Enemies of health, allies of poverty
The findings of the report give an intriguing -- and alarming -- insight into not just the current causes of disease and death and the factors underlying them, but also into human behaviour and how it may be changing around the world. Most of all they emphasize the global gap between the haves and the have-nots by showing just how much of the world's burden is the result of undernutrition among the poor and of overnutrition among those who are better-off, wherever they live.
The contrast is shocking. According to the report, at the same time that there are 170 million children in poor countries who are underweight -- and over three million of them die each year as a result -- there are more than one billion adults worldwide who are overweight and at least 300 million who are clinically obese. Among these, about half a million people in North America and Western Europe die from obesity-related diseases every year.
So it is clear that at one end of the risk factor scale lies poverty, where underweight remains the leading cause of disease burden among hundreds of millions of the world's poorest people and a major cause of death, especially among young children. The report shows that underweight remains a massive and pervasive problem in developing countries, where poverty is a strong underlying determinant.
All ages are at risk, but underweight is most prevalent among children under five years of age, and WHO estimates that approximately 27% of children in this age group are underweight. This caused an estimated 3.4 million deaths in 2000, including about 1.8 million in Africa and 1.2 million in countries in Asia. It was a contributing factor in 60% of all child deaths in developing countries. In other words, the report says, deaths from underweight every year rob the world's poorest children of an estimated total of 130 million years of healthy life.
In terms of global risk factors, underweight is closely followed by unsafe sex, the main factor in the spread of HIV/AIDS, with a major impact in the poor countries of Africa and Asia. The report says HIV/AIDS is now the world's fourth biggest cause of death. Currently 28 million (70%) of the 40 million people with HIV infection are concentrated in Africa, but epidemics elsewhere in the world are growing rapidly. The rate of development of new cases is highest in Eastern Europe and central Asia. Life expectancy at birth in sub-Saharan Africa is currently estimated at 47 years; without AIDS it is estimated that it would be around 62 years.
Current estimates suggest that more than 99% of the HIV infections prevalent in Africa in 2001 are attributable to unsafe sex. In the rest of the world, the 2001 estimates for the proportion of HIV/AIDS deaths attributable to unsafe sex range from 13% in East Asia and the Pacific to 94% in Central America. Globally, about 2.9 million deaths are attributable to unsafe sex, most of these deaths occurring in Africa.
In both Africa and Asia, unsafe water, sanitation and hygiene, iron deficiency, and indoor smoke from solid fuels are among the ten leading risks for disease. All are much more common in poor countries and communities than elsewhere. As with underweight, these risks continue to be some of the most formidable enemies of health and allies of poverty.
About 1.7 million deaths a year worldwide are attributed to unsafe water, sanitation and hygiene, mainly through infectious diarrhoea. Nine out of ten such deaths are in children, and virtually all of the deaths are in developing countries.
Iron deficiency is one of the most prevalent nutrient deficiencies in the world, affecting an estimated two billion people, and causing almost a million deaths a year. Young children and their mothers are the most commonly and severely affected because of the high iron demands of infant growth and pregnancy. The report also considers the disease burdens associated with deficiencies in Vitamin A, iodine, and zinc. Vitamin A deficiency is the leading cause of acquired blindness in children. Iodine deficiency is probably the single most preventable cause of mental retardation and brain damage. Severe zinc deficiency causes short stature, impaired immune function and other disorders and is a significant cause of respiratory infections, malaria and diarrhoeal disease.
Half the world's population is exposed to indoor air pollution, mainly the result of burning solid fuels for cooking and heating. Globally, it is estimated to cause 36% of all lower respiratory infections and 22% of chronic obstructive pulmonary disease.
Most of the risk factors discussed in this report are strongly related to patterns of living, and particularly to consumption -- where it can be a case of either too much or too little. At the other end of the scale from poverty lies "overnutrition" or, perhaps more accurately, "overconsumption".
Overweight and obesity are important determinants of health and lead to adverse metabolic changes, including increases in blood pressure, unfavourable cholesterol levels and increased resistance to insulin. They raise the risks of coronary heart disease, stroke, diabetes mellitus, and many forms of cancer. The report shows that obesity is killing about 220 000 men and women a year in the United States of America and Canada alone, and about 320000 men and women in 20 countries of Western Europe.
High blood pressure and high blood cholesterol are closely related to excessive consumption of fatty, sugary and salty foods. They become even more lethal when combined with the deadly forces of tobacco and excessive alcohol consumption, which also cause a range of cancers as well as heart disease, stroke and other serious illnesses.
The report traces the rapid evolution of the tobacco epidemic by showing that the estimated number of attributable deaths in the year 2000 -- 4.9 million -- is over one million more than it was in 1990, with the increase being most marked in developing countries. However, most of the smoking-related disease burden is still found in industrialized countries.
Global alcohol consumption has increased in recent decades, with most or all of this increase occurring in developing countries, according to the report. Worldwide, alcohol caused 1.8 million deaths, equal to 4% of the global disease burden; the proportion was greatest in the Americas and Europe. Alcohol was estimated to cause, worldwide, 20--30% of oesophageal cancer, liver disease, epilepsy, motor vehicle accidents, and homicide and other intentional injuries.
Until recently, all of these factors -- blood pressure, cholesterol, tobacco, alcohol and obesity, and the diseases linked to them -- had been thought to be most common in industrialized countries. Unfortunately, as this report demonstrates, they are now becoming more prevalent in developing nations, where they create a double burden in addition to the remaining, unconquered infectious diseases that have always afflicted poorer countries.
In a number of ways, then, this report shows that the world is living dangerously -- either because it has little choice, which is often the case among the poor, or because it is making the wrong choices in terms of its consumption and its activities.
Indeed, there is evidence that these risk factors are part of a "risk transition" showing marked changes in patterns of living in many parts of the world. In many developing countries, rapid increases in body weight are being recorded, particularly among children, adolescents and young adults. Obesity rates have risen threefold or even more in some parts of North America, Eastern Europe, the Middle East, the Pacific Islands, Australasia and China since 1980. Changes in food processing and production and in agricultural and trade policies have affected the daily diet of hundreds of millions of people.
The report says that while eating fruit and vegetables can help prevent cadiovascular diseases and some cancers, low intake of them as part of diet is responsible for almost three million deaths a year from those diseases. At the same time, changes in living and working patterns have led to less physical activity and less physical labour. The report finds that physical inactivity causes about 15% of some cancers, diabetes and heart disease.
Meanwhile, tobacco and alcohol are being marketed increasingly in low and middle income countries. Today, more people than ever before are exposed to such products and patterns, imported or adopted from other countries, which pose serious long-term risks to their health. For example, smokers of all ages have death rates two or three times higher than non-smokers.
The report warns that if global health is to be further improved and burdens of disease lowered, countries need to adopt control policies now. It says that risks such as unsafe sex and tobacco consumption could increase global deaths substantially in the next few decades and could decrease life expectancy in some countries by as much as 20 years unless they are brought under better control very soon.