Roundworms: A Human Health Threat

By: Michael Lamping, DVM

            Every year, more than 700 people in the United States, many of them children, develop a permanent partial blindness in one eye due to roundworm larva.  Roundworms are intestinal parasites commonly found in puppies and kittens, and they can be passed to humans (an event called zoonosis) through exposure to roundworm eggs in pet feces.  They are found throughout our country, including north Texas.  At Murphy Road Animal Hospital, 45 pets were diagnosed with and treated for roundworms in the past two years.  

Zoonosis of roundworms is a remarkably common occurrence.  According to a November 2007 CDC study, roundworms (scientific name: Toxocara) have infected an estimated 14% of the U.S. population.  While most people never display symptoms, some experience concerning symptoms of abdominal pain, neurological disorders, or permanent disruption of vision.  Worst of all is that most cases are in children.  There are many reasons for this.  First, children love dirt.  They love it so much they bring it back inside the house with them.  This affinity for earth and their tendency to not wash their hands before eating increases kids' odds for contracting roundworms.  Second, roundworms are very common.  They are so common in young pets that it is our standard of care to administer dewormer to every puppy, kitten, and stray adult pet which has been brought to us for the first time.  Lastly, roundworm eggs are hardy and resistant to decontamination efforts.  The eggs can survive for years in soil or sand in public places such as parks, sports fields, beaches, backyard spaces such as uncovered sandboxes and flowerbeds, and in front yards where inconsiderate pet owners leave their dog's poop for their neighbor to scoop.

            The CDC and the Companion Animal Parasite Council have issued guidelines for prevention of roundworm transmission to people.  Topping the list is testing and treating your pets for parasites.  By 8 weeks of age, begin giving a monthly preventative, which is often combined with a heartworm preventative.  When you take dogs on walks, out of courtesy and conscience, always clean up behind them.  Clean up poop from your yard at least once a week and then discard it.  Pet feces are a terribly risky, unhealthy choice for fertilizer.  Finally, cover sandboxes and wash children's hands after play.  Be a hero and prevent this common parasite from spreading further and causing harm.