Use of ELISA employing Leishmania (Viannia) braziliensis and Leishmania (Leishmania) chagasi antigens for the detection of IgG and IgG1 and IgG2 subclasses in the diagnosis of American tegumentary leishmaniasis in dogs.

American tegumentary leishmaniasis (ATL) shows a reduced humoral response in dogs and levels of specific antibodies may therefore not be detected by indirect immunofluorescence. Although the sensitivity of enzyme-linked immunosorbent assay (ELISA) is higher than that of indirect immunofluorescence, the best antigen for the diagnosis of ATL in dogs has not been defined. The detection of IgG subclasses represents an alternative to increase the efficiency of the serological diagnosis. In Rio de Janeiro, sporotrichosis is the main differential diagnosis of ATL in dogs, and a sensitive, specific and little invasive method that permits the discrimination of the two diseases is desired. In the present study, 69 serum samples, 34 obtained from dogs with ATL and 35 from dogs with sporotrichosis, all of them with a confirmed etiological diagnosis, were tested. The samples were analyzed by ELISA using Leishmania (Viannia) braziliensis and L. (L.) chagasi antigens for the detection of anti-Leishmania IgG, IgG1 and IgG2. The use of L. (V.) braziliensis antigens for the detection of IgG and IgG2 yielded the best results. Using L. (L.) chagasi antigen, the sensitivity and specificity for the detection of IgG were 82.4% and 100%, respectively, whereas both sensitivity and specificity were 97.1% with the L. (V.) braziliensis antigen. No improvement in the performance of the test was observed when IgG2 was analyzed separately. The IgG1 assays presented low accuracy, irrespective of the antigen used: sensitivity and specificity of 58.8% and 60% for L. (V.) braziliensis and of 64.7% and 77.1% for L. (L.) chagasi, respectively. The present results suggest that IgG ELISA using the L. (V.) braziliensis shows the best performance for the diagnosis of ATL, permitting the discrimination between cases of ATL and sporotrichosis in dogs.

Sporotrichosis: the main differential diagnosis with tegumentary leishmaniosis in dogs from Rio de Janeiro, Brazil.

Seventy-four dogs from the State of Rio de Janeiro with ulcerated cutaneous lesions were submitted to clinical, dermatological, parasitological, mycological, histopathological and cytopathological exams, a leishmanin skin test, an indirect immunofluorescence (IIF) test for leishmaniosis, and nonspecific laboratory tests such as blood count and serum biochemistry. Sporothrix schenckii was isolated from 41 dogs and Leishmania (Viannia) braziliensis was isolated from 33 animals. Most dogs with sporotrichosis were from the municipality of Rio de Janeiro (53.7%) and presented ulcerated cutaneous lesions on the head (68.3%). Laboratory alterations in these animals included anemia (58.5%), hypoalbuminemia (83%) and hyperglobulinemia (75.6%). Histopathology revealed the predominance of a chronic granulomatous inflammatory infiltrate (70.7%), and yeast-like structures were detected in 17% of the histopathological exams and in 32% of the cytological exams. Three of 41 dogs with sporotrichosis were seropositive by IIF for leishmaniosis and 2 of 20 animals tested within this group had a positive leishmanin skin test. Similarly, most of the 33 dogs with leishmaniosis were from the municipality of Rio de Janeiro (69.7%) and had ulcerated cutaneous lesions on the head (84.8%). Laboratory alterations in these animals included anemia (66.7%), hypoalbuminemia (100%) and hyperglobulinemia (91%). Histopathology showed the predominance of a chronic granulomatous inflammatory infiltrate (63.6%) and amastigote forms were detected in 30.3% of the histopathological exams and in 31.8% of the 22 cytological exams performed. About 72.7% of the dogs were seropositive by IIF and five of seven animals had a positive skin test. Due to the clinical similarities, histopathological and nonspecific laboratory results similarities, the serological and skin tests for leishmaniosis positive in dogs with sporotrichosis, and the overlapping endemic areas in Rio de Janeiro, the differential diagnosis between the two diseases requires the demonstration of their respective etiological agents.

Post mortem parasitological evaluation of dogs seroreactive for Leishmania from Rio de Janeiro, Brazil.

A parasitological study was conducted on 66 dogs seroreactive for Leishmania captured as a control measure of visceral leishmaniasis in the State of Rio de Janeiro, Brazil. Biological samples from different anatomical sites were collected during autopsy of the animals and cultured on biphasic medium (NNN/Schneider). The Leishmania isolates were characterized by isoenzyme electrophoresis. Leishmania was isolated from 80.3% of the animals: 12 animals with Leishmania (Viannia) braziliensis isolated exclusively from cutaneous lesions, 39 with L. (L.) chagasi isolated from different sites in the same animal, and 2 with simultaneous isolation of L. (V.) braziliensis from cutaneous lesions and L. (L.) chagasi from different sites. Isolation in culture revealed the absence of Leishmania parasites in 13 animals. The results obtained confirm the existence of mixed infections in dogs in Rio de Janeiro and indicate the need to complement the investigation of seroreactive dogs using methods for the parasitological diagnosis and identification of Leishmania species.