Evaluation of the euthanasia of seropositive dogs for canine visceral leishmaniasis as the only method of controling the disease in the enzootic area in the Midwestern Minas Gerais

Abstract

Human Visceral Leishmaniasis (VL) is expanding, and it is distributed in the five geographic regions of Brazil, with the Northeast being the region that presents the most significant number of registered cases. The main urban reservoir of the etiological agent of VL is the domestic dog, and it is known that canine cases precede human cases. One of the control actions of VL, recommended by the Ministry of Health, is performing the euthanasia of seropositive dogs. In 2013, in the municipality of Iguatama/MG, the first canine serological survey was carried out in the city, with a prevalence of 8.3% of seropositive dogs for Leishmania infantum. Of the seropositive animals for Canine Visceral Leishmaniasis (CVL) in this survey, 84% were euthanized, and 16% died within two years after diagnosis. No other control measures for CVL were taken in the municipality. The objectives of the present study were to determine the current prevalence of seropositive dogs for CVL in the municipality of Iguatama and to observe the impact of euthanasia of seropositive dogs to VL as the only control measure performed in this municipality, which is considered an enzootic area of the disease. For this, a new canine epidemiological survey was carried out in the municipality of Iguatama, following the guidelines of the Manual of Surveillance and Control of Visceral Leishmaniasis. Blood samples were collected from 270 dogs and tested by DPP® immunochromatographic test and by Enzyme-Linked Immunosorbent Assay (ELISA). The animals that presented inconclusive results had new blood samples collected and analyzed. The only animal that showed a positive result in DPP® and undetermined in the ELISA, in the first evaluation, became seropositive four months later, so this study reinforces the recommendation of the Ministry of Health to reassess dogs that present inconclusive results for CVL. From a total of 270 samples, 21 (7.8%) were reagents in both tests. Thus, the prevalence of seropositive dogs for CVL, in 2017, in the urban area of the municipality of Iguatama was 7.8%. The Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) molecular technique confirmed infection by L. infantum in the ten dogs sampled with CVL-positive serology. The comparison between the current prevalence (after euthanasia) with that found in 2013 (8.3%), there was no significant difference (p=0.764). The prevalence of CVL in the urban area of the municipality of Iguatama is still high, making it possible to presume that the euthanasia of seropositive dogs for CVL, and the absence of monitoring or other interventions measures, did not contribute to decrease the transmission of the parasite and was not sufficient for the control of CVL in the municipality of Iguatama, an area considered as non-endemic to CVL until 2013.

Epidemiology of canine visceral leishmaniasis in a vulnerable region in Brazil

“…These levels of infection are higher than those found in our study. Considering our results, we reiterate what has been discussed about the sensitivity of the different diagnostic methods for the diagnosis of canine VL (Lopes et al, 2017;Vaz et al, 2020). No test currently available has 100% specificity and sensitivity.…”

Análise espacial e epidemiológica da leishmaniose canina em animais mantidos em abrigos no leste e sertão do estado de Sergipe, Brasil

“…Nesse estudo, 49,30% (71/144; p<0.0001) dos cães atendidos foram reagentes para anticorpos anti-L. infantum no TR DPP ® em amostras sanguíneas do Agreste e Sertão de Sergipe, sendo superior aos valores observados no Ceará (1,3%) (Batista et al, 2021), Minas Gerais (7,8%) (Vaz et al, 2020), São Paulo (8,70%) (D' Andréa et al, 2015), Paraíba (15,02%) (silva et al, 2021), Rio de Janeiro (26,3%) (Abrantes et al, 2018) e no Rio Grande do Sul (24,4%) (Mariga et al, 2021).…”

Global Distribution of Canine Visceral Leishmaniasis and the Role of the Dog in the Epidemiology of the Disease

“…Nevertheless, studies such as those by Ashford et al [251], Costa et al [252], Nunes et al [253], Costa et al [254], and Bermudi et al [255] have shown that the elimination of infected dogs reduces the incidence of VL in humans and dogs. Conversely, some researchers have shown the opposite, such as Dantas-Torres et al [242], Dietze et al [256], Paranhos-Silva et al [257], and Vaz et al [258].…”