Ascariasis
Ascariasis is a human disease caused by the parasitic roundworm Ascaris lumbricoides . Perhaps as many as one quarter of the world's people are infected, with rates of 45% in Latin America and 95% in parts of Africa . Ascariasis is particularly prevalent in tropical regions and in areas of poor hygiene. Other species of the genus Ascaris are parasitic and can cause disease in domestic animals. Certain genes have been identified in human populations that may increase the susceptibility to infection. Infection occurs through ingestion of food contaminated with feces containing Ascaris eggs. The larvae hatch, burrow through the intestine, reach the lungs, and finally migrate up the respiratory tract. From there they are then reswallowed and mature in the intestine, growing up to 30 cm ( 12 in .) in length and anchoring themselves to the intestinal wall. Infections are usually asymptomatic, especially if the number of worms is small. They may however be accompanied by inflamma...