A revisit to cockroach allergens.

Area of Science:

• Environmental Health
• Allergology
• Immunology

Background:

• Cockroaches (CR), particularly German (Blattella germanica) and American (Periplaneta americana) species, are common household pests and significant sources of inhalant allergens.
• Exposure to CR allergens can lead to sensitization and exacerbate allergic conditions such as allergic rhinitis and atopic asthma, especially in atopic individuals.
• In Thailand, Periplaneta americana is the predominant cockroach species, with allergens found throughout infested homes, impacting sensitization and allergic morbidity.

Purpose of the Study:

• To investigate the prevalence and levels of cockroach allergens in homes in Thailand.
• To understand the relationship between cockroach infestation, allergen levels, and allergic morbidity.
• To explore the immunological mechanisms underlying cockroach allergy and discuss diagnostic and intervention strategies.

Main Methods:

• Quantification of cockroach allergens in dust samples using locally developed test kits.
• Correlation analysis between allergen levels, cockroach infestation, housing types, seasons, and geographical locations (urban slums).
• Review of immunological mechanisms, including IgE- and non-IgE-mediated pathways, T-cell involvement, and protease-activated receptor-2 (PAR2) roles.

Main Results:

• Highest cockroach allergen levels were detected in dust from wooden houses in urban slums, particularly during the cool and dry season in Thailand.
• Allergen levels in kitchens correlated with the degree of cockroach infestation.
• Cockroach allergens can originate from various insect parts, developmental stages, secretions, and excretions, existing as proteins, dimers, or isoforms.

Conclusions:

• Cockroach allergens are significant triggers for allergic rhinitis and asthma, with early-life exposure potentially leading to later-life allergic morbidity.
• The study highlights specific environmental and seasonal factors influencing high allergen exposure in Thailand.
• Understanding the complex immunological responses and implementing cockroach population control are crucial for managing cockroach allergy.