Papaya is a food which may result in allergy symptoms in sensitised individuals.

Papaya Allergy Test: Allergen Exposure

The papaya tree is widely cultivated in tropical and subtropical areas worldwide, but most likely originated in West India, Mexico or Central America. Two types of papaya fruit exist, Mexican and Hawaiian. The Hawaiian varieties are the papayas commonly found in supermarkets, pear-shaped fruits generally weighing about half a kilogram. Mexican papayas are oblong in shape and may weigh up to 5 kg.

The skin varies from yellow to green, while the flesh is bright orange, yellow or pinkish, depending on the variety, and small black seeds cluster in the centre. A properly ripened papaya is juicy, sweet and similar to a cantaloupe melon in flavour.

The fruit can be used to make drinks, salads, marmalade and sweets. The seeds have a spicy flavour, somewhat reminiscent of black pepper.

A protease enzyme, papain, is obtained from the latex of the unripe fruit, and is also present in the leaves and trunk. It has many industrial and consumer uses, including as a meat tenderiser, a clearing agent in the production of beer, a contact-lens cleaner, and a reagent in the biochemical and pharmaceutical industries.

Papaya contains butyric or butanoic acid, a fatty acid also found in butter and used in the manufacture of plastics.

Papaya Allergy Test: Allergen Description

Several allergens present in papaya have been characterised.

The latex is present in both the fruit and the plant, and is evident during various stages of ripening, after incision of the unripe fruit. The plant proteinases are present mainly in the unripe fruit of the papaya tree.
Additionally a profilin, probably with little clinical significance, has been demonstrated in papaya.

Papaya Allergy Test: Potential Cross-Reactivity

Extensive cross-reactivity between the different individual species of the genus could be expected, but in fact has not been reported.

Among patients with kiwi allergy, a group of researchers found strong reactions to apple and hazelnut; moderate reactions to carrot, potato, and avocado; and weak reactions to wheat and rye flour, pineapple and papaya, and their enzymes bromelain and papain.

In a study of latex allergy, cross-reacting IgE antibodies recognising latex and fruit allergens (papaya, avocado, banana, chestnut, passion fruit, fig, melon, mango, kiwi, pineapple, peach, and tomato) were demonstrated by RAST-inhibition tests.

A study concluded that allergic reactions to fresh or dried figs can present as a consequence of primary sensitisation to airborne Ficus benjamina allergens, independent of sensitisation to rubber latex allergens. Kiwi fruit, papaya, and avocado, as well as pineapple and banana, may be other fruits associated with sensitisation to Ficus allergens.

Papaya Allergy Test: Clinical Experience

Anecdotal evidence suggests that papaya may occasionally induce symptoms of food allergy in sensitised individuals; however, few studies have been reported to date.

Reactions may occur to individual commercially-extracted components of papaya, e.g. Papain or Chymopapain. Reactions include urticaria, colitis, and anaphylaxis (sometimes to Papain).

Papaya allergy is thought to be mainly due to cross-reactivity to latex, but may occur on its own.

Other reactions

Carotenemia has been associated with papaya ingestion.

Atmospheric surveys carried out in different parts of India reveal that papaya is one of the allergenically important pollens of the country. Asthma and hayfever to pollen from the tree have also been recorded elsewhere.