This covers Africa’s unique epidemiological history from the early migration of homo sapiens to the devastation of HIV/AIDS and, more recently, the unfolding impact of COVID-19. It explains how humans’ proximity to nature, slow urbanization and Africa’s distinct climatic conditions have led to an unusually high burden of communicable diseases, particularly the HIV/AIDS pandemic. It also explains the double-burden of communicable and non-communicable disease evident in Africa. It highlights the central role that infrastructural improvements and urban planning play in supporting better health outcomes and impact that poor basic infrastructure and lack of urban planning has in much of Africa. It places a particular emphasis on the central role of potable water and water-borne sanitation in preventing the spread of disease. Finally, scenario analysis is used to demonstrate the relationship between health and economics.

Learning Objectives

– Understand Africa’s unique health challenges in a historical context – Have a better awareness of origins, spread and impact of the HIV/AIDS epidemic.

– Know the difference between communicable and non-communicable disease

– Be able to define the double-burden of disease

– Understand the relationship between urbanization, infrastructure and health.

Homo sapiens evolved in Africa around 300,000 years ago and, although there is evidence of previous waves of migration, only successfully migrated from Africa some 70,000 years ago. Human DNA and archaeologists confirm that all humans who have ancestors outside of Africa today come from a single small group of migrants and not from earlier waves. About 50,000 years ago, they spread along the southern coast of Asia to Oceania, and eventually to Europe—a process that occurred over several thousand years. In the process Homo sapiens eventually displaced Neanderthals and eventually emerged as the dominant species globally. This was not a linear process and there is ample evidence that Homo sapiens, Neanderthals and others interbred and even cohabited.

1 Early humans gained an initial health reprieve that lasted for several thousand years when they moved out of Africa for cooler regions with fewer insect-borne diseases and ‘the many parasites and disease organisms that had evolved in parallel with the human species’.

2 As a result they multiplied rapidly in these new areas. The development of agriculture and farming was key to humanity’s rapid increase in numbers as it increased food production and allowed much higher population densities although density in turn bred new diseases. Larger population concentrations caused competition and sometimes conflict between people over grazing, land, food and status that required political organization and further role differentiation. Competition spurred innovation and technological advancement.

3 In contrast to the situation that developed elsewhere, large parts of ancient Africa’s interior appear to have been characterized by very low population densities very likely as a result of the scourge of sleeping sickness and other vector-borne diseases, such as malaria. Geography, and hence climate, therefore limited population growth in Africa compared to other regions.

Vector-borne diseases are illnesses caused by parasites, viruses and bacteria that are transmitted to humans by insects such as mosquitoes, ticks and tsetse flies that are commonly found in tropical and subtropical regions such as in Central Africa and places where access to safe drinking water and sanitation is limited. In temperate zones, such as much of Europe, parts of Asia and North Africa, the annual seasonal fluctuations serve as a natural constraint on the breeding cycle of insects.

4 In Central, West and East Africa where Homo sapiens originated, this cycle is not similarly disrupted, with the result that sub-Saharan Africa has a constant high burden of vector-borne diseases, come summer, autumn, winter or spring. Malaria, the deadliest vector-borne disease, is particularly prevalent in Africa. The continent also accounts for 34 of the 47 countries prone to yellow fever outbreak and about 40% of the global burden of lymphatic filariasis (elephantiasis).

5 Today, Africa is still home to 16 of the 30 countries listed by the World Health Organization (WHO) as having a high burden of tuberculosis, though none are under the top five.

6 Diseases including yellow fever and sleeping sickness were endemic, and insect-borne diseases also prevented the use of the horse, ox or camel, thereby limiting opportunities for more rapid progress.

7 The belt of open Savannah south of the Sahara and north of the tropical rain forests in central and western Africa eventually became an exception to the high burden of vector-borne diseases. Higher population densities allowed these regions to experience a modest agricultural revolution, although not on the same magnitude as seen elsewhere in the world.

8 Nature eventually reasserted itself into humanity’s new habitats outside of Africa. In fact, most of today’s most prominent infectious diseases only emerged in the last 11,000 years, following the rise of agriculture. Larger settlements in the form of permanent villages and towns swept away the spatial limitation on the spread of disease. In particular, the introduction of domesticated animals such as dogs, pigs, cattle, horses and cats increased human exposure to infectious diseases mostly spread by rats and fleas, very much like it did at the end of 2019 when the SARS-CoV-2 virus spread from Wuhan city, Hubei province in China, to become a global pandemic within a matter of months.

