First Evidence of Akodon-Borne Orthohantavirus in Northeastern Argentina.

Orthohantaviruses (genus Orthohantavirus, family Hantaviridae) are the etiologic agents of Hantavirus Pulmonary Syndrome in the Americas. In South America, orthohantaviruses are highly diverse and are hosted by sigmodontine rodents (subfamiliy Sigmodontinae, family Cricetidae), an also diverse group of rodents. The aims of this work were to (1) identify orthohantavirus hosts and (2) to study the spatial and temporal variations in the prevalence of infection and their associations with community, environmental and individual characteristics, in different environments of Misiones province, northeastern Argentina. Live-capture sessions were carried out during two years in different land uses, with a trapping effort of 31,653 trap nights. We captured 719 individuals from the species Akodon montensis, Rattus rattus, Mus musculus, Calomys tener, Thaptomys nigrita, Oligoryzomys nigripes, Euryoryzomys russatus, Oligoryzomys flavescens, Brucepattersonius sp., and Juliomys pictipes. Antibodies against orthohantavirus were detected in Akodon montensis in one natural protected and one periurban areas, and it was the most abundant species in almost every study sites. We observed the presence of spatial focality of orthohantavirus infection and a positive association with host abundance suggesting the existence of a threshold density. At the individual level, large, reproductively active, and male individuals were more likely to have antibodies against orthohantavirus. This is the first record of orthohantavirus infection in A. montensis in Argentina, which shows the importance of investigations about emerging diseases.

Hantavirus ecology in rodent populations in three protected areas of Argentina.

In this study, we identified hantavirus genotypes and their reservoirs and evaluated the spatial and temporal distribution of the virus in rodent population in three protected areas of Argentina over 3 years (2007-2010). A total of 837 rodents were captured with an effort of 22 117 trap-nights. We detected the genotype Lechiguanas in Oligoryzomys nigripes and O. flavescens and Pergamino in Akodon azarae. There was no correlation between seroprevalence and trap success of the host. The proportion of seropositive males was significantly higher than the proportion of seropositive females. The total length of seropositives was higher than that of seronegatives in each host species. Seropositive individuals were observed in warm months and not in cold months, which suggests an infection cycle. This investigation confirms that protected areas of central east Argentina are places with a variety of sylvan rodents species associated with different hantavirus genotypes where reservoirs are numerically dominant. Although there was more than one known reservoir of hantavirus, only one species had antibodies in each area. This can be explained because the transmission of the virus does need not only the presence of a rodent species but also a threshold density. Longevity of even a small proportion of the host population in cold months may provide a trans-seasonal mechanism for virus persistence. The seroprevalence detected was higher than the one found before in rodent populations of Argentina, and this explains the appearance of human cases in two of these three areas.