Tinea imbricata is a chronic dermatophyte infection caused by Trichophyton concentricum affecting large areas of the skin surface. Spontaneous improvement is unusual and relapse after apparently successful treatment is common. In this study in Papua New Guinea it was found that a high proportion of infected patients had immediate-type hypersensitivity (52%) or negative responses (46%) to intradermal trichophytin. The majority of patients failed to develop delayed-type hypersensitivity on skin testing or as assessed in vitro by leucocyte migration inhibition. However, 78% of patients investigated had antibody to T. concentricum. The relevance of T-lymphocyte hyporeactivity to persistence of the infection is discussed.

Tinea imbricata was studied in 102 patients on Goodenough Island, Papua New Guinea. Trichophyton concentricum was isolated from 98 skin samples. Seven different clinical patterns of infection were distinguished: concentric, lamellar, lichenified , plaque-like, annular, palmar/plantar, onychomycosis. Hypopigmentation was a prominent feature of the infection. The disease was most common in male children or adult women. Relapse after therapy, including oral griseofulvin, in patients remaining in the area was the rule. There was no evidence to suggest that those affected were abnormally susceptible to skin infections. An ineffective immune response to the infection may well explain the high relapse rate after treatment and the extensive nature of the lesions. Other susceptibility factors, such as a genetic predisposition, may also be involved and account for the high prevalence of the infection in this area.

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A fixed drug eruption related to the ingestion of Maloprim is described in Papua New Guinea Defence Force members and their dependants. Provocation tests using the two constituents of Maloprim indicated that dapsone was the cause. A fixed drug eruption caused by dapsone was reported in 1964 in deeply pigmented leprosy patients in Africa. This eruption has not been reported in Papua New Guinean leprosy patients on dapsone therapy. CASE REPORTSOn 20 January 1981 the sixteen-year-old son of a Papua New Guinean soldier was referred to our clinic by the Papua New Guinea Defence Force Health Centre. He had a two-day history of itchiness over "black spots" which had been present on the face and trunk for a year. He had had several episodes of itchiness in these spots during the past year. Initially the spots were flesh-coloured but became black after scratching. There were no systemic symptoms and his family history and past history were non-contributory. He had been on Maloprim since 1980 as prophylaxis against malaria.Subsequently 11 other PNG defence force personnel and dependants were seen with exactly the same complaint. Both sexes were affected and their ages ranged from five to 28 years.The behaviour of the lesions was the same in all patients. The lesions made their first