Ascaris lumbricoides is a large parasitic roundworm that infects the intestines of humans. It can grow up to 35 centimeters long and is often found in areas with poor sanitation. People typically become infected by ingesting eggs from contaminated food or water. Once inside the body, the eggs hatch, and the larvae migrate through the bloodstream to the lungs before returning to the intestines to mature. Infection with Ascaris lumbricoides can lead to various health issues, including abdominal pain, malnutrition, and intestinal blockages. Preventing infection involves practicing good hygiene, such as washing hands and ensuring food is clean. Treatment usually includes medications that effectively kill the worms.