PREVALENCE OF INFECTION WITH JUNIN VIRUS IN RODENT POPULATIONS IN THEEPIDEMIC AREA OF ARGENTINE HEMORRHAGIC-FEVER

We report the results of indirect fluorescent antibody screening for a ntibody to Junin virus in 1,101 sera from small mammals captured on tw o mark-recapture grids in the epidemic area of Argentine hemorrhagic f ever. Twenty-six of 29 seropositive animals were the cricetid rodent C alomys musculinus, for a 30-month prevalence of 7.9% in that species. Combining these data with previously published data on antigen detecti on provided an estimated total prevalence of infection of 10.9% for th is, the principal reservoir species. Other infected species included t wo cricetids, C. laucha and Bolomys obscurus, and a predatory carnivor e, Galictis cuja. Approximately half of infected animals simultaneousl y carried serum antibody and antigen in blood and saliva, some for 29- 61 days. Except for C. laucha, which was associated with crop habitats , seropositive animals were strongly associated with the relatively ra re roadside and fence-line habitats. Seropositive C. musculinus were p redominantly males in the oldest age and heaviest body mass classes, a nd seropositive males were twice as likely to have body scars as seron egative males. These observations suggest that most infections were ac quired through horizontal transmission and that aggressive encounters among adult, male C. musculinus in relatively densely populated roadsi de and fence-line habitats are an important mechanism of transmission of Junin virus within reservoir populations.