Indoor Allergens (cont.)

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What about allergies to molds?

Symptoms of hay fever (allergic rhinitis) and asthma can be caused by the inhalation of the spores of molds. Molds, or fungi, tend to grow on wet surfaces, either indoors or outdoors. The body of the mold produces spores or seeds, which are smaller than pollen and less potent as allergens. Large amounts of mold spores can be found in the air, especially in the spring and fall. They are usually most abundant at night, especially when it is damp, foggy, or during the rainy season.

Outdoor molds thrive in the soil, grass, dead leaves, haystacks, barns, and stables. They are often found in greater concentration when a hedge is located against a house, especially in shady areas. Spores from outdoor fungi typically enter the house through opened windows and doors.

Indoor molds can proliferate in bathrooms, especially in the shower stalls, damp cellars, drains, potted plants, closets, attics, house foundations, crawl spaces, and sealed-off rooms. A "musty" smell often radiates from these areas. On indoor plants, it is often the mold overgrowth and not the flowers that cause allergy.

What about allergies to pets?

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The "dander," or skin shedding, of an animal is more potent in causing allergic reactions than the animal's fur or hair. In addition to the skin sheddings and fur, allergic reactions can occur to the saliva and/or urine of cats, dogs, horses, and rodents.

The scope of the animal allergy problem is enormous. These allergies are believed to affect up to 20% of North Americans and are directly related to the increasing popularity of pets, particularly cats and dogs. Studies have shown that dog allergens were found in all examined homes in the U.S., even those without family dogs. Likewise, almost all homes were shown to contain cat allergens.

Cats

The most well-known indoor allergy is probably due to Felis domesticus, the domesticated cat. The main allergen is a protein that is produced by the sweat glands (sebaceous glands) in the skin and appears in the skin flakes or dander that are shed from cats. The allergen is also found to a lesser degree in the fur, saliva, and urine of cats. Even with a past history of tolerance to cats, it is possible for a person with an allergic tendency to develop a sensitivity to cats after constant exposure.

The cat dander allergen is not only confined to the cat but also clings stubbornly to carpets, walls, and furniture. The protein can linger there for months and can serve as a reservoir from which allergens can become airborne when disturbed. The allergen is also lightweight and can float in the air for hours. People can also carry the cat allergen around on clothes, thereby spreading it to work, school, or a friend's house. Accordingly, for those who are allergic to cats, it does not reduce the risk of allergic reaction to simply isolate the cat in another room of the house. The cat dander is present wherever the cat generally exists, and it is this dander that is the problem.

Allergy facts
  • An estimated 30% of households in North America have at least one cat.
  • About 6% of the U.S. population is allergic to cats.
Dogs

Domesticated dogs (Canis familiaris) are found in over 40% of homes in North America. About 33% of allergic individuals are sensitive to dog dander (as compared with almost 50% of allergic individuals who are cat-allergic). Since the allergic reaction is prompted by skin shedding and not fur, it makes little difference whether the dog has long or short hair; you can be as allergic to a Chihuahua as you can to a sheepdog. Small dogs can also cause as many allergy symptoms as large dogs. There is certainly no evidence that one species is less allergy-provoking than another one. Clearly, no breed is non-allergenic. Even poodles and wheaten terriers (often thought to be hypoallergenic) will likely induce allergy symptoms in sensitive individuals upon continuous exposure.

If your child has asthma and a known allergy, be especially careful not to allow the child to spend the night at the home of a friend or relative with a pet. Severe allergic reactions and even fatalities have been reported. Do not let this happen to your family or your friends.

Horses

Only 10% of allergic individuals have sensitivity to horses. The reason is probably due to less exposure since there is little horsehair in furniture or bedding anymore. Sensitive people, however, must avoid not only horses and stables, but also objects directly related to them, such as bridles, saddles, and riding clothes. Also be aware that horsehair may still be found in antique furniture and old toys. People who have problems with horses may also react to donkeys, mules, and zebras.

Allergy alert

Remember that a trip to the barn not only exposes you to animal dander, but also to mold, pollen, and lots of other irritants as well. If you suffer from asthma, be careful and be prepared.

Birds

Allergy to birds is more common among bird breeders where the exposure is highest. People who are sensitive to the feathers of chickens, geese, turkeys, and ducks can still eat the meat or eggs from these animals. They may well react, however, to the feathers in down comforters, pillows, and duvets. You should also remember that dust mites, another common allergen, hide in these bedding accessories.

Rodents

This family includes hamsters, rabbits, guinea pigs, gerbils, ferrets, mice, and rats. Most allergic reactions are caused by exposures in laboratories, but these animals are also common pets. Mouse urine is an especially potent allergen for personnel that handle laboratory animals. The urine of rats and guinea pigs also contains allergens as do the saliva and fur of rabbits. Rabbit hair can be found in fur coats, glove linings, slippers, foot muffs, pillows, and quilts. The fur of the Angora rabbit is said to be 10 times warmer than that of sheep wool. The soft yarn spun from Angora rabbit fur can be found in hand-knitted trimming, crochet work, gloves, hosiery, and knee pads. Alone or mixed with silk, it is also used in sportswear. And, of course, rabbits often appear in schools as the classroom pet.

Allergy alert

Frequently, parents will report that their child has "won the privilege" of caring for the classroom pet over the weekend or the holiday vacation. This often leads to the onset of a particular animal sensitivity. If you or your child already has allergies or asthma, do not volunteer for the job.

Medically Reviewed by a Doctor on 12/19/2014

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