Twenty eight per cent (15) of 53 workers engaged in a sheep blowfly breeding programme designed to control genetically the pest Lucilia cuprina experienced allergic manifestations resulting from contact with this insect. The most common symptoms were rhinitis, affected eyes, rashes, and lower respiratory symptoms, usually, but not always, immediate in type. A personal history of noninsect related asthma, allergic rhinitis, or eczema, or a combination of these was more common in the fly allergic group but some workers experienced allergic symptoms only when exposed to the adult sheep blowfly. Raised levels ofserum IgE antibodies specific for adult and larval allergens were found in approximately 70% of symptomatic workers, whereas only 30% and 7% of two groups of asymptomatic workers were found to have these antibodies. It is concluded that the sheep blowfly is an important source of airborne allergens and can prove a considerable occupational health hazard. Measures designed to reduce worker contact with blowflies and their emanations considerably reduced the incidence of allergic symptoms in the exposed workers.The true flies, members ofthe insect order Diptera, are widespread and common in our environment and many species impinge on our health and wellbeing.

An allergic reaction, provoked by exposure to the blowfly Lucilia cuprina and shown to be IgE-mediated, occurred in a subject employed in an entomological research laboratory. The subject's serum, and sera from three other asthmatic patients with IgE antibodies to blowfly extracts, also reacted with extracts from the screw-worm fly {Chrysomya bezziana). Results suggested that antigens from the two species share immunological cross-reactivity. Cross-reactions also exist between the difl"erent developmental stages of both species. Allergic reactions to inhaled insect allergens may not be uncommon in the Australian community.

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Sera from 30 workers in an entomological research institute and from five Sydney asthmatics, all with serum IgE antibodies to sheep blowfly (Lucilia cuprina) antigens, were studied with the aim of identifying individual IgE-binding proteins in extracts of L. cuprina adult flies, larvae and eggs, and in extracts of related species of flies from the order Diptera. Using protein blotting, 21, 18 and nine different IgE-binding components were identified in extracts of L. cuprina adult flies, larvae and eggs, respectively. A component(s) of MW 67 kD found in all three developmental stages, showed the highest frequency of IgE-binding; reacting, for example, with 70% of the sera tested with the adult fly extract. Some components were detected in only one of the three developmental stages. Investigations of possible allergenic cross-reactivity between L. cuprina and extracts from six other related species of flies revealed IgE-binding bands in each of the extracts as well as in an extract of Agrotis infusa, a cutworm not belonging to the order Diptera. One strongly reacting component of MW 20 kD was detected in extracts of five different fly species as well as in the A. infusa extract. The results suggested that allergenic cross-reactivity between some fly species exists, and may extend to taxonomically unrelated insect species.

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