Evaluation of Diagnosis Methods in Dogs Experimentally Infected with Leishmania Infantum
Dogs are the main reservoir of Leishmania infantum, the causative agent of zoonotic visceral leishmaniasis (ZVL). Early diagnosis constitutes a good strategy to control ZVL. In order to compare different diagnostic techniques for canine leishmaniasis we have carried out the experimental infection of beagle dogs and follow up the infection by immunological and parasitological methods. Six beagle dogs were infected intravenously with 108 L. infantum promastigotes and the clinical, immunological and parasitological status of the animals were monitored monthly during a period of 32 weeks. Leishmania infantum specific serum levels of antibodies were measured by the Indirect Immunofluorescence Antibody Test (IFAT), and the soluble Leishmania antigen (SLA) and rk39 ELISA (IgG, IgG1, IgG2); the cellular immunological response was studied by the in vitro lymph proliferation assay with SLA antigen. The parasitological status were determined by the lymph node, bone marrow aspiration, spleen aspiration helped with a ecography, skin biopsy and peripheral blood mononuclear cell subsets by culture in NNN medium and Ln-PCR. Specific Leishmania antibodies could be detected in the all dogs from the first month. It was observed high levels of antibodies by IFAT and SLA and rk39 ELISA in the dogs; the symptomatic dogs showed higher levels of antibodies by rk39 ELISA during the follow-up. All the dogs showed lymphoproliferative response to SLA at the first month after the infection. Parasites were found in five out of six dogs by culture and Ln-PCR (83.3%) at the fifth month. The clinical signs of diseases: exfoliative dermatitis, ulcerations, peripheral popliteal lymphadenopathy, dry hair, weight loss, onychogryphosis, hepato and splenomegaly, ocular symptoms were observed from the third month of the infections in 66.6% of dogs. This experimental model of infection has proved to be useful to study the evolution of the disease, for the establishment and standardization of early diagnosis methods, and the development of control strategies against ZVL Funded by ISCIII (MPY-1014).
Jorge Miret holds a fellowship from MAE-AECI, Javier Moreno is supported by a RyC contract from MEC.