Canine Visceral Leishmaniasis in an Area of Sporadic Transmission in Brazil.

Abstract

Canine visceral leishmaniasis is a zoonotic disease caused by the protozoan Leishmania infantum in Latin America. Visceral leishmaniasis (VL) diagnosis in Brazil includes two serological tests according to the Ministry of Health (MH) protocol. Sensitivity and specificity of diagnostic tests, as well as clinical signs of VL, are usually reported in disease-endemic areas; however, it is known that local epidemiological factors can influence these results. This study aimed to evaluate the clinical features, sensitivity, and specificity of TR-DPP® and EIE-LVC in naturally infected dogs in a region of sporadic VL transmission to humans in Brazil. A total of 288 dogs were clinically evaluated and serological and parasitological (lymph node aspirates) samples were collected for VL diagnosis. TR-DPP and EIE-LVC showed poor sensitivity (0.62 and 0.44, respectively) to detect infected animals, compared with the direct parasitological examination, which is considered a gold standard method. Thus, the protocol of MH presented low sensitivity (0.42) to estimate prevalence and control measures in this region. TR-DPP presented a high negative predictive value (0.89), resulting in its indication as a confirmatory test in sporadic transmission areas. Classical clinical signs of VL were not frequently observed; therefore, clinical scoring systems might not be useful in this region. Veterinarians of nonendemic areas should be alert for asymptomatic dogs, especially those presenting lymph adenomegaly.