Chapter 3. Global Health in Dermatology

The word “global” describing something that is worldwide is not a concept that is difficult to understand, whereas the term “health” is frequently misused on the assumption that it simply means freedom from disease. However, health and disease are not merely examples of the converse, a point that is captured by the mission statement of the World Health Organization (WHO), whose objective is to promote health. The WHO definition of health, which is widely used as the definitive descriptor of health, says that health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity. Therefore, global health implies a worldwide mission to promote complete well-being.

The rational basis for this idea is simple as no nation or region is a complete island in terms of health; what affects one country may well, in time, affect another. The most obvious examples of this concept from past history involve the spread of infections. At present, there is a concerted effort to follow the international spread of HIV or avian influenza. Both present global risks to health, which is the reason why their current distributions are tracked regularly and with accuracy.1 Spread of these diseases has occurred and will continue to occur through a combination of both social and economic factors and the movement of populations and individuals. Yet historically, infectious diseases that have spread rapidly to cause maximum chaos have often resulted from a relatively minor, and often unrecognized, episode rather than a large movement of individuals. For instance, the impact that a localized outbreak of bubonic plague had on medieval Europe when the besieged Genoese garrison in Caffa, in the Crimea, fled by ship bringing the rat host with them was not foreseen.2 The subsequent epidemic, caused by Yersinia pestis, known as the Black Death, reduced the population of Europe by a third over the following 2 years. In addition to the mortality and distress, it resulted in profound social and economic changes that long outlived the epidemic itself. Predicting and tracking the international course of infections is now a key element of global surveillance.

However, global health problems and disease are not limited to infections, although the propensity to spread is more demonstrable in this group; chronic noninfectious conditions are also global. The relentless increase in the prevalence of diabetes mellitus type 2 in aging populations is such an example. Global health is affected by other factors that include the impact of social, economic, and environmental change on populations. This reflects the fact that human populations are no more isolated socially than they are geographically, but manifest a measure of interdependence where what happens in Kazakhstan may be reflected, in time, in New York City. In the case of diabetes, the causes of changes in health status are different; the international dissemination and adoption of Western dietary behaviors are, at least partly, responsible for this. Health-determining trends such as diet, lifestyles, or global warming are all examples of noninfective risk factors that may affect global health. The international spread of risks to health may follow different routes, often simultaneously.

In many parts of Europe and the United States, the decline of tuberculosis was a marker of economic progress in the twentieth century,3 the main reduction in disease incidence, and subsequently mortality, preceding by many years the development of new specific treatments such as streptomycin or the introduction of BCG immunization. This health improvement reflected the huge social changes made during this era, such as the provision of sustainable and affordable water supplies and drainage, heating schemes, better housing, and nutrition. While the increasing prosperity and subsequent social reforms that affected the industrialized Western nations in the late nineteenth and early twentieth centuries had a huge impact, mainly for the good, in promoting better health, in international terms the benefits were relatively restricted and not global in their reach; large areas of the world did not benefit from this change. In the recent report by Michael Marmot,4 the continuing influence of social and economic conditions on both national and global health are clearly demonstrated and poor social and economic status linked closely to poor health indicators such as high maternal and infant mortality. He cites Sweden as an example of a country that has adopted a policy where the creation of appropriate social conditions would ensure the health of the nation. Much of this health initiative concentrates on social initiatives such as improvement of participation, economic security, and healthy working. This type of policy has been supported in both rich and poor countries. For instance, the Mexican initiative, Programa de Educacion, Salud y Alimentacion (Progresa), which provides financial incentives for families to adopt measures that will ensure social improvements leading to better health, is a good example.5 While this may seem oversimplistic, poor health is often an indicator of social ills and vice versa; the two are interdependent. Health can make a significant impact on both micro- and macroeconomics; conversely economic performance has a direct impact on health. The WHO report on macroeconomics and health6 asserted the view that the investment of both time and money on health improvement had multiple benefits through reduction of mortality and increase in the healthy employed, measures that would lead to improvement in both family and national economics. By ensuring good health of their populations nations would improve economic performance and social conditions, which, in turn, would improve health status of their peoples. So good health is an important facet of social and economic development, just as poor health is an indicator of poor performance in both domains. Therefore, global health becomes an important social aspiration in a world where international collaboration and interdependence as well as increasing global industry are slowly replacing, or at any rate adding another dimension to, the nation state.7

