Roundworms are parasites that live in the lymphatic, circulatory and digestive symptoms of the host body. Roundworms transfer to the human body in a variety of ways. Taking measures to help prevent a roundworm infection is best since most often the infection is preventable with clean water, adequate sanitation conditions and uncrowded living conditions, according to the National Institute of Allergy and Infectious Diseases.
Contaminated Soil
Some roundworms enter the body through contact with contaminated soil. Hookworms can enter a person who walks barefoot on soil that contains the larvae of the roundworm. The larvae enter through the skin and then migrate to the lungs and the small intestines, where they feed off blood. Threadworms also enter the body through the skin after a host has walked on contaminated soil. The threadworms migrate to the lymph nodes in the host and, after moving to the throat, the larvae make their way to the intestines. Eggs leave the body through feces and, in unsanitary conditions, the feces contaminates the soil. Dogs, cats and raccoons may carry roundworms. Anyone ingesting soil contaminated with the infected animal feces may develop the roundworm infection.
Contaminated Food and Water
Eating and drinking foods and water containing the eggs or larvae of roundworms may cause the infection in humans. After a person ingests the worm eggs, the adults hatch inside the intestines. This mode of transmission occurs for roundworm infections such as the whipworm, trichinosis and pinworms. The female roundworms may lay eggs that leave the host body through stool or the roundworm deposits the eggs directly on the anus, as with a pinworm infection. Without proper hand washing after having a bowel movement or scratching the anus, the eggs may contaminate any food touched by the individual.
Eating undercooked meats may cause a roundworm infection such as trichinosis. Cooking wild bear and pork to a proper temperature helps kill any roundworm eggs in the meat.
With Guinea worm disease, the roundworm enters the body through contaminated drinking water. The adult roundworm migrates to the skin on the legs and causes a painful blister to form. When the infected person has their legs in water, the tip of the roundworm protrudes through the skin to lay eggs, contaminating more water, according to the University of Maryland Medical Center.
Insects
Several roundworm infections can be transmitted by biting insects. Also referred to as river blindness, onchocerciasis affects approximately 18 million people and is the second leading cause of blindness worldwide, according to The Merck Manual of Medical Information. Female blackflies breed near rivers and fast moving streams in tropical and sub-Saharan areas of the world. After biting an individual, the blackfly passes larvae into the skin of the host. Mosquito bites may transmit several different roundworms, which travel through the lymphatic system in the host and circulate the roundworm eggs through the circulatory system of the host.
