Latin name: Trogoderma angustum (Solier)
Source material: Whole dried larvae
Common Trogoderma species:
Berlin beetle – T. angustum
Khapra beetle – T. granarium
Warehouse beetle – T. variabile
An insect, which may result in allergy symptoms in sensitised individuals.
Trogoderma is a genus of the Dermestidae family commonly found in warehouses, farm granaries, flour mills and food-packaging plants. From the food-packaging plants, the Berlin beetle may be transported to homes and infest food materials. It can also infest household food products after breeding in carpets, bird or insect nests, dead rodents, etc. (1)
The distribution of the beetle is worldwide, having been introduced in Germany in the 1930s from South America via the USA. It is considered to be a major pest in central Europe and has been reported to be a common pest in Berlin. (2)
Central heating is a prerequisite for survival of this desert insect, which thrives in food storage areas, larders and dining rooms. The Berlin beetle is known to be a common pest in Berlin households, where several studies have been conducted. It is also found in contaminated feeds and cereals, thus giving it the status of an occupational allergen. The exposure includes both beetle and larvae. (2, 3, 4) The spear-shaped hairs of larval skins may be the location of allergenic structures.
The closely related species T. variabile (also known as the warehouse or cabinet beetle) is known to infest food warehouses and processing plants. Although it feeds on almost anything, it prefers wheat, barley, or rice, and it is very difficult to eradicate because it can slow or accelerate its reproduction cycle based on the amount of food readily available. Trogoderma is very resistant to extreme temperature changes in the larval or adult stages. As a result, workers in these facilities inevitably have increased exposure to these insects, the by-products of which may also enter the human food chain. (5)
No allergens have yet been identified.
In a 42-year-old male machinist with occupational allergy to the closely related species T. variabile, the patient’s serum contained specific IgE to 15 different proteins in samples prepared from warehouse beetle materials. Extracts prepared from beetle larvae contained the most (10) IgE-binding proteins. Significantly, the patient showed IgE binding to the extract prepared from material collected from the workplace that was almost identical to the IgE binding to proteins in the beetle exoskeleton extract. (5) The authors suggested that the major sensitising allergen in the worker was derived from beetle exoskeletons, which was supported by the presence of specific IgE to a single protein of 31.3 kDa present in the authentic exoskeleton extract. This protein was also present in authentic adults, larvae, and faeces extracts. (5)
No cross-reactivity has been reported between T. angustum and cockroaches, although cross-reactivity is known in insects. (3)
a. IgE-mediated reactions
Sensitisation has been shown in perennial asthma and rhinitis patients, (6) where asthmatics reacted more severely to the skin test than patients with rhinitis. (2, 3) Exposure and sensitisation includes both beetle and larvae. (2, 3, 7)
The beetle was reported to be a common pest in Berlin, with approximately 35% positive reaction to Trogoderma-extract in patients with known inhalation allergy. (2, 3)
The most common setting for sensitisation is likely to be occupational. A case of chronic bronchial asthma attributed to T: angustum was described, exposure having included both the beetles and larvae. (7)
Similarly, occupational allergy was described to the closely related species T. variabile, in a 42-year-old male machinist in a pet-food manufacturing plant who presented with shortness of breath, chest tightness, and conjunctivitis immediately after airborne dust exposure created while cleaning a conveyor belt system. Prior to onset of symptoms, he had worked at this facility for 4 years. His FEV1 had decreased and showed no improvement after bronchodilator use. Results of skin-prick tests with seasonal and perennial allergens were completely negative. A dust sample from the workplace revealed warehouse beetle, and subsequent skin-prick tests with warehouse beetle extracts were positive. A titration nasal challenge to warehouse beetle dust extract prepared from the warehouse dust sample using acoustic rhinometry revealed a dramatic decrease in cross-sectional area and nasal volume after challenge. Patient serum contained specific IgE to 15 different proteins in samples prepared from warehouse beetle materials. IgE binding was not observed to dust mite, storage mite, or cockroach extract proteins. (5)
b. Other reactions
Compiled by Dr Harris Steinman, email@example.com
- Jung D. Schäden und Schädigungen durch die Käferart Trogoderma angustum SOL. Forum Umwelt Hygiene 1976;2:76-7.
- Rudolph R, Jung D, Baumgarten C, Kunkel G, Diller G, Kossack G, Schniggenberg E. Frequency of positive skin test reactions to larva integument-Trogoderma angustum Sol. Extracts. [German] Z Hautkr 1980;55(1):6-13.
- Klaschka F, Rudolph R. Trogoderma allergy: a new clinical experience. [German] Z Hautkr 1980;55(21):1411-6.
- Mosimann B, Peitrequin R, Blanc C, Pécoud A. Allergy to cockroaches in a Swiss population with asthma and chronic rhinitis. [French] / Allergie aux blattes (cafards) dans une population Siusse souffrant d'asthme et de rhinite chroniques. Schweiz Med Wochenschr 1992;122(34):1245-8.
- Bernstein JA, Morgan MS, Ghosh D, Arlian L. Respiratory sensitization of a worker to the warehouse beetle Trogoderma variabile: An index case report. J Allergy Clin Immunol 2009;123(6):1413-6.
- Kunkel G, Rudolph R, Muckelmann R. Indoor air and allergic diseases. [German] Schriftenr Ver Wasser Boden Lufthyg 1982;53:75-89.
- Klaschka F, Rudolph R. Trogoderma angustum Solier larva - a new inhaled allergen. [German] Derm Beruf Umwelt 1981;29(1):9-11.