Global life expectancy has risen by more than six years since 1990 thanks to falling death rates from cancer and heart disease in rich countries and better survival in poor countries from diarrhea, tuberculosis and malaria.
In an analysis from the 2013 Global Burden of Disease (GBD) study, health researchers said, however, that while life expectancy is rising almost everywhere in the world, one notable exception is southern sub-Saharan Africa, where deaths from HIV/AIDS have erased some five years of life expectancy since 1990.
"The progress we are seeing against a variety of illnesses and injuries is good -- even remarkable -- but we can and must do even better," said Christopher Murray, a professor of global health at the University of Washington in the United States, who led the study. It was published in The Lancet medical journal.
Murray said a huge increase in collective action and funding given to potentially deadly infectious diseases such as diarrhea, measles, tuberculosis, HIV and malaria has had a real impact, reducing death rates and extending life expectancy.
But he said some major chronic diseases have been neglected and are rising in importance as threats to life, particularly drug disorders, liver cirrhosis, diabetes and kidney disease.
The GBD 2013 gives the most comprehensive and up-to-date estimates of the number of yearly deaths from 240 different causes in 188 countries over 23 years -- from 1990 to 2013.
Murray's team's latest analysis found some poorer countries have made exceptional gains in life expectancy over that time period, with people in Nepal, Rwanda, Ethiopia, Niger, Maldives, East Timor and Iran now living on average 12 years longer.
Yet despite dramatic drops in child deaths over the last 23 years, malaria, diarrhea and respiratory infections such as pneumonia are still in the top five global causes of death in children under five, killing almost two million children between the ages of one month and 59 months every year.
Another mixed success is that, while worldwide deaths from HIV/AIDS have fallen every year since their peak in 2005, HIV/AIDS is still the greatest cause of premature death in 20 out of 48 countries in sub-Saharan Africa.