Life expectancy is falling in many parts of Africa due to the Aids epidemic, says a report from the World Health Organization.
There are many thousands of Aids orphans
The report says that in 14 African countries, child mortality is higher than it was in 1990, despite improvements elsewhere in the world.
WHO Director General Jung-Wook Lee is warning of a "growing gulf" in the standard of health care.
Next year, he said, was an "acid test" of world moral commitment to Africa.
The 2003 World Health Report covers everything from health campaigns against individual diseases such as Aids and polio, and compares changes in life expectancy in the richest and poorest nations.
Rich vs poor
While in Switzerland - the "home country" of the WHO - life expectancy is on average more than 80 years, in Zimbabwe, it is it is just under 38 years.
It is falling in many African countries - a girl born today in Sierra Leone could expect only to live to 36, in contrast to Japan, where today's newborn girl might reach 85 on average.
Other countries have shown falls - in Russia, for example, where health and social services have largely collapsed since the end of the Soviet era, a man can expect to reach only 58 years of age.
Aids is the leading cause of death among 15 to 59-year-olds, twice those caused in this age group by heart disease.
However, diseases related to tobacco are causing five million deaths a year, says the WHO.
Dr Jung-Wook Lee said that more effort was needed to introduce decent health care systems in even the poorest and worst-hit countries.
He said: "These global health gaps are unacceptable.
"Effective action to improve population health is possible in every country but it takes local knowledge and strength and sustained international support to turn that possibility into reality."
Average life expectancy (years) - examples
Zimbabwe - 37.9
Zambia - 39.7
Angola - 39.9
UK - 75.9 (M), 80.6(F)
France - 79.7
Sweden - 80.4
Switzerland - 80.6
Approximately 30m in African nations currently have HIV - accounting for 70% of the world's cases.
Infectious diseases are still claiming millions of children's lives on the continent, says the report.
It adds: "Those who do make it past childhood are confronted with adult death rates that exceed those of 30 years ago."
The risk for women dying in childbirth is 250 times higher in poorer countries than in rich ones - more than 500,000 women die each year as a result of complications during pregnancy.
The WHO Director General, writing in The Lancet medical journal, said: "We need a clear set of priorities - a new set of grand challenges, perhaps-for research, together with new funding to support this programme.
"The next 12 months and beyond will be acid test of our collective moral commitment."