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Ascariasis is an infection of the small intestine caused by Ascaris lumbricoides (A. lumbricoides), which is a species of roundworm.
Roundworms are a type of parasitic worm. Infections caused by roundworms are fairly common. Ascariasis is the most common roundworm infection. About 10 percent of the developing world is infected with intestinal worms, according to the World Health Organization (WHO). However, infections with parasitic worms are not as common in the United States, according to the Centers for Disease Control and Prevention (CDC).
Ascariasis is most common in places without modern sanitation. People get it through unsafe food and water. The infection usually causes no symptoms, but higher numbers of roundworms (heavier infestations) can lead to problems in the lungs or intestines.
You can become infected with ascariasis after accidentally ingesting the eggs of the A. lumbricoides roundworm. The eggs can be found in soil contaminated by human feces or uncooked food contaminated by soil that contains roundworm eggs. Children often become infected when they put their hands in their mouths after playing in contaminated soil, according to WHO. Ascariasis can also be passed directly from person-to-person.
After ingestion, the A. lumbricoides roundworm reproduces inside your intestine. The worm goes through several stages:
The roundworm is found worldwide, but it’s more frequently found in tropical and subtropical regions, including Latin America and sub-Saharan Africa. It’s also more common in areas where sanitation is poor.
Environmental risk factors for ascariasis include:
You can limit your exposure to roundworms by avoiding unsafe food and water. Keeping your immediate environment clean also helps. This includes laundering clothing exposed to unsanitary conditions and cleaning cooking surfaces well.
You should make sure to take precautions if you’re visiting a remote area. It’s important to:
Children who are 3 to 8 years old are most likely to be infected because of their contact with soil while playing.
People with ascariasis often have no symptoms. Symptoms become more noticeable when the roundworm infestation grows.
Roundworms in your lungs can cause:
Roundworms in your intestines can cause:
Some people with a large infestation may have other symptoms, such as fatigue and fever. A major infestation can cause extreme discomfort. You may have all or many of the above symptoms if you don’t receive prompt treatment.
Most cases of ascariasis are mild and don’t cause major problems. However, heavy infestations can spread to other parts of the body and lead to dangerous complications. They can include:
Children are more likely to have gastrointestinal complications because their small intestines increase their chances of having an intestinal blockage.
Doctors generally make the diagnosis by examining a stool sample for parasites and ova (eggs). If your doctor suspects you have ascariasis, he or she will ask for a stool sample from you.
If you’re diagnosed with ascariasis, you may need more tests, such as one of these imaging tests:
Imaging tests can show:
To evaluate your risk for complications, it’s important for your doctor to determine how long you’ve been infected.
Doctors usually treat roundworm with antiparasitic drugs. Medications most commonly used include:
If you have an advanced case, you may need other treatment. Your doctor may recommend surgery to control a larger infestation. You’ll need surgery if the roundworms are completely blocking your intestines.
Many people recover from ascariasis with minimal treatment. Symptoms may go away even before all the worms are gone.
However, ascariasis can cause complications when there are large infestations. If you think you’ve been infected with roundworms, be sure to see your doctor.
The best way to avoid ascariasis is by:
Written by: the Healthline Editorial Team
Medically reviewed on: Jun 28, 2017: Xixi Luo, MD
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