Cat allergy

from Wikipedia, the free encyclopedia
Classification according to ICD-10
J30.3 Other allergic rhinopathy
ICD-10 online (WHO version 2019)

A cat allergy is a hypersensitivity to a protein from the saliva of cats, which can trigger various allergic reactions . Correctly, these should not be called a cat hair allergy, but an allergy to cat epithelia .

Allergens

It is not the cat hair itself that is allergenic , but rather certain proteins that adhere to the cat hair. These cat allergens come mainly from the cat's saliva and skin flakes; H. Hairless cats also produce and spread allergens and they exist in the urine. The largest amounts are found on the cat's face. Cats often lick their fur to groom. The allergen with the designation Fel d 1 is distributed over the entire surface of the cat's body.

Fel d 1 is very small, sticky and light (particle size approx. 1–5 µm), can bind to dust particles and therefore has the property of remaining suspended for a very long time or adhering to objects. It settles in upholstered furniture, carpets, walls, mattresses and clothing, so that the allergens can be detected not only in households with cats, but also in small amounts in public places such as schools, offices and buses. The cat allergen could also be detected in places where a cat has probably never been (e.g. in the inland ice in Greenland). If you have a strong allergy, you can even react to cats in a neighboring apartment, as the air movement causes the allergens to get into every tiny crack, e.g. through closed doors.

In households, the allergen can persist for several years despite removing the cat. Due to the enormous shelf life of the allergen and the high population of cats that are kept in houses, it can be assumed that the amount of allergens in the households is constantly accumulating. Even after renovation or the most thorough cleaning, there will still be residues. Depending on the model, household vacuum cleaners emit small amounts of fine dust even with a HEPA filter. There is no 100% retention capacity with vacuum cleaners. Chlorine bleach is said to help with cleaning. Antibacterial agents, on the other hand, do not necessarily help because they are not bacteria but proteins. With an air purifier, the amount of airborne allergens can be reduced significantly, but a study did not find any improvement in the test subjects. With a heat treatment at 140 ° C, after 60 minutes. still 70% of Fel d 1 intact.

Fel d 1 is the major allergen of the cat, it is recognized all cats with allergies of more than 90% and also binds the most educated IgE - antibodies . Cats produce this protein, whose function in cats is still unclear, in the sebum , anal and salivary glands . From there it is transferred to the fur through licking and brushing. Males produce greater amounts of Fel d 1 than female cats. The amount is highest in sexually mature, uncastrated male cats.

Not everyone with a cat hair allergy reacts in the same way to different types of cats. This is related to the production of Fel d 1, as cats release different amounts of the substance depending on their age, breed, and gender. It is said that there are hypoallergenic cat breeds in which, via a modification of Fel d 1, the human body is said to react less. However, this claim has never been scientifically proven. Since a cat's hair is not a source of allergens, hairless cats are no exception.

Other cat allergens:

The other allergens trigger a willingness to allergies in approx. 50% of the cat allergy sufferers. Fel d 4 appears to be the second most important allergen after Fel d 1, which is also found in other mammals. There are cross-reactions to dogs and horses. Fel d 2 occurs in all other mammals and usually plays a very minor role. With Fel d 2 there may be cross-reactions with pork, for example.

Symptoms

Symptoms are an allergic runny nose with sneezing, hives (very itchy skin rash with wheals), reddened eyes and swelling and severe itching from scratches. Allergen contact also occurs through inhalation of the allergenic suspended matter, which then settles on the mucous membranes of the respiratory tract.

The reaction can happen immediately or a few hours later. Symptoms can persist for a few minutes or several hours after exposure.

It is assumed that an extremely small amount of 8 µg / g in house dust is sufficient to cause an allergic reaction even in highly sensitized people. In a study, this amount was found in over 40% of the classrooms examined. This explains u. a. why there are so many allergy sufferers who have never owned a cat.

If the allergy to said proteins from the cat's epithelia is ignored, there is a risk of allergic asthma . This becomes noticeable through breathing problems, up to and including an asthma attack, which in the worst case can be fatal. It is assumed that every third untreated allergy sufferer experiences a so-called “ floor change ” over time, during which the bronchial mucous membrane becomes hypersensitive, which can lead to allergic asthma. Due to their small size, cat allergens are more dangerous than e.g. B. pollen, as it gets into the lower respiratory tract more easily. In addition, in the case of very pronounced allergies, contact with the allergen in the organism can lead to a life-threatening systemic reaction, anaphylactic shock .

therapy

As with any allergy, the attending physician will first advise you to avoid contact with the allergen if possible ( allergen avoidance ). The main allergen Fel d 1 can, however, be found everywhere in small amounts, so that complete avoidance of contact with the allergens is practically impossible. The symptoms of the allergy sufferer can therefore - if the allergy is strong enough - also occur in places where there is no cat and where one has never lived. For example, upholstered furniture from a household with a cat may contain and release cat allergens. Cat allergens have even been found in the Greenland ice sheet. Apparently the small and light allergens are spread across the globe with the wind. They are brought into other buildings via the clothing and shoes of the visitors.

Before desensitization, a skin prick or blood test (IgE) is usually carried out, which, however, is not the only decisive factor in determining the cat allergy. There are many people who are sensitized to Fel d 1 but show no reactions. Conversely, there are severe cat allergy sufferers whose tests are relatively inconspicuous.

The only causally effective therapy for cat hair allergy at the moment is desensitization (specific immunotherapy, SIT, "allergy injections"), in which one tries to slowly get the body used to increasingly higher standardized concentrations of the allergen. The use of inhalers or nasal sprays, on the other hand, is not suitable as long-term therapy for cat owners with a cat allergy, as only the symptoms are treated. However, some health insurances do not cover the costs of desensitization to cat allergens. This should at least not hold in court if the cat hair allergy sufferer does not own a cat. Many doctors reject desensitization due to insufficient data and increased side effects. Other allergy sufferers have difficulty finding a doctor to perform SIT if the allergy sufferer does not want to part with their cat. But there are also allergists who, on the basis of pragmatic considerations, consider desensitization to be possible and effective even if the cat continues to live in the household of the allergy sufferer. Since desensitization is a long-term therapy (duration about two to three years) and should in principle be carried out at times of lower allergen exposure, the success of the therapy - at least for cat owners - is questionable.

The pharmaceutical industry is also developing vaccines for cats, which form antibodies and thus neutralize the Fel d 1 allergen in the animal.

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Web links

  •  Cat allergy - article on allum.de with some references
  • Entry on cat allergy in Pharmawiki  - overall presentation of the allergy picture with explanations of active ingredients and literature sources