Ascariasis symptoms depend on the amount of roundworms in your body, which organs are infected and your immune system health. Most people have no symptoms at all. But having a high number of worms makes symptoms more likely.

In the lungs

The tiny ascaris eggs are too small to see. After you swallow the eggs, they hatch in the small intestine. An early form of the worms, called larvae, come out of the eggs. The larvae travel into the lungs through the bloodstream or part of the immune system called the lymphatic system.

At this stage, you may have no symptoms, or symptoms may be like those of asthma or pneumonia. These symptoms include:

• Dry cough that may bring up blood.
• Shortness of breath.
• Wheezing.

After spending 10 to 14 days in the lungs, the larvae travel to the throat. You cough them up and then swallow them.

In the intestines

The larvae mature into adult worms in the small intestine. Most often, adult worms live in the intestine until they die. In mild or moderate ascariasis, worms in the intestine can cause:

• Vague stomach pain.
• Upset stomach and vomiting.
• Diarrhea or bloody stools.
• Loss of appetite.

If you have a large number of worms in the intestine, you might have:

• Serious pain in the stomach area.
• Constipation.
• Vomiting.
• Weight loss or not getting enough nutrients.
• A worm in your vomit or stool.

Talk with your healthcare professional if you have ongoing:

• Stomach pain.
• Diarrhea.
• Upset stomach or vomiting.

Ascariasis happens when roundworm eggs spread through human or pig stool. Most often, people get ascariasis when they swallow food or water tainted with stool that contains the worms. For example, eating vegetables or fruits that have not been washed, peeled or cooked can cause infection in places where ascariasis is common. So can eating pig or chicken liver that is infected and hasn't been cooked.

Tainted stool gets into food and water through soil. In some parts of the world, human or pig stool is used for fertilizer. Poor sanitary facilities also may allow stool to mix with soil in yards, ditches and fields.

Small children often play in dirt, and infection can happen if they put unwashed fingers in their mouths. Much less often, infection happens after breathing in tainted dust that's in the air.

Handling pigs or their manure for work also can cause ascariasis if infected pig stool is gets in the mouth, called ingested.

Life cycle of a worm

• Ingestion. The tiny ascaris eggs can't cause infection unless they first come into contact with soil. People can swallow tainted soil in various ways. These include hand-to-mouth contact or eating raw or undercooked fruits or vegetables that have been grown in contaminated soil.
• Travel through the body. Early forms of the worms called larvae hatch from the eggs in the small intestine. Then they go through the wall of the intestine and get into the bloodstream or part of the immune system called the lymphatic system. From there, they travel to the lungs. After growing for about 10 to 14 days in the lungs, the larvae break into the airway and travel up the throat. Then they're coughed up, swallowed and returned to the small intestine.
• Growth. Once they're back in the small intestine, the parasites grow into male or female worms. Female worms can grow to 13 to 15 inches (35 to 40 centimeters) in length. They can become about a quarter inch (6 millimeters) wide. Male worms tend to be smaller.
• Breeding. Female worms can produce 200,000 eggs a day if they mate with male worms in the small intestine. The eggs leave the body in stool. The fertilized eggs must be in soil for at least 2 to 4 weeks before they become able to infect people.

The whole process takes about two or three months. Ascariasis worms can live inside the body for about a year or two.

Risk factors for ascariasis include:

• Age. Most people who have ascariasis are 10 years old or younger. Children in this age group may be at higher risk because they're more likely to play in dirt.
• Warm climate. Ascariasis is most common in tropical and subtropical parts of the world with warm, wet climates.
• Poor sanitation. Ascariasis is widespread in places where human stool is allowed to mix with soil. The condition is rare in places with adequate sanitation.

Mild cases of ascariasis usually don't cause complications. But having many worms in the body may lead to problems such as:

• Slowed growth. Loss of appetite and poor absorption of digested food put children with ascariasis at risk of not getting enough nutrition. And that can slow growth.
• Intestine blockage and tearing. A mass of worms could block part of the intestine. This can cause serious stomach cramping and vomiting. The blockage also can make a hole in the wall of the intestine or in the appendix. The hole could cause internal bleeding or dangerous swelling of the appendix called appendicitis.
• Duct blockages. Sometimes, worms may block the narrow ducts of the liver or pancreas. This causes serious pain.

Follow these tips to help prevent infection:

• Practice good hygiene. Wash your hands with soap and water after you go to the bathroom and before you handle food. If your job involves raising pigs, wash your hands after handling pigs or their manure, or after cleaning pens.
• Eat and drink safely. Wash fresh fruits and vegetables thoroughly. Also peel or cook produce that's been grown in soil fertilized with manure. In places where ascariasis is common, eat only foods that are cooked and hot. Use bottled or boiled water.
• Supervise young children. Don't let them sit directly on soil or play in it.

Diagnosis of ascariasis involves a healthcare checkup to find out if the infection is the cause of your symptoms. Your healthcare professional asks you about your symptoms and may order tests.

If you have many roundworms in your body, you may see some after you cough or vomit. The worms can come out of other body openings, such as your nostrils. If this happens to you, take the worm to your healthcare professional. That way, your healthcare professional can identify the worm and make sure you get the right treatment.

Stool tests

Mature female ascariasis worms in the small intestine start laying eggs. In time, these eggs can be found in the stool.

Your healthcare professional checks your stool for the tiny eggs and larvae. But eggs won't appear in stool until at least 40 days after you're infected. And if you're infected with only male worms, you won't have eggs in your stool.

Blood tests

Blood tests can check for a higher than usual number white blood cells called eosinophils. Ascariasis can raise your eosinophil level, but so can other health conditions.

Imaging tests

• X-rays. If you have worms inside your body, an X-ray of the stomach area may show a mass of the parasites. Sometimes, a chest X-ray can reveal the larvae in the lungs.
• Ultrasound. An ultrasound may show worms in the pancreas or liver. This test uses sound waves to make images of internal organs.
• Computerized tomography (CT) scans or magnetic resonance imaging (MRI). Both types of tests create detailed images inside the body. The images can help your healthcare professional find worms that are blocking ducts in the liver or pancreas. CT scans combine X-ray images taken from many angles. MRI uses radio waves and a strong magnetic field.

Ascariasis treatment usually involves taking medicine. Sometimes surgery is needed.

Medications

Anti-parasite medicines can help the body get rid of roundworms that cause ascariasis. The most common medicines are:

• Albendazole.
• Mebendazole (Emverm).
• Ivermectin (Stromectol).

These medicines kill the adult worms in the small intestine. Albendazole and ivermectin are taken once. Mebendazole is taken once in a large dose or twice a day for three days in smaller amounts. Side effects can include mild stomach pain, headache and diarrhea.

Pregnant people may take an anti-parasite medicine called pyrantel pamoate.

Surgery

If many worms are in the body, sometimes surgery is needed to remove worms and repair damage they've caused. Intestine blockage or holes, bile duct blockage, and appendicitis are complications that may require surgery.

Your family healthcare professional might refer you to a doctor called a gastroenterologist, who is trained in digestive conditions. You may need to see a surgeon if the worms have blocked the intestines.

What you can do

Before your appointment, you may want to write down the answers to the following questions:

• When did your symptoms start?
• Does anything make your symptoms better or worse?
• Have you noticed worms in your stool or vomit?
• Have you traveled to developing countries lately?
• What medicines and supplements are you taking?

What to expect from your doctor

During the physical exam, your healthcare professional may press on parts of the stomach area to check for pain or tenderness. Your healthcare professional also may want a sample of stool for testing.