Olive tree trend sets country sneezing

By GAVIN ENGLISH

The increasing number of olive trees around New Zealand are making more than olive oil - they are giving more people hay fever.

Pollen from olive trees is a common cause of hay fever, but until now few New Zealanders knew they were allergic to them because there were so few around.

An increase in the number of olive orchards and a shift towards Mediterranean-style architecture has seen more olive trees being planted.

New Zealand Olive Association executive officer Alastair Bridge says there are about 750,000 trees nationwide - most planted in the past five years. He expects the number to increase over the next few years.

Most trees are in Nelson/Marlborough, Canterbury, around Whakatane and Waiheke island. Auckland has around 50,000 trees.

Lance Bert, sales manager for Sevilo, New Zealand's biggest olive tree nursery, near Levin, says the market for olive trees has exploded over the past 12 years.

"Our market includes mum, dad and the kids, who want 20 1.5m plants for their Mediterranean-style house, landscapers and developers, who want 2.5m fully established trees, garden centres, who on-sell, as well as people looking to set up orchards," he says.

Dr Vincent Crump, an allergy specialist from the Auckland Allergy Clinic, says he has seen a sharp rise in the number of patients allergic to olive tree pollen.

"It is quite a common allergy to see in Europe but has not been so common here," he says.

The olive tree flowers around August, the same time as several other trees that commonly cause hay fever, including elm, alder, oak, pine, wattle and hazelnut.

Dr Crump says these trees generally cause mild hay fever. More serious hay fever usually occurs around December, when rye grass flowers.

Identifying the exact pollen a patient is allergic to is important for drug-free treatment.

Allergy specialists can vaccinate for hay fever as they do for other diseases.

Patients are injected over several months with increasing doses of the pollen to which they are allergic.

Eventually they will build up an immunity, treating their hay fever for life.

"Hay fever is like a disease, in that the immune system is not working properly. It is overreacting," Dr Crump says.

Other treatments, including antihistamines and nasal steroids, treat the symptoms rather than the cause. Dr Crump recommends antihistamines for mild hay fever, nasal steroids for more serious bouts and vaccination for serious, prolonged hay fever that occurs every year.