Roundworms are parasitic organisms that live inside people, animals, and plants. They can cause a number of different types of infections and diseases in humans.
What Are Roundworms?
Roundworms are a group of tiny animals that have a long round body and no backbones (invertebrates). They live inside people, animals, and plants. Roundworms are considered parasites
. About 60 species of roundworms infect humans and billions of people are infected with one or more types of roundworms.
The eggs of roundworms live in the soil. They are picked up by animals or people through the mouth or the skin. Roundworms can cause disease in humans. Some of the diseases include:
- Ascariasis is the most common worm infection
in humans. It can grow from 6 to 13 inches. The larvae
and adult worms live in the intestine causing disease.
- Hookworm is an intestinal parasite of humans. The larvae and worms live in the small intestine. There are two main types of hookworm that affect humans, Ancylostoma duodenale and Necator americanus.
- Pinworm is a small, thin, white roundworm that causes colon and rectal infection. Pinworm is also called enterobiasis, oxyuriasis, seatworm infection, and threadworm infection.
- Toxocariasis is an infection transmitted from cats (Toxocara cati) and dogs (Toxocara canis) to humans. There are two forms of toxocariasis, visceral toxocariasis, which attacks the organs of the body, and ocular toxocariasis, which attacks the eye.
- Trichinosis, also called trichinellosis, is a disease that people get by eating raw or undercooked meat from infected animals.
How Common Is Roundworm Infection?
Roundworms are naturally occurring organisms in the environment. They can be picked up by animals and humans through the soil and by animal to human transfer or by human to human transfer. Nematodes, also known as roundworms, include almost half a million different kinds of species. The World Health Organization estimates that about 1.2 billion people worldwide are infected with ascariasis and that between 500 and 800 million people have hookworm infections globally. In the United States, about 4 million people are infected with ascariasis. The most common type of roundworm infection in the United States is pinworm infection with about 42 million cases reported.
What Are the Causes of Roundworm Infection?
Who Is at Risk for Roundworm Infection?
- Ascariasis: People living in warm and humid climates with poor sanitation and hygiene are at increased risk.
- Hookworm: People living in warm and moist climates with poor sanitation and hygiene are at increased risk.
- Pinworms: People most at risk for pinworm infection are schoolaged children, people living in institutions, and people who live with or care for people who are infected with pinworm.
- Toxocariasis: People who have dogs or cats in the home are at increased risk.
- Trichinosis: People who eat meat from infected animals are at increased risk. Animals most likely to be affected are carnivorous (meat eating) or omnivorous (meat and plant eating) such as bear, wild boar, or domestic pig.
What Are the Signs of Roundworm Infection?
- Ascariasis: Many people who are infected with Ascariasis show no signs of infection. Some will describe intestinal discomfort, such as nausea and vomiting and abdominal pain. If the condition has spread throughout the body, the person may have a cough or other symptoms associated with where in the body the disease has spread.
- Hookworm: Signs of infection include itching and a rash at the site of the entry through the skin. A person with a severe infection of hookworm may have abdominal pain, diarrhea, loss of appetite, weight loss, fever, fatigue, pale skin, and anemia
- Pinworm: Some people who are infected with pinworm have no signs. Those who do complain of itching around the anus (opening from the rectum).
- Toxocariasis: People who are infected with toxocariasis may or may not become sick from the worms. Those who do become sick may have eye inflammation
, fever, coughing, wheezing, abdominal pain, and fatigue.
- Trichinosis: Signs of trichinosis include nausea, diarrhea, vomiting, fever, abdominal discomfort, and tiredness (fatigue). As the disease progresses, the person may experience headaches, chills, cough, swelling of the face and eyes, eye infection, skin rashes, muscle weakness, and aching or painful joints and muscles.
How Is Roundworm Infection Diagnosed and Treated?
The healthcare provider obtains a complete health history asking specific questions about signs of the disease, the presence of pets in the home, exposure to possibly contaminated soil through gardening or farming, and handwashing and hygiene practices. Physical examination is done to confirm symptoms and to determine additional findings of parasitic infection. A blood sample is drawn to examine the blood for signs of infection, such as increased white blood cell count, or signs of anemia. As most of the roundworm infections are in some portion of the intestine, stool is often examined for presence of the eggs or parasites. Diagnostic studies that may be specific to the disease include:
- Ascariasis: A stool sample is examined looking for the presence of ascariasis eggs.
- Hookworm: A stool sample is examined looking for the presence of hookworm eggs.
- Pinworm: Observe for pinworms around the anus two to three hours after the person is asleep. Use transparent sticky tape to touch the area around the anus to pick up pinworm eggs, which can be seen under a microscope. Analyze scrapings from under the fingernails under a microscope to see if there are pinworm eggs. Because pinworm causes anal itching, when the person scratches the area they may pick up pinworm eggs.
- Toxocariasis: A blood sample is examined for signs of the Toxocara larvae.
- Trichinosis: A laboratory test is done to determine the presence of Trichinella antibody. A biopsy of muscle may also be done.
- Ascariasis: Anti-parasitic medications are used to treat ascariasis.
- Hookworm: Anti-parasitic (anti-helminthic) medications are used to treat hookworm. Iron supplements may also be prescribed if the person has anemia.
- Pinworm: Anti-parasitic medications are used to treat pinworm.
- Toxocariasis: There are two treatments depending on the type of infection the person has. Treatment for toxocariasis infection of the eye is usually focused on preventing damage to the eye. Treatment for toxocariasis in the body, other than the eye, is antiparasite medication.
- Trichinosis: Anti-parasitic medications are used to treat trichinosis. Can Roundworm Infection Be Prevented?
Can Roundworm Infection Be Prevented?
Roundworm diseases can be prevented by careful hygiene practices.
Specific prevention strategies for pinworm:
- Wash pajamas, nightwear, and sheets frequently
- Change underwear daily
- Avoid nail biting
- Avoid scratching the anal area
Specific prevention strategies for Trichinosis:
- Avoid eating meat from wild carnivorous
- Cooking meat thoroughly to an internal temperature of at least 170° F before eating
See also Global Health Issues: Overview
• Intestinal Infections
• Intestinal Parasites
• Parasitic Diseases: Overview
• Travel-Related Infections: Overview
• Zoonoses: Overview
Books and Articles
Holland, Celia. (ed.). Ascaris: The Neglected Parasite. Waltham, MA: Academic Press, 2013.
Despommier, Dickson D. People, Parasites, and Plowshares: Learning from Our Body's Most Terrifying Invaders. New York: Columbia University Press, 2013.
Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329. Toll-free: 800-232-4636. Website:
(accessed April 9, 2016).
National Institute of Allergy and Infectious Diseases. 5601 Fishers Ln., MSC 9806, Bethesda, MD 20892. Toll-free: 866-284-4107. Website:
(accessed April 9, 2016).
* parasites are organisms such as protozoa (one-celled animals), worms, or insects that must live on or inside a human or other organism to survive. An animal or plant harboring a parasite is called its host. Parasites live at the expense of the host and may cause illness.
* infection (in-FEK-shun) is the invasion and proliferation of microorganisms in the body, including bacteria, viruses, or parasites.
* larvae (LAR-vee) is the immature form of an insect or worm that hatches from an egg. The singular form is larva (LAR-vuh).
* anemia (uh-NEE-me-uh) is a blood condition in which there is a decreased hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.
* Inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.
* carnivorous (KARN-i-vor-us) refers to an animal or a plant which eats animals.
* omnivorous (om-NIH-vor-us) refers to an animal which eats animals and plants.