Work-Related Allergies in Insect-Raising Facilities

Complaints of skin and respiratory allergies have frequently been reported by employees in facilities that raise insects for entomologic research. In 1980, the U.S. Department of Agriculture asked the National Institute for Occupational Safety and Health (NIOSH) to conduct a health hazard evaluation among employees of the Agricultural Research Service (ARS). For this study, NIOSH used a mailed, self-administered questionnaire. This questionnaire was designed to assess the prevalence of symptoms possibly related to allergenic airborne particulates associated with raising colonies of insects in confined spaces; the frequency of insect bites or stings was not of major concern in the study.

The following case reports are representative of those elicited by the survey.

Case 1: A worker had onset of burning eyes and nasal and sinus "stuffiness" after working for about 2 years with various moth species. These symptoms typically began approximately an hour after exposure to the moths and would last up to 1 day after exposure ceased. Use of a battery-powered, air-purifying respirator prevented their occurrence. Serologic testing for antibodies to standard fungal antigens was negative. Skin tests for allergies to house dust, house-dust mite, molds, moth scales, and adult and larval stages of the screwworm fly were also negative. An extract of the larval stage of the Heliothis moth caused a positive skin reaction. The employee stopped working with Heliothis species, and the symptoms did not recur.

Case 2: A worker experienced nasal irritation and congestion, cough, and episodes of shortness of breath with chest tightness within one-half hour after exposure to scales and "frass" (debris or excrement) from several insects. After working for 2 years with Anthonomus grandis (boll weevil), the worker, because of these symptoms, was transferred to a job that involved working with Heliothis species. The symptoms recurred within 3 years of working with moths, and resolved after transfer to a job involving work with Musca domestica (housefly). The symptoms occurred again within 2 years' work with this insect. Symptoms recurred within 5 months after another job change to work with Cochliomyia homonivorax (screwworm) species. The worker's serum immunoglobulin E level was markedly elevated to 2,060 (normal less than 780), and eosinophil counts were elevated. Chest x-ray and pulmonary-function tests, including methacholine challenge, were normal. Allergy skin testing was positive for housefly and moth extracts and for extracts from the adult and larval stages of the screwworm fly. When the employee transferred to a job that did not involve insect-related work, the symptoms finally disappeared.

In November 1983, NIOSH reported results of the survey (1). Employees at 87% (85/98) of the ARS insect-raising facilities participated, representing 37 states; the overall response rate was 71% (753/1,062). Of those responding, 25% (190/753) reported current or past symptoms consistent with allergic reactions related to work. The most prevalent symptoms reported included sneezing or runny nose (73%), eye irritation (68%), skin irritation or skin rash (41%), cough (38%), wheezing (26%), and shortness of breath (24%). At 61% (52/85) of the respondent facilities, at least one employee reported current or past symptoms suggestive of work-related allergy; at five of the facilities, 10 or more employees reported such symptoms.

Of the entomologists and laboratory technicians who worked directly with insects, 33% (168/507) reported symptoms suggestive of work-related allergy, compared with 9% (22/246) of workers who had little or no direct contact with insects (p 0.001).

Symptoms began within half an hour after arriving at work in 48% (92/190) of the affected employees and between one-half and 4 hours after arrival in another 30% (57/190). Sixty-six percent of workers (125/190) reported improvement in the evening after going home; improvement or complete resolution on weekends was reported by 74% (141/190) and on vacations by 82% (155/190). Forty-four percent (83/190) consulted physicians because of symptoms; treatment was prescribed for 83% (69/83). Twenty-two percent (41/190) of those reporting symptoms suggestive of work-related allergy either discontinued working with the insect thought responsible for their symptoms or transferred to another work area or job.