9 Large populations (estimated at around 20 million people each at around 1000 years BC) eventually appear to have grouped in five regions globally: in China, the Indian subcontinent, Egypt, the Fertile Crescent10 and Iran, and in Europe.

11 Perhaps half of Africa’s much smaller population was by then concentrated in a single area along the fertile Nile Valley. Largely because of its low population densities and hence ability to continue with hunter-gatherer lifestyles, the technological developments that had accompanied the Bronze and the Iron Ages essentially bypassed much of sub-Saharan Africa. Because of its relative isolation from global trade and conquest, Africa was also less affected by the great plagues that affected the rest of the world such as the Plague of Justinian that reduced Eurasian populations by a quarter from 541 to 542 AD.

12 During the bubonic plague or Black Death that swept through Asia, Europe in the fourteenth century, anything between a quarter and two thirds of the European population died. However, such was the momentum provided by agriculture, that population numbers recovered and soon again started to increase.

13 For a while, it seemed that the African civilizations that had in the meanwhile developed in modern-day Ethiopia (Aksum) and in the west along the Niger River and that these could come to rival those elsewhere. South of the Sahara, the Bantu people had domesticated cattle and were growing sorghum and millet. They had also discovered iron but they and other groups were not technologically advanced enough to resist external intrusion. During the centuries of African slavery that followed from around 1500, first Muslim slave traders, and later the Atlantic slave trade denuded the continent of much of its ability to pursue farming since, without sufficient labor and the ability to store foodstuffs, it was not possible to identify and cultivate crops and domesticate animals—both prerequisites of farming. The growth of large cities that agriculture had enabled had required authorities to give attention to water-borne sewage and other measures to combat communicable diseases. But by the time that Africa started to become more urbanized towards the end of the nineteenth century, its higher population densities was partially enabled by imported modern medicine (vaccines and later the discovery of penicillin) that allowed for the prevention and treatment of these diseases. Larger communities of people were now able to live in larger settlements not because of city planning, housing laws, adequate municipal water and sewerage as was required elsewhere to contain disease and plague, but because modern medicines served as an effective alternative to keep infectious diseases under control.

14 Because of its climate and the much longer time period during which humanity and its predecessors coexisted, Africa has therefore had a significantly larger disease burden than other regions, which partly explains why it is here that human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome (AIDS) originated. The Impact of HIV and AIDS HIV’s ancestor is simian immunodeficiency virus (SIV), an infection of African monkeys that has also spread to chimpanzees. SIV is several thousand years old, and may even have been around millions of years ago.

15 That SIV spread to humans is no surprise, for several major human infectious diseases such as the plague, sleeping sickness, yellow fever, various forms of influenza, Creutzfeldt-Jakob’s disease and, most recently, Ebola, have all done so. Once transmitted to humans, SIV evolved to HIV. Like many other diseases, its origin in Africa is essentially a function of the fact that humanity and its primate predecessors have had a longer and closer relationship here than anywhere else. Scientists believe that the HIV virus originated in the western equatorial region of Africa (today known as Cameroon and the Democratic Republic of Congo) in the first half of the previous century. During the subsequent decades, subgroups of the virus were carried away from the epicenter to infect eastern, southern and western Africa. As a result, by the time that the epidemic was discovered, it had already silently spread across large areas. Its slow-acting, asymptomatic incubation period and the eventual appearance of diverse opportunistic infections defied prompt action until such time as it had reached momentous proportions.

16 By the mid-1970s, HIV/AIDS was a true pandemic. HIV/AIDS remained silent and unrecognized for so long because it affected the immune system, meaning that people were apparently dying from a variety of opportunistic infections that take advantage of a weak immune system and not from a single disease. It remained undetected because of Africa’s poor health systems, bad infrastructure and limited medical research capacity and silently spread across the continent. Africa has consistently shouldered between 75 and 85% of the global AIDS burden, which peaked in 2004–2005. In each of these years, more than 1.5 million Africans died from AIDS, although the actual number of people who passed away in the 1960s, 1970s and 1980s will likely never be known.

