[Prevalence of Flavivirus antibodies in young voluntary recruits to military service in the province of Formosa, Argentina].

The aim of the present study was to investigate the seroprevalence to Flavivirus, in young people living in risk areas. We analyzed 189 human sera from 3 towns in the Province of Formosa. This area corresponds to the border that limits Brasil and Paraguay and the aim was to search for a possible introduction of Dengue and Yellow Fever from these countries. Serological tests such as haemagglutination inhibition (HI), complement fixation (CF) and neutralization (NT) were performed using St. Louis encephalitis (SLE), Bussuquara, Ilheus, Yellow fever and dengue 1 and 2 viruses. No definite evidence for HI antibodies to dengue and Ilheus was obtained. One serum cross-reacted only with yellow fever and two sera only for Bussuquara by the HI test. Only one serum was confirmed to be positive for Bussuquara by NT test. A total of 22 sera from 189 were positive for SLE by the HI test and 40 were also reactive by the NT test. The seroprevalence measured by HI and NT antibodies was similar in the three departments studied. These results show that SLE virus is present in the North of Argentina with an important value of prevalence so that this agent could play an important role in the febrile infections not virologically confirmed.