Longitudinal study of Toxoplasma seroprevalence in South Yorkshire.

Serum samples collected from individuals of a wide range of ages in South Yorkshire between 1969 and 1990 provided the basis for a longitudinal seroprevalence survey of Toxoplasma gondii antibodies. Sera numbering 3868 were screened for T. gondii specific antibodies using a commercial latex agglutination test. The resultant temporal series of serological profiles revealed a rise, with age, in seroprevalence, the rate of which showed a decrease through time. A plateau of around 40-50% prevalence was attained by the 41- to 45-year age-class in 1969 which was not approached until the 66- to 70-year class in the 1988-90 data set. This trend for decline in seroprevalence was confirmed by statistical analysis for the age range 21-60 years. These results may be indicative of a decrease in the rate of toxoplasma exposure in this study community over the 20-year period. The survey of 1988-90 provides a base-line profile of present-day seroprevalence in which 11% of individuals in the age range 16-45 years (roughly corresponding to the childbearing age-range) show evidence of past infection. The representative nature of the serum collection and public-health implications of these results are discussed.