Recent increase of Dobrava-Belgrade virus (DOBV) in yellow-necked mice in northern Italy

Dobrava-Belgrade virus (DOBV) is the most pathogenic hantavirus in Europe with a case-fatality rate of up to 12%. DOBV infections have been reported in Italy following cross-sectional sero-epidemiological studies in rodents and humans since 2000, however, no clinical human cases have been confirmed thus far. In this study, we present a long-term pattern of serological changes in DOBV antibody prevalence in a population of A. flavicollis in the Province of Trento (northern Italy). From 2000 to 2012 the mean hantavirus seroprevalence was 2.7% (s.e.=0.3 %), ranging from 0% (in 2000, 2002 and 2003) to 12.5% (in 2012), a statistically significant increase (t-value=5.93, p<0.001). Using Generalized Linear Models (GLM) and multi-model inference, our results showed that the rise in mean annual precipitation together with higher individual body mass are responsible of the observed change in DOBV seroprevalence. We hypothesize that greater precipitation leads to a higher probability of survival and consequently, populations with a higher proportion of older (i.e. heavier) individuals, which have a higher rate of viral shedding. Alternatively, or in addition, increased precipitation could favour virus survival in the environment. Our findings underline the importance of a closer examination of these aspects and investigations are ongoing