Molecular detection of Leptospira spp. in rats as early spatial predictor for human disease in an endemic urban area

Abstract

Background Leptospirosis is considered a neglected zoonosis associated with infrastructure problems and low socioeconomic status, particularly slums. Since the disease is mainly transmitted in urban settings by rat urine, this risk factor may be important predictor tool for prompt control and effective prevention at the local level in urban endemic areas. Accordingly, the present study aimed to propose an early spatial predictor tool for human leptospirosis in urban settings, to test the methodology of molecular methods for assessing Leptospira spp. in trapped rats, and report associated environmental data. Methodology/Principal findings Official city records and previous study were used to select risk factors for human leptospirosis in an endemic neighborhood of Curitiba, Brazil. Neighborhood census sectors were divided in high- and low-risk areas using 12 selected factors: flood area, water supply, water course, green coverage, afforestation, sewage network, open sewage, open garbage, garbage collection, dumpster, pavement, and rodent complaints. In addition, rats were captured in pre-determined sites from January through March 2017, euthanized, and individual kidneys samples sent for molecular diagnosis. Human cases were obtained from official city records. In total, 95/112 (84.8%) census sectors were classified as low-risk to human leptospirosis. No significant statistical differences were found in human case frequencies between high and low-risk areas. Kidney samples from 17/25 (68.0%) trapped rats were positive for Leptospira spp. The main risk factors associated with rodent presence included inadequate water supply (p = 0.04), sanitary sewage (p = 0.04), unpaved streets (p = 0.04), and complaint of rodents (p = 0.04). Conclusions/Significance This study offers a new approach to score leptospirosis transmission risk, and to compare small areas and their heterogeneity in the same census sector of endemic areas. Environmental risk factors for Leptospira spp. transmission within the neighborhood were mainly due to differences in infrastructure and basic services. To the author’s knowledge, this is the first study using Leptospira spp. in rats as predictor for human disease in an urban setting of a major city. Although the number of rats trapped was low, this methodology may be used as basis for early and effective interventions, focused on high risk areas for leptospirosis prior to human cases, and potentially reducing morbidity and mortality in low-income areas of urban settings.

Prevalence and risk factors of Leptospira infection in urban brown rats (Rattus norvegicus), Vienna, Austria

“…These results can help public health authorities to assess spatial variations in the risk related to the presence of rats in the city. Because rats are ubiquitous in urban settings, have a small home range (Feng and Himsworth 2014), and because monitoring Leptospira infection in hosts is achievable on carcasses that can be provided by pest management professionals (Strand et al 2015), brown rats can be used as early spatial predictors of human leptospirosis cases in cities (Pellizzaro et al 2019) but also as sentinels for the early detection of emerging pathogenic Leptospira in urban ecosystems. The implementation of a surveillance programme through a One Health approach that monitors the Leptospira status of the wildlife reservoir, surveys the bacterial load in the environment, and identifies the circulating Leptospira species using an automated workflow is of high interest to urban health.…”

Leptospirosis trends in China, 2007–2018: A retrospective observational study

“…The southern regions of China have many major rivers and lakes, and abundant water energy resources. This area also contains a large number of ponds and small lakes, which are often contaminated by animal carriers that excrete pathogenic leptospires (Zhang, Wang, et al, ; Zhao et al, ). Previous reports showed that the leptospirosis has been considered as a neglected zoonosis associated with infrastructure problems and low socioeconomic status, particularly in slums and rural areas (Morikawa et al, ; Pellizzaro et al, ). Farmers engaged in rice cultivation, field management and animal herding are highly vulnerable to contracting leptospirosis (Suárez et al, ).…”

The Behavior of Consumers and Producers of Food of Animal Origin and Their Impacts in One Health

“…In addition, in illicit slaughter the animal stays in an open place, under environmental temperature, with the presence of other animals such as carnivorous birds and dogs ( Figure 2 ) that lick the carcass during the slaughter or feed on the remains of the carcass ( 23 ) and can be infected if the slaughtered animal is sick. The contact of the blood of a sick animal with open wounds or mucous membranes of the slaughterers who perform the slaughter also propitiate the spread of zoonosis, particularly the ones considered as neglected zoonosis associated with infrastructure problems and low socioeconomic status ( 32 ).…”