Threadworms in Children: Night-Time Itching, Treatment and Family Hygiene

Your child wriggles in bed, scratches their bottom in their sleep and wakes up grumpy. When you change their nappy or help them on the toilet, you spot a tiny white thread that moves. These are very probably threadworms (also called pinworms), the most common intestinal worms in children. It is unpleasant and a little embarrassing to admit, but harmless in the vast majority of cases.

The real challenge is not getting rid of them once, it is stopping them coming back. Here is how to recognise them, what treatment does, and the hygiene habits that make the difference for the whole family.

What do threadworms look like, and why do they itch at night?

Threadworms (the infection is called enterobiasis) are tiny white worms, 5 to 10 millimetres long, as thin as a piece of sewing thread. They live in the colon. In the evening and at night, the females come out to lay their eggs on the skin around the anus. This egg-laying triggers the itching, hence its night-time peak.

The most common signs:

• intense anal itching, especially at night, sometimes around the vulva in little girls;
• restless sleep, waking up, an irritable child during the day;
• small white worms visible in the stool, on the nappy, the underpants or around the anus;
• more rarely, tummy aches, weight loss or a return of bedwetting.

Many children have almost no symptoms. And repeated scratching can irritate the skin, even infect it.

How does a child catch worms?

By swallowing eggs, which are invisible to the naked eye. The route is always the same: the child scratches, the eggs lodge under their nails, then pass to their mouth, toys, comforter, sheets or food. According to the US CDC, eggs become infective two to three hours after being laid and survive two to three weeks on poorly cleaned objects. The UK’s NHS says up to two weeks.

That is why threadworms spread so easily at nursery, at school and between siblings (see our article on nursery illnesses). Once swallowed, the eggs hatch in the intestine and become adult worms within one to two months. A child can therefore reinfect themselves, again and again, as long as the hand-to-mouth route is not cut.

Threadworms, roundworms: which worms are we talking about?

When people say “intestinal worms”, in children they mostly mean threadworms. But other worms exist. Roundworm (Ascaris), a much bigger round worm, spreads through eggs found in contaminated soil: the WHO cites poorly washed or undercooked vegetables, contaminated water and children who play on the ground and then put their hands in their mouths. A light infection often goes unnoticed; a heavy one can cause tummy aches, diarrhoea and slow growth.

For these other worms, diagnosis usually involves a stool test prescribed by the doctor. That is why, in Morocco as elsewhere, it pays to wash raw fruit and vegetables well, especially those that grow close to the ground, and to wash children’s hands after the garden, the park or the beach.

How can you confirm it is threadworms?

Often, seeing the worms is enough for the doctor. If in doubt, they may ask for the sticky tape test: a piece of clear adhesive tape is pressed on the skin around the anus in the morning on waking, before any washing. The eggs stick to it, and the laboratory looks for them under the microscope.

Another trick, described by the CDC: look around the anus with a torch two to three hours after your child falls asleep, when the worms come out. Not glamorous, but effective.

Treatment: for whom, and why twice?

The doctor or pharmacist suggests a dewormer suited to the age. The dose and schedule are set by them, according to your child’s weight: do not reuse an old bottle “just in case”.

Two rules come up in every source:

1. The whole household is treated at the same time, even people with no symptoms, otherwise the eggs pass from one person to another. The CDC also includes the people who look after the child (grandmother, nanny).
2. The treatment is often repeated two weeks later. The medicine kills the worms, but not the eggs: the second dose eliminates those that hatched in the meantime.

Before age 2, during pregnancy or breastfeeding, the treatment is not necessarily suitable: ask the doctor’s advice before buying anything at the pharmacy. The NHS specifies that when medicine cannot be taken, hygiene measures alone, kept up for six weeks, can break the cycle.

Which hygiene habits prevent reinfection?

Treatment only does half the job. For at least two weeks after the dewormer, the NHS advises:

• very short nails, scrubbed, for the whole family; a pair of round-tipped children’s scissors makes the job easier;
• hand washing with soap after the toilet, after every nappy change, before eating and cooking;
• a shower in the morning, to remove the eggs laid during the night;
• underpants or closed pyjamas at night, changed every morning; for a little one who scratches, a sleepsuit limits hand access;
• sheets, pyjamas, towels and comforters washed at high temperature, for several days in a row after treatment;
• no shaking of laundry or sheets, which scatters the eggs;
• one towel per person, no shared washcloth, and toothbrushes rinsed before use;
• damp cleaning (a wet cloth, the vacuum) rather than sweeping, and kitchen and bathroom surfaces cleaned with hot water.

At the hammam too, everyone keeps their own mitt and towel during this period. For a child in the middle of potty training, this is the moment to make hand washing after the potty a non-negotiable ritual, with a little song if needed.

Sugar, the moon, garlic: what is true and what is not

“He eats too much sugar, that is why he has worms.” False. You catch threadworms by swallowing eggs, not because of what you eat. A child who never touches sweets can have them, and a sweet tooth may never get them.

“Worms wake up at full moon.” The itching happens every night, because night is when the females lay. The lunar calendar has nothing to do with it.

“A dewormer from time to time, to be safe.” The WHO recommends routine treatment only in regions where soil-transmitted worms are widespread, as part of public health programmes. For an individual child, it is the doctor’s call.

Garlic, pumpkin seeds and other family remedies: none of the medical sources we consulted suggests them as treatment. They are no substitute for the dewormer.

And if your child often has tummy ache with no sign of worms, other causes are more likely: our article on tummy ache in children helps you sort it out. The little critters on the head have their own guide: lice, nits and recurrences.