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Non-communicable diseases and conditions

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This analytical profile on noncommunicable diseases and conditions is structured as follows:

Contents

Analytical summary

Noncommunicable diseases are now responsible for an increasing share of Africa’s disease burden, with about 62% of older Africans dying from this cause. This double burden with communicable diseases (infectious diseases) requires coordinated approaches.

Noncommunicable diseases principally affecting the WHO African Region are cancers, diabetes mellitus, cardiovascular disease, and chronic lung and respiratory diseases. Violence, injury and disabilities also contribute a high proportion of morbidity and mortality.

Distribution of causes of noncommunicable burden of diseases (percentage of total disability-adjusted life years) in the WHO African Region, 2004

Lifestyle changes and urbanization are driving a latent cancer epidemic, much of which is infection related. Survival rates for cancer in the Region are low, due to problems with diagnosis, late presentation and appropriate treatment.

The cardiovascular disease burden is also a public health challenge in the Region, estimated at approximately 8 million. The higher profile now emerging is causing some countries to start taking action in respect of cardiovascular diseases. Many chronic respiratory diseases are leading killers and multisectoral action is needed to address the environmental and social determinants largely responsible.

The projected growth rate to 2030 for diabetes mellitus is almost 100%, showing that an epidemic is in the making. Oral health problems are still of concern, but data and services are in short supply. Screening and treatment for sickle-cell disease are rare and most patients die before the age of 5 years.

Epilepsy occurs more than twice as frequently as in industrialized countries and alcohol abuse accounts for 12% of young male mortality. Violence produces 35% of all injury deaths, while the Region has the highest fatality rate for road traffic accidents. Ten per cent of the Region’s population has some degree of disability, and eye and ear health is of particular concern. Half of all blindness is due to cataracts that can, in principle, be easily and cheaply rectified.

The majority of these noncommunicable diseases remain inadequately addressed for reasons of weak health systems, staff inadequately trained to respond to noncommunicable diseases, financial shortfalls and a lingering perception that the Region’s principal health focus should remain on infectious disease.


Disease burden

Distribution of causes of neuropsychiatric burden of diseases (percentage of total DALYs) in the African Region, 2004
Distribution of causes of intentional and non-intentional injuries (percentage of total DALYs) in the African Region, 2004

The increasing burden of chronic non-communicable diseases (NCDs) in the WHO African Region threatens already over-stretched health services. Conditions such as cardiovascular diseases, cancer, diabetes mellitus, mental health problems, chronic respiratory disease, violence, injuries and disabilities, and genetic disorders absorb substantial amounts of human and financial resources. Approximately 62% of older adults in Africa (those over 45 years old) die from NCDs[1]. In Africa in 1990, NCDs accounted for 28% of morbidities and 35% of mortalities. These figures are projected to rise to 60% and 65% respectively by 2020, adding to the already high burden of communicable diseases[2]. This double burden necessitates concomitant approaches and simultaneous interventions.

The economic impact of NCDs goes beyond the costs to health services. Indirect costs such as lost productivity can match or exceed the direct costs. In addition, a significant proportion of the total cost of care falls on patients and their families. People now die from chronic diseases at dramatically younger ages; but because NCDs are not always understood as development issues, and underestimated as diseases with profound economic effects, many African governments take insufficient interest in their prevention and control.

Cancer prevention and control

Cancer is a latent public health crisis in Africa for at least three main reasons. Firstly, as urbanization and life expectancy increase, the incidence of cancer will also rise as carcinogenesis is linked to ageing and unhealthy lifestyles. Secondly, the magnitude of the HIV/AIDS crisis in sub-Saharan Africa has diverted attention from cancer, while increasing its incidence through tumours such as Kaposi sarcoma. Thirdly, the cost of modern chemotherapy treatment has escalated beyond the reach of most African countries. Countries have difficult choices in finding the balance between curative and palliative care, and investment in preventive strategies to reduce the future burden.

Cancers associated with bacterial or viral infections, such as cervical, liver, and stomach cancer, comprise a large share of total cases in the African Region. As many as 36% of cancers in Africa are infectious-related – exactly double the world average[3]. Lung, colorectal, breast, and prostate cancers are becoming more common in Africa as lifestyles change.

