How to Recognize an Ascaris Infection

Co-authored by Carlotta Butler, RN, MPH

Last Updated: February 14, 2023 References

Ascariasis is a type of infection caused by a roundworm called Ascaris lumbricoides. These parasitic worms eventually settle and grow in the small intestine — they can grow to 12 inches or more in length and drain the body of nutrients.^{[1]
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Cleveland Clinic
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Go to source} Ascariasis is common worldwide, especially in children who live in tropical and subtropical regions and where there are poor sanitation practices, but it's fairly rare in the United States.^{[2]
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Research source} Most infected people show mild or no obvious symptoms, so detecting ascariasis is often difficult; however, recognizing the signs and getting appropriate treatment can help prevent a variety of health problems.

Part 1

Part 1 of 3:

Recognizing Ascariasis

1
Take notice of respiratory symptoms. Although most people infected with Ascaris lumbricoides worms don't have noticeable symptoms, those with weaker immune systems often do. Sometimes the first signs of ascariasis are similar to mild-to-moderate cases of asthma or pneumonia, such as persistent cough, shortness of breath, wheezing and mild chest pain. You may cough up mucus (sputum) and see blood. These initial lung symptoms are related to the worm's life cycle.^{[3]
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Centers for Disease Control and Prevention
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- After ingesting fertilized Ascaris eggs, they hatch in the small intestine and the larvae get absorbed into the blood and travel to the lungs, causing irritation and a type of allergic response.
- After spending about a week in the lungs, the larvae eventually get coughed up the trachea and into the throat, where they are swallowed down the esophagus into the stomach and pass into the small intestine.
2
Be aware of abdominal pain and nausea. The Ascaris larvae leave the lungs and end up in the small intestine, where they mature into adult worms over the course of a few weeks and live there until they die (many months or a few years). The worms don't always cause symptoms in the intestine, but if enough of them are there, one of the first signs is vague abdominal pain and mild nausea.^{[4]
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Cleveland Clinic
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- The worms can block the intestine or bile duct and this causes abdominal pain.
- The abdominal discomfort is difficult to pinpoint and can easily be mistaken for indigestion and bloating, but it's not relieved by passing gas or taking antacids.
- In mild cases, the nausea comes and goes, but does not usually lead to vomiting.
- Children who live in poor sanitary conditions and have weakened immune systems are much more likely to get infected and develop symptoms.
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3
Watch for bloody diarrhea. If the body's immune system can't fight the worm infection, then more of them grow and increase the likelihood of uncomfortable symptoms, such as severe abdominal pain and diarrhea. As the diarrhea becomes chronic and the worms irritate the intestinal wall, blood can often be seen in the toilet.^{[5]
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Cleveland Clinic
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- If the blood is dark and looks like coffee grounds, then it signifies bleeding from the small intestine. If the blood is bright cherry red, it signifies bleeding from the rectum from too much wiping or a burst blood vessel from straining too hard.
- In addition to blood in the stool, sometimes a visible Ascaris worm(s) can be seen in the toilet.
4
Look for chronic vomiting and weight loss. In moderate-to-severe cases of Ascariasis, the worms can nearly completely block the small intestine, which leads to severe abdominal pain and nausea, and triggers bouts of vomiting.^{[6]
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Cleveland Clinic
Educational website from one of the world's leading hospitals
Go to source} Once the vomiting becomes regular (daily) and chronic (for more than a few weeks), relatively rapid weight loss is seen.
- Even if food is available, it's often not eaten due to loss of appetite and painful digestion.
- Weight loss is most noticeable around the face, upper body and buttocks/thighs. The abdomen can still protrude due to the mass of worms and blockage of food and liquids.
- Worms can often be seen in the vomit of people with severe Ascaris infections.
5
Take note of signs of malnutrition. As the symptoms of ascariasis progress, particularly in children, signs of malnutrition become more obvious and include: severe weight loss, stunted growth (short for age), weakness, fatigue, skin rashes, visual problems and intellectual/developmental disability.^{[7]
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Research source} The most common nutritional deficiencies related to ascariasis are protein, vitamin A and vitamin C.^{[8]
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- A lack of protein causes muscle wasting and weakness, as well as a distended belly.
- Lack of vitamin A leads to visual problems and potential blindness, as well as skin issues.^{[9]
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- Lack of vitamin C leads to skin issues, internal bleeding, hair and teeth loss, as well as fatigue and listlessness.
6
Distinguish it from other infections. Ascariasis can mimic a great number of other types of infections and diseases. When the Ascaris larvae cause symptoms in the lungs, it can be similar to asthma and upper respiratory viral infections, such as influenza, the common cold and pneumonia. When the growing adult worms affect the gastrointestinal system, then it can mimic other parasitic infections, food poisoning and viral gastroenteritis (stomach flu).
- There's also some symptomatic overlap with gluten sensitivity, irritable bowel syndrome and Crohn's disease.
- It's only when actual worms are found in vomit or diarrhea that Ascariasis is more obvious to doctors and patients, and easily distinguished from other infections or diseases.

