infections
Hookworm Infection
Introduction
Hookworm infection is a roundworm infection of the intestines that can cause an itchy rash, respiratory and gastrointestinal problems, and eventually iron deficiency anemia due to ongoing loss of blood. People can become infected when walking barefoot because hookworm larvae live in the soil and can penetrate the skin. At first, people may have an itchy rash where the larvae penetrate the skin, then fever, coughing, and wheezing or abdominal pain, loss of appetite, and diarrhea. Severe, chronic infections can cause loss of blood and anemia that is sometimes severe enough to cause fatigue and occasionally heart failure and widespread swelling. Doctors diagnose the infection by identifying hookworm eggs in a stool sample. The infection is treated with antiparasitic drugs such asalbendazole. (See also Overview of Parasitic Infections .) Worldwide, between 576 and 740 million people are infected with hookworms, which are intestinal roundworms. The infection is most common in tropical areas where sanitation is poor. Hookworms thrive in warm, moist places. Two species of hookworm cause infection in people: Ancylostoma duodenale Necator americanus Both species are present in moist, hot areas of Africa, Asia, and the Americas.Ancylostoma duodenaleis present in the Middle East, North Africa, and southern Europe.Necator americanusis present mainly in the Americas and Australia. It once was common in the southern part of the United States and is still present in areas in that region where there is unsanitary disposal of human waste. Hookworm remains endemic on islands of the Caribbean and in Central and South America. Finally,Ancylostoma ceylanicum, a hookworm of dogs, cats, and hamsters present in parts of Asia and some South Pacific islands, can complete its life cycle in humans and on occasion causes hookworm disease. Hookworm eggs are passed in stool and hatch in the soil after 1 to 2 days if they are deposited in a warm, moist place on loose soil. Larvae emerge and live in the soil. The larvae can survive 3 to 4 weeks in the environment if conditions are favorable. After 5 to 10 days of development, larvae are able to cause infection and can penetrate the skin. A person can become infected by walking barefoot or sitting in contaminated soil. Larvae ofAncylostoma duodenalecan also cause infection when people consume food that contains the larvae. Once larvae enter the body, they move through the bloodstream to the lungs. The larvae pass into the air spaces of the lungs and move up the respiratory tract. They are coughed up into the throat and swallowed. About a week after penetrating the skin, they reach the intestine. Once inside the intestine, the larvae develop into adults. They attach themselves by their mouth to the lining of the upper small intestine, where they feed on blood and produce substances that keep blood from clotting. As a result, blood is lost, and Overview of Anemia may develop. Adult worms may live 2 or more years. 