Pathogenic Leptospira isolated from rodents in New Orleans, Louisiana USA, and associated site information

Land use change can elevate disease risk by creating conditions beneficial
to species that carry zoonotic pathogens. Observations of
concordant global trends in pathogen prevalence and disease incidence have
engendered concerns that urbanization could increase transmission
risk of some pathogens. Yet host-pathogen relationships underlying
transmission risk have not been well characterized within cities,
even where contact between humans and species capable of
transmitting pathogens of concern occur. We addressed this deficit
by testing the hypothesis that areas in cities experiencing
greater population loss and infrastructure decline (i.e.,
counter-urbanization) can support a greater diversity of host species and
a larger and more diverse pool of pathogens. We did so by characterizing
pathogenic Leptospira infection relative to rodent host richness and
abundance across a mosaic of abandonment in post-Katrina New Orleans
(Louisiana, USA). We found that Leptospira infection loads were highest in
areas that harbored higher rodent species richness. Areas with greater
host co-occurrence also harbored a greater number of hosts, including the
most competent hosts, indicating that Leptospira infection is
amplified by increases in overall and relative host abundance.
Evidence of shared infection among rodent hosts indicates that
cross-species transmission of Leptospira likely increases
infection at sites with greater host syntopy. Additionally, evidence that
rodent co-occurrence and abundance and Leptospira infection load parallel
abandonment suggests that counter-urbanization can elevate zoonotic
disease risk within cities, particularly in underserved
communities that are burdened with disproportionate concentrations of
derelict properties.