History

The important milestones that led to the full knowledge of congenital toxoplasmosis were the discovery of ‘parasitic cysts’ in the retina of a child who died with coloboma and hydrocephaly by Janku in Czechoslovakia (1923), the identification of this organism as toxoplasma by Levaditi in Paris (1928), the discovery of an encephalitozoic infantile granulomatosis associated with toxoplasma and evidence of its prenatal transmission by Wolf et al. (1939). The clinical pattern was delineated first in studies of a large series of patients investigated retrospectively (Feldman 1953; Couvreur & Desmonts 1962) and later in prospective studies (Desmonts & Couvreur 1974a).

Epidemiology

The prevalence of congenital toxoplasma infection in a given community is directly related to the rate of acquired infection in pregnant women adjusted by the 40% rate of materno–foetal transmission. Any evaluation of the prevalence of infection in newborns requires routine screening for seroconversion in the pregnant population and thorough study of their newborn infants. This prevalence can vary over years and it is influenced by preventive measures. This explains why it decreased in Paris from 3 to less than 1 per 1000 live births within 20 years (Remington & Desmonts 1990). The prevalence of neonatal infection has been reported as 0.6 to 2 per 1000 in Alabama, 2 per 1000 in Brussels, 0.25 to 0.7 per 1000 in London and 2 per 1000 in Melbourne. Frenkel (1974b) has proposed a mathematical epidemiological model for such evaluations.