HYPERSENSITIVITY TO CHIRONOMID LARVAE

Chironomid larvae (red midge larvae) are often used by aquarists as fi sh food Their hemoglobins can cause IgE-mediated allergic diseases in exposed and unexposed people. The aim of this study was to find out th e prevalence of positive skin tests to chironomids in patients sufferi ng from rhinitis and/or bronchial asthma in Ciudad Real (Spain). A tot al of 465 patients were submitted to skin prick tests with chironomids in addition to common inhalant allergens. The patients with positive skin prick test (wheal greater than or equal to 3 mm) to these larvae answered a questionnaire. Skin prick tests with Acarus sire, shrimp, c ockroach and mosquito (Culex pipiens) were carried out. Serum levels o f fetal IgE and anti-Chironommus thummi, anti-Dermatophagoides pterony ssinus, anti-shrimp, and anti-mosquito (Aedes communis) IgE were deter mined. Conjunctival or nasal provocation tests were carried out with c hironomids. Of the 465 patients skin tested 19 showed a positive skin prick test with chironomids, corresponding to 4.1% of all patients and 6% of the atopic patients. None were monosensitized. Significant corr elations were found between skin prick test results with chironomids a nd mites (p <0.005). Of the 19 patients, 15 had positive skin prick te st with the common mosquito C. pipiens. Seven patients showed elevated anti-D. pteronyssinus IgE, six elevated anti-shrimp IgE, and 10 showe d elevated anti-A. communis IgE. Provocation tests with chironomids we re positive in 14 patients (four nasal and 10 conjunctival tests). Con junctival provocation tests were carried out in 16 controls and were p ositive in three; all three showed positive skin prick test with chiro nomids. One patient had occupational allergy from the larvae (aquarist ). After mosquito bites, five patients showed immediate wheal reaction s and one patient suffered an anaphylactic reaction after several mosq uito bites. Only two patients remembered having been in contact with c hironomids as fish food We found hypersensitivity to these larvae in p atients without apparent contact to them. These patients could have be come sensitized in various ways, including: I) inhaling particles of c hironomids or others that are cross-reactive with them; 2) exposure to products used as fish food containing chironomids; and, 3) through cr oss-reactivity with other allergens such as mites, shrimp or mosquitoe s.