Background: Occupational exposure to Christmas cacti has been reported as a
cause of type I allergy. Therefore, the prevalence of immediate-type mucos
al and skin reactions related to cactus exposure was studied in 103 employe
es in a cactus nursery.
Methods: The study was based on a questionnaire followed by clinical examin
ation, skin prick tests (SPT) with standard inhalant allergens and cacti, a
nd a histamine-release test (HRT/Refix) using fresh cactus extracts as elic
itor.
Results: The questionnaire was answered by 84 (82%) of the nursery employee
s, and 63 (61%) were interviewed and skin prick tested; 58 of these were te
sted with HRT/Refix. Furthermore, 22 healthy controls were included and tes
ted in vivo and in vitro. Cactus-related contact urticaria and/or rhinoconj
unctivitis were reported by 37% of the cactus workers. Based on a combinati
on of positive history, positive SPT, and positive HRT/ Refix to cactus, 8%
of the cactus workers were allergic to cacti. No noncactus workers or cont
rols were allergic to cacti by these criteria. Testing with fresh cactus ma
terial elicited positive SPT and negative HRT/Refix in 27 nursery workers a
nd controls, of whom 12 had immediate-type skin and mucosal symptoms.
Conclusions: Christmas and Easter cacti seemed to be able to induce contact
urticaria and rhinoconjunctivitis on both an immunologic and a nonimmunolo
gic basis. Personal atopy was associated with positive reactions to cacti.