This study was conducted following an epidemic of contact dermatitis in a factory shelling grey shrimps (Gangas) imported from Holland. The objective of this study was to define the circumstances of onset and the aetiology of: these manifestations and to propose appropriate preventive measures. 127 (20%) of the 635 workers employed in this unit developed dermatitis. A clinical report form defined the history of allergy, clinical features and course of the dermatitis, work and social activities for each employee. Skin tests were performed with Tego 51 antiseptic, shrimp meat, benzoic acid and citric acid, with examination after 4 and 72 hours. The mean age was 29 years with a range of 18 to 40 years. The site of the dermatitis was fairly suggestive: the dermatitis was located on the fingers and dorsum of the hand in 89 cases and was interdigital in 38 cases. A distant site (eyelid, face and neck region) was also observed in 16 cases. Classical signs of allergic dermatitis were detected: isolated pruritus (10 cases); simple erythema (20 cases); pruritus + erythema (29 cases); pruritus + erythema + vesicles (68 cases). Superinfection was observed in 13 cases. The time to onset of the dermatitis was slightly delayed in relation to first contact, as sensitization only occurred after; a period ranging from one month to 2 yeard of repeated contact. However, in 50 per cent of cases, this sensitization occurred within six months following recruitment. The initial lesion was always interdigital and subsequently involved the dorsum of the hand. Spontaneous resolution of the lesions after stopping work was observed in the majority of cases and only 21 subjects required medical treatment. Recurrence of the lesions on resumption of work was recorded in every case within 48-72 hours after challenge. Patch tests were positive to Tego in 82 cases, shrimps in 13 cases and both agents in 32 cases, but remained negative to benzoic acid and citric acid. Prevention represents the only solution to contact dermatitis. The ideal proposal would be replacement of Tego 51. However, the use of a dilution less than 1 per cent and a duration of application not exceeding one minute allowed a very substantial reduction of the prevalence of this dermatitis. The use of protective gloves raises practical problems. The use of protective cream, recommended by some authors, is not sufficient. No measures are available in Morocco for compensation and prevention of contact dermatitis due to Tego and animal proteins.
