Head lice live in the hair, feed on blood from the scalp and lay eggs called nits. They are often most noticeable behind the ears and at the nape of the neck.
parasites
Threadworms (pinworms)
Threadworms do not go away by themselves, so they must be treated in order to eradicate them.
Cryptosporidium infection
Cryptosporidium is a microscopic parasite that can infect the intestines and cause gastroenteritis symptoms such as watery diarrhoea, abdominal cramps, nausea and vomiting.