Incidence: rare - a few cases have been described. The mechanism remains to be established, but may be due to a type of irritation. There are no reports that IgE is involved. Smoking has sometimes been desribed as a co-factor.
The cause is the leaf dust and debris from dry tea and a type of packaging material used when the tea is put into sacks. Of the many components of the tea leaf, epigallocatechine gallate (EGCg;mw:458 daltons) appears to be the most allergenic.
Rhinitis, cough, sporadic coryza, breathing difficulty and asthma.
Skin tests are negative. RAST/CAP RAST with tea.
Bronchial provocation test (in hospital) with tealeaf dust is positive with both an immediate and a delayed reaction.
Both skin prick tests and bronchial provocation tests with EGCg give rise to an immediate reaction.