The life cycle of Ascaris lumbricoides, a common human roundworm, begins with the ingestion of infective eggs. These eggs are passed in the feces of an infected individual and can survive in the environment for several weeks to months.
When the eggs are consumed, they hatch in the small intestine and the larvae migrate to the lungs through the bloodstream. In the lungs, the larvae mature and migrate up the bronchial tree to the throat, where they are swallowed and returned to the small intestine.
Once in the small intestine, the larvae develop into adult worms. Adult females can reach up to 40cm in length and adult males can reach up to 20cm. The adult worms live in the small intestine and reproduce sexually. The females release fertilized eggs which are passed in the feces.
The life cycle of Ascaris lumbricoides can take several weeks to a couple of months, depending on the conditions. Heavy infections can cause malnutrition, abdominal pain, and diarrhea. In rare cases, the migration of the larvae through the lungs can cause coughing and difficulty breathing.
The infection can be treated with medication such as albendazole or mebendazole. Good hygiene practices, such as washing hands regularly and properly disposing of feces, can help prevent infection.