Within this international perspective, there is a similar connection between global health, dermatology, and the spread of skin disease. Dermatology is subject to the same factors that regulate the spread of other diseases and determine its control; infection, social, and economic factors are all important in determining the prevalence and impact of skin disease.10 Skin infections are very common in all societies; tinea pedis (athlete's foot), onychomycosis, scabies and childhood pyoderma, viral warts, and recurrent human herpes virus (HHV1) are all examples of everyday skin infections that affect many people. There are also examples to show that this spread is mediated by human contact and, where there is facility for this to occur, for instance, in a swimming pool in the case of human papilloma virus infections of the feet and tinea pedis, there is a higher incidence of disease.11 Likewise, movements of numbers of individuals through travel, migration, or war increase the chance of global spread of these infections. For instance, the world diffusion of infection due to Trichophyton rubrum is said to have followed the displacements of populations and the movement of soldiers in the 1914–1918 and 1939–1945 wars.12 More recently, the spread of Staphylococcus aureus bearing the Panton–Valentin leukocidin (PVL) virulence gene causing furunculosis has been tracked, in some cases, to international travel.13 Despite this, in some parts of the world there are still unique and geographically localized skin infections, largely because these occur in remote areas. The lower limb infection of children and young adults seen in remote regions of the developing world where there is a high rainfall, tropical ulcer (Fig. 3-1), is an example of a condition that has remained relatively isolated14; the fungal infection of the skin, tinea imbricata, is a further example.15 However, even where there is relative isolation, changes over time such as migration can lead to epidemic spread of previously endemic disease. Tinea capitis has undergone a remarkable transformation in the Western hemisphere in the past 50 years. It has seen the introduction of an effective treatment regimen with griseofulvin initially and subsequent decline in infection rates followed by the relentless spread of one dermatophyte fungus, Trichophyton tonsurans, initially from a zone of endemic disease in Mexico, where it still remains as a stable infection of moderate incidence, to reach epidemic proportions in children in inner cities, initially in the United States, but subsequently in Canada, Europe, the West Indies, and Latin America.16 The spread appears to follow an increased susceptibility to infection of children with African Caribbean hair type; in recent years it has begun to spread in Africa as well.