ToRCH & Childhood Diseases

Toxoplasma Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii . It can infect most species of warm blooded animals, including humans, and can cause toxoplasmosis disease.

LIFE CYCLE OF T.GONDII

The only known definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives). Unsporulated oocysts are shed in the cat’s feces and these take 1-5 days to sporulate in the environment and become infectious. Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts. Cats become infected after consuming intermediate hosts harboring tissue cysts. Humans can become infected by any of the following routes: • Eating undercooked meat of animals harboring tissue cysts • Consuming food or water contaminated with cat feces or by contaminated environmental samples (such as fecal- contaminated soil or changing the litter box of a pet cat) • Blood transfusion or organ transplantation • Transplacentally from mother to fetus

Up to a third of the world’s human population is estimated to have been infected with toxoplasma gondii . Infection is usually asymptomatic, but during the first few weeks after exposure the infection may cause a mild, flu-like illness. However, in those with weakened immune systems, such as those with AIDS and pregnant women, it can cause a serious and sometimes fatal illness.

CONGENITAL TOXOPLASMOSIS

Congenital toxoplasmosis is a group of symptoms that occur when a fetus is infected with T. gondii. If a mother becomes infected while pregnant, the parasite can spread to a developing fetus across the placenta. The risk of congenital disease is lowest (10 – 25%) when maternal infection occurs during the first trimester and highest (60 – 90%) when maternal infection occurs during the third trimester. Congenital disease is most severe when infection is acquired in the first trimester. The overall risk of congenital infection from acute T. gondii infection during pregnancy ranges from approximately 20 – 50%.