Rain, Rats, and Residents: Tracking animal and human movement to understand disease risk in urban slums (acronym: RRRISK)

Rapid urbanisation has increased the global risk of infectious diseases, especially for >1 billion slum residents who live in a vicious cycle of disease and poverty. Inadequate sanitation in slums promotes the proliferation of diseases and their reservoirs and vectors.

One such disease is leptospirosis, a globally distributed bacterial disease of poverty that is transmitted in urban areas by Norway rats (Rattus norvegicus). Residents become infected upon contact with contaminated water or soil, especially after rainfall.

For leptospirosis and diseases transmitted through contact with a contaminated environment, mechanisms linking reservoir movement, pathogen distribution in the environment, and human movement and exposure remain unknown. Understanding these mechanisms enables fine-scale spatial and seasonal prediction of risk.

Here, in two urban slums in the city of Salvador, Brazil, we investigate how seasonal rainfall drives the distribution and movement of rats, mobilises and distributes bacteria in the environment, and how these, in turn, define spatial and temporal gradients in bacterial contamination.

Then, we will determine how socioeconomic and gender differences in resident movements affect human exposure and infection risk.

Thereby, using foundations of movement ecology, our project will help identify intervention targets, priority areas (risk hotspots), and timing of implementation to mitigate the risk of zoonotic and environmentally transmitted diseases.