Rodent Virus Diversity and Differentiation across Post-Katrina New Orleans

Concern about elevated disease risk following disasters has been growing with the progression of global trends in urbanization and climate, in part because shifts in socioecological conditions can promote greater human contact with pathogen reservoirs in cities. Remarkably little is known, however, about the diversity and distributions of pathogens carried by commensal reservoirs across disaster-affected urban landscapes. To address this deficit, we characterized the assemblage structure of viruses in the serum of three widespread commensal rodents ( Rattus norvegicus , Rattus rattus , and Mus musculus ) that were trapped in New Orleans (LA, USA) following Hurricane Katrina. We assessed virus diversity and differentiation according to host species identity, co-occurrence and abundance, as well as prevailing landscape features known to shape urban rodent assemblages. We detected ≥34 viruses in total, including several pathogens of concern, through metagenomic analysis of serum taken from ≥149 individuals of each host species. We found that virus richness as well as assemblage composition and spatial differentiation differed by host species. Notably, we detected associations with host species co-occurrence and abundance, and while we found that assemblage structure varied by study area, we did not detect strong associations with landscape features known to influence rodent hosts. Evidence that virus diversity and assemblage structure reflect host identity more so than other factors indicates that biotic benchmarks might serve as prognostic indicators of post-disaster pathogen exposure risk in cities worldwide.