Dogger Bank itch is a cutaneous condition characterized by an eczematous dermatitis caused by exposure to the sea chervil, Alcyonidium diaphanum, a seaweed-like animal colony.[1]:431 The disease, common in fishermen who work in the North Sea, has been recognized by the Danish Workman's Compensation Act since 1939.[2]
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A medical case reported in 1957 tells of a fishing captain who worked in the Dogger Bank in the North Sea. The sea chervil, abundant in the area, frequently came up with the fishing nets and had to be thrown back into the water. After doing this repeatedly, the captain "developed an itching red eruption on the flexor aspects of the elbows and forearms which became moist, oozed serum, and spread to involve the backs of the hands, fingers and most of the arms within a few days." Although the rash disappeared after leaving the area, it reappeared with greater severity when he returned to the area and performed the same activities; this time the rash spread to his neck and face, and continued to ooze serum for two months.[3]
The causative agent, A. diaphanum (older synonyms include A. gelatinosum), is a member of the Bryozoa phylum, which consists of minute, sessile, filter-feeding animals that live in colonies. A. diaphanum is a gelatinous, smooth, sponge-like colony up to 15–30 cm long, growing on rocks and shells from lower shore down to approximately 100 m; superficially, they resemble seaweed.[4] The distribution of this animal is from the North Sea to the Mediterranean.
The disease is especially prevalent among trawlermen working in the Dogger Bank, an important fishing bank in the North Sea.[5] It has also been reported in from the Baie de la Seine in France.[5]
The rash is caused by a type of cell-mediated hypersensitivity reaction; this type of hypersensitivity normally occurs in people who become sensitized while handling chemicals or repeatedly come into contact with other low-weight molecular weight substances. Although in some instances several years may be required to develop sensitivity, this time period may vary greatly depending on the individual. With Dogger Bank itch, sensitivity is acquired after repeated handling of A. hirsutum that becomes entangled in the fishing nets.
The specific allergen responsible for the Dogger Bank itch was determined to be the chemical (2-hydroxyethyl) dimethylsulfoxonium ion.[6] This compound, also isolated from the marine sponge Theonella aff. mirabilis, has potent cytotoxic activity against P388 leukemia cells.[7]
A report of two cases in 2001 suggests that the rash responds to treatment with oral ciclosporin.[4] In these two cases, initial treatments with oral prednisolone and topical steroids were ineffective.