Developmental Disorders

This chapter discusses the higher rates of severe mental retardation, visual impairment, and hearing impairment found in Sub-Saharan Africa than in more developed regions. An estimated 47 percent of visual and 50 to 66 percent of hearing impairments in Sub-Saharan Africa are found to be preventable. Risk factors include congenital disorders, perinatal and neonatal conditions, infections, environmental toxins, accidents, injuries, and malnutrition.

Lifestyle and Related Risk Factors for NCDs

Increased use of tobacco and increased consumption of fats, sugar, alcohol, and animal products are critical risk factors for many NCDs. At the same time, the amount of physical exercise has been decreasing, leading to a sedentary lifestyle that is associated with obesity, diabetes, and hypertension. This chapter provides an overview of the risk factors for the NCDs discussed in subsequent chapters.

Diabetes Mellitus

Three million people in Sub-Saharan Africa were afflicted with type 2 diabetes as of 1994, but that number is projected to increase by two- or threefold by 2010. The highest prevalence is found among populations of Indian descent, urban populations, and those with a family history of diabetes, obesity, or physical inactivity. The chapter includes a discussion of studies of diabetes onset and mortality in Tanzania and Zimbabwe. Challenges to the provision of health care for diabetes in Sub-Saharan Africa include short consultation times, inadequately trained staff, nonexistent referral systems, inadequate levels of staff, and poor record keeping.

Cancers

Cancers have been a low priority in Sub-Saharan Africa, yet the probability of a 65-year-old woman developing cancer in Sub-Saharan Africa is only 20 percent lower than in Western Europe. Factors affecting cancer incidence and mortality include increases in the prevalence of tobacco consumption; HIV-induced immunosuppression; increased use of alcohol; the high prevalence of cancer-associated agents like papilloma viruses, hepatitis B virus, and human herpes virus 8; and exposure to aflatoxins. The top three cancers for men are Kaposi's sarcoma, liver cancer, and prostate cancers; for women, cervical cancer, breast cancer, and Kaposi's sarcoma.

Cardiovascular Diseases

Cardiovascular disorders are the second most common cause of adult deaths in Sub-Saharan Africa, as well as a major cause of chronic illness and disability. Half of cardiovascular disease (CVD) deaths occur among people 30 to 69 years of age, which is 10 or more years younger than in more developed regions. Incidence of stroke in Sub-Saharan Africa is estimated to be about 1 per 1,000. Survival outcomes are poor, due to delayed hospitalization, absence of thrombolysis and angioplasty, and low socioeconomic status and illiteracy. Rheumatic heart disease, still prevalent among children and teenagers, is a disease of poverty that is related to overcrowding, poor housing, and undernutrition.

Mental Health, Alcohol and Substance Abuse

Depression in Sub-Saharan Africa is estimated to have an incidence rate of 15 to 18 percent and a lifetime prevalence rate of 18 to 30 percent. Common mental disorders (depression and anxiety) have a point prevalence rate that ranges from 1 to 5 percent. The point prevalence rate for schizophrenia is the same as in other parts of the world, ranging from 2 to 5 per 1,000 population, with a lifetime prevalence of 7 to 9 per 1,000. The Sub-Saharan Africa region, the most conflict-affected region of the world, has seen rates of post-traumatic stress disorder (PTSD), anxiety, and depression range from 20 to 60 percent, and alcohol abuse has seen a sharp increase. In South Africa, suicide is found to be much more frequent among those who are HIV positive.

Neurological Disorders

The prevalence of epilepsy in Sub-Saharan Africa ranges from 2.2 to 58.0 per 1,000 people. Stroke has been found to be as common in Sub-Saharan Africa as in the West. The leading causes of neurological disorders are infections during pregnancy, neonatal infections, and sequelae to the disorders that cause high under-five mortality. Challenges to the management of neurological disorders include the lack of adequately trained personnel able to recognize and manage the disorders, lack of equipment necessary to confirm a neurological diagnosis, and unavailability of the common drugs that would control epilepsy.

Violence and Injuries

Intentional injuries (violence) resulted in the deaths of more than 300,000 people in Africa in 2000. Intentional injuries also are estimated to result in at least 6.2 million disabled or incapacitated people, 20 times the number of deaths. Road traffic injuries, burns, drowning, war, and homicide are the major causes of injury mortality in Sub-Saharan Africa.

