Roundworms and Kids: Why Hand-Washing Is a Must

For children who live with pets, roundworms and their eggs are an unseen risk and potential hazard.

Kids who wash their hands after touching pets reduce their risk of contracting Toxocara-related disease. By: au_tiger01

How aware of hygiene are your children? Do you insist that they wash their hands after playing in the yard? How about after petting the dog?

OK, Petful is a site dedicated to pets, so you’ve probably guessed this article is about catching diseases from your cat or dog.

And yes, people can pick up diseases from their pets. To illustrate the point, let’s look at the most common worm in our domestic animals: the roundworm Toxocara.


Roundworms may not be a “sexy” subject, but if you have kids, please keep reading.

Between 2% and 31% of the European population tested positive for Toxocara, meaning that these people had a positive blood test that showed they had ingested Toxocara eggs, and their body mounted an immune response.

Think about it. At the higher end of the figures, it means nearly 1 in 3 people have eaten roundworm eggs!

It seems, however, that the immune system stops those roundworm eggs from developing into the larvae that cause health problems. In the UK, it’s estimated each year that there are only 2 clinical cases of Toxocara-related disease per 1 million people in the population.

It’s more dangerous for people with weak immune systems, such as those with cancer, those taking immunosuppressive drugs or those with young children. They are at greater risk of visceral larva migrans (VLM), where ingested roundworm eggs hatch into larvae and then “migrate” unchecked through the body’s tissue.

If this sounds vaguely familiar, it’s because every now and again cases hit the news where a child has gone blind because of migrating roundworm larvae in the back of the eye.

VLM isn’t just limited to blindness — it can cause liver and lung damage, and there seems to be a link to certain forms of seizure activity.

Where Do Kids Pick Up Worm Eggs?

Children are at greatest risk from infectious “embryonated” eggs (older, mature eggs).

These are found in old feces and soil and cling to dog hair.

Unfortunately, kids love to play in dirt and also put their fingers in their mouth; hence 2- to 4-year-olds are at greater risk.

Because roundworm eggs can stick to a pet’s coat, it’s essential to encourage hand-washing after stroking or petting a dog or cat — and most especially before eating.

Hunting cats and young animals are at the greatest risk of catching the Toxocara roundworm. By: sugarains

What Are the Risk Factors?

Some sobering facts:

  • The risk of catching Toxocara rises 3-fold if you have a dog in the house.
  • The risk goes up fivefold if you have a litter of puppies in the house.
  • The risk increases with each additional pet.
  • The risk is greatest with young animals or hunting cats.

Control and Prevention

This all sounds like pretty scary stuff, so please remember that clinical disease is rare. However, it pays to take measures to protect you and your family. You can do this by:

  • Getting regular worming done
  • Picking up feces
  • Practicing good hygiene

Regular Worming

The scientific evidence is that worming your pet 4 times a year decreases egg shedding, and monthly worming actually blocks egg production. In the UK, bodies such as the British Veterinary Association (BVA) advise quarterly worming treatments as a minimum requirement.

If you have young children, consider worming your dog every month.

This sounds like a lot, but remember: Most of the new-generation monthly spot-on treatments, such as Stronghold (UK), Revolution (US) and Advocate, are also effective against roundworms.

This informative video gives you an up-close view of Toxocara roundworm and how it affects pets:

YouTube player

Picking Up Feces

Prompt poop-scooping is an essential control measure because it removes feces and the opportunity for eggs to wash into the soil, where they embryonate at leisure.

Freshly passed Toxocara eggs are not infectious. It takes 2–7 weeks for an egg to grow inside the shell and “embryonate” or become infectious.

This means old feces left in the yard or park pose a much greater risk of infection than freshly passed poop.

Good Hygiene

Hand-washing is essential. The transfer of older eggs from fingers to mouth is most likely to cause infection. (Those 31% of the European population who were positive for Toxocara on a blood test were likely to have ingested dog fecal material. Yuck!)

Everyone, be they adult or child, should wash their hands after petting an animal, after gardening and before eating.

The simple act of good personal hygiene prevents mature eggs from getting into the mouth and, as a consequence, could prevent serious illness.

If you take one message home from this article, remember the importance of teaching your kids to wash their hands.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Nov. 2, 2018.