Residents of urban slums suffer from a high burden of zoonotic diseases due to individual, socioeconomic, and environmental factors. We conducted a cross-sectional sero-survey in four urban slums in Salvador, Brazil, to characterize how poverty and sanitation contribute to the transmission of rat-borne leptospirosis. Sero-prevalence in the 1,318 participants ranged between 10.0 and 13.3%. We found that contact with environmental sources of contamination, rather than presence of rat reservoirs, is what leads to higher risk for residents living in areas with inadequate sanitation. Further, poorer residents may be exposed away from the household, and ongoing governmental interventions were not associated with lower transmission risk. Residents at higher risk were aware of their vulnerability, and their efforts improved the physical environment near their household, but did not reduce their infection chances. This study highlights the importance of understanding the socioeconomic and environmental determinants of risk, which ought to guide intervention efforts.

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Several studies have identified socioeconomic and environmental risk factors for infectious disease, but the relationship between these and knowledge, attitudes, and practices (KAP), and more importantly their web of effects on individual infection risk, have not previously been evaluated. We conducted a cross-sectional KAP survey in an urban disadvantaged community in Salvador, Brazil, leveraging on simultaneously collected fine-scale environmental and epidemiological data on leptospirosis transmission. Residents’ knowledge influenced their attitudes which influenced their practices. However, different KAP variables were driven by different socioeconomic and environmental factors; and while improved KAP variables reduced risk, there were additional effects of socioeconomic and environmental factors on risk. For example, males and those of lower socioeconomic status were at greater risk, but once we controlled for KAP, male gender and lower socioeconomic status themselves were not direct drivers of seropositivity. Employment was linked to better knowledge and a less contaminated environment, and hence lower risk, but being employed was independently associated with a higher, not lower risk of leptospirosis transmission, suggesting travel to work as a high risk activity. Our results show how such complex webs of influence can be disentangled. They indicate that public health messaging and interventions should take into account this complexity and prioritize factors that limit exposure and support appropriate prevention practices.

Background Leptospirosis is a zoonosis caused by pathogenic species of bacteria belonging to the genus Leptospira. Most studies infer the epidemiological patterns of a single serogroup or aggregate all serogroups to estimate overall seropositivity, thus not exploring the risks of exposure to distinct serogroups. The present study aims to delineate the demographic, socioeconomic and environmental factors associated with seropositivity of Leptospira serogroup Icterohaemorraghiae and serogroup Cynopteri in an urban high transmission setting for leptospirosis in Brazil. Methods/Principal Findings We performed a cross-sectional serological study in five urban informal communities in the city of Salvador, Brazil. During the years 2018, 2020 2021, we recruited 2.808 residents and collected blood samples for serological analysis using microagglutination assays. We used a mixed-effect multinomial logistic regression model to identify risk factors associated with seropositivity for each serogroup. Seropositivity to Cynopteri increased with age in years (OR 1.03; 95% CI 1.01-1.06) and was higher in those living in houses with unplaster walls (exposed brick) (OR 1.68; 95% CI 1.09-2.59) and where cats were present near the household (OR 2.00; 95% CI 1.03-3.88). Seropositivity to Icterohaemorrhagiae also increased with age in years (OR 1.02; 95% CI 1.01-1.03) but was higher in males (OR 1.51; 95% CI 1.09-2.10), in those with work-related exposures (OR 1.71; 95% CI 1.10-2.66) or who had contact with sewage (OR 1.42; 95% CI 1.00-2.03). Spatial analysis showed differences in distribution of seropositivity to serogroups Icterohaemorrhagiae and Cynopteri within the five districts where study communities were situated. Conclusions/Significance Our data suggests distinct epidemiological patterns associated with serogroups Icterohaemorrhagiae and Cynopteri within the high-risk urban environment for leptospirosis and with differences of spatial niches. Future studies must identify the different pathogenic serogroups circulating in low-income areas, and further evaluate the potential role of cats in the transmission of the serogroup Cynopteri in urban settings.

