We are not talking about worms in the garden, those helpful little guys working away to help plants grow. We are talking about the type of worms that make you think “eww!” or “urgh!”. We are talking about threadworm (pinworm) infection. And while worms are more common in children, they can affect anyone in the family. So, what causes threadworms and how do they spread from one person to another?

Causes of worms in children

At a basic level, you catch threadworms when you get worm eggs on your hands and then put your contaminated hands or fingers in your mouth. The end result? A threadworm infection. So how do kids get worm eggs on their hands in the first place? Quite easily actually – by coming into contact with another person who has worms or by touching objects that have been contaminated with worm eggs, including their own bottom.

Wait a second – how did worm eggs get on your kids bottom? Well, once worm eggs have been swallowed, a cycle of infection and contamination begins. First, the eggs travel through the stomach to the intestines, where they hatch into little worms and live and grow for about a month. Then the female worms continue traveling down through the intestines to the anus – this is the opening in our bottom where faeces (poo) comes out. The female worms exit the anus and lay their eggs on the skin surrounding the anus, which causes itching. So, when a child scratches their itchy bottom, they transfer the freshly-laid worm eggs to their fingers. And when their contaminated hands touch their mouth or food, the cycle continues.

Causes of worms in adults

If that’s what causes worms in kids, what causes worms in adults? Adults are less likely to put their hands in their mouth after scratching their bottom, thank goodness! The basic process is the same though – contaminated hands or food will transfer eggs to an adult’s mouth and eggs will pass into the intestines to start the same infection cycle described above. But adults are more likely to pick up the highly contagious worm eggs directly from their children or from contaminated objects around the home. One of the reasons that worms can spread between people so easily is that with the right conditions, worm eggs can survive outside the human body for a few days and in some cases even more than 2 weeks!

Obvious culprits that can easily be contaminated with worm eggs include the toilet seat and handle, bath, and tap handles in the bathroom, as well as clothing, bed linen, and towels that come into contact with bottoms. But importantly, any household object that is touched frequently risks having eggs transferred to it. Think of objects like door handles, light switches, TV remotes, kids’ toys, and kitchen utensils and appliances. Less obvious items that can harbour worm eggs include bits of furniture and carpet or rugs.

Who’s most at risk of getting worms?

We mentioned at the start that threadworm infections are most common in children – why is that? Worms are highly contagious and spread easily in places where there are groups of people, especially when these people come into contact with each other frequently. This pretty much describes schools and daycare centres, which helps to explain why worms are so common in kids. Another factor that puts school-aged children at high risk of catching worms is that they often share food, toys, and other items that are easily contaminated with worm eggs. And unfortunately, kids may not always practice good hygiene habits such as regular hand washing before eating and they may be more likely to scratch their bottom or bite their nails where worm eggs can be hiding.

What about in the family home? Well, these same factors – groups of people in close contact that share contaminated objects – contribute to the spread of worms among a family who all live together. So, when your child brings home worms from school, it’s highly likely that the rest of the family will become infected too.

There you have it – now you know the cause of worms in children and adults, and how and why they can spread so easily between people. But here’s the good news: treating worms is easy with VERMOX®. VERMOX kills adult worms with one dose and treating the whole family can break the cycle of infection and contamination.

Frequently asked questions about what causes worms


Unfortunately yes – threadworms are highly contagious and can easily be spread from one family member to another.


Your child may go to school once they have been treated for worms but should be kept at home if they have any associated tummy upsets. Always check with your child’s school and doctor for any specific recommendations.


If food is prepared or touched with hands that have been contaminated with worm eggs, then these eggs can be ingested and start the cycle of worm infection.


You cannot catch threadworms from your family pets. While unlikely, it is possible that your dog or cat could end up with threadworm eggs in their fur after being patted by contaminated hands, which could then be passed to another family member.


Threadworm eggs can survive for a few days outside the human body – and even over 2 weeks under the right conditions! This means they can survive on fabric, including your clothes, sheets, and towels, and even on furniture, carpets, and curtains.