FEATURE
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ruary continuing into May , followed by grass pollination , which usually starts in March and is in full force by May with grass season ending in mid-June .
Studies have also shown that thunderstorms with significant downdrafts tend to cause asthma exacerbations and increased ER visits due to bursts of increased grass pollen being dispersed during these downdrafts on warm summer days . ( 5 ) Pollen allergy sufferers will usually tell you there is a lull in their symptoms in July , as grass pollen is typically absent and ragweed pollen has not yet started . The relief is brief , and by mid-August the beginning of ragweed season starts , which typically will continue through at least most of September and possibly into October until the first frost occurs . Mold can be a major issue as well with certain outdoor molds such as Alternaria being associated with increased severe life-threatening asthma attacks . ( 7 )
O ’ Halloran published a landmark study in the New England Journal of Medicine and retrospectively looked at ICU admissions at Mayo Clinic and determined these patients had a much higher rate of reactivity to Alternaria mold . Admission to the ICU correlated with airborne Alternaria mold levels present during the summer and early fall . ( 7 ) Some outdoor molds such as Ascospores and Basidiospores ( mushrooms and smuts ) are prevalent on humid damp days . Other outdoor molds such as Alternaria and Cladosporium produce higher spore counts on dry windy days . ( 8 )
THE ORAL ALLERGY SYNDROME
One unique characteristic that some very allergic pollen allergy sufferers can present with is the well-characterized oral allergy syndrome . ( 6 ) Have you ever had your patient tell you , “ Whenever I eat melon , my mouth itches ?” This describes the oral allergy syndrome in which certain pollens cross react with raw ( not cooked or processed ) fresh fruits and vegetables . It is as if the immune system believes the individual eating a raw apple is actually ingesting birch tree pollen in her mouth , and subsequent oral itching , swelling and irritation occurs . Anaphylaxis can occur , and an epinephrine auto-injector is recommended , though anaphylaxis is rare with oral allergy syndrome . ( 6 ) Avoidance of this fresh fruit or vegetable is highly recommended as further sensitization can occur and symptoms can progress . Cooking the fruit or vegetable will usually denature the antigenic protein and patients can usually eat that particular fruit or vegetable without symptoms . Table II summarizes
TABLE II . ORAL ALLERGY SYNDROME ( POLLEN-FOOD ALLERGY SYNDROME )
Pollen
Birch
Ragweed
Mugwort Grass
Cross-Reactive Foods
Apples , Pears , Carrots , Celery , Potatoes , Hazelnuts and Kiwi
Watermelon , Cantaloupe , Honeydew and Bananas
Apples , Carrots , Celery , Coriander , Fennel and Melons
Melons , Oranges and Tomatoes the pollen / food cross reactivity and is a helpful reference for your patients and will help explain their symptoms relating to eating fresh fruits and vegetables . ( 6 )
THE INDOOR ALLERGEN ENVIRONMENT AND HOW TO LOWER ALLERGEN EXPOSURE
The indoor allergen environment as it relates to the symptoms of asthma and allergic rhinitis has been well characterized . Threshold levels of indoor allergens including dust mites , cat , dog and cockroach have been identified that result in sensitization and the subsequent development of asthma . ( 9 )
Dust mites and indoor molds thrive in higher humidity where the humidity level is generally greater than 50 percent . Dust mites , as peculiar as it may be , actually feed on human scales , and it is actually the cysteine protease enzymes present in the feces of the mites that is responsible for allergic sensitization . ( 3 , 10 , 11 ) Studies have shown that even a new mattress can accumulate significant amounts of dust mite allergen within six months of use . ( 11 ) Barrier covers ( best is 2.1 micron pore size ) over the mattress , pillows and box springs have been shown to help decrease symptoms in mite allergic individuals . Washing bed linens in hot water ( below 120 degrees F to prevent scalding ) weekly also reduces dust mite allergen levels . HEPA air filters are not considered effective for lowering dust mite levels because dust mite fecal particles are a heavier allergen of 10 to 35 microns in size and are not airborne . Removal of carpet , avoidance of fabric furniture , and a bedroom free of pillow shams , stuffed animals , books and other dust collectors can all be helpful to lower dust mite allergen . ( 3 , 10 ) Certain chemicals such as acaricidies have also been used to lower dust mite levels to treat carpeting and furniture , with mixed results . ( 3 , 10 ) A common reservoir for allergens is carpet laid on concrete such as in a damp basement . In these damp areas , carpet should be avoided . Dehumidifiers to lower humidity below 50 percent may be beneficial .
In contrast to dust mites , cat dander , dog dander and other mammalian fur allergens are lighter weight are less than 10 microns in size . These airborne allergens are able to circulate throughout the home and can be found on walls , ceilings , flooring , and in ductwork . Hence , a HEPA air filter may help lower these allergen levels . ( 10 ) Cleaning ductwork and removal of the pet completely from the indoor environment has been helpful . Studies have shown that it may take as long as four to six months for cat and dog allergen levels to decrease significantly once the pet is removed and comprehensive cleaning instituted .( 12 ) Homes without cats and dogs have been found to have significant dog and cat allergen even though there has not been a pet present .( 13 ) Public areas such as schools , malls , movie theatres , public transportation , hospitals , and even allergists ’ offices have been shown to have detectable pet allergen levels indicating that dog and cat allergen travel on individual ’ s clothing . ( 14 ) OZONE air cleaners generally are not recommended , as charged OZONE particles can contribute to asthma . Likewise , using floor cleaners which put water or steam into the carpet may contribute to higher mold and mite levels and are to be avoided ; whereas , vacuum cleaners that utilize a HEPA filter may be beneficial . Hardwood floors , clean surface tile and areas that can be wiped clean are recommended for individuals allergic to indoor allergens . ( 3 , 10 )
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