Exposure to Toxoplasma gondii in Asian Elephants (Elephas maximus indicus) in Thailand

Abstract

Toxoplasma gondii is the causative agent of toxoplasmosis in humans and various animal species worldwide. In Thailand, seroprevalence studies on T. gondii have focused on domestic animals, and information on infections in Asian elephants (Elephas maximus indicus) is scarce. This study was conducted to determine the seroprevalence of T. gondii infection in archival sera collected from 268 elephants living in Thailand. The serum samples were analyzed for anti-T. gondii immunoglobulin G antibodies using the latex agglutination test (LAT) and indirect enzyme-linked immunosorbent assay (iELISA) based on T. gondii lysate antigen (TLA-iELISA) and recombinant T. gondii dense granular antigen 8 protein (TgGRA8-iELISA). The prevalence of antibodies against T. gondii was 45.1% (121/268), 40.7% (109/268), and 44.4% (119/268) using LAT, TLA-iELISA, and TgGRA8-iELISA, respectively. Young elephants had a higher seropositivity rate than elephants aged >40 years (odds ratio = 6.6; p < 0.001; 95% confidence interval: 2.9–15.4). When LAT was used as the reference, TLA-iELISA and TgGRA8-iELISA showed a substantial (κ = 0.69) and moderate (κ = 0.42) agreement, respectively. Although our findings suggest the widespread exposure of Asian elephants to T. gondii in Thailand, the source of infection was not investigated. Therefore, investigation of the predisposing factors associated with toxoplasmosis is necessary to identify the potential risk factors for infection.

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“…Toxoplasmosis is a disease caused by Toxoplasma gondii and occurs widely in animals and humans [28,39,87,88]. In humans, the infection results in a range of signs and symptoms, including gastrointestinal, malaise, anorexia, weight loss, pain, fever, systemic disease, or death, and transmission is characteristically fecal-oral, through contaminated soil, or fomites [28,39,87,88]. In elephants, individuals may be asymptomatic carriers, but infection may result in debilitating gastrointestinal and systemic disease conditions [125].…”

“…Relatively little is known regarding disease incidence or prevalence [23,32], although one study found antibodies in 45.5% of Asian elephants, indicating that animals had, at some point, been exposed to the pathogen [125]. Another study also showed widespread exposure but with no determination regarding the source of infection [39].…”