Toxoplasmosis -congenital and acquired Custom Search Toxoplasmosis is an infectious disease caused by a parasite called Toxoplasma gondii. The organism belongs to the group of Protozoa which are unicellular eukaryotic organisms (those having nucleus). This parasite is found in birds and animals. The life cycle of this organism has two phases. The sexual phase takes place in cats while the asexual phase takes place in other animals including humans and certain birds. Cats get infected by eating animals and birds having cysts of Toxoplasma gondii in their tissues. The parasites in the tissues are called bradyzoites. These enter the intestinal cells and divide forming merozoites. The merozoites cause rupture of affected cells, come out and invade other cells and multiply. After a few days some of the merozoites develop into male and female gametes. Sexual reproduction by the gametes produces oocysts which are passed in the cat’s feces. The oocysts can survive in soil for up one and a half years if there is moisture but not so long in dry conditions and extreme temperatures. The oocysts become infective after a few days and infect other animals including man. They invade the tissues of the host and reproduce asexually by producing merozoites. Human infection can be either congenital as a result of transmission of the parasite from pregnant women to the fetus or as a result of ingestion of the oocysts or tissue cysts (in improperly cooked meat) in later life. Congenital toxoplasmosis: This can manifest in many ways- abortion if transmission of the parasite occurs in early pregnancy, premature delivery or still birth. After birth the baby may have fever, microcephaly (small head due to poor development of brain), hydrocephalus (inflammation and scarring in the brain can cause obstruction to the normal flow of cerebrospinal fluid, accumulation of fluid in the head leading to enlargement of head) enlargement of liver and spleen, jaundice, convulsions, squint, skin rash, inflammation of the layers of the eye-chorea and retina leading to decreased vision, inflammation of lungs, inflammation of the heart muscle (myocardits) and decrease in the number of platelets. About 10 percent of babies with congenital toxoplasmosis succumb to the disease. Congenital toxoplasmosis has to be differentiated from other congenital viral infections like cytomegalovirus, rubella and herpes simplex. Acquired infection: In contrast to congenital infection acquired infection is usually mild in those with normal immune system. Many infections may be asymptomatic. When symptoms occur they are nonspecific and consist of fever, enlargement of lymph nodes, enlargement of liver and spleen, pain in muscles and fatigue. Eye involvement is less common. The disease is usually self limited. Enlargement of lymph nodes may persist for a long time and may be confused with infectious mononucleosis. Custom Search
Page last reviewed on 31st May 2010
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