Skin prick test positivity to house dust mites (HDM) in patients with chronic urticaria

Abstract

Background: The urticaria lasting for more than 6 weeks is termed chronic urticaria. The etiology of chronic urticaria and angioedema remains uncertain in most of the patients. Aeroallergens can induce or exacerbates chronic urticaria. The common aeroallergens are house dust mites (HDM), pollens, moulds, etc. House dust mites can trigger immunological process through ingestion, inhalation or inoculation. These mite allergens are resistant to high temperatures, and do not lose their antigenic property even on cooking. HDMs can also cause worsening of existing atopic dermatitis. Skin test with HDMs is well known to cause irritation due to their proteolytic enzymes.The study was undertaken with the objective to study the skin prick test positivity to house dust mites in patients with chronic urticaria. Methods: The study was done on 56 consecutive patients of clinically diagnosed cases of chronic urticaria attending the OPD. The skin prick test was done according to the standard protocol. Results: We had a total of 56 patients with chronic urticaria, of which males were 30 and females were 26 with a male to female ratio of 1:0.8. Of the 56 patients with chronic urticaria skin prick test to HDM was seen in 8 (14.2%) patients. D. pteronysinnus 6 (10.7%) constituted the majority among the HDM positivity followed by D. farinae 2(3.5%). We also found skin prick test positivity to pollens, moulds and animal dander in 5, 4 and 2 patients respectively. Conclusions: House dust mites can cause or trigger the urticarial symptoms and one should consider to do skin prick test to HDM in identifying the cause and thereby reliving the symptoms of urticaria on its avoidance.