Toxoplasma gondii: diagnosis of experimental and natural infection in pigeons (Columba livia) by serological, biological and molecular techniques

This study aimed to diagnose experimental and natural Toxoplasma gondii infection in pigeons (Columba livia) by serological, biological and molecular techniques. Twelve pigeons, free of infection, were inoculated with 50 sporulated oocysts of T. gondii (VEG sample) and four remained uninfected controls. Four birds (three infected and one control) were euthanized at 15, 30, 45 and 60 days post-infection (dpi), and their tissues were used to perform a bioassay in mice and nested-PCR using B1 gene as target. Blood was obtained weekly and it was tested for the presence of anti-T. gondii antibodies by the indirect fluorescent antibody test (IFAT) and modified agglutination test (MAT). Seven (58.3%) out of 12 inoculated pigeons were positive by serological techniques and titers ranged between 1:40 and 1:5120 by MAT and between 1:512 and 1:4096 by IFAT. Complete agreement was seen between the results obtained by serological techniques and nested-PCR in seven positive birds. In the bioassay in mice, five (41.7%) out of 12 pigeons inoculated were positive to T gondii. Only one pigeon died at 23 dpi due to toxoplasmosis. A second study with free-living pigeons was performed for detection of anti-T. gondii antibodies. Birds were captured in the municipalities of Sao Paulo, Ibiuna and Sorocaba, Sao Paulo State, Southeastern Brazil. All 126 free-living birds were negative to anti-T. gondii antibodies by MAT (titer < 1:5). Bioassays were performed in mice with tissues from all captured birds and T. gondii was not isolated in any pigeon.