Isolation and genetic characterization of Toxoplasma gondii from tissues of wild turkeys (Meleagris gallopavo) in Pennsylvania

Authors: CERQUEIRA-CEZAR, CAMILA - Non ARS Employee; DA SILVA, ANDRESSA - Non ARS Employee; MURATA, FERNANDO - Non ARS Employee; SADLER, MEGHAN - Non ARS Employee; Kwok, Oliver; BROWN, JUSTIN - Pennsylvania Game Commission, Bureau Of Wildlife Management; CASALENA, MARY JO - Pennsylvania Game Commission, Bureau Of Wildlife Management; BLAKE, MITCHELL - National Wild Turkey Federation; SU, CHUNLEI - University Of Tennessee; Dubey, Jitender

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2018
Publication Date: 5/6/2019
Citation: Cerqueira-Cezar, C., Da Silva, A., Murata, F., Sadler, M., Kwok, O.C., Brown, J., Casalena, M., Blake, M., Su, C., Dubey, J.P. 2019. Isolation and genetic characterization of Toxoplasma gondii from tissues of wild turkeys (Meleagris gallopavo) in Pennsylvania. Journal of Parasitology. 105(3):391-394. https://doi.org/10.1645/18-197.
DOI: https://doi.org/10.1645/18-197

Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, abortion in livestock, and contributes to mortality in wildlife. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Toxoplasmosis continues to be a public health problem worldwide. Humans become infected by ingesting water and food contaminated with oocysts excreted by cats or by eating undercooked infected meat from domestic livestock or hunted animals. In the present study, authors isolated live Toxoplasma from 5 of the 20 wild hunter-killed turkeys. Infected turkey meat can be a source of infection for humans, but more importantly, viscera left in field could be a source of infection for domestic and wild cats that could further contaminate the environment by shedding oocysts. The results will be useful for parasitologists and biologists.

Technical Abstract: Toxoplasmosis in wild turkeys (Meleagris gallopavo) is of epidemiological interest because turkeys feed from the ground and thus, detection of infection in turkeys indicates contamination by oocysts in the environment. During the 2018 Spring gobbler hunting season in Pennsylvania, fresh (unfixed, not frozen) samples were obtained from 20 harvested turkeys and tested for Toxoplasma gondii infection. Hearts from all harvested wild turkeys, and skeletal muscle from 1 were bioassayed for T. gondii by inoculation in outbred Swiss Webster (SW) and interferon-gamma gene knockout mouse (KO) mice. Antibodies to T. gondii were detected in 1:5 dilution of neat serum from 5 of 15 turkeys and in fluid from the heart of 1 of 4 turkeys by the modified agglutination test (MAT); neat serum was not available from 4 turkeys. Viable T. gondii was isolated from hearts of 5 turkeys, 1 with MAT of 1:10 1 with MAT of 1:5, and 3 seronegative (MAT <1:5). Toxoplasma gondii was isolated from both heart and skeletal muscle in the 1 wild turkey that had skeletal muscle submitted. The KO mice inoculated with tissue from all 5 infected turkeys died/euthanized when ill, 7-21 days post inoculation (PI). Tachyzoites were detected in lungs of all KO mice and the T. gondii strains were successfully propagated in cell culture. The SW mice inculated with tissues of turkeys remained asymptomatic and tissue cysts were seen in their brains of infected mice when euthanized in good health at 46 days PI; 1 of the 2 SW mice inoculated with heart of 1 turkey died on day 26 and tachyzoites were detected in its lung. Genetic typing on DNA extracted from culture-derived tachyzoites using the PCR restriction fragment length polymorphism with 10 genetic markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) revealed that 4 isolates belonged to ToxoDB PCR-RFLP genotype #5 and 1 was genotype #216.