Detection of cockroach allergens, monitoring their levels and mitigation strategies to reduce allergen levels in infested areas

The German cockroach, Blattella germanica, is obligatorily dependent on its association with humans, more so than any of the domiciliary cockroach species. There are two major direct risks associated with German cockroach infestations: transmission of pathogenic microbes, and cockroach-associated metabolites that trigger allergies and asthma. Asthma is a multifactorial, chronic lung disease characterized by bronchial inflammation that leads to recurrent episodes of breathlessness, wheezing, cough, tightness or pain in the chest, and an increase in hyperresponsiveness to a variety of environmental triggers. Although allergens associated with cockroaches have been known as asthma triggers for decades, only in recent years have cockroaches been recognized as a major source of inhalant allergens and a major cause of asthma morbidity, especially in inner-city homes, where persistent large infestations are often prevalent. We will review several German cockroach-produced allergens, their functions and expression patterns in B. germanica, physiological regulation, and patterns of excretion into the environment, detection strategies, cross-reactivities, association with housing types and socio-economic status, and various cockroach interventions to reduce allergen loads and asthma. Since the cockroach gut hosts an abundant microbiome and allergic disease and asthma can be exacerbated by endotoxins – products of Gram-negative bacteria that contribute to inflammatory effects – cockroaches may contribute endotoxins the home environment. We will discuss recent findings on endotoxin levels in cockroach-infested homes.