Prick testing in insect bite reaction

Iyshwariya, Sivadasan (2018) Prick testing in insect bite reaction. Masters thesis, PSG Institute of Medical Sciences and Research, Coimbatore.


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INTRODUCTION: Papular urticaria is characterised by pruritic papules or vesicles and varying degrees of local edema. Following antigen challenge in skin, wheal and flare reactions develop immediately. Careful observation for longer periods has shown that in many instances a late inflammatory response appears at the same site, and is different from the initial reaction. This late phase response appears 3-4 hours after challenge, peaks at 6-12 hours and resolves by 24 hours. OBJECTIVE: To assess the type 1 hypersensitivity reaction – early phase (assessed at 15 minutes) and late phase (assessed at 6 hours) with insect series in patients with papular urticaria. MATERIALS METHODS: Hospital based observational study of 30 patients with papular urticaria. All the patients were subjected to negative and positive control. Patients identified to have dermographism with negative controls and patients showing negative reaction with positive (Histamine) control were excluded from the study. The largest diameter of the wheal of each particular test is measured, a positive result was considered as wheal diameter of ≥ 3 mm. RESULTS: Among the 30 subjects, all have shown early phase positive reaction to at least 1 antigen. Among the individual antigens, highest proportion of early phase positive reaction was observed for Mite (D.Farinae) in 63.33%.The late phase positive reaction was observed in 5 (16.7%) subjects. Highest proportion of late phase positive reaction was observed for Mite (D.Farinae) in 4 (13.33%) subjects. CONCLUSIONS: Early phase urticarial reaction is common with many common insect antigens. Mites seems to be highly allergogenic, as compared to other antigens. The late phase urticarial reaction is also seen in nearly one sixth of the cases. Mite (DF) has caused highest proportion of late phase positive reaction. So we suggest prick testing in all cases of suspected papular urticaria as the management can differ. Patients showing late phase reaction may not be responsive to treatment with anti histamines and will require systemic steroids.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Papular Urticaria ; Prick Testing ; Late Phase Response.
Subjects: MEDICAL > Dermatology Venereology and Leprosy
Depositing User: Subramani R
Date Deposited: 27 Aug 2018 20:12
Last Modified: 27 Aug 2018 20:12

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