Toxoplasma gondii, Neospora caninum and Leishmania amazonensis antibodies in domestic dogs in the western Brazilian Amazon region

Blood samples from 99 domestic dogs were collected in the urban area (n = 33) and rural area (n = 66) of the municipality of Lábrea, state of Amazonas, Brazil. Among the rural samples, 40 were collected in riverine communities and 26 were collected in Indian communities, both along the Purus River. During the sampling, a questionnaire was applied to obtain information relating to sex, age, living in dryland or seasonally flooded areas, access to the streets (for urban dogs) and access to forests. The presence of antibodies against Toxoplasma gondii, Neospora caninum, Leishmania infantum chagasi and Leishmania amazonensis was detected by means of the indirect fluorescent antibody test (IFAT) with cutoffs of 16, 50, 40 and 40, respectively. The association of each qualitative variable, with each parasite and positivity for each of them, were evaluated using the χ2 test (p < 0.05). T. gondii, N. caninum and L. amazonensis antibodies were found, respectively, in 61.6%, 7.1% and 8.1% of the animals examined. None of the samples were positive for L. infantum chagasi. The variable of living in an urban area (p = 0.041) presented an association with occurrence of T. gondii and the positivity for T. gondii increased with age of the dogs (p = 0.0006). The variable of male sex presented an association with N. caninum (p = 0.018) and no variable presented any association with L. amazonensis. The antibody titers against T. gondii ranged from 64 to 32,768; against N. caninum from 100 to 800; and against L. amazonensis from 40 to 640. Both T. gondii and L. amazonensis are important zoonotic agents and are active in this region. The municipality studied, and especially its riverine communities, has geographic, social and ecological peculiarities. This region requires greater attention from the authorities for controlling these agents.