Data on cancer cases and deaths in African countries are both more limited, and less accurate, than in developed countries. The number of new cases is projected to increase globally from 10 million in 2000 to 15 million in 2020. Nine million would occur in developing countries. In the African Region, the top cancers among women, in order of incidence, are breast, cervical, stomach, lung, and colorectal cancer. Cervical cancer accounts for the greatest number of deaths. The two top cancers affecting men are prostate and liver[4]. The high incidence of infection-related cancers reflects weak public health systems that fail to control contaminants, bacteria, and viruses, as well as a lack of effective preventive and screening services. Longer life expectancies, unhealthy diets, and the globalization of tobacco markets are other determinants of cancer increase in the African countries.

Survival rates for some types of cancers such as oesophageal, liver, lung, and pancreatic cancer, are very low. For these cancers, primary prevention is the most practical and often the only possible intervention in the African Region. For a second group of cancers – large bowel, breast, ovarian, and cervical cancer – proven methods of early detection, diagnosis, and treatment can, in principle, be delivered through district health care facilities. For a third group of cancers, which includes leukaemia, lymphoma, and testicular cancer, survival rates are low because countries have a weak level of technology, scarce infrastructure, and low medical resources.

The Region faces a cancer epidemic if appropriate prevention and management policies and programmes are not urgently put in place. At present, there are difficulties over effective management of cancer cases, adequate scientific and epidemiological information, and shortage of trained professionals.

Cardiovascular diseases prevention and control

Cardiovascular diseases (CVDs) have a major socioeconomic impact on individuals, families and societies in terms of health-care costs, absenteeism and national productivity. CVDs include coronary heart disease (heart attacks), cerebro-vascular disease (stroke), raised blood pressure (hypertension), peripheral artery disease, rheumatic heart disease, congenital heart disease and heart failure. These are top killers, causing about 12 million deaths throughout the world.

The burden of CVDs is increasing rapidly, and has become a public health problem throughout the African Region. The epidemiology of CVDs in the African Region, reported mainly on hospitalized patients, may not represent the true pattern of heart disease. Rather, it suggests a high burden of neglected conditions such as rheumatic valve disease, cardiomyopathies, and tuberculous pericarditis. It differs across population groups, due to different risk factors such as unhealthy lifestyles, varying access to health care and environmental conditions, and cultural beliefs. Health infrastructures are inadequately equipped for diagnosis and care, and little research takes place.

WHO has reported that the number of disability adjusted life years (DALYs) lost to CVDs in sub-Saharan Africa reached 6.5 million for men and 6.9 million for women in 2000. This could rise to 8.1 million and 7.9 million respectively by 2010. CVDs cause higher mortality in Africa than in developed countries[5] and affect younger people and women disproportionately. Hypertension remains the most threatening risk factor, with national prevalence ranging between 15% and 30% in adults.

Barriers to care for people with CVDs compound the problem. These may include inadequate financing, low competence among health workers, and poor laboratory support[6]. Furthermore, cardiovascular research in Africa is low[7]. Lack of awareness on the part of health personnel, lack of education of the general public, limited access to clinics, unaffordable costs of penicillin, and fear of fatal penicillin allergy, all need to be overcome.

Despite these barriers, some attention has recently been focused on CVDs in Africa. National initiatives to identify risk factors and set guidelines are now under way. Some countries have carried out national epidemiological surveys, and others have begun to monitor and assess their programmes. Others, including South Africa and Nigeria, have drawn up their own guidelines for managing hypertension.

Chronic respiratory diseases prevention and control

Lower respiratory tract infections, chronic obstructive pulmonary disease (COPD), tuberculosis, and lung cancer are among the leading 10 causes of death worldwide.

In the African Region, CRDs are not yet being managed and controlled appropriately through the reduction or avoidance of exposure to common risk factors, started during pregnancy and childhood. Avoidance of direct and indirect exposure to tobacco smoke is of primary importance for healthy lungs, and as a preventative measure for the other three priority NCDs (CVDs, cancer, and diabetes) identified in the Global Strategy for NCD prevention and control.

Other shared risk factors include low birth weight, poor nutrition, and acute respiratory infections in early childhood, indoor and outdoor air pollutants, and occupational risk factors. For primary prevention to be effective, other sectors must be actively engaged. Environmental standards, for example, should be set and monitored to ensure the reduction of exposure to disease determinants and pollution risks. Populations should have regular information about healthy lifestyles, healthy nutritional habits, and the risks associated with tobacco, airway irritants and allergens. Likewise, early detection of occupational asthma is vital.

