Environmental Factors and Ecosystems Associated with Canine Visceral Leishmaniasis in Northeastern Brazil

Abstract

Environment influences the composition, distribution, and behavior of the vectors and mammalian hosts involved in the transmission of visceral leishmaniasis (VL), affecting the epidemiology of the disease. In Brazil, the urbanization process and canine cases of VL are indicators for local health authorities. This study aimed to investigate the occurrence of the canine visceral leishmaniasis (CVL) in Maranhão State, Brazil. Blood samples collected from 960 dogs from six municipalities and six different ecosystems (Baixada Maranhense, Mangue, Mata dos Cocais, Amazônia, Cerrado, and Restinga) to serological tests (enzyme-linked immunosorbent assay [ELISA], indirect fluorescence antibody test [IFAT], and chromatographic immunoassay methods [Dual Path Platform technology, DPP(®)]) and parasitological diagnosis. From serological tests, 11.14% (107) of the dogs were positive for CVL, with 59.16% (568), 14.5% (148), and 131% (126) positives to ELISA, DPP, and IFAT tests, respectively. Only seven animals (0.73%) were positive in a parasitological test. We also performed parasite isolation and phylogenetic characterization. All isolates of dogs obtained from Maranhão were grouped in a single branch with Leishmania infantum chagasi from Brazil. The ecosystem Amazonia presented the highest positivity rates to CVL in serological and parasitological tests. Brazilian biomes/ecosystems suffer large degradation and may favor, depending on climatic conditions, the installation of new diseases. In the case of VL, dogs are reservoirs of parasites and sentinels for human infection.

Uso e cobertura do solo e prevalência de leishmaniose visceral canina em Teresina, Piauí, Brasil: uma abordagem utilizando sensoriamento remoto orbital

“…This result is consistent with other studies that have pointed to higher canine seropositivity for Leishmania in dwellings close to forest areas 21,22,23,24,25,26 . The proximity to areas with more dense vegetation favors interaction between the sylvatic and peridomiciliary cycles of the disease and favors conditions for maintenance of sand fly populations 2 .…”

Leishmaniose visceral e sua relação com fatores climáticos e ambientais no Estado do Tocantins, Brasil, 2007 a 2014

“…Talvez, a pressão por necessidade de moradia associada à falta de infraestrutura urbana possa ocasionar mais proximidade dos moradores com áreas de floresta, favorecendo o contato com o vetor e aumento na transmissão da doença 21 . A proximidade de áreas com vegetação mais densa pode facilitar a transmissão fornecendo as condições para a manutenção da população do vetor da LV e do reservatório silvestre 33,34 . Dessa forma, a expansão desordenada das cidades que avançam em meio ao habitat natural do vetor da LV, associada às condições climáticas e ambientais favoráveis, aproxima o contato do vetor com animais domésticos e, consequentemente, mais ocorrência da doença.…”

Rural area of the Brazilian Pantanal wetlands associated with the occurrence of anti-<i>Leishmania</i> spp. antibodies in dogs

“…Anti-Leishmania spp. antibodies were evaluated by immunofluorescence assay (IFA), as described by Oliveira et al (2008), using the promastigote forms of isolate CBT 96 (Coleção Brasileira de Tripanossomatídeos) of L. infantum chagasi (COSTA et al, 2015) with a cut-off point at the initial dilution of 1:40 (BRASIL, 2006). Each slide contained sera previously known to be non-reactive (negative control) and reactive (positive control).…”