Embarrassing Illnesses

Threadworms are usually passed on through poor hygiene.  Threadworm eggs are transferred from the anus of an infected person to their mouth, or to another surface. If someone else touches that surface, and then touches their mouth, they will also become infected.

The cycle of infection

If you have threadworms, the female worms lay eggs around your anus or vagina (in females).

One female threadworm can release thousands of eggs, which are too small to be seen by the naked eye.

Transferring eggs

These eggs can be transferred from your anus to any of the following:

• underwear or clothes,
• bed sheets,
• towels, and
• carpet.

When laying eggs the female threadworm also releases an itchy mucus. If you scratch the affected area, eggs may be transferred on to your hands. Once the eggs are on your hands, they can be transferred to anything you touch including:

• children's toys,
• kitchen utensils,
• toothbrushes,
• furniture, or
• worktop surfaces in the kitchen or bathroom.

Swallowing the eggs

Threadworm eggs can survive on surfaces for up to three weeks. If you touch the eggs, they will be transferred onto your hands. If you then touch your mouth for, you may swallow the eggs.

It is also possible to breathe in the eggs and then swallow them. The eggs are so small that they can become airborne, for example, if you shake a towel or bed sheet that has eggs on it.

Once you have swallowed the eggs, they hatch in your intestines. After around two weeks the threadworms can reproduce and the cycle of infection will start again. 

Poor hygiene

Threadworms are most common in small children because they are not fully aware of the importance of good hygiene and they often forget to wash thier hands. Children can also prolong their infection by continually swallowing fresh eggs. As children regularly come into close contact with one another and share toys or hold hands while playing, re-infection is often easy.

Threadworms are often found in families, particularly in crowded conditions. The risk of transmission between family members can be as high as 75%.

Threadworms only infect humans and cannot be caught from animals. However, there is a small risk that threadworms can be caught from household pets if the animal's fur becomes contaminated with eggs. This could happen during petting or stroking. The eggs may then be passed onto the next human who touches the animal's fur.