Respondents identified the cause of their symptoms as airborne insect material (83% (157/190)), direct contact with an insect or insect part (52% (99/190)), insect stings (6% (12/190)), and insect bites (4% (7/190)). The most frequently implicated insects were in the Lepidoptera order (moths and butterflies) (66% of 282 multiple responses). No work-related symptoms of allergy was reported in areas of one insectary that was specially constructed of waterproof concrete blocks so that all surfaces could be thoroughly cleaned three times a week with a pressurized wet-spray, wash-down method. Reported by Div of Respiratory Disease Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: For many years, entomologists have recognized allergies associated with raising insects in confined spaces. Watery eyes, sneezing, and asthma were reported in 1918 by an entomologist raising the New Mexico range caterpillar (2); in 1965, symptoms of inhalant allergy were described by workers at a screwworm facility (3); in 1972, "terrible fits of asthma and itching eruptions of hands" were reported by entomologists working with cockroaches (4); investigation of allergic sensitivity in workers exposed to gypsy moths was reported in 1982 (5); and a case of hypersensitivity pneumonitis attributed to Penicillium mold was reported by an entomologist working at an insect-raising facility (6).

Employees in insect-raising facilities can be exposed to various potentially sensitizing airborne particulates, such as insect parts or excrement, components of culture media, and airborne bacteria or fungi. The relative importance of these agents in sensitizing the worker is not clear.

The symptoms observed in the NIOSH survey are consistent with results of a pilot survey conducted by the Insect Allergy Committee of the Entomological Society of America (7) and with other reports in the medical literature. Such reports indicate that eye irritation, respiratory symptoms (sneezing, cough, chest tightness), and skin irritation or rash are the major symptoms of insect allergy in these facilities (8,9). The findings are also consistent with results of outbreak investigations of allergic reactions occurring in the general population when the number of insects markedly increases (5,9).

Several measures are recommended to prevent sensitizing exposures of workers in insect-raising facilities: (1) segregating insect colonies in one building or in one part of a building; (2) designing facilities so that all surfaces can be readily washed down; (3) establishing a "single pass" air-handling system for insect-raising rooms independent of systems circulating air to the general laboratory area and office space; (4) equipping the independent air-handling system with high-efficiency particulate air filters; (5) substituting vertical laminar flow biologic safety cabinets for the horizontal laminar flow cabinets that cause air to pass across the insects toward the workers' faces; and (6) using laboratory coats and disposable gloves at all cabinets and insect-handling work stations. Protective devices--such as battery-powered, air-purifying, full-face respirators--may reduce the potential for contact of airborne allergens with mucous membranes but are considered less effective than environmental controls. Transfer to other jobs may be the only satisfactory alternative for hypersensitive workers with severe symptoms.

References

1. NIOSH. Health hazard evaluation report no. GHETA 81-121. Morgantown, West Virginia: National Institute for Occupational Safety and Health, 1983.

2. Caffrey DJ. Notes on the poisonous urticating spines of Hemileuca oliviae larvae. J Econ Entomol 1918;11:363-7.

3. Gibbons HL, Dille JR, Cowley RG. Inhalant allergy to the screwworm fly. Preliminary report. Arch Environ Health 1965;10:424-30.

4. Bernton HS, McMahon TF, Brown H. Cockroach asthma. Br J Dis Chest 1972;66:61-6.

5. Etkind PH, O'Dell TM, Canada AT, Shama SK, Finn AM, Tuthill R. The gypsy moth caterpillar: a significant new occupational and public health problem. J Occup Med 1982;24:659-62.

6. Solley GO, Hyatt RE. Hypersensitivity pneumonitis induced by Penicillium species. J Allergy Clin Immunol 1980;65:65-70.

7. Wirtz RA. Occupational allergies to arthropods--documentation and prevention. Bull Entomol Soc America 1980;26:356-60.

8. Burge PS, Edge G, O'Brien IM, Harries MG, Hawkins R, Pepys J. Occupational asthma in a research centre breeding locusts. Clin Allergy 1980;10:355-63.

9. Bellas TE. Insects as a cause of inhalant allergies: a bibliography. Division of Entomology Report No. 25. 2nd ed. Canberra City, Australia: Commonwealth Scientific and Industrial Research Organization, 1982.

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