Original article Occupational allergy in laboratory workers caused by the African migratory grasshopper Locusta migratoria Exposure to insects is a common health problem, particularly among workers exposed to laboratory ani- mals. It is becoming increasingly evident that exposure to insects results in increased risk of sensitization to insect antigens which in turn, can lead to clinically important inhalant allergies including severe respiratory disease. It has been estimated that occupational exposure to insects results in a high prevalence of allergic sensitization, exceeding 25%, while approximately 10% of those exposed will develop asthma (1). Occupational groups commonly affected include scientists, technicians, veter- inarians, animal carers and breeders in the pharmaceu- tical industry as well as universities and research institutes. Insects, which induce occupational allergies among exposed workers, belong to the phylum Arthropoda, which include other allergenic taxa such as Crustacea (see Fig. 1). Insect species of at least 12 different orders have been implicated in the promotion of inhalant allergy in humans. Orthoptera and Blattodea have species that are frequently encountered in the occupational environment, such as locusts and cockroaches (2). Although allergies to insects are recognized as an important occupational health problem, studies on the factors determining the incidence of the disease in specific exposure settings and the patterns of immunological responses observed have been very limited. It is apparent, however, that the different allergens derived from various sources can be very potent allergens. Sensitivity to locusts was previously reported by Burge et al. (3) to be an important contributory factor to health problems in exposed laboratory workers. One-third of the workforce (n ¼ 10) in this study reported wheezing, rhinitis and urticaria and over half of all workers showed a positive skin-prick test (SPT) to locust extracts. A more recent study by Tee et al. (4) demonstrated multiple allergens by Western blotting and identified the peri- trophic membrane in the gut as a major source of allergen. Specific IgE antibodies were identified using a radioallergosorbent test (RAST) employing mixed protein extracts of locusts Locusta migratoria and Schistocerca gregaria. Background: Recent reports of fatal asthma cases associated with swarms of locusts affecting African countries have highlighted the importance of this insect in causing asthma morbidity and mortality. However, only limited information is available about the allergic health outcomes such as asthma and its determi- nants in exposed individuals. In this study, workers exposed to the African migratory locust Locusta migratoria were evaluated for allergic health outcomes as well as the nature of the offending allergens. Methods: Ten scientists and technicians exposed to locusts in a laboratory were investigated for locust-related allergy using questionnaires and immunological tests. The presence of allergy was determined by quantification of specific IgE and IgG to L. migratoria using the UniCAPÒ system and via skin-prick testing (SPT). The allergens were characterized by Western blot and ImmunoCAP inhibition assays. Results: Six of the 10 workers experienced symptoms ranging from urticaria and rhinoconjuctivitis to asthma. Seven individuals demonstrated sensitivity on SPT and five had specific IgE antibodies to L. migratoria. Significant cross-reactivity was demonstrated for allergens in the locust faeces, body and wings but not to cockroach allergens. Novel allergens with molecular weights of approximately 70 kDa were identified in locust wings, which are distinctly different from other known allergen sources from locusts. Conclusion: Exposure to L. migratoria allergens is a potential sensitizer in exposed individuals. Raised levels of locust-specific IgE can be readily quantified. The wings of this insect species have been identified as a novel allergen source. A. L. Lopata 1 , B. Fenemore 1 , M. F. Jeebhay 2 , G. Gäde 3 , P. C. Potter 1 1 Division of Immunology, Department of Laboratory Sciences, National Health Laboratory Services, University of Cape Town, Cape Town, South Africa; 2 Occupational and Environmental Health Research Unit, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa; 3 Department of Zoology, University of Cape Town, Cape Town, South Africa Keywords: allergy; environmental allergens; insects; IgE immunoglobulins; IgG immunoglobulins; locusts; occupational allergy; occupational asthma. Dr Andreas L. Lopata Division of Immunology, Department of Laboratory Sciences Groote Schuur Hospital, OMB H-47 Observatory 7925 Cape Town South Africa Accepted for publication 4 May 2004 Allergy 2005: 60: 200–205 Copyright Ó Blackwell Munksgaard 2005 ALLERGY DOI: 10.1111/j.1398-9995.2005.00661.x 200