Ragweed is an allergenic weed of public health concern in several European countries. In Italy ragweed occurs prevalently in north-north-eastern regions, where sensitization is increasing. Because of the small diameter of pollen grains, ragweed pollen is often involved in episodes of long-range transport, as already shown in central Italy. The objective of this study was to evaluate the extent of such transport by comparing pollen and meteorological data for two northern Italian cities (Parma and Mantova) with data from Pistoia and Florence in central Italy. In 2002 and 2004 peaks in ragweed pollen levels were detected in these four cities on the same day, and concentrations of the grains were above clinical thresholds. Weather-map analysis and computation of back-trajectories showed that air masses from eastern Europe might carry ragweed pollen to a wide area of central and northern Italy. These findings suggest that episodes of long-range transport of ragweed pollen could be clinically relevant, resulting in sensitization of a large number of people. The results might provide a basis for monitoring and forecasting periods of long-distance transport with the objective of reducing their effects on allergic patients.

RATIONALE: Aeroallergens and the environment play an important role in the pathogenesis of respiratory allergies. We present a 13-year study carried out in the Parma geographic area (Northern-Italy), to evaluate, in the same period, the effects of monitored airborne pollens and meteorological conditions on incidence of allergic asthma and rhinoconjunctivitis. METHODS: Among 10,405 subjects examined for respiratory pathologies at our Allergy Unit, Parma Hospital, Italy, from 1992 to 2004, only 1,196 positive to only one type of inhalant allergen at the skin prick test (SPT) were studied, to avoid bias of cross reactivity. Allergy and clinical aspects were compared with duration of the pollination period, peaks and total concentrations of airborne pollens. RESULTS: Our data showed a significant increasing trend of allergy to mites, pets and birch family pollens, a significant increase in asthma, a significant decreasing trend of positive reactions to grasses and a decrease in rhinoconjunctivitis. At the same time, there was a significant decrease in total pollen count, concentration peaks and pollination period of grasses. A significant increase was only observed in ragweed and ash-olive family total pollens and concentration peaks. CONCLUSIONS: Significant correlations between the increasing incidence in asthma and allergy to mites, pets and birch family pollens are shown. The decrease in total pollen count and concentration peaks of grass pollens was correlated to the decreasing trend of rhinoconjunctivitis. The increasing concentration trend of ash-olive family and ragweed was not accompanied by an increase in the related allergy.

Background: Aeroallergens and the environment play an important role in the pathogenesis of respiratory allergies. In a 12-year study carried out in Northern Italy (geographic area of Parma), the effects of airborne pollen and meteorological conditions on the incidence of allergic asthma and rhinoconjunctivitis were evaluated. Patients and Methods: Among 9,060 subjects examined for respiratory pathologies at our Allergy Unit, Parma Hospital, Italy, from 1992 to 2003, only 1,054 positive to only one type of inhalant allergen in the skin prick test were studied, to avoid bias of cross-reactivity. Allergy and clinical aspects were compared with the duration of the pollination period, and peaks and total concentrations of airborne pollen. Results: Our data showed a significantly growing trend of allergy to mites, pets and birch pollen and a significant increase in asthma, and a significantly decreasing trend of positive reactions to grasses and a decrease in rhinoconjunctivitis. At the same time, there was a significant decrease in total pollen counts, concentration peaks and pollination period of grasses. A significant increase was only observed in ragweed and ash-olive total and peak pollen concentrations. Conclusions: Significant correlations between the increasing incidence in asthma and allergy to mites, pets and birch pollen are shown. The decrease in the total pollen count and concentration peaks of grass pollen was correlated to the decreasing trend of rhinoconjunctivitis. The trend of increasing concentrations of ash-olive and ragweed pollen was not accompanied by an increase in the related allergy.