Several studies have identified socioeconomic and environmental risk factors for infectious disease, but the relationship between these and knowledge, attitudes, and practices (KAP), and more importantly their web of effects on individual infection risk, have not previously been evaluated. We conducted a cross-sectional KAP survey in an urban disadvantaged community in Salvador, Brazil, leveraging on simultaneously collected fine-scale environmental and epidemiological data on leptospirosis transmission. Residents’ knowledge influenced their attitudes which influenced their practices. However, different KAP variables were driven by different socioeconomic and environmental factors; and while improved KAP variables reduced risk, there were additional effects of socioeconomic and environmental factors on risk. For example, males and those of lower socioeconomic status were at greater risk, but once we controlled for KAP, male gender and lower socioeconomic status themselves were not direct drivers of seropositivity. Employment was linked to better knowledge and a less contaminated environment, and hence lower risk, but being employed was independently associated with a higher, not lower risk of leptospirosis transmission, suggesting travel to work as a high risk activity. Our results show how such complex webs of influence can be disentangled. They indicate that public health messaging and interventions should take into account this complexity and prioritize factors that limit exposure and support appropriate prevention practices.

The new Lancet Commission on water, sanitation, and hygiene (WASH) hopes to reimagine and guide global WASH efforts. This comes at a time when unequal living conditions and global disparities in response and recovery have been highlighted by the COVID-19 pandemic and recent large impact trials have delivered mostly disappointing results suggesting the need for radically more effective interventions to improve global public health. We find ourselves at an inflection point in global WASH with an opportunity to build new approaches with potentially more equitable, cost-effective, and scalable solutions. Mobile health (mHealth) technology is an important and innovative tool for WASH advances. Yet, the use of mHealth has not been equally distributed in terms of its benefits nor is its impact guaranteed. In resource-constrained settings, where technology can increase inequalities, special attention should be paid to structural and systemic hierarchies during the development of mHealth programs along with the acknowledgment and understanding how these systems can reinforce the systematic exclusion of those most vulnerable. The WASH sector needs to adapt to a future that is innovative and inclusive with a commitment to rethinking the resources needed to enhance scope and impact. We highlight urban sanitation in Brazil as a case study to demonstrate that mHealth can support and enhance publicly funded infrastructure and to help reimagine WASH for postpandemic and beyond.

Rodents have been reported to be associated with the transmission of major public health diseases as well as agricultural and economic losses. The lack of site-specific and national standardised rodent surveillance in several disadvantaged communities has rendered interventions targeted towards rodent control as often ineffective. Here, by using the example from a study in The Bahamas, we present a unique experience in which, through multidisciplinary and community engagement, we simultaneously developed a standardised national surveillance protocol, and performed two parallel but integrated activities: 1) eight days of theoretical and practical training of selected participants; and 2) a three-month post-training pilot rodent surveillance in the urban community of Over-the-Hill, Nassau, The Bahamas. In order to account for cultural and environmental conditions in The Bahamas, we modified the Centers for Diseases Control and Prevention (CDC) exterior and interior rodent evaluation form and other instruments that have been previously validated for evaluating rodent infestation (tracking plates and snap trapping) to test and to reach a standardised site-specific rodent surveillance protocol for The Bahamas. Our engagement with local communities pointed towards ownership problems, unapproved refuse storage, exposed garbage, sources of animal food, poor bulk wastes management and structural deficiencies as major factors fueling rodent proliferation in the study area. Accordingly, results from our pilot survey using a generalized linear model with a logistic link and binomially distributed error structure confirmed that these variables are significantly correlated with the rodent activities reported and monitored across the study area. Our successful experience could serve as a reference to encourage a standardised protocol for monitoring rodent activities in many disadvantaged urban settings of the Global South, while also aiding the holistic understanding of rodent proliferation. Through this case-study and pilot program, we advocate for the feasibility of developing sustainable rodent control interventions that can be acceptable for both local communities and public authorities, especially through the involvement of a multidisciplinary team of professionals and community members.

Leptospirosis, an endemic disease in Brazil, with high lethality, is related to the environmental health of the territories, mainly impacting populations in a state of socioeconomic vulnerability. The present work aimed to investigate the gradients of environmental health in popular neighborhoods of Salvador-Bahia and its influence on Leptospira infection. The investigation involved the collection of primary and secondary data about the environmental health and the occurrence of individuals with antibodies against Leptospira. An Environmental Health Index (EHI) for the areas of study was elaborated, the information was georeferenced, and the data were statistically analyzed. The results indicated that fifteen of the twenty-three study micro-areas had unsatisfactory environmental health conditions and the statistical and spatial analyzes indicated a relation between low EHI scores and higher concentration of individuals with antibodies against Leptospira. In conclusion, the prevention and control of the disease must involve integrated and integral actions for basic sanitation in the territory, surpassing a medicalassistance approach.