Seroepidemiology of toxoplasmosis in Amerindians from western Venezuela

A survey of 447 Amerindians aged 1-69 years (mean age, 18.6 +/- 15.8 years) in 3 mountain and I lowland communities from Venezuela were studied to det ermine the seroprevalence of Toxoplasma gondii, the environmental risk fact ors for the infection, and how the process of acculturation may affect the transmission rate. Serum samples were tested for immunoglobulin G antibodie s by a commercial indirect hemagglutination test. The overall prevalence of infection was 49.7% (222 of 447) and ranged 38.2-62.4%. A higher antibody rate was found in the lowland setting as compared with those from the mount ain area (P < 0.001). The geometric mean titer in the overall population wa s 280.3. No age-antibody association was detected in the mountain communiti es, although a gradual increase in positivity with increasing age (P < 0.01 ) was observed in the lowland setting, reaching a peak of 83.3% in the olde st group. The results suggest that transmission by infective cat feces may play a predominant role in the spread of infection in this population. This study demonstrates the environmental Toxoplasma infection pressure in this sylvatic population and how transmission rate is facilitated by environmen tal changes produced by acculturation.