Low Toxoplasma antibody prevalence in serologic surveys of humans in southern Mexico.

Antibody prevalence to Toxoplasma gondii among residents of a Pacific coastal region of Oaxaca State, Mexico is among low rates reported worldwide. From 60 small, rural communities, 3229 persons from ages 6 months to over 70 years provided blood specimens that were stored on filter papers. 124 (3.8%) of the eluates were seropositive (positive titer greater than 1:256) in the indirect hemagglutination test, and 43 (1.3%) had titers greater than 1:1024. Seropositive rates increased by age group and females were positive twice as often as males. There was no difference in rates for persons who lived at sea level, compared to those who lived between 600 and 1800 meters. In two small communities in which the number of persons tested were a large percentage of the total population, seropositive rates were 1.0 and 1.9%, respectively. The probable explanation for these low rates is the near absence of cats and paucity of meat in the diet. By contrast, sera tested from 479 persons living about 150 km to the east in the coastal, urban towns of Tehuantepec of Salina Cruz showed positive reactions among 122 (125.5%), and 71 (14.8%) had titers less than 1:1024. These people had a higher standard of living, more meat in their diet, and a few cats.