Patch testing to detect Dermatitis and Allergies to plants.

Background and Objectives: Partheniumhysterophorous weed often referred to as ‘scourge of India’ is a major cause of systemic as well as cutaneous allergies ( Phyto-Dermatitis) in India. Awareness of the allergic potential of this weed is high in India but knowledge of its various allergic manifestations and related weeds is poor. Patch testing may reveal underlying sensitivity to the weeds in populations which are closely associated with them. This study is done to evaluate the awareness and prevalence of allergy to Parthenium and associated plants. Methods: Five hundred and fifty consenting subjects among the populations closely associated with plants were interviewed of which 202 with past history and/or signs, symptoms suggestive of plant allergy were tested. Results: Chrysanthemum was well recognized (89.6 %) than Parthenium (34.7%).Five subjects had a positive result for all antigens. Parthenium(9) Xanthium(8) and chrysanthemum (14) were the distribution of positive reactions among subjects. Overall 8.4% subjects had positive testing for one or more antigen. The age of 46-60 had the highest positivity. Farm workers were at maximum risk of acquiring allergy (14.5%), followed by green grocers/fruit sellers (11.8%), florists (10%) and horticulturists, gardeners,others (8%).Rural subjects had a higher positivity (10.6%) compared to Urban (6.5%). Interpretation and Conclusion: Majority of Subjects who could recognize and identify Parthenium and Xanthium as plants causing allergy were unsure of the potential risk from Chrysanthemum, a common commercial flowering plant and was unknowingly considered least allergic. But patch testing proved otherwise.