17 AIDS is, of course, not the first modern pandemic. The Spanish influenza killed 40–50 million people in 1918. Asian flu killed two million people in 1957 and Hong Kong influenza killed one million people in 1968. The AIDS pandemic had a dramatic impact on Africa’s ability to improve health outcomes relative to other developing regions, with a serious knock-on effect on economic productivity and disastrous impacts on families and communities. For example, between 1980 and 2000, life expectancy in sub-Saharan Africa improved by only about 2.5 years, compared to an increase of about 5.5 years globally and close to nine years in South Asia. The first known case of HIV was eventually traced to a man who died in 1959 in the Democratic Republic of the Congo. Initially global attention focused on young homosexual men but, by 1982, it was understood that the ‘slim disease’, a condition previously considered to be a wasting disorder linked to malnutrition, was in fact HIV/AIDS.

Once it was identified, lack of government capacity and the denialism of influential leaders such as President Thabo Mbeki of South Africa led to the unnecessary loss of hundreds of thousands of lives. Mbeki’s stance, in the country with the largest AIDS death rates globally at the time, would eventually contribute to his ouster as president in 2008 in favor of a flawed replacement, Jacob Zuma. While life expectancy in Africa has recovered to a certain extent in the last decade, it has still not caught up with the rest of the world. In 2018, the gap in life expectancy between Africa and the global average was about eight years—in spite of the fact that the ready availability of medicines for most communicable diseases should allow Africa to make much more rapid progress. By 2040 the gap in life expectancy between Africa and the global average should be slightly below five years. In contrast, South Asia more than halved the gap in life expectancy between itself and the rest of the world—from 11 years in 1960 to less than four years today. HIV/AIDS dealt sub-Saharan Africa a devastating blow. It came at a time when the continent had shown signs of a turnaround from the declining economic growth prospects in the 1980s and 1990s. This change in fortune was the result of various factors, including a determined effort by some in the international community to place poverty alleviation at the core of global concerns—an occurrence that was facilitated by the end of the Cold War. It remains to be seen what the medium and long-term impact of the COVID-19 virus will be in Africa. At the time of writing it is still too early to responsibly model the interplay between competing variables including Africa’s much younger population (the virus affects elderly people more seriously resulting in much higher levels of morbidity), low levels of urbanization (providing rural people with a degree of initial protection meaning it could spread more slowly here), the challenge of comorbidity (given the continents high communicable disease burden such as from HIV/AIDS and tuberculosis) and a host of other factors including low levels of testing, the very limited public health capacity, and low levels of access to potable water and water-borne sewage. And then there are the climatic and seasonal impacts that are all still speculative. The damage that COVID-19 will inflict in the short term cannot, however, be disputed. Millions more Africans will be condemned to extreme poverty, incomes will decline and many will succumb to lack of food as the efforts to constrain infection rates reduce economic activity, jobs and impact upon livelihoods. The unfolding global recession will hit Africa very hard particularly given the commodity dependence of many of its economies. The result will be to constrain growth and economic improvements—but eventually the deep drivers of economic growth in Africa will reassert themselves.

Africa’s Approaching Health Transition

Looking back over time, it is clear that Africa’s high communicable disease burden partly explains its unique development trajectory. More concerning, because Africa has such low levels of safe water and poor sanitation, it is potentially more susceptible to the impact of new viruses such as COVID-19 although the virus generally affects younger populations less severely. To an extent the HIV/AIDS pandemic occurred as part of a long-term characteristic of Africa’s high burden of communicable diseases compared to other regions that have first experienced a declining burden of communicable diseases and only later an increased incidence of non-communicable diseases. Sub-Saharan Africa has a much younger population than other regions in the world. With a median age below 19 years it naturally suffers from a much higher communicable (or infectious) than non-communicable disease burden because children are especially susceptible to the former. The median age in Asia is 27 and in Europe it is 43 years. Poor living conditions including unsafe water, poor housing and inadequate sanitation also create an environment for pathogens to propagate. Infants and children often die of infectious diseases while elderly people generally die of chronic diseases or die from communicable diseases after living for a while with non-communicable. As incomes rise, people live longer, eat more processed foodstuffs and more readily develop heart disease, high blood pressure, diabetes and cancer. The so-called epidemiological transition takes place when improved food security and innovations in public health and medicine result in infectious diseases, such as influenza, being replaced as the dominant cause of death by chronic diseases, such as cancer. This transition is generally associated with age and income as it relates to lifestyle, and is often used as an indicator of the transition from developing to developed nation. In Europe and North America the transition from communicable to no communicable diseases as the main cause of death occurred more than a century ago. In Latin America and the Caribbean, the transition happened around 1970 and in North Africa around 1980. In South Asia it occurred around 2000 but is only set to occur around 2030 in sub-Saharan Africa.

