Dogs and cats usually become infected with roundworms by ingesting roundworm eggs from a fecal-contaminated environment (a park where other animals are walked or an area populated with wildlife); by ingesting an infected host (such as a mouse or flea); or through nursing from an infected mother as puppies or kittens.


Effect on Cats and Dogs
Infected pups and kittens may present with a pot-bellied look (the one so many owners think is so cute), ill thrift, diarrhea, vomiting, and in cases of severe infection, neurological disease and even death have been known to occur.  While dogs over 1 year of age MAY develop some immunity to roundworms, infections can occur at any time.  Cats are susceptible to infection from this parasite throughout their lives.

Effect on Humans

Humans are most often infected through ingestion of the eggs from a contaminated environment.  Roundworm eggs are commonly found in soil from playgrounds or parks, and the eggs survive and remain infective for many years.  When these eggs are ingested, the larvae they contain migrate internally in the human resulting in the disease, Toxocariasis.  Syndromes of Toxocariasis include visceral larva migrans, which is usually characterized by an enlarged liver, pulmonary disease and an increase in the white blood cells; neural larva migrans, characterized by progressive neurologic disease; ocular larva migrans, characterized by a unilateral granulomatous retinis which may result in blindness (seen in image to the left); and covert Toxocariasis, in which chronic abdominal pain or other nonspecific symptoms develop.

Roundworms are extremely common throughout the world.  Although infection rates are likely to be higher in pets that spend a lot of time outdoors or are allowed to consume prey species that may harbor roundworms, the ability of the parasite to be transmitted from mother to nursing offspring, together with the hardy nature of the eggs in a contaminated environment, contribute to the high prevalence of infection even among pets that are well cared for and routinely treated for intestinal parasites.  And yes, even the indoor, never-goes-outside cat is at risk for infection.

Diagnosis
Fecal flotation: A single adult roundworm can produce as many as 85,000 eggs per day, making detection of eggs in feces quite easy.  The eggs are so small that they can only be seen with the aid of a microscope.  In heavy load cases, the pet may vomit up or poop out the adult "spaghetti"-like worm. We can run a fecal float here at our clinic if you bring in a fresh stool sample.

Prevention
Prevention of disease caused by infection with zoonotic roundworms requires preventing the ingestion of eggs from the environment.  Young children should be closely monitored so that the ingestion of contaminated objects or dirt can be discouraged, particularly in public areas known to be frequented by dogs and cats or populated with raccoons.  Frequent washing of the hands when outside gardening or doing yard work helps to prevent inadvertent contamination. Always wash your hands before eating.

Clean up after your pet.  This cannot be emphasized enough.  Too many pet owners fail to see the risk they put their family and community in whey they fail to pick up fecal matter from their pets.  This should be done EVERY TIME your pet has a bowel movement, whether in your yard, the park or next to the street.

Early and regular deworming of your pet is essential in preventing contamination of the environment with roundworm eggs. Essentially every pup or kitten is likely to harbor developing roundworms and that is why we routinely deworm your puppy or kitten.  Keeping your adult dog on a monthly heartworm preventative also has the added benefit of being a monthly dewormer for roundworms especially if you have toddlers in the household.

Routine fecal examinations are  recommended to ensure your pet does not have an active infection.  Treating pets to prevent egg shedding is critical because the eggs are very hardy and long-lived in the environment.  Once present, the eggs can be removed or destroyed only through extreme measures such as placing concrete or asphalt over kennel areas or areas of pet defecation, complete removal of topsoil, or prescribed burns.

 

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