Background: Based on subjective symptom, it has been documented that so high as 21 to 62% of patients with Japanese cedar pollinosis has pollinosis symptom before the start of pollen season. Since this is not objectively evidenced, we aimed to clarify whether or not it is true.
Method: We quantified intranasal pollen by means of our nasal lavage method in patients with Japanese cedar pollinosis shortly after the onset of symptom during pre-, mid- and post-season from 1997 to 2005.
Result: Significant differences in intranasal pollen count were revealed among mid- and pre- and post-season. Intra-nasal pollens, so few as 1 or less, were found in 67.8% of patients having pre-seasonal symptom, while in 12.5% during the mid-season. The majority of patients had not sufficient number of intra-nasal pollen to induce pollinosis. However, the intranasal pollen counts in preseason were related well with total airborne pollen amount in next spring. Pollens other than Japanese cedar pollen were also detected in lavages.
Conclusion: Many factors such as method of pollen survey, personal nasal hyper-reactivity and irritation by cold air, or with pollens other than Japanese cedar may cause the pre-seasonal pollinosis symptom. High frequencies of pre-seasonal onset in previous reports may be over-estimated due to inaccurate diagnosis of Japanese cedar pollinosis.