ALLERGIC POLLEN GRAINS OF INDIA
Major causative agents for allergic diseases like seasonal rhinitis, asthma, hay fever, atopic dermatitis and various kinds of bronchial troubles are pollen grains, fungal spores, dust mites, insect debris, animal epithelia, etc. The magnitude of incidence of any symptom in a particular area depends on the kind of aeroallergen found in that area, genetic constituent of the population, etc. It is estimated that around 10 – 35 % of the population suffer from allergenic diseases during various season. Pollen allergens also cross react with other pollen allergens among the same family as well as food. Knowledge about allergens has progressed with molecular and immunological understanding of the diseases. Perhaps high vehicular and other kinds of emission and pollution are somehow related with the rising incidence of pollen induced respiratory allergy. It has been reported that gases like SO2 and NO2 affects pollen grains and these pollutants are capable of modifying the morphology of these antigen carrying agents, and also alter their allergenic potential.
Aerobiological studies in different parts of the country to ascertain concentration and seasonality of pollen grains has been conducted by various workers. Reports show that in north India the dominant pollen types are Ailanthus, Ricinus, Xanthium, Cannabis, Amaranthus, Holoptelea, Putranjiva, Casuarina, Eucalyptus, members of Poaceae, etc. In eastern India Azadirachta, Amaranthus, Xanthium, Argemone, Chenopodium, Trema orientalis, Pongamia, Cocos, Borassus, Eucalyptus, Carica papaya, etc. are the dominant types. Asteraceae and Chenopodiaceae are maximum in June. Trema orientalis has high concentration from May to July. In southern India studies show the dominant pollen types are Parthenium, Casuarina, Chenopodium, Amaranthus, Cocos, Peltophorum, members of Poaceae, etc. Pollen of Poaceae are most abundant from June to August. Ricinus, Ailanthus, Holoptelea, Argemone, Cocos, Parthenium, Chenopodium, Amaranth, Poaceae, Asteraceae, Apocyanaceae, etc,. are dominant pollen types in west and central India. Pollen calendars are very useful for clinicians and allergic patients.
Various precautions can control the situation to some extent like closing windows in the evening when pollen generally settle down to minimize their concentration, avoid outdoors when pollen are present in high concentration, airconditioning indoors. Though allergenicity varies from person to person, avoiding plants which have usually high allergenicity may help in controlling the situation.
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