There is low prevalence of the disease in low elevation, arid sites. Sin Nombre is more prevalent in male mice than in females. Sin Nombre is more prevalent in larger male mice than in smaller males. Centers of infection may span less than 1 kilometer. The density of mice in an area is not as strong a predictor of the rate of infection as the issue of salt desert versus other habitats.
Prevalence varies over time with the observed incidence of infection dropping to zero in some sites.
The level of infection at various sites is being used to reconstruct spatial patterns. This will ultimately be used in a simulation model. And if we have the process correct, we will be able to derive the rate of recurrence of the virus in a certain area. In other words, if the virus is not in an area now, the model can be used to predict how long before the virus comes back and once it's back, how long it will be there. Sin Nombre is only one of many recently discovered causes of disease in humans.