A pan-European study organised by GA²LEN, the Global Allergy and Asthma European Network, tested more than 2000 patients to ragweed allergy in 10 European countries (1). Results published this week on the Allergy journal website (2) show an unexpected extension of allergic sensitisation to ragweed across Europe (3).

The study indicates that more and more Europeans are likely to suffer from ragweed allergy or already have an allergy to ragweed. Ragweed is the main cause of allergic rhinitis in North America but, until now, very few European regions were affected.

"The prevalence of ragweed sensitisation is clearly above 2.5%, the currently accepted threshold for 'high prevalence'," said Prof. Zuberbier, from the Charité University of Medicine in Berlin, who led the study. "The study highlights the spreading of ambrosia pollen and the dissemination of the plant throughout Europe. If we consider the apparent climate change, further evolutions in regional vegetation can be expected. GA²LEN therefore calls for a pan-European surveillance system to carefully monitor trends in sensitisation patterns which might allow coordinated counter-measures."

In the study, a positive reaction to the skin-prick-test shows that the patient is sensitised to ragweed allergens…