Cats may worsen the symptoms of any allergy sufferer

Posted: Aug 2007  (Return to the original web page from this print version)

It has been well known that cats are the worse source of pet allergens. Up to 40% of asthma sufferers show some degree to sensitivity to cat allergens. Our airway normally constricts in response to an irritant, so as to protect the body from inhaling it. However, people with allergic or asthmatic problems experience an exaggerated response to external irritants with severe airway constriction.

A recent study found that even for people not specifically allergic to cats, they experience some constriction in the airways in the presence of cats. All types of allergy sufferers showed greater airway constriction in response to a testing irritant when their homes contained high levels of cat dander.

Another research showed that children exposed to high levels of cat allergen in the first 2 years of life had higher risks of becoming allergic to cats, but exposure after 6 years old did not seem to increase such risks.

Effect of cat allergens to different types of allergy sufferers:

Researchers in the Imperial College of London, UK, studied 1,884 adults from 20 areas across Europe. Blood tests were conducted for all participants to detect allergies to 4 types of allergens, namely cat dander, dust mite, grass pollen and mould.

The participants were then exposed to a testing irritant in their homes, with the extent of airway constriction measured. It was found that all types of allergy sufferers showed greater airway constriction in these tests when their homes contained a relatively high amount of cat dander. But the level of dust mites in their homes did not result in significant difference in the tests.

Therefore it may be advisable for people with any type of allergy not to keep cats at home, and even to avoid cat-friendly neighbourhood. In earlier studies, the same group of researchers found that the level of cat allergen in the homes of non-cat-owners depended on the number of cats in the neighbourhood.

The report of the above research was published in the July 1, 2007 issue of the American Journal of Respiratory and Critical Care Medicine. (Related News: July 2, 2007)

Exposure to cats in infancy may increase allergy risk

A number of previous studies on the relationship between cat ownership and allergy risks produced opposite results. However, most of these studies only focused at one point in time.

In a recent study by the GSF-National Research Center for Environment and Health in Nuremberg of Germany, researchers followed the allergy status of 2,166 children from birth until 6 years old. They found that the higher the levels of cat allergens in house dust when the children were 3 months old, the more likely they would develop sensitization to cat allergens by 2 years old.

Exposure to high levels of cat allergens in the first 2 years of life resulted in increased risk of becoming allergic to cats. The total cat exposure over time, defined as the presence of cat at home and contact with cats outside, would increase the chance of sensitization among children up to 6 years old.

However, researchers found that by age 6, there was no significant correlation between exposure to cat allergens in infancy and sensitization to the allergen, or the presence of any type of allergic symptoms or disease.

According to the researchers, it is advisable for people with a family history of allergic disease to avoid having cats at home, and to reduce contacts with other cats outside the home environment. The report of this research was published in the May 2007 issue of the Journal of Allergy and Clinical Immunology. (Related News: May 14, 2007)

Related Web Page: Common Allergens : Animal Dander

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