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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #365799

Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: High seroprevalence but low rate of isolation for Toxoplasma Gondii from wild elk (cervus canadensis) in Pennsylvania

item KOLOREN, ZEYNEP - Non ARS Employee
item MURATA, F.H.A. - Non ARS Employee
item Kwok, Oliver
item BANFIELD, J.E. - Pennsylvania Game Commission, Bureau Of Wildlife Management
item BROWN, J.D. - Pennsylvania Game Commission, Bureau Of Wildlife Management
item SU, C - University Of Tennessee
item Dubey, Jitender

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2019
Publication Date: 11/18/2019
Citation: Koloren, Z., Cerqueira-Cezar, C., Murata, F., Kwok, O.C., Banfield, J., Brown, J., Su, C., Dubey, J.P. 2019. High seroprevalence but low rate of isolation for Toxoplasma Gondii from wild elk (cervus canadensis) in Pennsylvania. Journal of Parasitology. 105(6):890–892.

Interpretive Summary: Among these zoonotic pathogens, the protozoan parasite T. gondii is perhaps the most ubiquitous, having been identified in the tissues of a variety of animal hosts, including both mammalian and avian species. Toxoplasma gondii is estimated to chronically infect one third of the world’s human population, causing ocular toxoplasmosis in immunocompetent individuals and often-fatal encephalitis in the immunocompromised, as well as birth defects and mortality following vertical transmission to developing fetuses. Humans become infected postnatally by eating undercooked meat infected with T. gondii tissue cysts or by ingesting oocysts from the environment. Cats (domestic and wild) are the main reservoir of infection because they are the only hosts that can excrete the environmentally resistant stage, the oocyst. Oocysts are highly infectious for people and animals. Game meat, including venison can be source of infections for humans as well for wild cats that can further spread infection. Humans can become infected by eating undercooked venison. In the present study authors found high prevalence of Toxoplasma antibody (69%) but a very low rate of T. gondii isolation, indicating that unlike white tailed deer, elk are not a good reservoir of T. gondii infection. The results will be of interest to biologists, parasitologists, public health workers, and hunters.

Technical Abstract: Toxoplasma gondii infections are prevalent in most warm-blooded animals worldwide. During the 2018 November hunting season in Pennsylvania, fresh (unfixed, not frozen) samples obtained from 99 harvested elk (Cervus canadensis) were tested for T. gondii infection. Antibodies to T. gondii were detected in 69 of 99 (69.7%) elk tested by the modified agglutination test (MAT, 1:25 cut-off). Tongues and hearts from 16 elk with high MAT titers (>1:200) were bioassayed for T. gondii by inoculation in outbred Swiss Webster (SW) and interferon-gamma gene knockout mouse (KO) mice. Viable T. gondii was isolated from tongues of 2 elk with MAT titers of 1:200 and 1:3200. Toxoplasma gondii from both isolates were successfully propagated in cell culture. 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 both isolates belonged to ToxoDB PCR-RFLP genotype #5, widely prevalent in wildlife in USA. Results suggest that elk are not poor host for T. gondii and apparently clear organisms from their tissues.