The worlds biggest killer and the greatest cause of ill-health and suffering across the globe is listed almost at the end of the International Classification of Diseases. It is given the code Z59.5 - extreme poverty.
Poverty is the main reason why babies are not vaccinated， why clean water and sanitation are not provided， why curative drugs and other treatments are unavailable and why mothers die in childbirth. It is the underlying cause of reduced life expectancy， handicap， disability and starvation. Poverty is amajor contributor to mental illness， stress， suicide， family disintegration and substance abuse. Every year in the developing world 12.2 million children under 5 years die， most of them from causes which could be prevented for just a few US cents per child. They die largely because of world indifference， but most of all they die because they are poor.
In the time it takes to read this sentence， somewhere in the world a baby has died it its mother s arms. For that mother， the message that her neighbours infant will live is no consolation. It does not stem her grief to know that 8 out of 10 children in the world have been vaccinated against the five major killer diseases of childhood， or that globally since 1980 infant mortality has fallen by 25%， while overall life expectancy has increased by more than 4 years， to about 65 years.
Beneath the heartening facts about decreased mortality and increasing life expectancy， and many other undoubted health advances， lie unacceptable disparities in health. The gaps between rich and poor， between onepopulation group and another， between ages and between the sexes， are widening. For most people in the world today every step of life， from infancy to old age， is taken under the twin shadows of poverty and inequity， and under the double burden of suffering and disease.
For many， the prospect of longer life may seem more like a punishment than a gift. Yet by the end of the century we could be living in a world without poliomyelitis， a world without new cases of leprosy， a world without deaths from neonatal tetanus and measles. But today the money that some developing countries have to spend per person on health care over an entire year is just US $4 - less than the amount of small change carried in the pockets and purses of many people in developed countries.
A person in one of the least developed countries in the world has a life expectancy of 43 years according to 1993 calculations. A person in one of the most developed countries has a life expectancy of 78 - a difference of more than a third of a century. This means a rich， healthy man can live twice as long as a poor， sick man.
That inequity alone should stir the conscience of the world - but in some ofthe poorest countries the life expectancy picture is getting worse. In five countries life expectancy at birth is expected to decrease by the year 2000， whereas everywhere else it is increasing. In the richest countries life expectancy in the year 2000 will reach 79 years. In some of the poorest it will go backwards to 42 years. Thus the gap continues to widen between rich and poor， and by the year 2000 at least 45 countries are expected to have alife expectancy at birth of under 60 years.
In the space of a day passengers flying from Japan to Uganda leave the country with the world s highest life expectancy - almost 79 years - and land in one with the world s lowest - barely 42 years. A day away by plane， but half a lifetime s difference on the ground. A flight between France and C？te dIvoire takes only a few hours， but it spans almost 26 years of life expectancy. A short air trip between Florida in the USA and Haiti represents a life expectancy gap of over 19 years.
The purpose of the report is to highlight such inequities and to tackle the wider question： what are the global health priorities？ It also tries to answer other crucially important questions. Which are the major diseases， the major causes of death， handicap， disability and diminution of the quality of life？ Which conditions cause most misery， although they may not be fatal？ Which countries， or communities within countries， have the greatest health needs？ Where should health resources be targeted？
The report， for the first time， has attempted to examine the burden of ill-health not just by disease， but also by age， as the impact of illness differs across the age spectrum. Where possible， the analysis of health status has been carried out for infants and children， adolescents， adults and the elderly. On the basis of the data available and considered to be reasonably reliable， ten leading causes of death， illness and disability have been identified. There is also an explanation of what WHO is doing to bridge the gaps in health， an attempt to assess health trends in the coming years， and an effort to chart a health future for mankind - a future in which a baby lives， not dies， in its mothers arms.
The number of children under 5 years who died in 1993 - more than 12.2 million - equals the entire populations of Norway and Sweden combined. Of such deaths in the developing world， the great majority could have been avoided if those countries enjoyed the same health and social conditions as the world s most developed nations. The gap between the developed and the developing world in terms of infant and child survival is one of the starkest examples of health inequity.
The estimated global figure for mortality among children under 5 years in 1993 was 87 per 1 000 live births， an encouraging fall from rates of 215 during the period 1950-1955 and of 115 in 1980. Yet in parts of the developed world only 6 out of 1 000 liveborns die before reaching age 5， whereas in 16 of the least developed countries the rate is over 200 per 1 000， and in one country it is 320 per 1 000.
