Lung signs and symptoms
Mild ascariasis — with only a few parasites in your body — may cause no symptoms. Symptoms occur with moderate or heavy infestations, sometimes progressing as the parasite migrates through your body. After you ingest ascaris eggs, they hatch in your intestine and the larvae migrate into your lungs. At this stage, you may experience symptoms similar to asthma or pneumonia, including:

• Persistent cough
• Shortness of breath
• Wheezing

Intestinal signs and symptoms
The ascaris larvae eventually reach your throat, where you cough them up and then swallow them. They then enter the intestine, where they mature and mate. In mild or moderate ascariasis, the intestinal infestation can cause:

• Vague abdominal pain
• Nausea and vomiting
• Diarrhea or bloody stools

Heavy infestation signs and symptoms
If you have a heavy intestinal infestation — a large number of worms — you may experience:

• Severe abdominal pain
• Fatigue
• Vomiting
• Weight loss
• A worm in vomit or stool 
• A worm emerging from nose or mouth

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The ascaris parasite can be transmitted when infected human feces are mixed with soil. In many developing countries, human feces are used for fertilizer or poor sanitary facilities allow human waste to mix with local soil in yards, ditches and fields. The microscopic eggs require 10 to 14 days in soil at warm temperatures to become capable of infecting a new host, and can remain viable in the soil for a long time. The eggs infect their hosts when humans eat contaminated vegetables or fruit grown in that soil.

After you ingest ascaris eggs, they hatch in your intestine and the larvae migrate to your lungs. Eventually the larvae reach your throat, where you cough them up and then swallow them. They then enter your intestine, where they mature into adults and mate. Adult worms can live up to two years, and female worms can produce more than 200,000 eggs daily. About two months after you first ingest ascaris eggs, mature worms begin laying eggs in your intestine. You then expel those eggs in your feces. If those eggs are ingested by someone else, the ascaris life cycle begins again.

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Risk factors for ascariasis include:

• Poor sanitation and the use of human feces as fertilizer. Ascariasis is more widespread in developing countries where human feces are allowed to mix with local soil. There, the eggs become infective and are capable of infecting people who eat produce grown in contaminated soil or otherwise ingest the eggs.
• Warm climate. Ascaris worms thrive in milder climates. In the United States, ascariasis is more common in the South. But it's more prevalent in developing countries with warm temperatures year-round.

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If you have gastrointestinal problems that won't go away, such as abdominal pain, diarrhea or nausea, consult your doctor.

However, if you have only mild ascariasis, you may never need medical attention. While symptomatic infections usually warrant treatment, infections with no symptoms typically don't need to be treated. In some cases, ascariasis will resolve on its own. This occurs when there are no male worms to mate with females and the females eventually die.

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In heavy infestations, it's possible to find worms after you cough or vomit, and the worms can come out of other body openings, including your nose. If you notice anything resembling a worm when you cough or vomit, or if one emerges from your nose or mouth, keep it to let your doctor examine it. Other tests, such as stool tests, blood tests and imaging tests, also can help your doctor identify ascariasis.

Stool tests
About two months after you ingest ascaris eggs, the ascaris worms mature and begin laying thousands of eggs a day. These eggs travel through your digestive system and eventually can be found in your stool. To diagnose ascariasis, your doctor will examine your stool for the microscopic ascaris eggs and larvae.

Blood tests
Eggs will not appear in stool until at least 40 days after you are infected. And in some cases — if you are only infected with male worms — you won't have any eggs at all. A blood test that shows you have an increased number of a certain type of white blood cell (eosinophils) may indicate the presence of ascariasis.

Imaging tests
If you are infested with a large number of worms, the mass of worms may be visible in an X-ray. An ultrasound may show if any ascaris worms are in your pancreas or liver. A CT or MRI scan may show if any worms are in your liver or bile ducts.

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Complications related to typical ascariasis are rare. However, potentially dangerous complications can develop if you have a heavy infestation.

• Nutritional deficiencies. Children with ascariasis are especially at risk of nutritional deficiencies. Loss of appetite and insufficient absorption of digested foods can occur as a large number of parasites take nourishment from the host's body.
• Intestinal blockage and perforation. In heavy ascariasis infestation, a mass of worms can block a portion of the intestine, causing severe abdominal cramping and vomiting. The blockage can even perforate the intestinal wall or appendix, causing hemorrhage or appendicitis.
• Allergic reactions. Some people develop allergic reactions to the ascaris worm's excretions and secretions, or to dead and dying worms. These reactions can cause signs and symptoms such as asthma, insomnia, eye pain and rashes.

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Medications
Anti-parasite (anti-helminthic) medications are the first line of treatment against ascariasis. The most common are mebendazole, albendazole (Albenza) and pyrantel pamoate (Pin-X). These medications work by killing the adult worms. You may have mild gastrointestinal side effects during treatment. Each medication can be taken as a single dose.

Although they are more than 90 percent effective at killing adult worms, you may need to take multiple doses to get rid of the infestation completely or if you become reinfected. You'll likely need repeat treatments in two or three months if testing indicates you still have eggs in your stool.

Surgery
In cases of heavy infestation, surgery may be necessary to repair damage the worms have caused and to remove worms. Intestinal obstruction or perforation, bile duct obstruction and appendicitis are complications that may require surgery.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.

The best defense against ascariasis is good hygiene and common sense. Follow these tips to avoid infection:

• Practice good hygiene. Ascariasis is spread by ingesting parasite eggs from contaminated soil. Before handling food, always wash your hands with soap and water, and wash fresh fruits and vegetables thoroughly.
• Use care when traveling. Ascariasis is the most common roundworm infection in the world, with higher infection rates in developing and warm-climate countries. When traveling, use only bottled water and avoid raw vegetables unless you can peel and wash them yourself. As a rule, eat only foods that are cooked and hot.

©1998-2009 Mayo Foundation for Medical Education and Research (MFMER). Terms of use.