In order to determine the impact of global health, a consortium of international bodies such as the World Bank in 1990 commissioned a report on the global burden of disease (GBD); a project that has now gone through several iterations involving other organizations, including WHO and an international group of universities.8 In doing this work, there were two key objectives, namely: (1) to provide up-to-date information on the incidence of disease states in all the regions of the globe and (2) to assess their impact on mortality and disability. In carrying out this work, the interdependence of health and social and economic well-being was clearly recognized. These large surveys of global disease have had to draw on the availability of studies that can provide the necessary information. A subsequent development from GBD, aimed at health in developing countries, was the Disease Control Priorities Project (DCPP), an international report focusing on sustainable measures of disease elimination or control.9 The latest GBD round of studies is incomplete at the time of writing.8 However, it differs from other studies in that much of the work of collecting data is the task of specialist groups, including one for dermatology. The target is to provide data covering diseases and risk factors (such as consumption of alcohol or atmospheric pollution) in the WHO designated regions and, where this is missing, to provide robust means of adducing the data using defined mathematical models. The study aims to target disease incidence at two time points—(1) 1990 and (2) 2005. It will also provide measures of mortality as well as disability. The methods used to assess the latter is more refined than previously in that lay panels (i.e., patients) will be asked to assign the weighting that determines the disability that accompanies disease states.

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.

In a similar way, noninfectious skin disease, as with other illnesses, is also affected by those social and economic changes that are international in dimension. The complex history of the medical reaction to the fashion for sun exposure was formed initially by the recognition of the health promoting, and then health limiting, effects of sun and ultraviolet (UV) light.17 The current concern over excessive exposure to both natural sun or UV exposure, for instance, in sunbed parlors, or as part of UV therapies, is an important stage in an exercise that started as genuine attempt at health promotion. The ancient Greeks, for instance, promoted sun exposure or heliotherapy as beneficial for a number of medical problems.3 While largely ignored for the best part of two millennia the revolution in medical ideas in the nineteenth century led to sun exposure being adopted as a health-giving practice with the discovery of Vitamin D and the award of the Nobel Prize to Finsen for light therapy. Health-giving sun exposure was adopted widely and became a fashion that was the rage of the health conscious, delivered in spa environments such as William Kellogg's Battle Creek clinic.18 However, the habit, perhaps fueled by the recognition that exposure to natural light was in some ways health giving, led inevitably to one of the consequences, the sun tan. It is not certain if the recognition of the sun-tanned skin as fashionable can all be laid at the door of Coco Chanel, who is said to have been overexposed to the sun during a holiday in Cap Antibes in France. The resulting effect on her skin color was soon to be adopted by the fashionable and white wherever they lived.19 Soon it became a global trend in fashion. The recognition that sun exposure also led to a rising incidence of skin cancer followed more slowly, but perhaps with greater speed than that concerned with the connection between smoking and lung cancer. Protection against sun exposure has become a major global focus of preventive measures of public health medicine, from public education to the risks involved to early detection of melanoma and nonmelanoma skin cancers. Dermatological organizations have reacted with admirable speed to the recognition of the risk of UV exposure. This has been accomplished through seminars, magazine articles, public health campaigns, and training camps. The introduction of educational programs in schools has been a welcome addition.

The trend to the opposite, skin lightening, in women of color has been an equally global trend where the use of skin bleaching products has been adopted by different cultures throughout the world. The common agents in use include hydroquinone- or steroid-containing creams—with a resulting risk of the development of skin disease such as ochronosis and more general medical problems, including low birth weight infants in pregnant women using topical corticosteroids to achieve lightening.20 As with infections, there are also examples of skin diseases that are caused by social customs or economic conditions that remain geographically localized. Erythema ab igne of the forearms is almost unknown in most parts of the world but is associated with the cooking of tortillas (enfermedad de las tortilleras)—so it is only seen where the tortilla is a staple of diet; oral submucous fibrosis occurs where the Betel nut is chewed is another example. However, some noninfective skin conditions occur in isolated communities for a different reason, genetic susceptibility, such as actinic dermatitis seen in native American communities in North and South America (Fig. 3-2). These are not the only examples of the relation between noninfectious skin disease as an international concern and social and economic factors. One of the earliest public health campaigns that crossed national boundaries stemmed from the recognition that industrial workers exposed to oil during the operation of large-scale spinning were susceptible to skin cancer and the ingestion of arsenic at work or as a medication was also potentially harmful through the development of skin cancer.21 Recently, much international interest has focused on the changing face of atopic dermatitis and although the evidence suggests that this is a condition associated with societies enjoying improved socioeconomic status,22 the quest for modifiable risks whose resolution may, in turn, provide benefit to children with this condition is now the subject of a global initiative (the ISAAC study).