Infant mortality - deaths of children under 1 year - varies from 4.8 per 1 000 live births to 161 - a 33-fold difference. The gap in infant mortality between developed and developing world narrowed by 50% during the years 1960-1993， from 113 to 54 per 1 000 live births. But at the same time the gap widened between least developed and developing countries.
Malnutrition contributes substantially to childhood disease and death but often goes unrecognized as such. In 1990 more than 30% of the world s children under 5 years were underweight for their age. As many as 43% of children in the developing world - 230 million - have low height for their age. Micronutrient malnutrition is estimated to affect at least 2 billion people of all ages， but children are particularly vulnerable. As a result of iodine deficiency - a public health problem in 118 countries - at least 30 000 babies are stillborn each year and over 120 000 are born mentally retarded， physically stunted， deaf-mute or paralysed. A quarter of all children under age 5 in developing countries are at risk of vitamin A deficiency.
There have been improvements in child health， and 1993 saw the number of children dying from vaccine-preventable diseases reduced by 1.3 million compared to 1985 - equal to the population of Trinidad and Tobago. Nevertheless， around 2.4 million children under 5 years are still dying every year from such diseases， particularly measles， neonatal tetanus， tuberculosis， pertussis， poliomyelitis and diphtheria. There are also worrying signs that recent immunization gains ae being eroded or even reversed by economic and social conditions.
Every year in the developing world acute respiratory infections， particularly pneumonia， kill more than 4 million children under 5 years - one death every 8 seconds - and are a leading cause of disability. They account for 30-50% of visits by children to health facilities everywhere. Significant reductions in mortality could be achieved by treating the underlying bacterial infections with low-cost antibiotics for a few days.
Diarrhoeal diseases， resulting from unsafe water and poor sanitation coupled with poor food-handling practices， are responsible for a further 3 million deaths a year among children under age 5 in the developing world - one every 10 seconds - and are a graphic example of the deadly synergy of poverty and lack of knowledge. Worldwide there are an estimated 1.8 billion episodes of childhood diarrhoea annually. Many of the deaths from diarrhoea could be prevented by using oral rehydration salts， which cost just US $0.07 on average.
Health of school-age children and adolescents
Across the world some 2.3 billion people， about 40% of the total population， are aged under 20. Although teenagers and young adults are generally healthy， they are among the most vulnerable in terms of the diseases of society - poverty， exploitation， ignorance and risky behaviour. In squandering the health of its young， the world squanders its tomorrows. The behaviour patterns established in adolescence， highly influenced by the adult world， are of immense importance to an individuals life span and to public health as a whole.
In many countries health services are not meeting adolescent needs， and there are concerns that education， training and jobs for the young are inadequate. Education is a vital， although often unrecognized， contributor to the well-being and sensible fertility practices of young people， because schooling is linked with health status and pregnancy rates. A blackboard and piece of chalk can be as influential as antibiotics and contraceptives in protecting health. Improving the education of adolescents in general， and girls in particular， is one of the most effective ways to promote equity， enhance development and protect health for all.
The desire for sex and a fulfilling relationship are powerful driving forces for most young people， who at the same time are under pressure to engage in sexual relationships too early. Yet many young people are denied even basic knowledge about their own bodies or the means to protect themselves from unwanted pregnancy and sexually transmitted diseases （STDs）。 These diseases are most frequent in younger sexually active people， and appear to be increasing worldwide. The highest rates for notifiable STDs are generally seen in the 20-24 age group， followed by those aged 15-19 and 25-29. In nearly all parts of the world the peak age of infection is lower in girls than in boys.
At the same time HIV and AIDS are having a devastating effect on young people. In many countries in the developing world， up to two-thirds of all new HIV infections are among people aged 15-24. Overall it is estimated that half the global HIV infections have been in people under 25 years - with 60% of infections of females occurring by the age of 20. Thus the hopes and lives of a generation， the breadwinners， providers and parents of the future， are in jeopardy. Many of the most talented and industrious citizens， who could build a better world and shape the destinies of the countries they live in， face tragically early death as a result of HIV infection.
Other health dangers facing adolescents include tobacco， alcohol and other drug misuse， their exploitation as cheap and often illegal labour， and the worrying growth in the numbers of street children. Recent estimates suggest there may be as many as 100 million street children， at high risk of malnutrition， infectious diseases， STDs including HIV/AIDS， and criminal and sexual exploitation. The rise in accidents， violence and suicides involving young people in many parts of the world is a cause for deep concern.