Investigação de Trypanossoma caninum em cães de municípios das regiões do Cerrado e Pantanal no Brasil

Abstract

Trypanosoma caninum (T. caninum) has been identified and reported in different regions of Brazil by isolation from healthy dog skin, growth in axenic culture and subjection to molecular detection and sequencing. However, more sensitive diagnostic methods using specific targets are required to estimate the actual frequency of infection. This study aimed to detect the parasite load of T. caninum in samples of intact skin, blood, and lymph nodes from dogs in different municipalities located in the central-west region of Brazil using quantitative polymerase chain reaction with a specific target for T. caninum and parasitological culture. Of the 349 dogs analysed, 54 (15.5%) tested positive regardless of the technique used. T. caninum infection occurred in all municipalities, with a high frequency reported in Várzea Grande (66.7%). Frequency of T. caninum infection was significantly associated with visceral leishmaniasis infection (p = 0.02). Parasitological culture and quantitative PCR were positive in 1.4% and 14% of the dogs, respectively. Parasite DNA was found in the skin, lymph nodes, and blood of 10%, 3.7%, and 1.7% of dogs, respectively. The mean T. caninum parasite load was the highest in skin samples, followed by lymph node and blood samples, however, with no significant difference (p = 0.06). T. caninum infection was higher than previously reported, indicating that frequency of this parasite is underestimated. No risk factors were associated with infection (p > 0.05), but dogs with visceral leishmaniasis had a 2.2 times-higher risk of infection by the parasite than dogs without the disease. Parasite load in the biological samples was considered low; however, the skin had the highest number of DNA copies, reinforcing the predilection for this site and low occurrence of clinical alterations in infected dogs.