Widespread IgE-mediated hypersensitivity in Northern Sudan to the chironomid Cladotanytarsus lewisi ('green nimitti').

Hypersensitivity to Chironomidae (non-biting midges) has been a problem in Northern Sudan since about 1927 and is probably due to the working of dams which have produced lake-like conditions on parts of the Blue and main Niles where breeding has evidently increased. Studies were undertaken to determine whether this hypersensitivity is mediated by IgE. Sixteen Sudanese, with bronchial asthma associated with exposure to the chironomid, Cladotanytarsus lewisi ('green nimitti'), were investigated. All patients gave a positive immediate-type skin reaction to an extract of the midge and the majority had markedly elevated concentrations of circulating IgE. Serum from all patients passively sensitized human lung fragments in vitro for the release of histamine and slow-reacting substance of anaphylaxis by the 'nimitti' antigen. This tissue-sensitizing activity could be removed by immunoabsorption with an anti-IgE. These results indicate that this widespread and important hypersensitivity in the Sudan is IgE-mediated and thus may potentially be treated by desensitization.