Congenital toxoplasmosis: Clinical features, outcomes, treatment, and prevention

Toxoplasmosis is caused by a coccidian parasite, Toxoplasma gondii. The parasite is highly prevalent both in humans and in warm-blooded animals. Cat family animals are definitive host, and these animals excrete the infective oocysts in their feces. Humans, though not definitive host, get infection by consuming water or food contaminated with cat feces. Rarely, infection can also take place through transfusing the infected blood, through transplantation of infected organs, or transplacentally from infected mother to fetus. Transplacental infection can cause congenital infection with varied degree of clinical manifestations, which depend on the age of fetus when infection took place. Diagnosis of congenital toxoplasmosis is difficult to establish until it is suspected and laboratory investigations are carried out. In more than 75% of cases, acute infection is missed due to very mild or unnoticeable clinical symptoms and signs. In India, a prevalence rate of 22.4% (8.8-37.3%) has been reported with an overall IgM positivity of 1.43%. It is estimated that approximately between 56,737 and 176,882 children per year are born in India with a possible risk of congenital toxoplasmosis. The diagnosis of congenital toxoplasmosis can be made by serological methods which are most commonly used. The other methods are parasite isolation by culture and molecular methods. Toxoplasmosis is treatable and transplacental transmission can be prevented by spiramycin, which concentrates in the placenta. However, if infection has done any damage to the fetus or the parasite has passed the placenta, spiramycin cannot reverse the damage. Prevention remains the best remedy.