Etiologic significance of mosquito (Anopheles stephensi) in respiratory allergy in India.

The etiologic significance of Anopheles stephensi, a common mosquito species in Delhi, in respiratory allergic disorders was investigated. Intradermal (ID) tests with the mosquito whole body extract (WBE) were performed on 247 patients with bronchial asthma and/or rhinitis and 50 healthy nonallergic volunteers. Of these 247 patients, 118 (47.8%) had positive (1+ to 4+) reactions including 72 (29.1%) with markedly positive (2+ to 4+) ID reactions. We did not observe any 2+ to 4+ skin reactions in normal healthy volunteers, giving evidence for the specificity of markedly positive ID response. The skin test positivity was not influenced by various clinical characteristics (age at onset, duration and type of disease, and family history) of patients included in the study. The specificity of positive ID response was further supported by the results of mosquito RAST with the sera of 14 patients. Ten of the 12 sera (83%) from patients with positive ID response to mosquito WBE were RAST positive. Sera from two patients with negative ID reactions were RAST negative. The bronchial provocation tests (BPTs) were uniformly negative in all five healthy volunteers and two patients showing negative ID responses to mosquito WBE, while the three patients showing 2+ to 4+ responses gave positive BPTs. Our results suggest that mosquito-derived particles are important inhalant allergens in the etiology of IgE-mediated respiratory allergic disorders in India.