Ascaris parasites live in the intestine. Ascaris eggs are passed in the faeces (poop) of infected people. If an infected person defecates outside, if the faeces of an infected person are used as fertilizer, worm eggs are deposited on soil. The worm eggs can then grow into a form of the parasite that can infect others. Ascariasis is caused by ingesting those worm eggs.
- Ascaris lumbricoides is the largest intestinal nematode of humans.
- Females are up to 30 cm long; males are smaller.
- Three types of eggs may appear in faeces: fertilized, unfertilized, and decorticated.