Dr. Kripa Dongol

Allergic diseases are the conditions in which our body’s immune system becomes hypersensitive to harmless substances in the environment. The immune system protects us against pathogens. Whenever it fails to identify such harmless substances as pathogens, allergic reactions occur. Common allergens include pollen, dust mites, fungi, animal dander, different kinds of food, nuts and various drugs.

It is estimated that globally 30 to 40 per cent of the population is suffering from one form of allergy or the other. Allergy is a major public health problem. After cardiovascular disease, cancer and diabetes, allergy is the most common non-infectious disease. Worldwide, the prevalence of allergic diseases is drastically increasing both in developed and developing countries. However, there is a lack of valid epidemiological data in our country. Most patients with allergies are children and young adults. Therefore, allergic diseases are likely to burgeon in the future as well.

Common Diseases
Common allergic diseases are allergic rhinitis, allergic conjunctivitis, urticaria, atopic dermatitis (eczema), allergic asthma, food allergy, drug allergy and anaphylaxis. It is estimated that about 10 to 30 per cent of the world’s population is suffering from allergic rhinitis. According to the World Health Organisation, the number of asthmatic patients is around 300 million in the world and it is expected to increase to 400 million by 2025. Allergy patients may show symptoms such as sneezing, an itchy nose, watery nasal discharge, nasal congestion, red and itchy skin with hives, a dry chronic cough, dyspnoea, wheezing and chest tightness. Patients with food or drug allergies may show symptoms of diarrhoea, vomiting, abdominal pain, headaches, hives in the skin or dyspnoea. Allergic manifestations can range from mild and short-duration symptoms to life-threatening symptoms.

Multiple allergies can co-exist in a single patient. For example, patients with allergic rhinitis could have allergic conjunctivitis simultaneously. Similarly, patients with bronchial asthma could have a food allergy. Likewise, patients with allergic rhinitis are three times as likely to develop bronchial asthma. Poorly treated patients with allergic rhinitis are at risk of asthma exacerbations, which may require them to be hospitalised. Therefore, early and adequate treatment of allergic rhinitis is of utmost importance to prevent the development of asthma or to prevent asthma exacerbations.

Children and people of productive age groups are the common victims of allergic diseases. Allergy could diminish the quality of life significantly. Allergic rhinitis and asthma can lead to poor sleep, fatigue, poor concentration, reduced learning and thinking capabilities, poor memory power and sometimes depression. Childre n can suffer from poor school performance with adverse effects on their physical and psychological health. Because of the cost of medicines and the loss of workdays, the economic burden on patients and the nation can increase considerably.

Allergy is assumed to result from complex interactions between genetic predisposition and the environment. Some people have atopy, which means they have a genetic tendency to develop an allergy. Allergic symptoms may be seasonal in some patients, whereas they persist all year round in others. Seasonal allergies could be due mostly to outdoor pollen exposure. However, persistent allergies could be due to indoor allergens such as dust mites, pets and insects. Sometimes, exposure to trigger factors such as the cold, dust, smoke, fumes, infections, endocrine disorders and stress may exacerbate allergy symptoms.

Industries and vehicles are the major sources of air pollution. The particulate matter, nitrous oxides, sulfur dioxides and carbon monoxide released from vehicles could act as a trigger. Tobacco smoke, biomass fuel, global warming and changes in the weather are some of the few factors that give rise to allergic diseases. Food allergy is also on the rise because of the intake of processed foods and the inclusion of western dishes in our menu. The common foods that cause allergies are eggs, milk, peanuts, tree nuts, fish, shellfish, wheat, soy and sesame.
The management of allergies needs to be integrated into the national healthcare system as a holistic approach as multi-system involvement is common. Proper history-taking, clinical examination and investigations are necessary for correct diagnosis. The specific diagnosis of allergies is necessary to identify causative allergens.

Diagnosis
The skin prick test is recognised as a gold standard test for the diagnosis of allergies. Under this test, different possible allergens are tested in patients and allergic sensitization is noted. The skin prick test is popular across the world because it is a minimally invasive, safe, cheap, sensitive and specific test of allergy. Multiple allergens can be tested in a single setting. The results are quickly obtained and made available to patients. Other investigations, such as serum specific IgE assay and basophil activation tests, could be done to diagnose allergies. However, these tests are expensive and time-consuming.

Identification of allergens is essential because the most effective treatment is to avoid causative allergens or to start immuno-therapy. Medicines are only helpful for the temporary relief of the symptoms of allergy. In the present-day scenario of Nepal, most of the patients with allergies take over-the-counter antihistamines (anti-allergy medications) because of a lack of awareness about the necessity of visiting specialists.
Allergic diseases are under-diagnosed and under-treated most of the time. This is due to a lack of trained and skilled manpower in the field of allergy. There is less public awareness about allergic diseases and their long-term consequences if left untreated. The government needs to focus on incorporating allergy as a separate sub-speciality in the medical field and encourage research in this field. The government should also embark on various programmes to enhance public awareness about allergic diseases.

(Dr. Dongol is an assistant professor at the Department of ENT, Tribhuvan University Teaching Hospital)