Sensitizations to pollen differ between Central European and Sub-Saharan African atopic dermatitis patients

Atopic dermatitis (AD) is often associated with allergic comorbidities, such as allergic asthma or allergic rhinoconjunctivitis (ARC). Sensitizations to pollen can directly impact AD, as patients can experience exacerbation during pollen season. This study aims to gain more insights into the pollen sensitization patterns of AD patients in Central Europe compared with sub-Saharan Africa (SSA).

We performed a case–control study involving a total of 90 participants: 20 AD patients and 10 healthy controls (HC) each from Switzerland (CH), Tanzania (TZ), and Madagascar (MD). We collected clinical data and serum samples and performed a multiplex IgE test (ALEX² Allergy Explorer, MacroArray Diagnostics, Vienna, Austria).

The prevalence of ARC and asthma in AD patients was similar in all countries (ARC: 60% TZ, 70% CH, 75% MD; asthma: 25% TZ, 30% CH, 20% MD). Total IgE levels were significantly higher in both SSA HC populations compared with the Swiss HC. The analysis of specific IgE levels revealed major differences in sensitization patterns between Africa and Europe, especially regarding grass pollen allergens. Swiss AD patients were sensitized to various grass pollen such as Bahia grass, Bermuda grass, common reed, perennial ryegrass, rye, and timothy grass. However, these allergens were irrelevant in the SSA population: no AD patient or HC subject was sensitized to the tested grass pollen.

The considerably different sensitization patterns between European and SSA AD patients warrant the development of allergy testing and desensitization therapies tailored to the African setting. Therefore, there is a need to characterize local pollen types and counts.