So skin disease is subject to different, but nonetheless global influences, compared with other illnesses and in the pursuit of skin health there is a great need to promote international cooperation. This objective is identified, not just in order to share learning experiences, but also because the burden of skin disease is spread unequally around the world and many of the poorest nations face the greatest problems.9 Here, the social and economic factors plus uncontrolled or poorly controlled infection play key roles in determining the pattern of disease.

In the poorest countries skin disease usually ranks as one of the first three common disorders encountered in frontline medical facilities, i.e., the first point of call for a patient seeking treatment. Whereas in the developed countries many of the problems facing dermatologists and primary care practitioners are noninfectious skin diseases, the opposite is true in developing countries where infections dominate the pattern of presentation.23 Where infections occur in the industrialized countries, the general public have widespread access to treatment through pharmacies or primary care doctors as well as specialists. Access to treatment is limited by a number of factors that range from poor training of health care workers to the need to journey considerable distances in order to obtain help.24 Likewise in the poorest communities ready access to cash is more limited, with a large part of household economics depending on self-sufficiency in growing food or creating housing from local materials. Cash is necessary for some things such as clothing and for additional food. Treatment of even the simplest of conditions such as scabies or pyoderma presents a competing call on the available household cash income (Fig. 3-3); poor or ineffective treatment is a drain on resources that would otherwise be spent on food. The exact sums are small but their impact is large.25

The burden of skin disease is often unrecognized at national or international level as it is perceived to come low in the global league table of illnesses and, compared with diseases that carry a significant mortality such as HIV, community acquired pneumonias and tuberculosis, skin disease-related mortality is low. However, as skin problems are generally found to be amongst the most common presentations of diseases seen in a primary care setting in tropical9 and nontropical10 areas, in some regions, where transmissible diseases such as tinea imbricata or onchocerciasis are endemic, they are the commonest reason for an individual to present themselves for treatment. The GBD estimates for 2001 indicated that skin disease was associated with mortality rates of 20,000 in Sub-Saharan Africa.8 This was comparable to mortality rates attributed to meningitis and hepatitis B, obstructed labor, and rheumatic heart disease in the same region. The disability rate calculated as disability adjusted life years (DALYs) in the same report showed an estimated total of 896,000 DALYs recorded for the region in the same year; this was comparable to that attributed to gout, endocrine disease, panic disorders, and war-related injury. While, as described before, these figures are currently being reassessed, it suggests that the burden of disease due to skin-related illness is high. Many of the international studies that have focused on the impact of illness on individuals utilize disability scores. Those interested in skin disease frequently use patient-focused measures Quality of Life (QOL) scales.26 While these may be less objective they do, by concentrating on the impact of disease on personal values and performances, provide, according to many interested in the impact of disease, a more realistic measure of how patients are likely to use health services. Assessing the impact of skin disease on quality of life in comparison with other chronic nondermatological diseases is difficult. However, the decline in QOL for patients with the common skin disease, acne, is similar to that experienced by patients with chronic disorders such as asthma, diabetes, and arthritis; all showed comparable deficits in objective measurements of life quality.26 Skin disease related to HIV, which constitutes an important skin disease burden, particularly in Sub-Saharan Africa, leads to a similar diminution of QOL compared with non-HIV related skin problems, although the use of antiretroviral therapy produces a significant improvement.27

