Avaliação da Reação em Cadeia da Polimerase (PCR) e da PCR em tempo real (qPCR) no diagnóstico da Leishmaniose Visceral Canina utilizando diferentes amostras biológicas

Abstract

Canine visceral leishmaniasis (CVL) is an important parasitic zoonosis endemic in Brazil, caused by the protozoa known as Leishmania infantum. In the urban area, the dogs are considered the main reservoir of this parasite. Thus, the importance of dogs in the urban environment has stimulated numerous studies for the assessment of diagnostic techniques. Among these studies, several have proposed the molecular tools (e.g. Polimerase Chain Reaction (PCR) and Real time PCR (qPCR)) as important methods for diagnosis of infection by L. infantum in dogs. However, little is known about the better biological samples used in these techniques, considering that several samples may be utilized (e.g. bone marrow, lymph node, spleen, skin). Hence, the aims of this study were i) to determine the performance of polymerase chain reaction (PCR) and real-time PCR (qPCR) in the diagnosis of CVL using different biological samples; ii) to quantify the parasite load in the skin, bone marrow, lymph node and spleen of dogs and relate the findings to clinical status. For such, infected dogs by L. infantum from an endemic area were utilized. Samples of bone marrow, lymph node, spleen and skin were collected by assessment of PCR and qPCR, and quantification of parasite load. In the present study, qPCR was able to detect a greater number of positive animals in comparison to PCR. No significant differences between biological samples were found in the detection of L. infantum DNA using PCR or qPCR. Considering the parasite load on different biological sample, it was not observed significative difference, on the other hand, among the clinical group was detected significative difference. The findings of the present study suggests that the parasite load on bone marrow, lymph node, spleen and skin is greater among those dogs with more clinical signs (parasite load on polysymptomatic animals > parasite load on oligosymptomatic animals > parasite load on asymptomatic animals). In addition, considering the easy of acquiring lymph node samples further demonstrates the greater viability of this biological material in the routine diagnosis of infection by L. infantum in dogs.