High seroprevalence of Toxoplasma gondii in elk (Cervus canadensis) of the central Appalachians, USA

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 (MAT) (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 of 142 (56.3%) elks were seropositive for T. gondii, but we found no infection or titer differences between sexes (U = 2146, P = 0.128). However, odds of T. gondii infection significantly increased with elk age (β = 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 that 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.