Comprehension of environmental factors which drive interactions between humans and reservoirs of zoonotic diseases are critical to understand disease risk and predict incidence. An appreciation of these relationships is particularly important in light of anticipated changes in climatic. Sin Nombre virus (SNV) is a directly transmitted pathogen, reservoired by deer mice (Peromyscus maniculatus). This virus spills over from deer mice to humans in peridomestic environments, causing Hantavirus Pulmonary Syndrome (HPS), a disease which has a significant mortality rate (~35% of cases). However, factors which influence entrance of deer mice into peridomestic structures, and human-deer mouse interactions, are poorly understood. Here, we examine underlying connections between environmental factors, human-deer mouse interactions and incidence of HPS.
Evidence suggests increased precipitation in arid and mediterranean climatic regions leads to increased reproduction and dispersal of deer mice from moderately moist (mesic) refugia to areas which are normally dry (xeric). When these temporarily mesic environments transition back to their “normal” xeric conditions deer mice seek out local refugia that are more mesic, such as peridomestic structures. We hypothesize human-deer mouse interactions and HPS incidence in dryer environments are due to local fluctuations in moisture conditions, from xeric-mesic-xeric. At a larger scale, we have found HPS incidence across the US to be strongly related to precipitation, indicative of what would be expected under our hypothesis. Predicted changes in climate over this century for states experiencing high rates of HPS incidence are for increased amount and frequency of precipitation events. These predictions suggest that, if our hypothesis is correct, rates of HPS incidence among these states are likely to increase. Further research quantifying environmental determinants of peridomestic use by deer mice and human exposure to SNV in these environments is critical.