One Health Approach to Leptospirosis: Human–Dog Seroprevalence Associated to Socioeconomic and Environmental Risk Factors in Brazil over a 20-Year Period (2001–2020)

Abstract

Despite being considered a neglected, re-emerging and the most widespread zoonotic disease worldwide, human-dog leptospirosis has not been subjected to One Health approach, and neither were its socioeconomic and environmental risk factors, as well as concomitant spatial analysis over time. Accordingly, notified human leptospirosis cases, incidence rate and urban hotspot areas, in addition to a systematic review of dog leptospirosis cases, were performed nationwide from 2001 to 2020 in Brazil. Data on Gross Domestic Product (GDP), flooding and study areas were also assessed and tabulated. Human–dog leptospirosis cases were simultaneously mapped with overlapping flooding areas, along with the main circulant serovars. Comparative outcome has shown that dogs may be exposed similarly to humans, becoming important sentinels and/or reservoirs for human leptospirosis in larger geographic areas. Moreover, the study herein can help in the decision and implementation of public policies in Brazil and may serve as a model for other tropical countries worldwide.

One Health Approach to Leptospirosis: Dogs as Environmental Sentinels for Identification and Monitoring of Human Risk Areas in Southern Brazil

“…antibody prevalence in dogs may be a consequence of several factors including the rodent population and environmental conditions such as temperature, rainfall and flooding [47,48]. As expected, the municipality of Pinhais presented the highest dog seropositivity (38.9%) in 2010 [4], the highest number of human leptospirosis cases reported by SINAN (Figure 3), along with a major city flooding affecting around 30,000 habitants [49][50][51].…”

“…Despite restricted regional access and a low sample size, the study herein aimed to refine the survey on a local scale, with 10/133 (7.52) seropositive dogs for Leptospira interrogans , lower than a previous same-city report with 33/228 (14.4%) dogs in 2009 and 35/90 (38.9%) in 2010 (14.4 to 38.9%, mean 26.6%) [ 4 , 36 ] and within the range from 35/378 (9.3%) to 36/189 (19.0%) in a monitoring study (0 to 27.8%, average 13.7%) in Curitiba, the neighboring state capital and the eighth largest Brazilian city [ 37 , 38 , 39 , 40 , 41 ]. In addition, results herein were within the range of the northern Paraná state (0 to 46.7%, average 18.6%) with 35/175 (20.0%) in 2011, 41/335 (12%) in 2006–2008, 51/236 (21.6%) in 2004–2012 and 155/729 (21.3%) in 2015–2016 [ 10 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ].…”

“…The disease is caused by bacteria of the genus Leptospira (order Spirochaetales, family Leptospiraceae), of which 64 species have been recognized and divided into two main clades: “Saprophytes” containing noninfectious species isolated in a natural environment and “Pathogens” including all responsible species for human and animal infections, along with environmental species with unproven virulence [ 3 ]. In this last group are the species ( L. interrogans , L. kirschneri , L. noguchii , L. santarosai , L.mayottensis , L. borgpetersenii , L. alexanderi and L. weilii ) that have been mostly associated with severe human infections [ 3 ] while L. interrogans , L. kirschneri , L. noguchii , L. santarosai , L. borgpetersenii and L. weilii have been reportedly found in dogs from Brazil [ 4 ]. Optimal conditions for Leptospira growth have been reported at pH 6.7 to 8.0 in river water and nearby moist soils [ 5 ], while a high salt concentration may not be suitable for the long-term survival of pathogenic Leptospira [ 6 ].…”

“…Leptospirosis has been historically endemic throughout the Brazilian territory, with a higher incidence of human cases in the southern, southeastern and northern regions, particularly in urban areas of major cities [ 4 ]. In addition, a systematic review of dog leptospirosis in Brazil has shown overlapping with flooding areas, indicating the need for local scale studies to confirm dogs as environmental sentinels in urban areas [ 4 ], as dog the role of dogs in the Leptospira cycle remains to be fully established [ 4 , 10 , 16 ]. Dogs have been considered as accidental hosts for most serovars except Canicola, for which dogs have been reportedly considered as maintenance hosts [ 17 ].…”

A Cross Sectional Study on the Bidirectional Interactions Between Leptospirosis and HIV Infection Among Patients from Maputo Central Hospital, Mozambique

“…Leptospirosis is a re-emerging zoonotic and neglected disease caused by the spirochetal bacteria of the genus Leptospira. [1][2][3][4] Though the disease is widely distributed around the world, higher incidence is found in low-income countries where poor sanitation, heavy rainfall, floods, and close contact with infected animals prevail, all associated with limited infrastructure for diagnosis and lack of awareness of the disease among health professionals. [5][6][7] Globally there are approximately, 1.03 million cases and 60,000 deaths per year 8,9 due to leptospirosis, with highest incidence reported in Oceania (150.68 cases per 100,000, 95% CI 40.32-272.29), South-East Asia (55.54, 95% CI 20.32-99.53), Caribbean (50.68, 95% CI 14.93-87.58), and East sub-Saharan Africa (25.65, 95% CI 9.…”