Kiwi Allergy

The Kiwi fruit, also called Chinese gooseberry, is the fruit of a bush, native to China. New Zealand started growing the fruit for export in 1906 and named it after their national bird, the kiwi. It is now produced in New Zealand, Japan, Australia, Chile, USA, Italy, Greece and Spain. Kiwi belongs to the botanical family Actinidiaceae and its Latin name is Actinidia deliciosa. The fruit is often eaten as such and can be an ingredient in fruit salads and juices. Symptoms The oral allergy syndrome (OAS) and urticaria (nettle-rash) are the most common manifestation of allergy against kiwi. OAS consists of itching of the mouth and throat, formation of small blisters in the oral mucosa, and irritation and swelling of lips, vocal cord and upper parts of the throat Other symptoms reported are indigestion, nausea and vomiting, wheeze and other respiratory symptoms, rash (urticaria) on skin contact as well as very severe allergic reactions, i.e. anaphylaxis. In a Swedish inquiry study, 83% of 161 kiwi allergic patients reported OAS, 18% skin symptom, 6% allergic symptoms from nose or eye, 4% asthmatic symptoms and 4% gastrointestinal symptoms. In another Swedish study the 361 kiwi allergic patients graded the severity of their symptoms as follows: slight symptoms 40%, moderate 32% and severe symptoms 28 %. Systemic reactions seem to be more common in non-pollen allergic patients than in pollen allergic ones, who more often get oral allergy syndrome. In extremely sensitive individuals very small amounts of kiwi allergen can induce symptoms. Thus anaphylaxis was induced by skin prick testing with kiwi in one patient and by a lover’s kiss in another case. Related foods (cross reactivity) Because of related (cross-reactive) allergens, some inhalant allergies will also influence the occurrence of food allergy to kiwi. In studies using skin tests, blood samples and other methods, cross reactions are found between kiwi and pollen from birch, timothy, mugwort and olive and between kiwi and latex (natural rubber). Many of these cross reactions are, however, of very limited clinical importance, i.e. allergic symptoms are not induced by kiwi, although the patient show positive test results with the fruit allergen. The most important cross reactions from a clinical point of view are those between kiwi and birch, and between kiwi and latex. There are also cross reactions between kiwi and several other fruits, such as fig, avocado, banana, chestnut, melon, sesame seeds, poppy seeds, hazelnuts, and rye grain. In many cases these cross reactions can be seen in blood samples, but lack clinical importance. Who, when, how long, and how often? The occurrence of kiwi allergy is increasing in some European countries in the last few decades. The explanation to the increase is probably an increased consumption of kiwi fruit. Kiwi allergy was ranked among the top-ten foods in recent studies from Sweden, Denmark, Estonia, Finland and The Canaries. In inquiry studies from Northern countries about 1/3 of 1139 food allergic patients reported kiwi allergy, with higher figures (45%) in Sweden and Denmark, and lower figures in Estonia, Lithuania and Russia (18%). Kiwi allergy was found in 4% of 163 asthmatic children in France. Kiwi allergy occurs in all ages but is more common in adults than in children. Risk factor for allergy against kiwi is the existence of birch pollen allergy or latex allergy. There are regional differences in the prevalence of kiwi allergy, probably mainly depending on differences in cross-reacting pollen allergies. The long-term development of kiwi allergy in the individual person has not been studies and it is not known if kiwi allergy can be outgrown. Diagnosis In most cases of kiwi allergy, the patient's history is sufficient for diagnosis. It is usually not necessary to perform diagnostic tests. An allergic sensitization against kiwi can be shown by skin testing, e.g. prick to prick testing with fresh fruit, as well as by blood test measuring IgE antibodies against kiwi. The tests have, however, low specificity, which means that many false positive test results are seen, i.e. positive test result in individuals tolerating kiwi. With kiwi, as well as with several other fruits, elimination diets that rely only on the results of allergy testing, can result in unnecessary restriction. If a reliable diagnosis is a necessity, a blinded food challenge should be performed. Avoidance Avoidance of kiwi is presently the only available treatment for patients with an allergy to the fruit. Persons at risk, i.e. birch pollen allergic patients and latex allergics, should be informed about the possibility of getting a food allergy, related to their inhalant allergy. They should not, however, be advised to omit kiwi, if they have not noted any adverse reactions to the fruit. Similar information could be given to individuals belonging to groups with increased risk for latex allergy: health personnel using latex gloves and patients to children with spina bifida. Regarding labelling rules it should be noted that kiwi is not included in Annex IIIa of the new EU labelling directive.