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
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
Researchers have hypothesized that T. gondii oocysts originating
from cat feces survived or bypassed sewage treatment and traveled through
coastal water systems to contaminate Californias seawater, and results of
several previously conducted studies confirmed the presence of the parasite in
mussels from the region. Another studys 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
- 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 goats milk (adjusted OR=5.09; 95% CI,
- Having three or more kittens (adjusted OR=27.89; 95% CI,
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.