Inquérito sorológico e molecular de leishmaniose visceral canina no município de Alfenas-MG

Abstract

Canine visceral leishmaniasis (CVL) is a chronic, systemic disease, and the dog is considered the main domestic reservoir of the parasite. The control programs recommend the conduction of serological surveys for the identification of serologically positive dogs, since the canine infection precedes the human infection. This is a study for serological and molecular investigation of CVL in the municipality of Alfenas-MG, located in area that is considered non-endemic for the disease, but with large flow of health service demand and presence of students from different regions of the country, including ones that are endemic for this disease. Detection of L. (L.) infantum chagasi infection in dogs was performed by serological methods (Immunochromatographic rapid test DPP® Bio-Manguinhos, ELISA and IFAT both in house), in 87 serum samples, and by molecular methods, with conventional PCR (RV1/RV2) and Real-Time PCR (Linj31, Ldon and DNAPOL), in 87 whole blood samples from de municipal kennel and veterinary clinics in the County.To evaluate cross-reactivity with other agents, 87 serum samples were submeted to reaction of IFAT for Toxoplasma gondii, and 66 samples were submeted to IFAT for Neospora caninum and Rickettsia spp. and conventional PCR to SSU rDNA genes, target for Trypanosoma cruzi, to cytochrome B for trypanosomatids and chitinase gene related to interaction between phlebotomines and Leishmania sp. The results show that of the 87 samples analyzed, eight (9%) were positive in the rapid test DPP®, but only two (2.3%) were confirmed by ELISA and two (2.3%) were undetermined. In the molecular tests using conventional PCR, 91 samples analysed (87 of whole blood, two spleen fragments and two liver fragment), four samples (4.4%) were positive for the conventional PCR with the marker RV1/RV2, and six samples (6.6%) for the real-time PCR, with Linj31, Ldon, and DNApol markers. Two samples of spleen and liver were positive on the two procedures employed, while two whole blood (2.2%) were positive only in real time PCR. The sequencing results showed total identity with L. (L.) chagasi (access AJ 000304.1). In testing for other parasites, 30 samples (34.5%) were positive for T. gondii, while for N. caninum only a sample (1.5%) showed positive result. All animals in the Kennel were asymptomatic, which leads to suggest that positive serology results found may be due to cross-reactivity with other parasites. Thus, these results indicate that would not be occurring this transmission of this parasites among residents in the municipal Kennel of Alfenas. However were confirmed the first cases of CVL in the region of Alfenas, these dogs attended in veterinary clinics in the municipality, although it is not possible to say that might be occurring transmission between dogs from veterinary clinics, since it has not possible to determine the origin of them. The Ministry of health recommends the DPP ® as ELISA screening and confirmatory tests, but others such as are required for the diagnosis conclusive, inasmuch as the serologic tests showed cross-reactivity and can generate false positives.