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. Sensitised people are more likely to develop allergic reaction to ragweed at some point of their lives.

Results confirmed Hungary to be the most affected country in Europe with close to 58-60% of sensitised people. Ragweed has spread in Hungary since the beginning of the nineteenth century, with a rapid extension in the early 1990s.

The study reveals an unexpectively high prevalence in Central-Western European countries and Denmark:

– 14% of the people tested in the three German research centres reacted positively to the skin prick test;

– 15% in the Netherlands;

– close to 20% in Denmark.

The lowest rates were observed in Italy and Finland, the latter being the only country to show a rate inferior to the threshold: 2.4% of the people tested during the study were sensitised.

1. The GA²LEN Skin-Prick-Test study involved 3000 patients from 17 research centres in 14 countries. Sensitisation to 18 indoor and outdoor allergens was assessed following a standard, comparable protocol for skin-prick-testing. Allergens include cat hair, indoor fungus, house dust mite, trees and plants pollens. Ambrosia was tested on more than 2000 people in 10 countries: Austria, Denmark, Finland, France, Germany, Hungary, Italy, Netherlands, Poland and Portugal.

2. Allergy is the official journal of the European Academy of Allergy and Clinical Immunology. It is an international journal including original research in the field, reviews of selected subjects of interest to the allergologist and immunologist and comments on topical aspects contemporary methodology. www.blackwellpublishing.com/ALL

3. Ragweed sensitization in Europe – GA²LEN study suggests increasing prevalence. Allergy 2009, In Press, DOI: 10.1111/j.1398-9995.2009.01975.x

4. Pictures of ragweed and skin-prick-testing are available upon request (noelie.auvergne@ga2len.net).