Prevalence of Skin Diseases
Few studies aimed at estimating the prevalence of skin diseases have been carried out in Western societies. However, Rea, Newhouse, and Halil's (1976) study in Lambeth, south London, which used a questionnaire-based, population-centered approach backed by random examination, reveals an overall 52 percent prevalence of skin disease, of which the investigators judged that just over half the cases required treatment. Studies from developing countries have generally adopted a more inclusive approach that uses systematic, community-based surveys backed by examination. Published figures for the prevalence of skin diseases in developing countries range from 20 to 80 percent.
In a study in western Ethiopia, between 47 and 53 percent of the members of two rural communities claimed to have a skin disease (Figueroa and others 1998), but when they were examined, 67 percent of those who denied having skin problems were found to have treatable skin conditions, most of which were infections. However, prevalence alone does not equate with disease burden. For instance, most communities recognize scabies as a problem because of its intractable itching and secondary infection, whereas they may ignore tinea capitis, which is equally common among the same populations, because they are aware that it follows a benign and asymptomatic course in many patients.
Researchers agree about the main risk factors associated with skin disease in developing countries, the most important of which appears to be household overcrowding. In primary schools in western Ethiopia, more than 80 percent of randomly examined schoolchildren had at least one skin disease, which was usually caused by one of four conditions: scabies, pediculosis capitis, tinea capitis, or pyoderma (Figueroa and others 1996). Those figures mirror work carried out elsewhere. For instance, in Tanzania, in a survey of two village communities, Gibbs (1996) found that 27 percent of patients had a treatable skin disease, and once again, infections were the most common diseases. Overcrowding was a major risk factor in that survey. A similar community-based survey in Sumatra, Indonesia, showed a 28 percent prevalence of skin disease (Saw and others 2001). What seems to influence the overall prevalence and pattern of skin conditions in certain areas is the existence of a number of common contagious diseases, notably, scabies and tinea capitis. Hot and humid climatic conditions may also predispose populations to pyoderma, thereby affecting the distribution of disease.