Toxoplasmosis with special reference to peninsular Malaysia and Singapore.

Toxoplasmosis is a zoonotic infection caused by Toxoplasma gondii, a protozoan belonging to family Toxoplasmidae and Class Toxoplasmida(1). T. gondii was described by Nicolle and Manceaux(2) in a small North African rodent Ctenodactylus gondii. It has a world-wide distribution, but frequency of infection in man and animals varies from country to country. In general, the prevalence rate of infection is greater in the tropics and subtropics than in colder regions. Only a single species of Toxoplasma has been described so far. However, a number of strains have been reported from different parts of the world by different authors. Different strains of Toxoplasma vary in their virulence and virulence of a strain is determined on the basis of its ability to kill white mice(3). Toxoplasma gondii has little host specificity and it parasitises man and a large number of other mammals and birds. The organism is an obligatory intracellular parasite of nucleated cells, especially of the lymphoid macrophage system, muscles, the central nervous system and the retina. It may, however, circulate for short periods in the lymph and blood(1) or in the ventricular fluid as free endozoites(4). T. gondii was first recognised in man by Wolf and Cowen(5). It was first suspected of causing human illness by Castellani(6). The case reported by Janku in Czechoslovakia, may have also been toxoplasmosis(7).