By 2025, over two billion people will live in low-income urban communities with inadequate provision of public water, sanitation, and hygiene (WASH) services.

These unsanitary conditions favour the transmission of diseases that are transmitted to people from soil and water, or infected rodents or domestic animals. The public health burden of these diseases is expected to increase with continued global urbanisation and extreme weather events caused by climate change. Despite this, little is known about exactly how inadequate WASH leads to high risk for a range of different diseases or how we can prevent human infections through hygiene interventions.

The aim of this research is to examine the mechanisms through which sanitation can improve health by studying three pathogens (Leptospira spp, Toxoplasma gondii and Helicobacter pylori) that are transmitted to people from the environment or animals.

The study is evaluating how improving sewerage systems impacts their transmission in urban communities in the city of Salvador, Brazil, and identifying where risk for the different diseases is concentrated in the same areas. It aims to provide a better understanding of the different mechanisms by which hygiene interventions prevent disease transmission by studying multiple diseases together and collecting data on several indicators of transmission: human infection, environmental contamination and the presence of rats and other animals. The project will communicate these findings through academic articles, workshops with local policymakers and international researchers, blogposts, and videos and infographics created by the community.

The findings of this project will create new knowledge on the specific role of inadequate WASH in transmission of these diseases. It will also generate evidence to support better-informed decisions on the development and use of sewerage interventions that target a wider range of diseases than has previously been considered.