Most people infected with ascariasis have no symptoms. Moderate to heavy infestations cause symptoms that may vary, depending on which part of your body is affected.
In the lungs
After you ingest the microscopic ascariasis eggs, they hatch in your small intestine and the larvae migrate through your bloodstream or lymphatic system into your lungs. At this stage, you may experience signs and symptoms similar to asthma or pneumonia, including:
- Persistent cough
- Shortness of breath
After spending six to 10 days in the lungs, the larvae travel to your throat, where you cough them up and then swallow them.
In the intestines
The larvae mature into adult worms in your small intestine, and the adult worms typically live in the intestines until they die. In mild or moderate ascariasis, the intestinal infestation can cause:
- Vague abdominal pain
- Nausea and vomiting
- Diarrhea or bloody stools
If you have a heavy intestinal infestation — a large number of worms — you may experience:
- Severe abdominal pain
- Weight loss
- A worm in vomit or stool
When to see a doctor
Consult your doctor if you have persistent abdominal pain, diarrhea or nausea.
Ascariasis isn't spread directly from person to person. Instead, a person has to come into contact with soil mixed with human feces that contain ascaris eggs. 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.
Because small children often play in dirt, infection can occur if they put their dirty fingers in their mouths. Unwashed fruits or vegetables grown in contaminated soil also can transmit the microscopic eggs that cause ascariasis.
Life cycle of a worm
- Ingestion. The microscopic ascariasis eggs can't become infective without coming into contact with soil. People can accidentally ingest contaminated soil through hand-to-mouth contact or by eating uncooked fruits or vegetables that have been grown in contaminated soil.
- Migration. Larvae hatch from the eggs in your small intestine and then penetrate the intestinal wall to travel to your lungs via your bloodstream or lymphatic system. After maturing for about a week in your lungs, the larvae break into your airway and travel up your throat, where they're coughed up and swallowed.
- Maturation. Once back in the intestines, the parasites grow into male or female worms. Female worms can be more than 15 inches (40 centimeters) long and a little less than a quarter inch (6 millimeters) in diameter. Male worms are generally smaller.
- Reproduction. Male and female worms mate in the small intestine. Female worms can produce 200,000 eggs a day. You expel the eggs in your feces. The fertilized eggs must be in soil for at least 18 days before they become infective.
The whole process — from egg ingestion to egg deposits — takes about two or three months. Ascariasis worms can live inside you for 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 worms thrive in mild climates. In the United States, ascariasis is more common in the Southeast. But it's more prevalent in developing countries with warm temperatures year-round.
- Poor sanitation. Ascariasis is widespread in developing countries where human feces are allowed to mix with local soil.
Mild cases of ascariasis usually don't cause complications. If you have a heavy infestation, potentially dangerous complications may include:
- Nutritional deficiencies. Children with ascariasis are especially at risk of nutritional deficiencies. Loss of appetite and insufficient absorption of digested foods can occur.
- Intestinal blockage and perforation. In heavy ascariasis infestation, a mass of worms can block a portion of your intestine, causing severe abdominal cramping and vomiting. The blockage can even perforate the intestinal wall or appendix, causing internal bleeding (hemorrhage ) or appendicitis.
- Duct blockages. In some cases, worms may block the narrow ducts of your liver or pancreas, causing severe pain.
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 hot and cooked.