Toxoplasmosis Outbreak Associated With Toxoplasma gondii-Contaminated Venison—High Attack Rate, Unusual Clinical Presentation, and Atypical Genotype

Abstract

Background During 2017, in response to a physician’s report, the Wisconsin Department of Health Services, Division of Public Health, began investigating an outbreak of febrile illness among attendees of a retreat where never frozen, intentionally undercooked, locally harvested venison was served. Preliminary testing tentatively identified the illness as toxoplasmosis. Methods Confirmatory human serology panels and testing of the venison to confirm and categorize the presence and type of Toxoplasma gondii were completed by French and American national reference laboratories. All 12 retreat attendees were interviewed; medical records were reviewed. Results All attendees were male; median age was 51 years (range: 22–75). After a median incubation period of 7 days, 9 (82%) of 11 exposed persons experienced illness lasting a median of 12 days. All 9 sought outpatient healthcare for symptoms including fever, chills, sweats, and headache (100%) and ocular disturbances (33%). Testing confirmed the illness as toxoplasmosis and venison as the infection source. Multiple laboratory results were atypical for toxoplasmosis, including transaminitis (86%), lymphocytopenia (88%), thrombocytopenia (38%), and leukopenia (63%). One exposed but asymptomatic person was seronegative; the other had immunity from prior infection. The T. gondii strain was identified as closely related to an atypical genotype (haplogroup 12, polymerase chain reaction restriction fragment length polymorphism genotype 5) common in North American wildlife but with previously uncharacterized human clinical manifestations. Conclusions The T. gondii strain contaminating the venison might explain the unusual clinical presentations. In North America, clinicians and venison consumers should be aware of risk for severe or unusual presentations of acute toxoplasmosis after consuming undercooked game meat.

Outbreaks of clinical toxoplasmosis in humans: five decades of personal experience, perspectives and lessons learned

“…Viable T. gondii, however, was not isolated by bioassay in mice, probably because the sample had been frozen. Genetic characterization of DNA from venison by 15 microsatellite testing revealed the strain was atypical, most aligned to TOXODB genotype #5, belonging to haplogroup 12 [9]. Toxoplasma gondii infections are common in whitetailed deer (WTD) in the USA.…”

“…In most persons, symptoms (when present) are mild and mimic other ailments such as flu, Lyme disease, Q fever, hematological alterations, and mumps. Therefore, it is likely that in many persons these symptoms are missed, or the diagnosis is delayed [8,9]. For example, in an outbreak of confirmed clinical toxoplasmosis in 35 persons associated with a riding stable in the USA, the diagnosis of toxoplasmosis was missed by 22 of 25 physicians [10].…”

Seroprevalence and risk factors ofToxoplasma gondiiinfection in wild ungulates that cohabit in a natural park with human–animal interaction in the Mediterranean ecosystem

“…been reported (Fecková et al 2020). Cases of clinical toxoplasmosis including ocular manifestations have been documented in humans who consumed undercooked venison (Gaulin et al, 2020;Ross et al, 2001;Sacks et al, 1983;Schumacher et al, 2020), and acute toxoplasmosis has been reported in hunters that consumed uncooked infected meat from wild pigs (Choi et al, 1997). However, the extent of transmission between large-game species and humans is unknown.…”

Seroepidemiology of Toxoplasma gondii in wild ruminants in Spain

“…Hunters and consumers of raw meat, as well as people who process meat, are at higher risk for T. gondii infection (Fecková et al, 2020). Importantly, clinical toxoplasmosis and even T. gondii outbreaks have been reported after consumption of raw or undercooked venison (Gaulin et al, 2020;Ross et al, 2001;Schumacher et al, 2020).…”