http://www.humanillnesses.com/Infectious-Diseases-He-My/Intestinal-Parasites.html Strongyloidiasis (stron-juh-loy-DYE-uh-sis) is caused by another roundworm, Strongyloides stercoralis. This common infestation can be especially dangerous in people with weakened immune systems. If a person comes into contact with contaminated soil, the larva of the parasite can burrow through the skin. It travels to the lungs and then, in a manner similar to ascaris, is swallowed and ends up in the intestines, where the worm grows to adulthood and begins laying eggs. What is special about this parasite is that the eggs can hatch inside the intestines and the worms can continue to cycle through many generations (called the autoinfective cycle), causing an infestation that can last for decades.
In people with weakened immune systems, particularly those taking drugs such as corticosteroids * , strongyloidiasis can become overwhelming, and huge numbers of larvae can invade the lungs and other organs. This problem is called the hyperinfection syndrome and, although rare, it can be fatal.