Allergy to pollens from Betulaceae and Corylaceae in a Mediterranean area (Genoa, Italy)--a ten-year retrospective study.

Allergy to pollens from Betulaceae and Corylaceae is becoming a leading problem in Genoa, a northern Mediterranean area in Italy. The results of a 10-year retrospective study on combined observations both on the aerobiological presence of Betulaceae and Corylaceae pollens (Alnus, Corylus, Ostrya) and on the incidence of positive SPT in the allergic population living in the same area are reported. Among 3473 patients suffering from seasonal respiratory allergy with positive SPT to one or more pollens, 558 (16.06%) showed SPT positivity to Betulaceae and/or Corylaceae pollens, both isolated and associated with other allergens. These patients suffered from winter or early spring hay fever, with a high incidence of bronchial asthma. A statistically significant increase (0.02 < p < 0.05) in the number of these sensitizations from 1981 to 1990 has been observed. Some possible explanations for this phenomenon, including an increase in the total amount of local airborne pollens, are suggested. About 24% of the patients with positive SPT to these pollens referred oral allergic syndrome associated with the ingestion of some foods, especially apples and nuts, with or without other additional clinical symptoms.