Chagas disease, caused by the protozoa Trypanosoma cruzi, is a zoonosis that constitutes a major (yet neglected) public health problem from the southern United States (US) to Argentina. The burden of the disease is 7.5 times higher than that of malaria in affected areas, where T. cruzi infects ≥6 million people and is responsible for ≥10,000 deaths per year. While T. cruzi is known to circulate in suburban and rural wildlife (e.g., opossums, racoons, and woodrats), little work has been done to assess prevalence in urban wildlife despite increasing evidence of autochthonous transmission (from vector to human) in cities. Here we examined the prevalence of T. cruzi infection in the urban rodent community of New Orleans, Louisiana, where one of the first autochthonous cases of Chagas was recorded in the US. We assessed (1) how T. cruzi prevalence varies across the city; (2) how prevalence varies by host species; and (3) if species co-occurrence influences prevalence. We did so by testing blood sampled from 1428 rodents representing 5 species trapped at 91 sites situated in 11 study areas spanning urban, suburban and peri-urban habitat. Rodents were trapped during winter and summer seasons from 2014 to 2017.
Results/Conclusions
We found evidence of T. cruzi infection in all five rodent species trapped in the study area, resulting in an overall infection prevalence of 11.1% (158/1428). Roof rats (Rattus rattus) and house mice (Mus musculus) were the most common reservoir for T. cruzi, accounting for 41.8% (66/158) and 34.2% (54/158) of all positive rodents respectively. Hispid cotton rats (Sigmodon hispidus) exhibited the highest per-species prevalence at 25% (5/20). There was no significant difference in prevalence between species. While multiple species tested positive for T. cruzi at several trapping sites, initial results indicate that sites with 2 host species present had a higher prevalence than other sites (p<.05). We detected infected rodents in all 11 study areas including the two most central urban neighborhoods where prevalence was 10.5% (11/105) among all sampled rodents. These findings demonstrate that T. cruzi reservoirs penetrate into urban centers, which runs contrary to prior work suggesting that risk of transmission is limited to rural and natural landscapes. Evidence of T. cruzi in highly urbanized areas indicates that there are significantly more people at risk of infection in enzootic areas, highlighting the need for further research on urban pathogen reservoirs.