Despite the unequal comparison of mortality rates with other diseases, there are a number of important and relevant reasons why the needs of the populace for effective remedies or control policies for skin conditions should be in place. Firstly, the diseases are very common and patients present in very large numbers in primary care settings. In some cases more than 60% of the population has at least one skin disease.23 Even though significant numbers never seek treatment for a variety of reasons, including lack of awareness that treatments are available, the workload generated by patients presenting with skin problems at primary care level can be huge. This is a problem in all countries but particularly in those with the lowest gross domestic product.28 Children and the elderly, in particular, are affected, adding to the burden of disease in already vulnerable groups. Secondly, the morbidity can cause significant disability through disfigurement or restriction of movement. For instance, the effects of elephantiasis secondary to lymphatic filariasis last for years after the elimination of the filarial parasites. As stated previously, the relative economic cost of treating even trivial skin complaints in families in poor regions reduces the capacity of families to contribute to their local economies as their disposable cash is exchanged for poor medicine rather than other goods.25 The skin is often the site where changes of a number of other neglected tropical diseases are present. Leprosy, onchocerciasis, guinea worm, HIV/AIDS, tuberculosis, yaws, and Buruli ulcer are all examples.29 A shortage of elementary skills in the recognition and management of disease that present with skin abnormalities reduces the capacity for surveillance of these important diseases. In truth, skin disease in the tropics is a neglected problem that should be added to the list of neglected tropical diseases.

Globally, one of the current problems highlighted in a number of studies has been the management of skin disease in primary care settings. In the developing world high treatment failure rates of over 70% are common in frontline health posts.30 The same may be true in settings in industrialized nations where lack of recognition of some skin problems at primary care level is a factor limiting effective treatment. This situation is compounded by changes to the undergraduate medical curriculum where, in many countries, the factual and academic content, such as knowledge of skin or eye disease, has been reduced to allow students to assimilate greater patient-oriented skills such as communication; the gap in learning for those not intending to follow a career in subjects, such as dermatology, yet who have some responsibility for managing skin problems, has not yet been plugged satisfactorily. One way forward in streamlining the capacity to cope with common diseases, such as skin disease, has been to prioritize treatment options. For instance, in the developing world a small number of common skin diseases, mainly infections, account for the vast majority of the disease burden. Therefore, implementation of effective treatment targeted on these conditions confers significant gains to both personal and public health. Two prime examples are scabies31,32 and pyoderma.33 In the industrialized nations concerted efforts to prevent or diagnose skin cancer at an early stage have formed key elements of public health strategy.34

In Western societies there have been few studies aimed at estimating disease prevalence or risk, a necessary prelude to health intervention. However, a study in Lambeth, South London in 1976 using a questionnaire-based population-centered approach, backed by random examination, revealed an overall 52% prevalence of skin disease of which just over half the cases were judged by the investigators to require treatment.35 The NHANES study in the United States36 produced very similar figures. More recent studies of skin disease burden in the United States and the United Kingdom confirm these earlier investigations. Studies from developing countries have generally been conducted through systematic community-based surveys backed by clinical examination. Published figures for skin disease prevalence in developing countries range from 20% to 80%.9 From these studies it became clear that different populations have different levels of awareness of illness. For instance, in a study in Ethiopia between 47% and 53% of members of two rural communities claimed to have skin disease.30 However, when they were examined 67% of those who denied having a skin problem were found to have a treatable skin condition; the majority of these were infections. Tinea capitis, which is equally common in the same population may be ignored because it is common knowledge that this follows a benign and asymptomatic course in many patients, although in those communities where the clinical form of tinea capitis, favus, occurs, the local populations recognize that this type of infection is associated with permanent scalp scarring and so present for treatment.

The main risk factors associated with skin disease in developing countries are largely socioeconomic; the most important of these appears to be household overcrowding estimated by person per room in living accommodation. For instance, in Tanzania, Gibbs found that 27% of patients had treatable skin disease in surveying two village communities; once again infections were the most common diseases found.37 Overcrowding was a major risk factor in this latter survey. What also seems to influence the overall prevalence and pattern of skin conditions is the existence of a number of common contagious diseases, notably scabies and pyoderma, in certain areas. Hot and humid climatic conditions may also predispose to certain skin infections such as pyoderma, thereby affecting the distribution of disease.

Using the World Bank figures (World Development Indicators 2002) for low-income populations in 2000, the estimated numbers of individuals infected with pyoderma and scabies based on the highest prevalence figures from community surveys in the developing world are 400 and 600 million, those based on the lowest prevalence figures are 40 and 50 million. For tinea capitis the estimated number of cases based on the highest estimates of prevalence for Sub-Saharan Africa alone is 78 million.9

Overall these data suggest that significant improvements could be made in reducing the burden of skin disease by focusing on the small group of conditions, particularly infections, which comprise the majority of the community caseload. This may be accomplished by community control programs (see Chapter 4). The examples of scabies and skin cancer have already been cited. There are now a number of different bodies that understand the need to prioritize and have started, at first individually but increasingly in collaboration, to try to improve this situation.

