Rattus norvegicus is a near-globally distributed species of rat that is classified as an invasive pest throughout most of its range. This species poses consistent threats to food stocks, developed infrastructure, and human health. We looked at the impacts of rat movement patterns on human disease risk in both New York City, U.S.A. and Salvador, Brazil. In NYC we estimated gene flow in 133 rats collected between 5 sites in Manhattan using SNP data, and surveyed the ectoparasite and internal pathogen communities each rat harbored. We used multivariate statistical analyses to determine if and how the parasite/pathogen communities varies based on the patterns of movement in the host rats, and also microhabitat variation across each urban site. In Salvador, we use spatial statistical analyses to determine how the risk of leptospirosis infection in people co-varies with the distribution of rats over space and time.
Results/Conclusions
In NYC, ectoparasite community similarity was positively associated with geographical proximity; however, there was no general association between distance and pathogen communities of rats. Sites with greater overall parasite diversity also had rats with greater infection levels and parasite species richness. Parasite community similarity among sites was not linked to genetic relatedness of rats, suggesting that these communities are not associated with genetic similarity among host individuals or host dispersal among sites. Discriminant analysis identified site-specific associations of several parasite species, suggesting that the presence of some species within parasite communities may allow researchers to determine the
sites of origin for newly sampled rats. The results of our study help clarify the roles that colony structure and geographical proximity play in determining the ecology of R. norvegicus as a significant urban reservoir of zoonotic diseases. Our study also highlights the spatial variation present in urban rat parasite communities, indicating that rats across New York City are not reservoirs for a homogenous set of parasites and pathogens. Our results from Salvador are in progress as of this abstract submission.