveillance and health education was evaluated by comparing two outcomes before and after the day of the interventions: 1) the number of days from symptom onset to case-patient isolation or death and 2) a reported epidemiologic link to a prior Ebola case.


RESULTS
The case fatality ratio among the 50 confirmed Ebola cases was 64.0 %. Twenty-three cases occurred among females (46.0 %); the mean age was 39 years (median: 37 years; range: 5 months to 75 years). Forty-three (87.8 %) cases were linked to the index case; 30 (61.2 %) were either at the funeral of Patient 1 or had contact with him while he was ill. R was 0.93 (95 % CI: 0.15-2.3); excluding the funeral, R was 0.29 (95 % CI: 0.11-0.53). The mean number of days in the community after onset of Ebola symptoms decreased from 4.0 days (median: 3 days; 95 % CI: 3.2-4.7) before the interventions to 2.9 days (median: 2 days; 95 % CI: 1.6-4.3) afterward. An epidemiologic link was reported in 47.6 % of case investigations prior to and 100 % after the interventions.


CONCLUSIONS
Initial case investigation and contact tracing were hindered by delayed reporting and under-reporting of symptomatic individuals from the community. Active surveillance and health education contributed to quicker identification of suspected cases, interrupting further transmission.
['Stehling-Ariza|Tasha|T|http://orcid.org/0000-0001-8117-7243', 'Rosewell|Alexander|A|', 'Moiba|Sahr A|SA|', 'Yorpie|Brima Berthalomew|BB|', 'Ndomaina|Kai David|KD|', 'Jimissa|Kai Samuel|KS|', 'Leidman|Eva|E|', 'Rijken|Dingeman J|DJ|', 'Basler|Colin|C|', 'Wood|James|J|', 'Manso|Dumbuya|D|']
D000293:Adolescent D000328:Adult D000368:Aged D002648:Child D002675:Child, Preschool D003150:Community Health Workers D003299:Cooperative Behavior D004196:Disease Outbreaks D029043:Ebolavirus D004777:Environment D005191:Family Characteristics D005260:Female D006266:Health Education D006268:Health Facilities D019142:Hemorrhagic Fever, Ebola D006801:Humans D007223:Infant D008297:Male D008875:Middle Aged D010356:Patient Isolation D012307:Risk Factors D012424:Rural Population D012807:Sierra Leone D055815:Young Adult
Surveillance Health education Ebola virus disease Sierra Leone