Allergic diseases in Swedish school children.

Area of Science:

• Pediatric Allergy and Immunology
• Environmental Health
• Epidemiology

Background:

• Allergic diseases are a significant global health concern in children.
• Geographic variations in allergic disease prevalence suggest environmental influences.
• Understanding risk factors is crucial for prevention and management.

Purpose of the Study:

• To investigate the prevalence of childhood allergic diseases (asthma, allergic rhinoconjunctivitis, eczema) in different Swedish climates.
• To identify geographic variations and associated environmental factors.
• To examine the role of heredity and infant feeding in disease development.

Main Methods:

• A questionnaire-based study of 20,000 school children aged 7, 10, and 14 across three distinct Swedish climatic regions.
• Data collection on allergic disease occurrence, parental history of allergies, infant feeding practices, and other exposure variables.
• Statistical analysis to compare prevalence rates and identify significant risk factors.

Main Results:

• Overall prevalence: Asthma 2.4%, allergic rhinoconjunctivitis 7.4%, eczema 7.8%, total allergic diseases 16.9%.
• Significantly higher prevalence in northern, colder, and drier climates compared to southern regions.
• Geographic variation was not linked to heredity or infant feeding, but to climate. Parental history increased offspring risk 2-9 fold.

Conclusions:

• Cold and dry climate is a significant environmental factor associated with increased childhood allergic disease prevalence.
• Genetic predisposition plays a strong role, with parental history increasing risk substantially.
• Breast-feeding's protective effect on allergy onset is limited, primarily observed in high-risk children with a double parental history.