D3.47 - Changes in Poaceae and Betulaceae pollen seasons correlate with patient sensitization profiles: a single-centre study over 4 decades

Recent publications on long-term atmospheric pollen seasons have shown substantial shifts in pollen integrals (APIn), as well as seasonal pollination beginnings and durations.  We analyzed retrospectively whether these changes in seasonal pollen counts correlated with the sensitization profile of patients with seasonal respiratory allergies.

Daily pollen concentrations were monitored at the Centre Hospitalier de Luxembourg since 1991 using a 7-day volumetric spore trap. Analysis included the annual pollen integrals (APIn), season starts and durations for hazel, alder, birch, oak, grass and mugwort pollen, the main allergenic taxa in Luxembourg. Patients seeking advice at the outpatient unit for seasonal upper and/or lower respiratory allergies, were skin prick tested with a standard aeroallergen panel. Positive tests were  confirmed by specific IgE testing. The patient’s detailed allergy diagnosis was recorded in a specific repository. In this review, the sensitization profile of 100 consecutive patients per year, aged 1-40, was analyzed. Data were retrieved from 1982, 87, 92, 97, 2002, 2007, 2010 and 2019.

APIn of hazel, alder, birch pollen (Betulaceae family) as well as oak-pollen (Fagaceae family), roughly doubled during the observation period (1991-2020).  Pollen season duration increased significantly for hazel and alder, mainly due to an earlier season start. During the same observation period, grass pollen (Poaceae) and mugwort pollen APIn decreased by 50%. In Brussels, the nearest foreign pollen monitoring station, where observations started a decade earlier, the same trends in Betulaceae pollen increase and Poaceae and Mugwort decrease have been observed and published.

In 1982, among 100 patients with seasonal respiratory allergies:  92% were sensitized to grass (Poaceae) pollen and 24% to Betulaceae pollen. During the next two decades, birch pollen sensitization increased to 70% while grass pollen sensitization decreased to about 70%.  Progressive sensitization changes were  most visible in the age brackets 1-10 and 11-20 years.

Between 1982 and 2019, patient sensitization to Betulaceae pollen increased significantly, while grass pollen decreased moderately. These changes occurred mainly between 1982 and 2002, in parallel, but with some delay, to pollen APIn changes.