Alphaviruses: Serological Evidence of Human Infection in Paraguay (2012-2013).
INTRODUCTION
Alphaviruses can produce febrile illness and encephalitis in dead-end hosts such as horses and humans. Within this genus, the Venezuelan Equine Encephalitis virus (VEEV) complex includes pathogenic epizootic subtypes and enzootic subtypes that are not pathogenic in horses (except subtype IE, Mexican strains), although they can cause febrile symptoms in humans. The Rio Negro virus (RNV-VEEV subtype VI) circulates in Argentina, where it was associated with undifferentiated febrile illness. Mayaro (MAYV) and Una (UNAV) viruses belong to a different group, the Semliki Forest virus complex, with confirmed circulation.


OBJECTIVE
The present study aimed to determine RNV, MAYV, and UNAV seroprevalences by plaque reduction neutralization test in 652 samples of Paraguayan individuals mainly from the Central Department, between years 2012 and 2013.


METHODS
Samples with antibodies titer >1:20 against RNV were also tested for Mosso das Pedras-subtype IF, subtype IAB, and Pixuna (PIXV)-subtype IV viruses that belongs to VEEV antigenic complex.


RESULTS
The overall seroprevalence of RNV was 3.83%, and for UNAV it was 0.46%, and no neutralizing antibodies were detected against MAYV in the studied population. Two of the twenty-seven heterotypic samples were positive for PIXV. The 50.1% of neutralizing antibody titers against RNV were high (equal to or greater than 1/640), suggesting recent infections. The effect of age on the prevalence of RNV was negligible.


CONCLUSIONS
These results bring new information about neglected alphaviruses in South America, and these data will serve as the basis for future studies of seroprevalence of other VEEV, and studies to search potential hosts and vectors of these viruses in the region.
['Cardozo|Fátima|F|', 'Konigheim|Brenda|B|', 'Albrieu-Llinás|Guillermo|G|', 'Rivarola|María Elisa|ME|', 'Aguilar|Javier|J|', 'Rojas|Alejandra|A|', 'Quaglia|Agustín Ignacio|AI|', 'Paez|Malvina|M|', 'Guillén|Yvalena|Y|', 'Diaz|Adrian|A|', 'Vallejos|María Asunción|MA|', 'Herebia|Lilian|L|', 'Recalde|María Lidia|ML|', 'Contigiani|Marta Silvia|MS|', 'Mendoza|Laura|L|']
D000293:Adolescent D000328:Adult D000368:Aged D000369:Aged, 80 and over D000524:Alphavirus D018354:Alphavirus Infections D000914:Antibodies, Viral D002648:Child D002675:Child, Preschool D004666:Encephalitis Virus, Venezuelan Equine D005260:Female D006801:Humans D007223:Infant D008297:Male D008875:Middle Aged D010239:Paraguay D016036:Seroepidemiologic Studies D055815:Young Adult
alphaviruses serological evidence Paraguayan human population Una virus Venezuelan Equine Encephalitis virus.