Toxoplasma gondii seroprevalence in Mali

The protozoan parasite Toxoplasma gondii is globally distributed, with considerable local variation in prevalence based on behavioral and environmental factors. To assess prevalence and estimate risk in Mali, we conducted a survey of 760 serum samples previously collected for malaria studies. A modified agglutination test detected antibodies in ∼27% of the adult population, with no significant differences between men and women, or between urban and rural study sites. In the village of Kolle, seroprevalence rose from 0% in infants (<1 yr, but after weaning of maternal immunoglobulin G) to 0.8% (1-5 yr), 2.7% (6-10), 11.3% (11-15), and 26.8% (>15); differences between the <10-, 11-15-, and >15-yr age groups were highly significant (P ≤ 0.01). We also observed an increase in anti- T. gondii antibody titers with age. Modeling the observed age distribution suggests a seroconversion rate of ∼1%/yr, indicating that congenital toxoplasmosis may be an under-appreciated public health concern in Mali.