The Impact of HIV/AIDS

A striking feature of DMSSA-2 is the documentation of the direct impact of HIV/AIDS on the epidemiology of almost all infectious diseases included in this volume, as well as on overall adult and child mortality. According to the United Nations' (UN) 2004 projections, life expectancy at birth has dropped by three years since 1990 for the region as a whole; for countries most affected by HIV/AIDS, the drop in life expectancy has been 20 years or more.

As shown in the chapters in this volume, HIV is linked to worsening trends in many diseases, for both adults and children. For example, Madhi and Klugman (chapter 11) state that as much as 45 percent of hospitalizations and 80 percent of deaths due to lower respiratory tract infections occur among HIV-infected children, and strides made in reducing childhood mortality from lower respiratory tract infections during the 1980s and the early 1990s have been reversed. In chapter 13, on tuberculosis, Dye and his colleagues discuss how people latently infected with Mycobacterium tuberculosis are at greater risk of developing active tuberculosis if their immune systems are also weakened with HIV infection. Consequently, the tuberculosis caseload has increased by a factor of five or more in the countries of eastern and southern Africa most affected by HIV.

Malaria has a two-way relationship with HIV/AIDS. Anemia resulting from malaria increases the risk for HIV infection through increased use of blood transfusions. In the review of malaria (chapter 14), Snow and Omumbo report an odds ratio for HIV infection of 3.5 for malaria patients transfused once, 21.5 for those transfused twice, and 43.0 for those transfused three times during a single admission. HIV infection, in turn, increases the risk of malaria, which is associated with higher density of parasitemia and more severe symptoms of malaria in adults.

HIV/AIDS not only affects the incidence of communicable diseases but is also a risk factor for several noncommunicable diseases. As discussed in chapter 10, children with HIV infection are at special risk for developmental disabilities. Low birthweight, prematurity, poverty, malnutrition, and micronutrient deficiencies, more frequently seen in HIV-infected children, are likely to compromise early child development. Maternal-child interaction is also affected; even HIV-uninfected children of HIV-infected mothers are at higher risk for cognitive and language delays.

Kaposi's sarcoma, now ranked first for male cancers and third for female cancers in the region, is also associated with HIV/AIDS. Prior to the epidemic, this was a rare cancer, but it has increased twentyfold, and in countries with a high prevalence of HIV, Kaposi's sarcoma is the leading cancer in children.

As discussed by Mbewu and Mbanya (chapter 21), 30 percent of those living with HIV show evidence of cardiac involvement. Mental health also shows the impact of HIV/AIDS: psychiatric sequelae of HIV/AIDS include depression, anxiety disorders, manic symptoms, and atypical psychosis.

Maternal HIV infection compromises the provision of care and undermines global cognitive development even in the uninfected children. HIV-infected infants demonstrate lower mental and motor development (Baingana, Thomas, and Comblain 2005). Other effects of HIV on the nervous system are discussed in chapter 23.

The direct impact of HIV on the incidence of and mortality from both communicable and noncommunicable diseases is documented in the chapters that follow. HIV/AIDS further affects health and mortality because of the social and economic consequences of the disease, including a large increase in the number of orphans, the burden on health services, the impact on human resources for health, and the impoverishing consequences of the disease. The extraordinary impact of HIV/AIDS has created a "development crisis" that extends far beyond its epidemiological effects.

The Socioeconomic Context

Growth in GDP per capita in low-income countries in Sub-Saharan Africa has continued to lag behind most other regions (figure 1.1), and real per capita GDP growth was negative for the period 1991 to 2000. Growth accelerated during the first few years of the twenty-first century but still lagged behind that of all other regions except Latin America and the Caribbean in 2004; the World Bank predicts that it will remain slow until 2015. In the 1980s, per capita income expressed in purchasing power parity (PPPs, international dollars) was higher in Africa than in other low-income countries, but it has gradually deteriorated (figure 1.2) and, as of 2004, was well below that of other low-income countries (World Bank 2005c).

Figure 1.1

Real GDP per Capita Growth, by Region, 1991–2015 Source: World Bank 2005a.

Figure 1.2

Real GDP per Capita, by Developing Region, 1980–2003 Source: World Bank 2005c.

