Investigating the patterns of coinfections with gastrointestinal helminths and Sin Nombre virus in deer mice

Zoonotic pathogens are infections in wildlife that are transmittable to humans. In natural settings, most wild animals host multiple species of parasitic organisms and other zoonotic pathogens. These parasites may interact and increase host susceptibility to secondary infections including zoonotic agents. Thus, understanding the parasite community of wild animals is important from ecological and public health perspectives, since parasites may increasing the risk of transmission of zoonotic pathogens to humans in close association with wildlife. The purpose of this thesis was to identify the helminth parasites and to document patterns of coinfections between helminths and Sin Nombre virus (SNV) in deer mice (Peromyscus maniculatus) from two distinct ecoregions in Utah. I utilized a long-term database collected over seven years (2003-2009) along with necropsy of freezer-archived deer mice to identify patterns of coinfection between helminths and SNV. In year 2006, I found that SNV prevalence negatively correlated with helminth infection. This result suggests that one infection provides protection against the other. I sought to further elaborate on this study by live-sampling deer mice in a peridomestic habitat in Emigration Canyon, Utah from June 2010 through August 2010. I found similarities between the helminth communities in this study, but I found an additional species Trichuris peromysci. Due to low SNV prevalence, I did not observe SNV / helminth coinfections. Finally, I designed a method to study tradeoffs between mounting a humoral antibody response to SNV antigen and bacterial killing capacity of serum in deer mice. I injected treatment mice with SNV nucleocapsid antigen while control mice received vehicle injection. Both the treatment and control mice significantly increased bacterial killing post injection; there were no significant differences between groups post injection. This suggests there is no tradeoff between mounting a humoral antibody response and the ability to kill bacteria. In summary, this was the first study to consider the role of parasite coinfections on the emerging viral pathogen, Sin Nombre virus. Since parasites can increase susceptibility to secondary infections, it is important for researches to investigate coinfections instead of focusing on a single parasite species.