Diabetes mellitus control

Diabetes mellitus has emerged as an important NCD in sub-Saharan Africa.[8],[9]. WHO estimates that more than 180 million people worldwide have diabetes[10]. In 2000, the prevalence of diabetes in the WHO African Region was estimated at 7.02 million people, the vast majority of which had type 2 diabetes[9] .

Estimates by the International Diabetes Federation[11] in 2009 suggest that the number of adults with diabetes in the world will expand by 54%, from 6 million in 2010 to 4 million in 2030. The projected growth for sub-Saharan Africa is 98%, from 1 million in 2010 to 9 million in 2030. Mortality attributable to diabetes in sub-Saharan Africa is estimated, in 2010, at 6% of total mortality. The absolute and relative mortality rates are highest in the 20–39 age-group — i.e. the most economically productive population. Traditional beliefs play a role in how many Africans perceive the disease its risk factors[12], with obesity still being positively valued. Culturally appropriate health promotion campaigns are needed.

Clinical findings suggest that the characteristics of type 1 diabetes in sub-Saharan Africans can differ from those in European populations. Age at onset tends to be later in African communities, on average from 22–29 years, and preponderance in women was reported in South Africa[13]. Type 2 diabetes is currently the most common form in the Region, similar to other regions of the world. Most of the available data for diabetes prevalence in Africa are based on standardised 1985 WHO criteria. In contrast with frequently held beliefs, diabetes is not rare in sub-Saharan Africa, although rates of less than 3% have been recorded.

In most African communities, the patient pays for diabetes care. Health care systems are state-funded, with priority given to communicable diseases. If an individual with diabetes cannot afford the drugs, the situation may be fatal[14]. Africa is now facing an epidemic of type 2 diabetes, and preventive action is urgently needed on lifestyle issues. The development of comprehensive and integrated national NCD plans that include a diabetes component is critical.

Oral health and noma

Dental and oral health refers to the well-being of the oral cavity, including the dentition and its supporting structures and tissues. The oral health profile is not homogeneous across Africa, and differs today from previous decades. Dental caries and periodontal disease in African countries appear to be neither as common nor of the same order of severity as in the developed world. Oral diseases must, however, be individually assessed in the local context in terms of prevalence and severity. A number of serious oral conditions exist in the African Region, and these need to be urgently addressed due either to their high prevalence, or to the severe damage or death they can cause. Cancrum oris (Noma), and the acute necrotizing ulcerative gingivitis with which it is associated, is still common among children in Africa.

The most recently available annual incidence figure for Noma is 20 cases per 100 000 population. The disease occurs in 39 of the 46 countries of the African Region. Historically, Noma is a disease occurring along the “Noma belt” of Mauritania, Senegal, Mali, Niger, Chad, Sudan, and Ethiopia. But cases from outside the “Noma belt” have been reported with an increased incidence, related to the HIV/AIDS pandemic. About 90% of children with Noma die without receiving any care. In conditions of poverty, where many children are malnourished or undernourished, the prevalence of conditions such as Noma is likely to increase.

The prevalence of oral and pharyngeal cancers is also on the increase in Africa.4 Greater alcohol use is associated with increasing levels of oral cancer. Rapid urbanization, and increasing use of tobacco, are factors also considered to greatly increase the incidence of oral pre-cancer and cancer. The oral manifestations of HIV/AIDS are very widespread, and most commonly include fungal infections such as those caused by Candida, necrotizing gingivitis or oral hairy leukoplakia. National surveys and smaller studies in Africa have shown the prevalence of dental caries to be quite low, but with substantial regional variations. Most of these cases (90%) remain untreated.

Maxillo-facial trauma has increased in many countries as a result of interpersonal violence, motor vehicle accidents and war. Chronic destructive periodontal disease is known to occur in a small proportion of most populations, regardless of location or socioeconomic status. Harmful practices such as the removal of tooth germs of deciduous canines, extraction of upper and lower anterior teeth, and the trimming or sharpening of upper anterior teeth, still prevail. Fluorosis is common in areas such as the Rift Valley in east Africa, and malnutrition is known to increase the likelihood of fluorosis in children. Edentulism, congenital malformations and benign tumours occur, but little prevalence data is available. The African Region faces an acute lack of recent, reliable and comparable data on oral health issues.