Although some countries experienced rapid growth, more countries showed declines in real per capita income (expressed in US$) during both the 1980s and 1990s (table 1.1). Growth rates have also been more volatile: of the 45 Sub-Saharan African countries, only 5 consistently recorded real per capita growth rates above 2 percent per year (Botswana, Cape Verde, Mauritius, the Seychelles, and Swaziland), whereas nearly three-quarters of the countries experienced at least one year of per capita growth lower than minus 10 percent (World Bank 2005a).

Table 1.1

Gross National Income, per Capita, 1980, 1990, 2003 (current US$).

Closely linked to the low level of economic growth is the lack of progress in reducing poverty. Although most of the world is on track to achieve the Millennium Development Goal (MDG) of a 50 percent reduction in the number of people living below $1 per day, poverty has been on the increase in Sub-Saharan Africa: in 1990, 44.6 percent of the population lived below the $1 per day line; this had increased to 46.4 percent by 2003.

There is little doubt that slow economic growth and increasing poverty are related to slow progress in health outcomes. Wagstaff and Claeson (2004) summarized findings on income, coverage of interventions related to health, and health outcomes, documenting that higher incomes lead to improved access to and use of preventive and curative interventions, such as antenatal care, immunizations, use of treated bednets, and receipt of therapy for diarrhea and medicines for reducing fever. Income is also an important determinant of access to nutritious food, which, in turn, leads to lower levels of malnutrition, a key risk factor for many childhood diseases.

While some countries at lower-middle levels of income have achieved good health outcomes, such examples are rare for the countries with the lowest incomes. A basic package of health interventions would in the case of the poorest low-income Sub-Saharan African countries overwhelm public health budgets, and prospects for scaling up public health services from domestic resources are unfavorable.

The Demographic Context

Sub-Saharan Africa is the "youngest" of the World Bank regions, as measured by the proportion of the population below age 15 and by the median age of the population. About 44 percent of the population is younger than 15 (compared with 28 percent globally), and the median age of the population is just 17.5 years (compared with 27 years globally; figures 1.3, 1.4). In countries such as Uganda and Niger, the proportion below age 15 is close to 50 percent of the population. Fertility in Sub-Saharan Africa continues to be the highest in the world despite some decline in recent years. From 1990 to 2003 the total fertility rate (TFR) declined somewhat, but it is still higher now than in any other region in 1990 (figure 1.5).

Figure 1.3

Population below Age 15, 2003 Source: United Nations 2005.

Figure 1.4

Median Age of Population, 1990 and 2003 Source: United Nations 2005.

Figure 1.5

Total Fertility Rate, 1990 and 2003 Source: United Nations 2005.

The youthfulness of the population reflects fertility and mortality rates, which in turn have an impact on the epidemiological characteristics of the population. High fertility and high adult mortality lead to a high proportion of young people, who are much less likely to be vulnerable to chronic diseases that typically affect the adult and elderly populations. Epidemiology and demography thus interact to generate the overall disease and mortality patterns in which infectious diseases are dominant over noncommunicable diseases and conditions.

Population growth averaged 2.5 percent during 1990 and 2003 for the region as a whole, exceeding 3 percent in countries such as Chad, the Republic of Congo, The Gambia, and Niger. At a rate of 2.5 percent, the population would double in less than 28 years. However, population growth rates are projected to fall precipitously in countries in which HIV/AIDS has infected a large number of people. World Bank projections for the region as a whole show the population growth rate declining to 2.0 percent during 2000–10, and 1.9 percent during 2010–15. In the most affected countries in southern Africa, World Bank projections show a decline to between 0.2 and 0.5 percent growth per year. Other agencies that have published demographic projections show an even greater impact of AIDS mortality, leading to population decline by 2010 in some countries. Due to the high mortality of AIDS during the young adult years, age structures of the affected countries will become characterized by an unusually small number of adults, as shown in the age pyramid for Botswana (figure 1.6).

Figure 1.6

Age Pyramid for Botswana, 2005, with and without AIDS Source: U.S. Census Bureau 2004.

Increasing International Attention to Health in Sub-Saharan Africa

In the years since the publication of DMSSA-1, the attention being paid to health conditions in Sub-Saharan Africa has rapidly increased, as evidenced by the number of studies and reports, new initiatives that draw attention to particular diseases, and increased financing from donor countries, foundations, and multilateral agencies.

