The distribution and abundance of rodents and rodent-borne pathogens in a post-trauma urban landscape
Weather-related disasters are predicted to increase in both frequency and severity as a result of global climate change and growth of coastal cities. By triggering rapid and abrupt shifts in socioecological interactions, traumatic events can act as cross-scale mediators that promote disease outbreaks, particularly in cities because urbanization establishes a set of pre-conditions that favor pathogen transmission. Yet surprisingly little is known about the prevalence of zoonotic pathogens in post-trauma urban environments.
In this study, we investigated whether the prevalence of rodent-born pathogens parallels the distribution and abundance of commensal rat hosts across post-Katrina New Orleans (Louisiana) to determine if pathogen prevalence and pathogen load vary (1) with host density, and (2) with seasonality. We did so through exhaustive removal trapping to estimate population size of Rattus sp.at 78 city blocks across 8 neighborhoods during both summer and winter seasons. Additionally, ecto- and macro- parasites were collected from all captured individuals. Tissues also were collected to screen individuals for a panel of bacterial and viral pathogens.
Populations of both Rattus rattus and R. norvegicus were detected across New Orleans. The size of R. rattus and R. norvegicus populations varied widely across neighborhoods, blocks within neighborhoods, and between seasons. Similarly heterogeneous patterns of infection were detected, with highly variable levels of infection across host species, populations, and individuals. Preliminary results suggest that prevalence and load of some parasites is greatest in high-density populations. Additionally, some potentially important pathogen vectors, such as fleas, are highly aggregated within rat populations across the city, representing potential hotspots of infection. Lastly, preliminary results also suggest that the prevalence of some parasites shows seasonal patterns. Together, these results indicate that zoonotic disease risk can vary widely across post-trauma urban landscapes, highlighting the need to better understand factors that influence host and pathogen communities following catastrophic events.