The nature of the epidemiological transition is, however, changing. Modern medicine means that people in sub-Saharan Africa are now living long enough to succumb to non-communicable afflictions, with the result that many people in poor countries are contracting the ‘diseases of affluence’ at younger ages. So in sub-Saharan Africa the transition is happening at lower levels of income and urbanization than elsewhere. At the same time, the burden of communicable diseases remains high, resulting in the so-called double-burden of disease. This will present health systems with very large cost implications as they navigate increasingly complex public health landscapes. The high costs associated with non-communicable diseases will pose a major problem for many African countries as their comparatively low average incomes translate into limited state budgets and capacity to provide the necessary health care. Providing a US$2 mosquito nets to every vulnerable person in Africa every two years is one thing, but ensuring that every African has reliable access to insulin (annual cost more than US$300 per person18), cancer screenings and dialysis is quite another. The result of the approaching double-burden of disease will be more sick adults, leading poor countries to have to devote more resources to preventing and treating costlier non-communicable diseases. Pollution and tobacco are also proving to be a huge challenge, as tobacco companies are now actively targeting the next generation of smokers, all of whom are in the developing world. Still, communicable diseases continue to have a disproportionate and devastating impact on Africa, by any standard. In 2018, about 90% of malaria deaths worldwide occurred in Africa—for HIV/AIDS the figure was about 80%. The continent accounts for nearly 50% of all communicable disease deaths worldwide, despite making up only 16% of the global population, as shown in Fig. 3.1. In other words, people in Africa are about four and a half times more likely to die from a communicable disease than people elsewhere. This trend is forecast to continue beyond 2040 in the Current Path. By then, Africa is projected to account for about 95% of global malaria deaths, 80% of global AIDS deaths and almost half of total communicable disease deaths worldwide. It is partly because of this disease burden that the average life expectancy at birth in 2018 in Africa (at 66 years) is so much lower than that in the rest of the world (at 75 years) and is also forecast to remain significantly below global averages beyond the 2040-time horizon.


It is quite likely that we underestimate the relationship between health and economic growth, and in Chapter 16, I compare the fiscal and economic impact of the Improved Health scenario with other scenarios. The analysis reflects findings in other studies, such as one that found a one-year increase in life expectancy could be associated with a 4% increase in GDP.37 Another by the UN Economic Commission for Africa found that the impact of the Ebola epidemic reduced the GDP of Guinea, Liberia and Sierra Leone by between 2 and 5% compared to the Current Path.38 Moreover, the inclusion of infrastructure in the Health scenario underscores the imperative to design health programme that extend well beyond the health sector itself. In Africa, providing basic infrastructure like WASH facilities and electricity reduces the impact of diarrheal and vector-borne diseases, as well as the respiratory harm caused by indoor use of traditional fuels like dung and charcoal. There is also a role for the international community. Installing taps and toilets has historically not been as attractive to donors (and sometimes governments) as say, eliminating river blindness, but it would have a tremendous impact on livelihoods on the continent. Demographic growth and technological change can work in Africa’s favor, but deferred action will be extremely costly. Delays in urban planning will only result in larger and more dangerous unplanned urban spaces. In addition to provision for roads, railways and ports, urban planning in Africa must emphasize the provision of basic infrastructure like clean water, improved sanitation facilities and electricity, as well as increasing access to, and the general quality of, health and education services. Africa’s health systems are desperately trying to battle the world’s worst communicable disease burden with rising rates of non-communicable. diseases. This is a complex challenge with many moving parts, but a better understanding of the trade-offs in health policy versus investments like providing basic WASH infrastructure should lead to better outcomes. Against this background, getting more rapidly to Africa’s demographic dividend and improvements in education—the subject of the next two chapters—may be among the most important drivers of better health in much of Africa, among its various other obvious benefits. Awareness and information programme can contribute greatly to communicating the benefits of good hygiene and preventing the spread of communicable diseases like HIV/AIDS. They can also instill healthy, lifelong habits around the importance of exercise and healthy diets, which could help to prevent or at least delay the onset of expensive lifestyle diseases like type-2 diabetes and heart disease. Spending more money on WASH and health requires more rapid progress in moving Africa through its demographic transition.


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