They are also round and white. Adult pinworms inhabit the large intestine, and at nighttime, the fertilized female ventures towards the rectum to deposit her eggs. These eggs are quite sticky, and irritating, so that most children, and adults, will eventually scratch the area, and more than likely then put their fingers in their mouth, or onto someone else s hands. In this way, the infection can be easily passed on to others, or perpetuated within oneself. The usual symptoms are itching around the rectal area, at night, though sleeplessness, abdominal pains or vaginal symptoms may also occur.
Tapeworms are a bit different.
They are flat. They are contracted by eating raw or undercooked meats. This is sometimes the local custom, sometimes due to carelessness, and sometimes due to a need to sample the food as it is being prepared. The symptoms of tapeworm infections are usually mild, and it is usually a short segment wriggling around the rectum that gives it away. Most travellers who pick up some sort of intestinal worm in the tropics do not become terribly ill.