Conectando roedores, ambiente e humanos na dinâmica de transmissão da leptorpirose urbana; efeito de intervenções ambientais e sanitárias

Abstract

Leptospirosis remains a serious health problem in impoverished urban communities in developing countries. The presence of polluted bodies of water and open sewage contributes to environmental contamination by the Leptospira bacteria and the abundance of rodents, representing the main source of exposure for residents in these locations. Ineffective rodent control programs and the absence of sanitary interventions contribute to the high incidence of Leptospira infection. Once sanitary and/or sewage interventions are implemented, their impacts should be evaluated to understand their effects on disease transmission, such as leptospirosis, and environmental health. This work is a study to evaluate the impact of government and community sanitary interventions on the environmental burden of Leptospira, the presence of rats, and Leptospira infection in the city of Salvador, Brazil. In the first chapter, we found that sewage intervention reduces rat refuge and movement sites, decreasing the likelihood of their presence in these areas. However, the intervention did not reduce the incidence rates of Leptospira infection, as residents' exposure did not vary between the periods before and after the intervention, limiting the understanding of the intervention's effect on disease burden. In chapter two, we show that government interventions to close sewage reduce the burden of Leptospira in the environment. The canalization and blocking of sewage and bodies of water prevent overflow during heavy rains, directing all water flow and reducing soil contamination. Integrated sanitary interventions, with local community involvement, in conjunction with other urban basic services such as garbage collection, paving, and stormwater drainage, may be crucial in reducing the pathogen burden and transmission. This study proposes an evaluation protocol for government sewage interventions with social participation (chapter three). This model of co-participatory sanitation interventions, i.e., integrating decision-makers with the local community, can contribute to the effectiveness of reducing multifactorial environmental diseases. Additionally, we evaluated how restrictions caused by the COVID-19 pandemic affected the circulation of zoonotic reservoirs, rats, within an urban community in SalvadorBa (chapter four). We found an increase in rat sightings during the pandemic period, which may represent a risk of leptospirosis, reinforcing the need for urgent actions to control the reservoir and the disease in these communities. Finally, we suggest comprehensive and integrated sanitation interventions; these actions can contribute to addressing the gap of how these actions can impact transmission mechanisms and the burden of Leptospira infection in residents, as well as guide future interventions with long-lasting effects in other locations around the world.