Canine visceral leishmaniasis (CVL) remains a significant disease worldwide. In Brazil, its treatment is performed using miltefosine, which has demonstrated promising outcomes in dogs. This study represents the first attempt to treat and monitor dogs with CVL in natural conditions over the course of one year. The dogs were divided into two groups: G1 received miltefosine and allopurinol for 28 days, while G2 received miltefosine for 28 days, followed by allopurinol for one year. The follow-up involved clinical, hematological, and biochemical evaluations, as well as the detection of Leishmania DNA in skin and bone marrow samples. By the end of the follow-up, dogs in G2 exhibited improved staging compared to their initial conditions, whereas those in G1 showed worsened staging. Leishmania DNA in skin and bone marrow decreased between 6 and 12 months after treatment. Our observations indicate that the treatment using miltefosine reduces the detection of the parasite in the skin and bone marrow for up to one year following its administration. The continuous use of allopurinol contributes to control of the disease in dogs. These findings provide valuable insights into the response of dogs treated in natural conditions, offering essential information for veterinarians and public health authorities.

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.

This study investigated the sand fly fauna of the municipality Iguatama, in the Midwest Region of Minas Gerais state, Brazil, including Leishmania infection rates and blood meal sources. Sand flies were collected during four periods over the course of a single year, encompassing both dry and rainy seasons, using CDC light traps placed in peridomiciles where dogs were seropositive for visceral leishmaniasis (VL). A total of 762 sand fly specimens, representing 12 species across seven genera, were collected. Lutzomyia longipalpis was the most abundant species, comprising 57.6% of the collected specimens, followed by Nyssomyia neivai (19.6%) and Nyssomyia whitmani (10.5%). Species richness and diversity varied among collection periods, with the highest diversity observed in January 2019. Molecular analysis detected Leishmania DNA in 12.5% of the sand fly specimens, with Le. infantum being the predominant species. Blood meal analysis revealed feeding on multiple vertebrate species, including humans, rats, dogs, and chickens. The presence of Leishmania DNA in sand flies, and the identification of human blood meals, highlight the potential role of these species in VL transmission. These findings underscore the importance of continued surveillance and control measures to prevent the spread of VL and reduce transmission risk in the region.

Females of laboratory-reared Culex quinquefasciatus were allowed to take blood meals on individuals with low (1-100 microfilariae/ml of peripheral blood), moderate (101-500 microfilariae/ml), and high (> 500 microfilariae/ml) microfilaremia. The mosquitoes ingested 1.39-3.80 microl of blood and infective third-stage (L3) larvae were first recorded 13-14 days after the infecting blood meal. The number of microfilariae ingested by mosquitoes was proportional to the density of microfilariae in the peripheral blood of the human subjects, but with a concentration factor of up to 6.5 times the expected number. Survival of mosquitoes was not influenced by the density of microfilariae in the peripheral blood of infected individuals. Infectivity indices were proportional to microfilaremia in human subjects. The number of L3 larvae/female (intensity of infection) was not influenced by individual microfilaremia. The highest vector efficiency and the best experimental infection index were recorded in mosquitoes that blood fed on individuals with moderate microfilaremia. The results are discussed in relation to the transmission on Bancroftian filariasis in the study area.

A Organização Mundial de Saúde e o Ministério da Saúde do Brasil preconizam a importância de avaliar a ocorrência de doenças negligenciadas, entre elas as Leishmanioses, em regiões consideradas indenes, pois a identificação precoce de áreas de ocorrência dessas enfermidades favorece a implementação de medidas preventivas de forma mais eficaz. Objetivo: Determinar a prevalência de leishmaniose visceral (LV) canina, a frequência de LV humana e identificar espécies de Leishmania circulantes na cidade de Cláudio, região Centro Oeste de Minas Gerais. Método: Foi realizado inquérito sorológico amostral canino na área urbana do município utilizando dois testes imunológicos (imunocromatografia rápida, ensaio imunoenzimático), e diagnóstico sorológico em humanos por três testes (imunocromatografia rápida, ensaio imunoenzimático, imunofluorescência indireta) em residentes de casas com cães parasitados e/ou onde foram capturados Lutzomyia longipalpis, inseto vetor de Leishmania infantum. Resultados: Dos 430 cães examinados, cinco foram sororreagentes nos dois testes imunológicos, com prevalência de 1,2% (IC95%: 0,4%–2,7%). Nas amostras de medula óssea, baço e linfonodos dos cães sororreagentes, foram identificadas formas amastigotas e através do diagnóstico molecular constatou a presença de L. infantum, parasito causador da leishmaniose visceral. Na pesquisa da Leishmaniose visceral humana foram avaliados 74 indivíduos, não sendo identificado nenhum com sorologia positiva. Conclusão: É muito importante a implantação de estratégias de prevenção e controle da leishmaniose visceral canina no município, evitando a propagação da parasitose entre a população canina e consequentemente a transmissão para população humana, pois essas enfermidades estão em franca expansão na região Centro Oeste de Minas Gerais, e em humanos pode levar ao óbito se não diagnosticada e tratada precocemente.