The prevalence of oral disease closely mirrors levels of social deprivation. Increasing urbanization has been shown to lead to observable increases in the prevalence of oral disease. Where public or private oral health services do function, they are treatment oriented, providing mainly for the relief of pain and sepsis. A successful approach to oral health in Africa needs to focus on the social and environmental determinants of oral disease in local context, and ensure equitable and universal access to affordable health services.

Sickle cell disease and other genetic disorders prevention and control

Sickle cell disease (SCD) is a genetic disease occurring in most countries of sub-Saharan Africa; its prevalence depends on the Sickle Cell Trait (SCT); where SCT prevalence is higher than 20%, SCD is estimated at least at 2%[15]. In many countries of west and central Africa, the prevalence of SCT varies between 20% and 30%. In some secluded areas of Uganda it is as high as 45%[16]. Population-based data on SCD in Africa is lacking, as most studies are hospital-based.

National policy and approaches to the management of SCD are scarce, and where control programmes do exist, they do not have national coverage or adequate basic facilities to manage patients. Systematic screening for SCD is not commonly practised, laboratory facilities are limited, and diagnosis does not usually occur until severe complications occur. While most SCD manifestations are easily treated with available interventions, the majority of patients do not receive them. Adequately trained health professionals are few, specialized health care facilities are insufficient, and effective drugs, vaccines and safe transfusion are usually unavailable. Consequently, the majority of patients with SCD die before the age of five years; survivors suffer end-organ damage that shortens their lifespan. There is a crucial need for early case identification and comprehensive health care management (CHCM).

Recurrent sickle-cell crises interfere with education, work and psychosocial development. Persons with SCD are often stigmatized. At present, even in countries where stem-cell transplantation can be contemplated, there are no widely acceptable public health interventions for the clinical cure of SCD. Neonatal SCD, screened as part of comprehensive health care management, has been successfully practised in some parts of Africa[17];[18].

Mental health

Mental and neurological disorders are prevalent in all countries of the African Region. As major contributors to morbidity and premature mortality, they amount to about 5% of the burden of disease. The projection for 2030 predicts an increase, especially for depression[19]. Epilepsy, with an incidence of 64–156:100 000 population, is 2–3 times more common than in developed countries. The median prevalence in some studies is 15:1 000 population. More than 50% of cases are due to secondary causes that include perinatal insults, infections such as meningitis, cerebral malaria, neurocysticercosis, and head injuries.

Harmful use of alcohol is responsible for about 2% of the disease burden in sub-Saharan Africa, with wide variations between sub-groups of the population. Alcohol use is responsible for 12% of all deaths among young men aged 12–29. New evidence suggests a relationship between heavy drinking and infectious diseases, so the alcohol-attributable burden in Africa could be higher. It is estimated that unrecorded consumption accounts for about 50% of overall alcohol consumption in African countries.

Societal adversities in general, and natural and man-made disasters such as mass violence and conflicts, contribute greatly to an increase in mental disorders throughout the Region. Poverty, low education, and malnutrition are also major contributors. The extended family may act as a protective factor, but in large African cities it is increasingly replaced by small nuclear families unsupported by the health and social sectors.

Violence and injuries

Injuries account for 10% of the world’s deaths, with 5.8 million people dying each year from this cause[20] An increase of 40% in injury-related deaths is expected by 2020 in low-and-middle-income countries. The three leading global causes of death from injury are road traffic accidents (23%), suicide (15%) and homicide (11%)[20]

The African Region has the world's highest rate of violence-related deaths. In 2004, violence accounted for 35% of all injury deaths in Africa, and the death rate of 37:100 000 was considerably higher than the global average of 25:100 000 population. The pattern of violence-related deaths was dominated by homicide, particularly among young males, which accounted for half of all violence-related deaths in the Region, and occurred at nearly three times the global average homicide rate of 9:100 000. Suicide was the second leading cause of violence-related deaths in the Region, with a rate of 13:100 000 population, and deaths directly due to collective violence occurred at a rate of 5.5:100 000 population[21].

