Cockroach allergy

Cockroaches belong like:

• insects
• Arachnids
• Crabs
• millipedes

to the arthropods and are widely represented in the animal kingdom.

Sensitization to cockroaches is only moderately frequent. They are mainly caused by the excretion products of cockroaches. The extent of sensitization depends on the intensity of contact with cockroach allergens. In the USA, cockroach allergen exposure (especially in the lower-income population) is higher in inner-city areas than in suburban areas. In a patient-based European study, the sensitization rate was between 8.9 and 12.0%.

More than 4600 species belong to the order of cockroaches (Blattodea). Their representatives occur worldwide. Cockroaches are nocturnal and are mainly found in the tropics and subtropics. The best studied cockroaches in dwellings as sources of allergens are the German cockroach (Blattella Germanica), which dominates in number in America, the American cockroach (Periplaneta americana), and the Oriental cockroach or common cockroach (Blatta orientalis). The infestation of containers transported by ship or air causes the spread of another cockroach species in Europe, Periplaneta fuliginosa. Periplaneta fuliginosa was originally only native to Japan, Southeast Asia and the Southeast states of the USA.

Name of the allergens (leaf deodorant - cockroaches)

Identified single allergens of the German and American cockroach (according to IUIS Allergen Nomenclature Sub-Committee)

• Blattella germanica (German cockroach)
  • Bla g 1
  • Bla g 2 Aspartic protease
  • Bla g 3 Hemocyanin
  • Bla g 4 Calycin
  • Bla g 5 Glutathione S-transferase
  • Bla g 6 Troponin C
  • Bla g 7 Tropomyosin
  • Bla g 8 Myosin, light chain
  • Bla g 11 Alpha-amylase
• Periplaneta americana (American cockroach/American cockroach)
  • Per a 1
  • Per a 2 aspartatic protease-like
  • Per a 3 Arylphorins/TO Arthropod hemocyanins
  • Per a 6 Troponin C
  • Per a 7 Tropomyosin
  • Per a 9 Arginine kinase
  • Per a 10 serine protease

Cockroach allergens can be subdivided into more than ten protein groups with different physiological functions. They have been found in cockroach excrements, eggs or scales. In other cockroach species homologous, possibly cross-reactive allergens are described. The main allergens are found in protein groups 1-5 (Bla g 1 - 5). Homologous allergens of different cockroach species, e.g. Bla g1 and Per a1, show a cross-reaction. The tropomyosins Bl g7 and Per a7 and in the argeninic kinases Per a 9 are very similar to homologous allergens of other arthropods. The clinical significance of these cross-reactivities has not yet been fully clarified.

1. Heinzerling LM (2009) GA(2)LEN skin test study I: GA(2)LEN harmonization of skin prick testing: novel sensitization patterns for inhalant allergens in Europe. Allergy 64:1498-1506
2. Hilger, C et al (2014) Allergies to cockroaches, ticks, storage mites and other arthropods. How far has molecular allergy diagnostics progressed? Allergo J Int 23: 18-24