Many reports have either explicitly focused on Africa or have focused on health conditions in poor countries, leading to a strong emphasis on Africa. Among the more prominent recent studies are the 2001 report Macroeconomics and Health: Investing in Health for Economic Development (Commission on Macroeconomics and Health 2001); the 2005 report Our Common Interest (Commission for Africa 2005); and World Bank studies and publications, such as the 1998 publication Better Health in Africa: Experiences and Lessons Learned, the 2005 report Improving Health, Nutrition, and Population Outcomes in Sub-Saharan Africa: The Role of the World Bank, and the Global Monitoring Report 2005: Millennium Development Goals—From Consensus to Momentum (World Bank 1998World Bank 2005b, 2005a, respectively).

New initiatives and partnerships formed or strengthened during recent years have similarly provided advocacy for increased attention to diseases of the poor, generally with a focus on Africa. Among these are partnerships that focus on neglected diseases that mostly affect Sub-Saharan Africa, such as guinea worm, trypanosomiasis, onchocerciasis, and schistosomiasis. Other global partnerships have increased the availability of pharmaceuticals at lower costs, through pooled procurement, for diseases such as malaria and tuberculosis and for vaccine-preventable diseases. Foundations and funds, such as the Bill & Melinda Gates Foundation or the Global Fund to Fight AIDS, Malaria, and Tuberculosis, have made large amounts of new financing available to address diseases that disproportionately affect Sub-Saharan Africa. Traditional donors, such as bilateral development agencies, the World Bank, and regional development banks, have also increased financing for health, and the joint WHO–World Bank High-Level Forum on the Health MDGs is considering new mechanisms to expand the availability of resources to combat communicable diseases.

An important influence on priorities for the global health agenda are the MDGs, endorsed by 147 heads of state at the UN Millennium Summit of September 2000. The goals include numerical targets that are to be achieved between 1990 and 2015. Of the eight goals, three are directly concerned with mortality and morbidity, and six have been identified as "health related" (box 1.2). The focus of the MDGs on achieving health outcomes has increased the awareness of the lack of progress in Sub-Saharan Africa. Other low- and middle-income regions show progress toward some of the MDGs (although current trends indicate that not a single World Bank region is making sufficient progress to reach all of them). Sub-Saharan Africa is not on track to achieve a single one of the targets. Halfway through the period from 1990 to 2015, not a single Sub-Saharan Africa country is on track for the under-five mortality rate target, and only one in four would achieve the malnutrition target on current trends. The increased focus on monitoring of trends has also provided evidence that many countries in the region have worse indicators than they did 15 years ago.

Box 1.2

The Health-Related Millennium Development Goals and Indicators. Goal 1: Eradicate extreme poverty and hunger
–Target is to cut in half the proportion of people who suffer from hunger between 1990 and 2015. Progress is measured by the (more...)

Expanding Data Collection Efforts

Efforts to collect more data on health outcomes have intensified over the past decade, and as a result DMSSA-2 is more empirically based than the previous edition. Household surveys, including the Demographic and Health Surveys, the UNICEF Mulitiple Indicator Cluster Surveys, the World Bank's Living Standards Measurement Surveys, and other surveys conducted by the World Health Organization as well as by country statistical offices, have vastly increased the availability and quality of the data.

Demographic surveillance sites have joined in an alliance, called the INDEPTH Network, which has published standardized reports on demographic indicators, including a set of life tables. The network, which has grown to include 20 African sites, supports cross-site collaboration, capacity building, and dissemination of the collected data. Another area in which surveillance has greatly improved is HIV surveillance in antenatal clinics. Through annual reports of the data, such surveillance has been used to document the sharp increases in HIV prevalence among pregnant women in southern African countries, as well as the decline in HIV prevalence in Uganda. Other areas of improvement over the past decade include the surveillance and reporting of cancers, from an increased number of cancer registries, and injuries, from injury surveillance systems. Advances have also been achieved in malaria mapping and in the estimation of diabetes and lung disease incidence.

