Congenital toxoplasmosis in England, Wales, and Northern Ireland: some epidemiological problems.

It has been suggested that congenital toxoplasmosis could be prevented by antenatal serological screening, followed by treatment or by termination of pregnancy if infection occurs. The only study of the incidence of congenital toxoplasmosis in England, Wales, and Northern Ireland took place more than 10 years ago. To obtain more recent figures laboratory reports of cases occurring from 1975 to 1980 were analysed. A total of 91 cases were reported over the six years. By criteria established to classify these infections only 34 were congenital, 20 were acquired postnatally, and 37 were unclassifiable. The mean annual number of cases of congenital toxoplasmosis was considerably smaller than that found in other recent studies. The condition could be underdiagnosed or rates of placental transmission could be lower in Britain than in other countries. Variation in reporting criteria of the laboratories made the data difficult to interpret. Improved diagnosis of congenital toxoplasmosis would not only clarify the epidemiology but would also help clinicians in management of suspected cases. Further antenatal surveys are necessary to assess the role of screening in the prevention of congenital toxoplasmosis.