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Sunday, February 15, 2009

Zoonosis Week: Roundworms & Hookworms

Zoonosis: An infectious disease in animals that can be transmitted to people. The natural reservoir for the infectious agent is a animal.

I thought that I would go back to a theme, doing an informational one this time. Zoonotic diseases are something that we don't talk about as much as we should, and are extremely important. There is much misinformation out there, and human doctors are often not as knowledgeable about these topics as are veterinarians. That's probably because we vets are the most likely to be exposed to them! So we're going to make darn sure we know what we're at risk for and how to prevent it.

So let's begin by talking about roundworms and hookworms. These are common intestinal parasites in dogs and cats, especially kittens and puppies. When we do a fecal exam, one of the things we look for is the eggs of these parasites. Both of these worms normally live in the intestines of their host, shedding eggs into the feces. These eggs can contaminate the environment, adhering to the animal's fur, the grass and leaves, or basically anywhere that feces have been touching. This includes the floors of our homes, which is not uncommon as we are trying to housebreak our new puppies. When an animal (or human) swallows anything contaminated by the eggs, the can become infected themselves.

Puppies and kittens are very commonly infected because the larvae of the worms migrate through the host's body. They can form cysts that are impossible to detect and are a dormant stage that are resistant to antiparasitic medications. During pregnancy, the cysts open, and the worms migrate through the uterus or into the mammary glands, providing two sources of infection for the babies.

Humans are most commonly infected through poor hygeine. Sandboxes can be a good place for stray cats to defecate, potentially contaminating a child's environment. Stray dogs and cats will sometimes eliminate in the soft ground cover of playgrounds. A pet's fecal materials can get into the grass in which children roll around and play. You can likely think of similar situations in your own lives. In any case, the people touch the area that has been contaminated, and then touch food or their mouths without washing their hands first. Suddenly, the person (often a child) has swallowed the eggs, and will become infected. Other sources of infection include being licked in the face by an infected pet (the eggs can be in saliva), and migration through the skin (in the case of hookworms...their larva can get into a person through bare feet).

In pets, both kinds of worms can cause diarrhea and poor body condition as the worms upset the intestinal tract and interfere with food absorption. Hookworms drink blood from the intestines and can cause life-threatening anemia in small pets.

In humans, these worms can cause the most serious disease through "larval migrans". The larvae move through a person's body, and can end up in unusual places, such as the lungs or the eyes. This can lead to pulmonary disease and blindness.

Thankfully, these worms are easily preventable and treatable. A veterinarian can detect these parasites in a fecal sample, and it is recommended to perform these checks twice per year. Routine heartworm preventions in both dogs and cats also include preventions for roundworms and hookworms. If an infection is detected, there are several very effective medications that a vet can use to eliminate the parasites.

For human risks, you can take the following simple steps. Any time a child has handled a dog or cat, make sure they wash their hands immediately afterwards. Pick up any feces from the yard at least weekly, if not immediately. If a pet has defecated in the house, clean and disinfect that area as soon as you notice it. Keep your pets on heartworm prevention to help with intestinal parasites as well. If your vet detects parasites in your pet, try to avoid anyone being licked in the face until the infeciton is cleared.

It doesn't take much to protect your family against potentially serious parasitic disease.