Calendrier pollinique et rhinite allergique à Caen (14)

The aim of this prospective cohort study, carried out from February to September in 2001 and 2002, was to establish a local pollen calendar for Caen, France and to compare the results with allergic symptoms observed in the local population. This pollen calendar was established by identifying the different pollen and their concentration, the dates of identification and the duration of detection. Concurrently, allergic clinical manifestations (rhinitis, conjunctivitis, asthma) in the local population were documented by specialists of the local Réseau national de surveillance aérobiologique (RNSA). The following data were obtained: In Caen, pollination started at the beginning of March with pollen of conifers (thuja) and alnus (alder), followed by fraxinus (ash) and betulla (birch) in the first half of April. Quercus (oak) was detected in the end of April. Pollen of gramineae (grasses) were detected in the middle of June and pollen of castanea (chestnut) in July. The concentration of pollen was variable in both years, but the dates of detection were similar. In 2001, the highest percentage of consultation for allergic rhinitis was 9.1% (compared with a yearly mean of 4.62%), which corresponded to the period of pollination of the gramineae. During this period, the percentage of consultation for other allergic symptoms was 18.65% (compared with a yearly mean of 12.8%). In 2002, the highest percentage of clinical consultations for allergic rhinitis was 7.2% (compared with a yearly mean of 3.48%), which corresponded to the period of pollination of the betulla. During this period, the percentage of consultation for other allergic symptoms was 15.5% (compared with a yearly mean of 10.62%). These findings correspond with results of studies published from 1978 to 1999, which demonstrated a relation between the concentration of pollen and the incidence of allergic symptoms. In conclusion, this study established a correlation between the pollen calendar and allergic manifestation detected in the population of Caen. Predictions of precise periods of high pollen concentrations based on a pollination calendar published annually can alert the population at risk to adopt measures of avoidance or contemplate prophylactic treatment.