Alternaria alternata is a plant rot fungus which contains allergenic proteins which can cause allergic symptoms. It is in the Pleosporaceae family of fungus. It looks like dark brown or black spots on the leaves of the plant.

It is most commonly associated with spinach, but has also been found on tomato plants, cucumber, peppers, apple, melons and citrus fruits. This allergy is more likely to affect people who eat spinach over the other foods as this is the plant where the leaves are eaten rather than the fruit.

The World Health Organization (WHO) recognises 12 airway allergens in the mould which can affect those who have asthma. One of theses proteins is enolase, which is found in other moulds, fungus and yeasts. Other allergenic proteins include heat shock proteins, ribosomal proteins, Glutathione-S-transferase, Manganese superoxide dismutase and a serine protease.

An allergy to Alternaria alternata is sometimes called Alternaria Spinach Syndrome.

The most common associated symptoms from eating this mould is increased asthma symptoms or those usually linked to oral allergy syndrome, like itchy throat, lips and a cough.

Enolase is found as an airway allergen in some grasses, penicillin, yeast, plane tree pollen and in cockroaches. As a food allergen enolase is found in chicken and fish like salmon and tuna.

Heat Shock proteins are found in yeast, penicillin and dust mites and ribosomal proteins are in penciliin and other plant moulds.

Glutathione-S-transferase is found in dust mites, cockroaches, roundworms and birch pollen.

Manganese superoxide dismutase is found in almonds and yeast.

Note these food lists are not exhaustive, you can find the most up to date information on the Cross Reactivity Tool.

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