They can easily go undetected because the signs are difficult to see. Threadworms grow in the gut of humans - their entire life is based around living in our bodies. Contrary to the popular belief, threadworms can not be picked up from animals, explain pharmacists. Animals may be infected by other types of worms but transfer to humans is very rare. Worms like whipworm or hookworm are rare in New Zealand because of our good hygiene standards.
Pharmacists say threadworms are about as easy to pass on between people as the common cold.
For example, a child simply needs to scratch his or her bottom, which has been irritated by the threadworms, to catch some eggs under their fingernails. Then when the child touches his or her mouth or food, the threadworm is reintroduced to the body and the life cycle continues. They are passed from person to person by sharing things such as food, clothes and utensils. Threadworms look like short pieces of white cotton, about 5 to 10 mm long. When you swallow the eggs, they hatch in the gut.