Prevalence of antibody to Toxoplasma gondii in Hyogo Prefecture, Japan: comparison at a 10-year interval.

We have previously surveyed antibody to Toxoplasma gondii among Japanese populations. In this report, we studied the current situation of antibody prevalence and compared it with the situation approximately 10 years before. A total of 1,800 human serum samples were collected at the Central Laboratory of Kobe University Hospital from June through September, 1995, and were examined for Toxoplasma antibody using enzyme-linked immunosorbent assay. The overall prevalence was found to be 16.4% with similar seropositivities in males (16.8%) and females (15.9%). Prevalence of antibody increased with age, reaching 41.0% in males and 59.0% in females at 80 years or more. Comparison with data obtained at the same hospital in 1981 to 1982 indicated that seropositivities at 30-39 years significantly decreased in both males and females. A positivity currently obtained at a certain age group was similar to a positivity previously obtained at the corresponding age group (10 years younger), indicating that the previous age prevalence curve shifted to the current position. A serological survey among stray cats collected in Hyogo Prefecture in 1990-1991 indicated that 44 (19.0%) of 231 cats were positive for Toxoplasma antibody as determined by the latex agglutination test. These results suggested less transmission of Toxoplasma to humans in Hyogo Prefecture at least for the last 10 years comparing with the situation in the past, although the transmission cycle among cats was still active in nature.