Summary

• Ascaris lumbricoides, the largest intestinal nematode known to infect humans, infects 800 to 1200 million people worldwide.
• Infection is concentrated in developing countries of Asia, Africa, and Latin America.
• Acquired by ingesting eggs that are passed in human faeces and mature in the soil. Diagnosis can be made in most cases by finding characteristic eggs in a stool sample.
• Infection is usually asymptomatic, but the parasite can produce allergic pneumonitis and intestinal obstruction.
• Secondary complications include biliary and pancreatic obstruction, cholangitis, appendicitis, malnutrition, and cognitive and growth delay in young children.
• Drugs used in treatment include albendazole, mebendazole, ivermectin, and pyrantel pamoate.