Nevertheless, the availability of morbidity and mortality data is far from sufficient for monitoring disease outbreaks, the impact of health interventions, or even annual monitoring of incidence and prevalence of most diseases. Routine vital registration is still absent in almost all countries (except Mauritius and the Seychelles), although progress has been made in mortality registration in South Africa. One consequence of this lack is the general unavailability or reliability of the denominators needed to estimate overall mortality or cause-specific rates. Efforts to expand the coverage of vital registration beyond urban areas would have substantial payoffs for improving the quality of epidemiological information.

Human Resources for Health: A Worsening Crisis?

Human resources have been described as "the heart of the health system in any country," and "the most important aspect of health care systems" (Hongoro and McPake 2004). The recent study Human Resources for Health: Overcoming the Crisis, by the Joint Learning Initiative (2004), suggests that both the number and the skill levels of health workers in Sub-Saharan Africa are far below what is needed to reduce mortality (table 1.2). The region has 25 percent of the world disease burden, but only 1.3 percent of the share of the world's health workforce (Commission for Africa 2005). Central to the problem are issues of supply, demand, and mobility (transnational, regional, and local). These include large differences in remuneration and nonrewarding work in the low-income countries juxtaposed with a growing demand for skilled workers, in particular, nurses, in the high-income countries (Joint Learning Initiative 2004). The problem of low staff numbers is compounded by low morale and skills and the maldistribution of staff geographically. Further challenges are the wars and other internal conflicts that adversely affect health infrastructure, services, and personnel retention. The HIV epidemic increases the workload, and AIDS mortality has reduced the number of health workers. In countries such as Malawi and Zambia, it is estimated that the illness of health workers has increased five- to sixfold (Padarath et al. 2003).

Table 1.2

Overview of Health Worker Vacancy Rates for Four Countries.

Conflicts, Refugees, and Internally Displaced People

In the years since DMSSA-1 was published, the continent has undergone numerous armed conflicts, including civil wars and genocide. Since 1980, more than 30 wars have plagued Africa. It is estimated that as of the end of 2003, 16 million people in Sub-Saharan Africa had been displaced through conflict (WHO 2002). Low-income countries are disproportionately affected by conflicts. Fifteen countries in the region had a major conflict between 1990 and 2003 (UNICEF 2005). Table 1.3 illustrates the relative global burden of conflict-related deaths by region.

Table 1.3

Conflict-Related Deaths by Region (per 100,000 people).

Injuries due to collective violence are concentrated in Sub-Saharan Africa. In the last decade, the bulk of lives lost to war injuries in Africa have resulted from conflicts in the Democratic Republic of Congo, Liberia, and Rwanda. The legacy of war in the form of landmines continues to contribute to mortality in the continent. As of October 2004, 1.2 million Sudanese had been uprooted from their homes, many killed by militias, and those who found their way into Chad faced disease, poor nutrition, and inadequate shelter. In a typical five-year war, the under-five mortality increases by 13 percent and adult mortality even more. During the first five years of peace, the average under-five mortality was found to be 11 percent higher than the corresponding level before the war. Sexual violence during conflicts increases the spread of HIV (UNICEF 2005).

In Sub-Saharan Africa, for children who survive the first four years of life, injury becomes the most likely cause of disability and death. Most intentional injuries are caused by war; it is estimated that 120,000 to 200,000 child soldiers age 5 to 16 years are participating in conflicts, putting them at risk for bullet and shrapnel wounds, burns, and land mine injuries (UNICEF 2005). Psychosocial and mental disorders resulting from conflicts had affected 15.5 percent of the population in Rwanda five years after the genocide; depression, anxiety, and PTSD can range from 20 to 60 percent in conflict-affected populations (Baingana, Thomas, and Comblain 2005).

The most dramatic outbreak of a diarrhea epidemic occurred in July 1994 among Rwandan refugees in Goma, Democratic Republic of Congo, when almost 50,000 refugees died (see chapter 9). Conflicts have also had an impact on immunization rates. From 1990 to 2000 the vaccination rates for diptheria, pertussis, and tetanus (DPT) in the Central African Republic fell from 82 percent to 29 percent, and in the Democratic Republic of Congo, from 79 percent to 33 percent (see chapter 12). The probability of surviving from age 15 to age 60 in 2000 was less than 50 percent in almost half of the Sub-Saharan Africa countries, due in part to the conflicts.