Along with the WHO Eastern Mediterranean Region, the WHO African Region has the highest fatality rate for road traffic accidents, at 32:100 000 population[21]. Almost half the road deaths are among pedestrians, motorcyclists and cyclists, termed "vulnerable road users". Injuries resulting from other causes (most notably drowning and burns) are responsible for death and disability in several million more. In the African Region, 10% of the population (81.2 million people) has some degree of disability.

Many African countries are taking steps towards reducing the injury burdens. These include adopting and enforcing legislation aimed at reducing drink-driving and speeding, and increasing seat-belt and motorcycle helmet use.

Eye and ear health

Eyesight problems are expected to increase. Although data is lacking, it is estimated that 27 million African people are visually impaired, and that 9 of every 45 blind people globally are Africans. Without action, the number of blind is likely to increase to 15 million by 2020[22]. Blindness and severe visual impairment have a significant impact on the socioeconomic development of individuals and societies, and exacerbate the problem of poverty.

The main cause of avoidable blindness remains cataract (about 50%). Cataract surgery can rapidly reduce avoidable blindness, and is one of the most cost-effective of all health interventions with a cost-saving per DALY in the order of US $ 20–40[23]. Glaucoma and diabetic retinopathy cause 12% and 5% of global blindness respectively. On the positive side, trachoma and onchocerciasis, major infectious causes of avoidable blindness in Africa, are increasingly being controlled through broad international alliances between WHO and major partners[24]. There are estimated to be 153 million people with visual impairment due to uncorrected refractive errors. Globally, uncorrected refractive errors are the main cause of visual impairment in children aged 5–15 years. In the African Region, data are lacking on the prevalence and types of refractive errors in different populations and age groups[23].

The global strategy, “Vision 2020: the Right to Sight,” was launched in Africa in 2000[25]. A partnership between WHO and the International Agency for the Prevention of Blindness, its aim is to tackle avoidable blindness by the year 2020. Thirty-three of the 46 African countries have set up or drafted national Vision 2020 plans, and begun their implementation, although resources are short.

At least two thirds of the estimated 278 million people with disabling hearing impairment are in developing countries. Half of all hearing loss can be prevented. Hearing loss imposes a huge social and economic burden on society. In the African Region, programmes to prevent and treat ear diseases and hearing impairment are scarce[26].

Disabilities and rehabilitation

Disabilities are increasing in all African countries, due to the rise in non-infectious chronic diseases, and increases in trauma injuries from road traffic accidents[23]. While polio is on the decrease, other genetic birth malformations such as spina bifida, club-foot and cerebral palsy still prevail. Although accurate data on disabilities is generally scarce, fragmented or outdated, recent surveys in four east African countries showed average disability prevalence at 6.25% of the population (Kenya 4.6%[27], Madagascar 7.5%[28], Rwanda 5.8%[29] and Uganda 7.1%[30] ). Data from these surveys suggest also that physical or motor impairments are predominant at about 40%.

Injuries and disabilities impose heavy costs on individuals and services. Road traffic accidents, for example, are estimated to cost African countries 1–2% of GNP, rising to 5% of GNP in some cases[21].

Provision of adequate rehabilitation services, however, remains a major challenge. Many countries do not have effective national policies, plans, or budgetary allocations for early prevention of disabilities, or for the mainstreaming of rehabilitation into medical training programmes. Lack of data further hampers efforts to put in place prevention strategies.

State of surveillance

All countries of the African Region have completed the STEPS survey for NCD risk factor surveillance. However, accurate information is scarce. Mortality statistics in Africa are sparse, due to the absence of comprehensive death registration in the great majority of countries. Since 1995, only two countries (Mauritius and South Africa) have contributed to the WHO mortality database.

Cancer statistics are obtained from population-based cancer registries. Cancer registration has, however, been slow to develop in African countries. A rapid survey carried out in 2009 showed that there were cancer registries in 26 countries of the Region, with some having more than one registry. In three countries, however, the registry was inactive. Only three of these cancer registries (Setif in Algeria, Kyadondo County in Uganda, and Harare in Zimbabwe) contained data of a quality considered adequate for publication in the International Agency for Research on Cancer (IARC) series, “Cancer Incidence in Five Continents” (volume IX).

Endnotes: sources, methods, abbreviations, etc.

References

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