Relationship of human behavior within outbuildings to potential exposure to Sin Nombre virus in western Montana.

Sin Nombre virus (SNV) causes hantavirus cardiopulmonary syndrome (HCPS) in humans. Transmission of SNV among the deer mouse (Peromyscus maniculatus) host predominates during spring and summer, and is greater in peridomestic than sylvan settings where, protected from UV light, SNV may survive longer. Incidence of HCPS reflects these times and settings and is associated with inhalation of mouse excreta. Little is known, however, about how human use of outbuildings contributes to potential exposure to SNV. Here, the frequency and seasonality of outbuilding use by humans was evaluated, via a survey of rural residents in western Montana, to quantify human behaviors and potential risk of exposure to SNV. Retrieving or return of tools and scooping feed/grain were the most frequently undertaken activities. Seasonal activities coinciding with seasons of highest HCPS incidence and times of potentially high viral shedding by deer mice, included retrieving or returning tools, calving or lambing, and, to a lesser extent, feeding livestock and sweeping or cleaning. Human behavior is a component of SNV transmission risk and this preliminary study provides a basis from which to further evaluate this route of exposure.