The main focus of these efforts has been the identification of the health needs for skin disease in poor countries, the simplest methods of dealing with the majority and the development of programs to cope with these. In most cases, the key elements necessary to deliver an effective program are as follows:

1. Data on skin disease and current resources that could be mobilized to deal with the problem.

2. Education of those charged with improving skin health.

3. Evidence of the efficacy of each project.

Data on Skin Disease

Data on the global epidemiology of skin disease are inadequate, not just because current estimates of global health are subject to enormous variations. In skin disease a major and recurrent problem has been the very small number of studies that document the prevalence or incidence of disease at population level. The reasons are not difficult to identify. Firstly, because skin disease is not associated with significant mortality, the first international indicators of disease activity, death rates, have not triggered a demand at governmental or even regional levels for comprehensive epidemiological surveys. Secondly, and allied to the first point, the disability associated with skin disease is often thought to be minor—another reason why there has been few central calls for further investigation. There are also practical reasons why studies of this nature have been few until recently. Because the diagnosis of changes in the skin depends on a visual assessment, whose accuracy is largely based on experience, it becomes very difficult to teach those without the relevant experience to assign diagnostic labels. It is only comparatively recently that attempts have been made to simplify and validate diagnostic criteria for use in large population studies and those originating from the international studies of allergy now provide a global picture of the prevalence of atopic dermatitis.38 However, this is but one example and there have been a few similar initiatives in other areas of dermatology, for example, classification of skin changes in lymphatic filariasis.39 The upshot has been that skin disease has remained a subject where epidemiological studies have relied on the diagnosis of a trained observer, usually a dermatologist. The large studies of global disease have had to draw on the availability of a few surveys that can provide the necessary information. Most of these are the fruits of a comparatively small number of dermatologists who have taken on the task of investigating the impact of skin disease and developing measures for assessing disease prevalence and quality of life. Yet there are examples where disease presenting in the skin has attracted more global attention. Yaws, for instance, was one of the first examples of an infectious disease that was targeted by WHO for elimination through mass penicillin therapy.40 In the first few years, the campaign made extraordinary advances with massive reductions in the numbers of new cases. As with other diseases lack of resources and major disruption, such as human conflict, have ensured that there are still pockets of yaws that have yet to be brought under control. The recognition of the risk of skin cancer has stimulated regional and national initiates in areas such as Australia34; but there are still few cancer registries that collect data on nonmelanoma skin cancer.

Education and Training

More effort has gone into education to improve knowledge of skin disease and its management and the examples of initiatives established by departments and national and international dermatology societies are important to recognize. These range from the national programs of skin cancer prevention to Web sites that promote public awareness. These often also include training for other health professionals, such as pharmacists, who may encounter skin disease. In the developing world the International Foundation for Dermatology has established a number of such programs.41,42 The first of these, the Regional Dermatology Training Centre (RDTC) in Moshi, Tanzania was set up as collaboration between the International Foundation for Dermatology; The Ministry of Health and the Good Samaritan Foundation is an example of a training initiative that affects many countries. The Centre trains clinical officers with regional responsibility for skin disease, sexually transmitted infection, and leprosy, and more recently it has established an international dermatology residency-training program for Sub-Saharan Africa. Other programs of training or assistance established in Mexico,43 Mali,44 Ethiopia,45 Haiti,46 Fiji,47 and Cambodia amongst others are all examples of international collaboration to improve skin health in poorer countries.

How Effective Are These Initiatives?

These initiatives have been less successful in the provision of evidence that the campaigns have worked. There are some data from the sun protection programs that the incidence of advanced melanoma is improved by early screening measures.48 However, measuring the impact of education on disease incidence is difficult, but it is clearly needed in order to justify the outlay of time and expense.

In summary, the global incidence of disease affecting the skin is very large; the disability related to it is less, but is nonetheless significant. Managing this burden remains the responsibility of those specially trained in the field. Increasingly, dermatologists and dermatological nurses have turned their attention to adopting measures that benefit a wider group of individuals than the patient sitting on the other side of the consulting desk. To do so means setting up partnerships and alliances both nationally and internationally. Whether developing or assisting local or global public health schemes to control, eliminate, or improve skin problems through education or community initiatives is realistic is a matter for debate. What is certain, though, is that intervention to improve the health of those with skin problems within communities improves both the health of the people as well as the image of the profession.