Ascariasis Life Cycle

Ascariasis life cycle, understood

Ascariasis is a species of parasitic roundworm that can use the human body as a host for its eggs and larvae until they reach adulthood. Mature ascariasis can reach over a foot in length. So, what is an ascariasis life cycle?

Who can be affected by ascariasis?

Ascariasis generally affects children under the age of 10 and is not particularly common in the United States. Where it does occur in the US, it is largely confined to the warm climate of the south-eastern states. In tropical developing countries with poor sanitation and water, ascariasis is more common.

Children are more commonly affected than adults because they pick up worm eggs while playing in the dirt and then put their fingers into their mouths, swallowing the eggs without realizing that they have done so. Eating unwashed fruit in worm-affected areas can also transfer eggs into a child's body.

It's not possible to transfer an infestation from person to person.

What are the symptoms of ascariasis?

The symptoms of an ascariasis infection are somewhat tied to its life cycle as different parts of the body are affected by the passage of the maturing worms.

After the eggs have been initially ingested, they hatch out in your small intestine. The larvae then migrate through your bloodstream or your lymphatic system to reach your lungs. Here they may cause the following symptoms:

  • Shortness of breath
  • Wheezing
  • A persistent cough

The larvae spend a week to 10 days in the lungs before traveling up to the throat; you then cough up the larvae and swallow them, allowing the larvae to travel to your small intestine.

Once they have entered the small intestine, the worms mature into adults and remain there until they die. While the worms are in your intestine, you may experience:

  • Abdominal pain
  • Nausea and vomiting
  • Bloody stools or diarrhea

In cases of severe infestation, you may feel very tired and you will also lose weight. Dead worms may be seen in your vomit or stools.

Ascariasis lifecycle

The whole ascariasis life cycle of the worm takes between two and three months and the worms can live inside your body for up to two years.

The first part of the life cycle is the initial ingestion. The ascariasis eggs are microscopic and cannot become infective unless they come into contact with soil. Ingestion usually occurs through hand-to-mouth contact or by eating unwashed, uncooked vegetables or fruit that have been grown in soil that is contaminated.

Once ingested the eggs hatch into larvae in your small intestine.

The larvae then migrate through the intestinal wall, traveling through your bloodstream or lymphatic system until they reach the lungs. After spending a week or so maturing in the lungs, the larvae break through into your airway and travel up into your throat. Here they are coughed up and swallowed.

During the maturation stage, the worms mature into male or female parasites in your intestines. Females can reach 15 inches in length, whereas males are slightly smaller.

Once the worms have matured, they enter the reproduction phase of their life cycle. The worms mate in the small intestine where the females can lay as many as 200,000 eggs in one day. The eggs leave the body in the feces and must then lie in soil for at least 18 days, before they are infective.

Treatments and drugs

Generally speaking, only infections that cause the symptoms outlined above need treatment. Sometimes, ascariasis will resolve by itself without the need for treatment.

The usual line of treatment against ascariasis worms is anti-parasite medications, commonly:

  • Albendazole (Albenza)
  • Ivermectin (Stromectol)
  • Mebendazole

Once you have taken the medication, the adult worms die and are passed out of the body in the feces. You may experience mild stomach pains or diarrhea for a day or so.


Ascariasis worms usually affect children under the age of 10 who live in the south eastern US states. If you think that your child may be affected, always consult your family doctor without delay.

Last Reviewed:
August 22, 2017
Last Updated:
October 16, 2017