High seroprevalence of toxoplasma gondii in Elk (Cervus canadensis) of the Central Appalachians, USA

Authors: COX, JOHN - University Of Kentucky; SLABACH, BRITTANY - University Of Kentucky; HAST, JOHN - University Of Kentucky; Kwok, Oliver; Dubey, Jitender

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2017
Publication Date: 1/27/2017
Citation: Cox, J., Slabach, B., Hast, J., Kwok, O.C., Dubey, J.P. 2017. High seroprevalence of toxoplasma gondii in Elk (Cervus canadensis) of the Central Appalachians, USA. Parasitology Research. 116:1079-1083.

Interpretive Summary: Human toxoplasmosis, caused by single-celled parasite, Toxoplasma gondii, accounts for an estimated one-fifth of all diagnosed foodborne infections in the United States, and one fifth of the economic costs attributable to any foodborne pathogen. Pregnant women and their fetuses are exposed to elevated health risks. The ingestion of under cooked infected meat, including venison is considered an important source of toxoplasmosis in humans. The Elk is one of the largest species within the deer family and mature animals can weigh up to 750 pounds. In the present study the authors found Toxoplasma specific antibodies in 81 of 142 (57%) elk hunted in Kentucky. Hunted elk are gutted in the forest and viscera of infected deer could be a source of infection for wild cats that in turn can shed oocysts and spread infection. An infected elk could be a source of Toxoplasma infection in many persons if meat is consumed undercooked. The results will be of interests to parasitologists, public health workers and biologists.

Technical Abstract: Toxoplasma gondii is an important protozoan parasite of mammals that impacts animal health and behavior. Although this parasite has been documented in several cervid species, including red deer (Cervus elaphus) in Europe, little is known about T. gondii impacts on the closely related North American counterpart, the elk (wapiti, Cervus canadensis), which has increased in number and expanded in range during the past century. We assessed seroprevalence of T. gondii antibodies using a modified agglutination test (1:25 titer) and blood collected from 142 free-ranging elk in Kentucky, USA, where the species was reintroduced during 1997–2002 after over a century of absence. Eighty-one of 142 (57.0%) elk were seropositive for T. gondii. We found no infection or titer differences between sexes (U = 2146, P = 0.128). Odds of T. gondii infection significantly increased with elk age (_ = 0.429, P = 0.001) by a factor of 1.54 (95% CI: 1.19–1.99), and titer increased commensurate with age (JT = 3071, P < 0.001). High prevalence of T. gondii infection in elk of this region may be explained by sympatry with two primary hosts, the bobcat and domestic cat, as well as shed oocysts in the soil of this relatively wet and humid region. We suggest wildlife agency personnel incorporate warnings about proper elk meat preparation into their hunter education outreach programs and literature to reduce the chances for human infection from consuming contaminated venison.