Life Cycle of Ascaris

Ascaris, a roundworm parasite, resides within the small intestine of the host human or animal. The female worm can easily attain a length of up to 12 inches within the body, according to the Centers for Disease Control and Prevention. Infections occur in tropical and subtropical regions of the world that often lack proper sanitation or hygiene.

  1. Transmission

    • The eggs of the ascaris thrive in feces. When feces comes into contact with soil, the eggs become infectious. A person or animal must inadvertently swallow the eggs of the ascaris to become infected. Pigs have also been known to pass ascaris to humans when their fecal matter is used to fertilize gardens and crops. Children contract ascaris infestations more than adults because they often play in infected dirt and then touch their mouths.

    Egg Laying

    • A female ascaris worm can lay up to 240,000 eggs per day, according to the Michigan State University. After the eggs are passed out of the host's body in the fecal matter, the eggs require a period of fetal growth within the soil. Most eggs become infective within 18 days but a few may take longer.

    Larvae

    • Once the eggs are consumed, they hatch into larvae in the intestinal tract of the host. The larvae invade the intestinal mucosa to gain entrance into the systemic circulation of the body. Once within the system they quickly invade the lungs. Once inside the lungs the larvae begin to mature over a period of 14 days.

    Larvae Travel

    • The larvae invade the bronchial tubes outside the lungs to make their way to the throat, where they are swallowed by the host. Once the larvae are swallowed they head for the intestinal tract where they grow into adult worms. The entire cycle from egg to adult worm takes approximately three months. An adult worm will live out its life inside the host's intestinal tract. Most worms live between one and two years.

    Symptoms and Treatment

    • Humans and animals suffering from infestation with ascaris rarely exhibit symptoms. The sufferer may have abdominal pain if the infestation is severe. The adult worms feed on the intestinal food which can cause malnutrition to occur in young children. On rare occasions the penetration of the larvae into the lungs can cause blood to pool. Pneumonia can develop. Once a diagnosis of ascaris is made, the patient will normally be prescribed Benzimidazoles for treatment, according to eMedicine.