Roundworms CDC

Human Infectious Roundworms More Prevalent Than Previously Thought, Reports CDC

December 17, 2008

About 14 percent of the U.S. population is infected with Toxocara, or internal roundworms, contracted from dogs and cats, according to Centers for Disease Control (CDC) study announced today at the American Society of Tropical Medicine and Hygiene in Philadelphia. After doing the math, that’s about 1 in every 8 people. This statistic is higher than previous reports of the prevalence of worms transmitted by dogs and cats to humans.

The CDC study shows the transmission of roundworm from dogs and cats to people is most common in young children and youth under age 20, it is highest in lower socioeconomic and less-educated populations. All children, however, are more susceptible to infection given their propensity to play in and sometimes eat contaminated soil.

Infections are acquired by accidental ingestion of roundworm eggs found in environments contaminated with feces of infected dogs and cats. This includes play areas and sandboxes.

The results of this study demonstrate that roundworm infection in the United States is more widespread and common than previously understood, said Peter Schantz, VMD, PhD, an epidemiologist in the Division of Parasitic Diseases at the CDC and a founding board member of the Companion Animal Parasite Council (CAPC). Although most persons infected with roundworm have no apparent symptoms, this infectious agent is capable of causing blindness and other serious systemic illness, which makes it a public health issue. While rare, the visual impairment most often affects children.

The nonprofit CAPC was formed to educate pet owners about zoonotic disease and steps they can take to virtually eliminate the risk of pets making people sick.

The CAPC recommends that pet owners administer year-round preventive medicines that control internal and external parasites such as roundworms, heartworm, fleas and ticks for the life of their dog or cat no matter where they live, said Michael Paul, DVM, executive director of the CAPC. If you prevent parasitic infections in companion animals, you greatly reduce the chances of zoonotic transmission to people.

The American Animal Hospital Association, the American Association of Feline Practitioners and Schantz of the CDC all endorse the CAPC guidelines that call for year-round parasite control in companion animals to protect both pets and people from zoonotic disease. Parasite control today is simple, safe and effective. Treating dogs and cats for parasites with a monthly product is one of the easiest and most effective ways to keep pets healthy and eliminate related health risks to humans.

Despite the availability of effective treatments to prevent them, parasites remain a common fact of life for dogs and cats. Most companion animals have the potential for exposure to parasites all year long. Experts agree there is a year-round threat in all regions of the country, even those that experience below-freezing temperatures, since parasites such as fleas and ticks thrive inside homes regardless of weather conditions outdoors.

Fortunately, your pet and your family are protected by following the recommendations of Murrayhill Veterinary Hospital when using Sentinel® for your dog or Revolution® for your cat. If you have any questions or concerns about parasite control or any other health related topic, please call us at 503-579-3300.

CAPC information can be found at:

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