November 01, 2009
1 min read

New risk factor identified for Toxoplasma gondii infection

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Eating raw oysters, clams or mussels was associated with Toxoplasma gondii infection in a case-control study involving more than 500 participants, conducted by researchers to better target toxoplasmosis prevention efforts.

T. gondii is a widely prevalent parasite that is potentially responsible for significant morbidity and mortality in the congenitally infected child and those with immunosuppression and for high morbidity in all persons in the form of ocular disease,” the researchers wrote.

Researchers have hypothesized that T. gondii oocysts originating from cat feces survived or bypassed sewage treatment and traveled through coastal water systems to contaminate California’s seawater, and results of several previously conducted studies confirmed the presence of the parasite in mussels from the region. Another study’s results linked mollusk consumption to T. gondii infections in sea otters.

In this study, the researchers received completed questionnaires from 148 case patients who were recently diagnosed with T. gondii from the Palo Alto Medical Foundation Toxoplasma Serology Laboratory from August 2002 to May 2007. They compared these responses with a group of 413 control patients. Findings indicated that a subgroup of participants who were surveyed regarding consumption of raw oysters, clams and mussels had a significantly elevated risk for T. gondii infection (adjusted OR=2.22; 95% CI, 1.07-4.61).

Additional multivariate analysis confirmed the following known risk factors:

  • Eating raw ground beef (adjusted OR=6.67; 95% CI, 2.09-21.24).
  • Eating rare lamb (adjusted OR=8.39; 95% CI, 3.68-19.16).
  • Eating locally produced cured, dried or smoked meat (adjusted OR=1.97; 95% CI, 1.18-3.28).
  • Drinking unpasteurized goat’s milk (adjusted OR=5.09; 95% CI, 1.45-17.80).
  • Having three or more kittens (adjusted OR=27.89; 95% CI, 5.72-135.86).

“Reduction of T. gondii contamination of meat and increased education of health professionals and the public about the factors identified in this study could help to further reduce the burden of toxoplasmosis in the United States,” the researchers wrote.

Jones JL. Clin Infect Dis. 2009;49:878-884.