Hookworms are the type of soil-transmitted helminth, or intestinal parasite that is transmitted through contaminated soil, entering people through their feet. People usually become infected with hookworms by walking barefoot on soil that contains the larval form the worm, although infection may also occur from any other soil-skin contact or ingestion. About 576 to 740 million people have hookworm infections, according to the Centers for Disease Control and Prevention in 2010.
Adult hookworms thrive in the intestines of carnivores, such as humans, cats or dogs. Hookworms lay eggs that exit the body with feces. Hookworm eggs hatch within a few days into their larval form, in which they can penetrate human or animal skin. Larvae move from the skin to the lungs and then the trachea, where they are swallowed. Hookworm larvae mature into adult worms in the intestines, where they attach to the intestinal walls and lay eggs, continuing the life cycle.
People acquire hookworm infections through contact with contaminated soil, such as through walking, sitting or playing in soil. Hookworm larvae usually require 5 to 10 minutes of contact with the soil to penetrate the skin, according to Iowa State University.
Symptoms of Infection
Hookworm infections cause itching and a localized rash where the hookworm larvae entered the skin, usually on the feet. People also often experience an itchy or painful allergic reaction as the larvae moves through the body, a reaction called cutaneous larva migrans. Although light hookworm infections may not cause symptoms, severe infections often cause weight loss, diarrhea, abdominal pain, fatigue, loss of appetite and anemia.
Doctors diagnose hookworms by examining a stool sample under a microscope and looking for eggs. Doctors sometimes also treat high-risk groups, such as school-age children and pregnant women, in developing countries without first testing for the parasite. This is called preventive treatment.
Treatment and Prevention
Doctors treat hookworm infections with anthelmintics, or drugs that cause the body to expel parasitic worms. Treatment is usually effective in one to three days. People who have lost large amounts of blood may also need blood transfusions or iron therapy. Prevent hookworm infections or reinfections by not walking barefoot in soil, especially in areas that have hookworms or where humans defecate outside. Wear gloves when gardening and avoid touching soil that might be contaminated.