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People Made Sick by Animals?and Vice-Versa

There?s lots of circumstantial evidence that pets in the home can cause allergies and asthma, but scientists aren?t sure exactly how it works. For instance, a recent study in Finland found that the risk of developing asthma was higher among people who had previously owned pets. But there are also studies suggesting that living with pets can actually protect children from allergies and asthma. "It's certainly too early to make a firm statement as to what parents should do," says Dr. Thomas Platts-Mills of the University of Virginia.

"One of the leading hypotheses is that the timing of the exposure [to pets] is critical," says Dr. Bruce Lanphear, of the Environmental Health Center at Cincinnati Children's Hospital. "It may be that if you are exposed early in life you are protected, or it may be that if you are exposed early you are at increased risk."

Research supports both sides. A March 2001 suggests children growing up in houses with cats produced antibodies to cats, but did not show increased risk of allergies or asthma. "We're pretty sure that the cat can induce a form of tolerance," says Platts-Mills.

However, this tolerance may not last a lifetime. Children who spend the first 17 years of life living with a cat and then leave home and no longer have a pet will often have more severe allergic reactions to the cat when they return home. It?s called "The Thanksgiving Effect" and happens to college students all the time. "The idea here is that if you have constant exposure to a pet, latex or other kinds of allergens, it may be desensitizing. But when you take those daily exposures away, you may mount a more aggressive hypersensitivity response," says Lanphear. "Constant low-dose or high dose exposures may be OK, but intermittent high or moderate doses of exposure may be more problematic."

"The truth is there is going to be an element of genetics in this," says Platts-Mills. "In other words, there are genetics that say if you are going to become allergic. Some people as far as we can see can do whatever they like and never become allergic. Perhaps half of the population is like that."

The rest of us are divided into two groups: Those who become allergic and develop tolerance and those who never will. For the second group, the only solution is to remove the pet. And pets can spot us?they head right for us when we visit a pet owner?s home.

People are always afraid of getting sick from animals, but it turns out animals are also in danger of getting diseases from us.

Researchers think that three outbreaks of tuberculosis among mongooses and meerkats in Botswana were spread by humans. These would have been ecotourists, who were trying to be leave the African jungle exactly as they found it, but they spread disease anyway. Conservationists are worried because ecotourism provides much of the money needed for wildlife conservation in Africa.

There have been signs of human infection in the wild mountain gorillas of East Africa, as new intestinal parasites have been found in their feces since tourists began arriving in large numbers. Now a team of researchers has proof that humans can pass diseases on to wild animals.

Kathleen Alexander, Botswana's Senior Wildlife Veterinary Officer, has discovered two outbreaks of TB in the mongooses and meerkats in the Kalahari Desert. The mongooses probably caught it from rooting through contaminated trash cans outside a tourist lodge. It?s not clear how the meerkats became infected.

But no matter how the animals caught the disease, they must have caught it from humans since there are no animals in the area that naturally carry human TB. Alexander says, "We need to be addressing the threat that humans pose to wildlife."

If you can communicate with animals from afar, you won?t have to get close enough to exchange germs. Learn how to psychically communicate with other species by reading ?Is Your Pet Psychic?? by Richard Webster, click here.

To learn about how humans can get sick from animals,click here.

To learn about how animals can get sick from humans,click here.

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