Identification of ficus fruit allergy

In the second of our series on allergies, Dr Michael Radcliffe looks at allergy to fig fruit and plants.

Gillian, a 49-year-old shop manager, attended a week ago about attacks of itchy eyes and face, lip swelling and nasal congestion lasting an hour or more on two consecutive evenings.

A third attack the following evening caused throat narrowing, weakness, hypotension and wheezing and she needed urgent hospital treatment including adrenaline, IV fluids, hydrocortisone and antihistamines. She remained wheezy for a day or so and then recovered fully.

At A&E it was suggested that she should have food allergy tests. Gillian had medical insurance, and the GP requested a full set of food-specific IgE (RAST) blood tests after taking into account the last meal she had eaten, seven hours before the attack of anaphylaxis. However, the blood tests were all are negative.

History
Nothing like this had ever happened before and Gillian had no history of asthma, hay fever or eczema.

She had been concerned about attacks of coughing and wheezing, especially at night, for several months.

The meal Gillian had eaten seven hours before the attack of anaphylaxis had been sushi, and RASTs had been ordered for tuna, shrimp, soya and sesame. For safe measure the GP also requested nut and seafood panels.

Gillian was certain that she ate no other foods at this meal.

The GP prescribed a pair of 300 microgram adrenaline auto-injectors, encouraged her to join the Anaphylaxis Campaign (www.anaphylaxis.org.uk), asked the nurse to provide full anaphylaxis counselling and referred her to the allergy clinic.

An allergy specialist's view
The GP had done an excellent job, but a seven-hour interval is well outside the limit for food-induced anaphylaxis and so there had to be another explanation; had she eaten anything else?

When questioned, the patient remembered the box of chocolates she had been given earlier in the week and realised that she had been eating them at about the time of each attack.

Luckily, she had eaten no more after the last attack, and could bring the remainder into the clinic.

The list of contents was missing, but it was possible to identify dried apricot, dried date, almond and hazelnut, and these were used for skin prick tests, which were negative. However, another morsel seemed most likely to be fig and a skin-prick test using this was strongly positive. She then remembered two interesting facts. About a year before she had eaten a fig and it had caused a burning sensation in her mouth. She also mentioned that she had two ornamental fig trees (Ficus benjamina) in her house. A 1:10 eluate in saline was prepared using the dried sap from one of the plants and a skin test with this was positive (10mm). A skin prick test using a fresh fig was also positive (6mm).

The patient was instructed to avoid further fig ingestion. No further allergy or anaphylaxis attacks have occurred since.

Discussion
Occupational airborne allergy to F benjamina occurs commonly, causing rhinoconjunctivitis. Sensitisation is increasing in non-occupationally exposed atopic and non-atopic patients. Studies have demonstrated cross-reactivity between the food fig and the ornamental fig.

Reports of cross-reactivity between weeping fig (F benjamina) latex and rubber (Hevea braziliensis) latex have not been confirmed.

Dr Radcliffe is a consultant in allergy medicine at the Royal Free NHS Trust.

Next week: Food-induced anaphylaxis

References

  • Axelsson I. Allergy to Ficus benjamina (weeping fig) in nonatopic subjects. Allergy 1995; 50: 284-5.
  • Bircher A, Langauer S, Levy F, Wahl R. The allergen of Ficus benjamina in house dust. Clin Exp Allergy 1995; 25: 228-33.

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