Sources of toxoplasma infection in pregnant women: European multicentre case-control study. European Research Network on Congenital Toxoplasmosis.

OBJECTIVE: To determine the odds ratio and population attributable fraction associated with food and environmental risk factors for acute toxoplasmosis in pregnancy.

DESIGN: Case-control study.

SETTING: Six large European cities.

PARTICIPANTS: Pregnant women with acute infection (cases) detected by seroconversion or positive for anti-Toxoplasma gondii IgM were compared with pregnant women seronegative for toxoplasma (controls).

MAIN OUTCOME MEASURES: Odds ratios for acute infection adjusted for confounding variables; the population attributable fraction for risk factors.

RESULTS: Risk factors most strongly predictive of acute infection in pregnant women were eating undercooked lamb, beef, or game, contact with soil, and travel outside Europe and the United States and Canada. Contact with cats was not a risk factor. Between 30% and 63% of infections in different centres were attributed to consumption of undercooked or cured meat products and 6% to 17% to soil contact.

CONCLUSIONS: Inadequately cooked or cured meat is the main risk factor for infection with toxoplasma in all centres. Preventive strategies should aim to reduce prevalence of infection in meat, improve labelling of meat according to farming and processing methods, and improve the quality and consistency of health information given to pregnant women.