Abstract

Allergic occupational asthma can be caused by a number of substances, mostly proteins, derived from animals, plants,foods, and enzymes. Insect exposure is not very common in Western countries. However, laboratory workers or other professional groups may have direct contact with these animals.

Nowadays, many insect species belonging to different orders have been implicated in allergic processes. It has been estimated that 50% of animal-sensitized individuals will develop rhinoconjunctivitis, 25% skin reactions, and 25% asthma, and most allergic processes in these individuals affect multiple target organs.

We present a patient with occupational asthma and rhinoconjunctivitis caused by inhaling cricket (Acheta campestris) particles and contact urticaria after handling of crickets. A 28-year-old man with no previous personal history of asthma or other respiratory disorders and who had never
smoked came to our allergy unit with a 4-year history of frequent episodes of cough, dyspnea, and wheezing accompanied by rhinoconjunctivitis and occasionally chemosis and urticaria. He had worked for 7 years as an assistant in a reptile shop, where he fed reptiles with live crickets, which themselves were fed with cornmeal. He developed the symptoms after
a latent period of 3 years. The patient reported improvement of the respiratory symptoms and disappearance of cutaneous symptoms at the weekend and during holidays.
Skin prick tests with a battery of common inhalant allergens, including dust mites, pollens, moulds, cat and dog dander, and insect (German cockroach, oriental cockroach, and American cockroach), were negative. Skin prick test with a manufactured cricket extract at a concentration of 1 mg of freeze-dried material per milliliter was positive (7 mm wheal diameter) and negative in 5 control individuals. Skin prick test (prick by prick) with a cornmeal extract was negative. Spirometric values were in
the normal range (forced vital capacity [FVC], 5.18 L [89% of predicted]; forced expiratory volume in 1 second, 4.11 L [89% of predicted]; forced expiratory fl ow at 25%-75% of FVC, 3.68 L/s [80% of predicted]) and the results of a bronchodilator test were negative. Serial determinations of peak expiratory flow were seen to drop by more than 20% during work periods and returned to normal values at the weekend. A specific nasal challenge test, measured with acoustic rhinometry, was performed with a cricket extract and showed an immediate response at 1:1000 dilution
of the extract used in the prick test, with a reduction in nasal volume of more than 30% between the 2nd and 5th centimeter into the nostrils measured at 10 minutes. A nasal challenge with phosphate buffered saline was negative. Specific nasal challenge test with cricket extract was performed in a control patient with a negative result. The protein profile of the cricket extract showed several bands with a molecular weight range of 10 to 100 kDa. Immunoblot experiments showed several bands with
immunoglobulin (Ig) E binding capacity. The most prominent bands corresponded to proteins with a molecular weight of 17, 32, 47, and 62 kDa. No bands were recognized with a pool of sera from healthy control individuals.

Patients with IgE sensitization to crickets, without evidence of clinical relevance, have been reported in previous studies and most of them showed cross reactivity with other insects.Bagenstose et al reported 2 patients whose clinical history strongly suggested an asthma-related allergy linked to their occupation, but the diagnosis was not confirmed by respiratory
function tests. Crickets appeared to be involved. The suspected cricket allergy was confirmed by a skin test and bronchial inhalation challenge. However, both patients were sensitized to several common aeroallergens and also other allergens they were exposed to in their jobs, including crickets.

In conclusion, this is the first reported case of unequivocal occupational asthma and rhinoconjunctivitis with contact urticaria in a patient monosensitized to cricket. The clinical relevance was demonstrated by specific nasal challenge test measured by acoustic rhinometry. More studies are necessary to determine the immunochemical characteristics of the allergens and cross-reactivity with other insect groups.

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