system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do parasites, like tapeworms, manage to survive the gastric juices of the stomach and get to the rest of the digestive tract?
gpt
Threadworms or pinworms actually use the stomach acid to trigger hatching. The eggs are ingested and the stomach acid strips away the sacrificial outer layer causing them to hatch later when they have passed through to the lower intestines. The adult worms irritate the sphincter to aid the dispersal of the eggs by scratching so that they are not simply passed into the stools of the host but are instead lodged beneath the fingernails etc.