Part 2

Part 2 of 3:

Preventing Ascariasis

1
Avoid contact with contaminated soil. Ascaris worms thrive in soil that has human and animal feces (poop) in it. In many places in the world, fecal matter is intentionally used to fertilize crops, so be cautious when traveling in undeveloped countries, particularly rural farming areas. Children who live in these areas often become infected after putting their hands into their mouths after playing or working in contaminated soil.^{[10]
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Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services
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- Eating uncooked food (fruits and veggies) grown in contaminated soil or irrigated with wastewater is another frequent cause of infection.
- Always thoroughly wash produce at home before you eat, regardless of where you bought it from. Consider cooking all raw veggies before you eat them.
- Soaking fresh produce in water with some iodine, hydrogen peroxide and/or white vinegar might help kill parasites, as well as some viruses and bacteria.
2
Practice good hygiene. In addition to washing your produce, washing yourself and practicing good hygiene is another method to help prevent Ascaris worm infection.^{[11]
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Research source} Always wash your hands after going to the bathroom and before and after handling food. Ascaris worm larvae and eggs are spread in feces, either in soil, in water or from unwashed hands.
- Wash your hands frequently with warm water and soap, especially if you're traveling and buying food in undeveloped countries in Asia and Africa.
- When traveling, carry a small bottle of alcohol-based hand sanitizer with you and use it often to clean your hands.
- If you're without soap and sanitizer, try using fresh citrus juice (from lemons, limes or grapefruits) on your hands to clean them.
3
Avoid traveling to developing countries. If you really want to reduce your risk of Ascariasis then the best advice is to avoid under-developed countries where the infection is most common, such as rural China, Southeast Asia, sub-Saharan Africa, India, Latin America, the Caribbean and parts of the Middle East.^{[12]
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Research source}
- If you do need to travel to these areas for work or family reasons, take the sanitary precautions mentioned above. Wash your hands frequently, keep your hands away from your mouth, use only bottled water and avoid eating raw veggies.
- In the U.S., ascariasis is most common in the Southeastern states, but not nearly as prevalent as it is in developing countries with warm temperatures year-round.^{[13]
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Part 3

Part 3 of 3:

Treating Ascariasis

1
Wait and see. Typically, only Ascaris infections that cause symptoms need to be treated, which is in the minority of cases. In many cases, the symptoms of ascariasis will flare up for a short period of time (a few weeks), then become unnoticeable for long stretches of time. In some cases, ascariasis completely resolves on its own due to a stronger immune system being able to defeat it.
- In many parts of the world where ascariasis is endemic, the lack of nutritious food and clean water is more of a concern than parasitic infections.
- Adults usually deal with ascariasis much better than kids. If a child is failing to thrive and losing weight, then it's time for a doctor's visit to see why.^{[14]
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- A doctor will look at a stool sample for Ascaris eggs in order to make a diagnosis.
2
Take anti-parasitic medication. Anti-parasitic (or anti-helminthic) drugs are considered the first line of treatment against ascariasis and most other parasitic worm infections. The most commonly prescribed medications to kill Ascaris worms are albendazole (Albenza), ivermectin (Stromectol) and mebendazole.^{[15]
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Trustworthy Source
Centers for Disease Control and Prevention
Main public health institute for the US, run by the Dept. of Health and Human Services
Go to source}Ascaris infections are typically treated for between one to three days with pills.
- An effective single dose of albendazole is 400 mg; for mebendazole it's 500 mg.^{[16]
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- Albendazole and mebendazole are not recommended during pregnancy; pyrantel pamoate is the drug of choice for pregnant women.
- These drugs effectively kill the adult worms and usually don't cause any side effects. People often carry larvae that aren't killed by drugs, so they need a follow-up treatment within six months.
3
Consider surgery as a last resort. In cases of severe Ascaris infections and heavy intestinal infestation, surgery may be necessary to remove the mass of worms and repair the damage they've caused. The primary reasons for surgery include: intestinal blockage (obstruction) or perforation, bile duct blockage, pancreatitis, and/or an appendicitis flare up related to the infection.^{[17]
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PubMed Central
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- Your doctor will likely take x-rays (abdomen and chest), ultrasound, CT scan and/or an MRI to determine the extent of your problem before recommending surgery.
- Surgery is usually performed with an endoscope — a small tube with a cutting device and a camera on the end that's inserted either down the throat or up through the anus to reach the worms in the small intestine.