Do you or any of your relatives or friends shy away from certain food items, like peanuts, prawns or eggs? Or try to steer clear of pollen grains, animal fur, dust etc.? These are all common allergens, and those prone to allergic reactions are well-advised to stay away from them.
Why is it that some people are allergic to particular food items or things like pollen grains or animal fur, while others don’t react adversely to these or any other substances?
There is no single well-defined reason, but different hypotheses are offered on allergies, says Dr Chitta Spurthi Reddy, paediatrician at Rainbow Children’s Hospitals and Fellow in Allergy and Asthma “One hypothesis is that allergy can be genetic or run in families — an atopic family is one where members are sensitive to different types of allergens. There are also studies on epigenetics or how a person behaves in different environments based on the DNA’s response to different environmental changes or effects of the environment on the genes. For example, it has been found that Asian children born in Australia are more prone to food allergies and atopic dermatitis than Australian children born to Australian parents. It is also seen that allergies have plateaued in Western countries, while they are rising in developing nations including India,” she says.
“There is also the hygiene hypothesis, according to which, individuals living in farms or close to nature develop fewer allergic symptoms than those whose living conditions are cleaner, and who have never played in the mud and dust, and so they have not been exposed to even the usual germs. Their immune systems are unable to differentiate between harmful and harmless irritants. Thus, they are more prone to developing allergic reactions if exposed to even harmless substances,” explains Dr Spurthi.
Common allergens
Aero allergens (pollens and dust), followed by food items (milk, eggs, wheat, soya, peanuts dry fruits, shellfish and seafood like shrimps, oysters) are the most common. Proteins in eggs, fish and seafood, mushrooms and soya are usually the culprits. While 80% of children outgrow allergies to milk, eggs, wheat and soya within six years of age, allergies to shrimps and peanuts can remain throughout life. People can also be allergic to certain medications, such as penicillin, cosmetics and dyes, insect stings or bites, pet fur, dander and saliva etc, say doctors.
Symptoms of allergies
According to doctors, depending on the systems involved, symptoms can be related to the skin, eyes, nose, upper respiratory tract etc. These include itchy, runny or blocked nose, sneezing, watery, swollen, burning, red eyes, wheezing, chest tightness, laryngeal oedema, breathing difficulties, throat pain, cough, and bumpy, red, itchy rashes on the skin. Other symptoms include low blood pressure, changing heart rate, dizziness and fainting. Some food allergies can also cause diarrhoea and vomiting. Pollution and dust trigger allergic rhinitis or allergic asthma and in children, 90% of allergic reactions are related to allergic asthma.
Vulnerable groups
Dr M Sheetal Kumar, senior general physician and diabetologist, Yashoda Hospitals, Secunderabad, says, “Children are at higher risk of allergy, especially those who have a family history of allergies. Some studies show that children born by Caesarean section may have a higher risk of allergies, as they do not have exposure to the mother’s microbiome during childbirth. Other vulnerable groups include those from the poor socio-economic strata (due to poor hygiene), those employed in dusty environments or exposed to pollen, rural people exposed to agricultural dust or allergens and urban people exposed to traffic pollution.”
Dr Spurthi adds, “In pregnant women, allergies can worsen or disappear based on their hormonal changes. In children, certain food and skin allergies that occur up to one year of age get better as they grow up. Respiratory allergies increase between the ages of 2 and 16, plateau in the 30s, then surge again till about 60 years of age. Post 60, they tend to disappear as metabolism slows down.”
Identifying the culprits
Observing symptoms, taking the medical history of the individual (both personal and family history) and clinical examinations and tests can help identify specific allergens for each patient. Tests include skin prick tests and blood tests (indicated by eosinophilia and elevated serum IgE), says Dr Sheetal Kumar.
Treatment options
“The best treatment is to identify and avoid the allergens, but it is not always possible to do so. Medical treatment options are available. Drugs like antihistamines, decongestants and corticosteroids will help. Immunotherapy is a treatment in which gradually increasing of doses of allergens are given to help the patient develop long-term tolerance,” shares Dr Sheetal Kumar while Dr Spurthi adds that adrenaline injections can be given in case of severe life-threatening allergic conditions.
Escalating allergen load
Allergens are increasing with pollution and growing adulteration of food and products used in day-to-day life like cosmetics, detergents etc. “Pollution includes not only automobile exhaust-related contamination, but also indoor pollution created by fragrances and mosquito repellents. Global warming, rising temperatures and release of carbon dioxide and other gases are also indirectly increasing allergens. It is causing early onset of the spring season, which leads to trees pollinating earlier and for a longer duration. So, more pollen grains are found in the air,” explains Dr Spurthi.
Minimising risks
Personal and household hygiene and routine self-protective and occupational hygiene will reduce allergic tendencies. Soft toys and pillow covers and bedsheets often cause allergies in children. So, these should be washed once a week in hot water to kill dust the mites. Also, children should avoid handling pets too much; if they play with pets, their clothes should be changed and their hands washed each time, as pet fur is known to cause allergies,” advises Dr Spurthi.
