Clusters of Hantavirus Infection, Southern Argentina

Abstract

Person-to-person transmission of a hantavirus was first confirmed during a 1996 outbreak of hantavirus pul- monary syndrome in southern Argentina, where Andes virus is endemic. To identify other episodes of secondary transmission, we reviewed reports of 51 cases of han- tavirus infection from this region (November 1993–June 2005). Nine clusters involving 20 cases (39.2%) were found. Two patients, who had symptoms 3 weeks after they shared risks for rodent exposure, were considered a clus- ter. The other 8 clusters each began with an index case, which was almost always fatal, followed 19–40 days later by the illness of at least 1 person who had close and pro- longed contact with the index case-patient. Person-to-per- son transmission was considered the probable source of these 8 clusters. The probability of initiating secondary cases was 41% for patients who died versus 4% for those who survived (p = 0.005). Interpersonal transmission of Andes virus infection should be considered even when rodent exposure cannot be definitively excluded.