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A dog is a tapeworm's best friend.

Tapeworms in dogs and other pets can also mean tapeworms in humans who care for these pets, said Clell Bagley, Utah State University Extension veterinarian.For Utahns, the Hydatid disease of humans is one example. This disease, also called echinococcosis, is caused by the larval stage of a tapeworm of dogs. The adult stage of this tapeworm, Echinoccus granulosus, is small and difficult to see. It produces microscopic eggs, sometimes transferred from the dog (hair to hand) or environment (grass, dirt to hand) to a person's mouth (wiping lips, chewing fingernails), Bagley said.

Sanpete County had high infection rates of this tapeworm in both sheep and dogs in the early 1970s. While control efforts have reduced the disease, they have not eradicated it, he said.

"People in other areas of Utah should not feel they are without any danger," the veterinarian said. "Sheep and dogs from Sanpete County have been transported to all parts of the state. It is very likely that the Echinococcus tapeworm has gone along for the ride."

After the eggs of this tapeworm pass into the digestive tract, they penetrate the gut wall, enter the bloodstream and travel to the liver, lung and other places. "Here they attach and form cysts that gradually grow larger until surgically removed or until the person dies."

Bagley said humans are considered a "dead end" host in this disease because the infection doesn't spread from an infected person to another person, or even to a dog.

"The intermediate host is sheep," he said. "The cysts grow in them just as in man. However, if dogs eat the internal organs of infected sheep, they become infected and the larval tapeworms develop into adults."

If this happens, the dog begins to shed eggs from its intestinal tract within about seven weeks and the cycle repeats.

Other tapeworms affect dogs, but they are much larger and easily visible, he said.

In the tapeworm world, multiplication means survival.

"Parasites, in general, survive by sheer masses," he said. "That is the case with hydatid disease. A heavily infected dog may shed thousands of eggs each day."

Of these thousands, he said, it only takes one to get from the tail hair to the dog muzzle, to a person's hand, to the mouth, to result in hydatid disease for that person. It just needs the right circumstance and time for it to show its effect.

Control is most effective when carried out on a community, area, or countywide basis. Bagley said it must include:

- Deworming all dogs that may have eaten uncooked sheep viscera (internal organs). Repeating at later times after any possible exposure.

- Proper disposal of dead sheep and sheep viscera to prevent dogs from eating them.

- Elimination of stray dogs.

- Control of all dogs to keep them from defecating in and around children's play areas.

- Washing hands after handling or playing with dogs.

In treating for tapeworms, Bagley said, bear in mind that not all deworming products are effective. Similarly, not all deworming products available for common tapeworms are effective against Echinococcus. Some, however, are highly effective. Three such products are Droncit, Vercom and Cestex.

Dog owners should know they can start a control program of their own to give them a reasonable degree of security against hydatid disease.

He said pet owners should practice good hygiene and sanitation and provide well-timed preventive treatments for their pets.