The world is suffering an acute shortage of doctors, nurses, and other health workers, according to a global group of health leaders. They say overburdened health workers on the front lines of survival are losing the fight against diseases such as HIV, tuberculosis, and malaria.

A new report blames feeble national health systems for the rollback of spectacular gains made over the last century in human survival. The authors are with the Joint Learning Initiative, an independent network of more than 100 health leaders from institutions such as the World Health Organization, the World Bank, and universities and government public health agencies globally.

They note that there are too few health workers around the world, and those there are lack the support they need to stave off disease. Many are collapsing under the strain or dying, especially from AIDS. Many others are fleeing to rich countries at accelerating rates to seek a better life and more rewarding work.

But the experts say the dramatic health reversals resulting from this shortage threaten not just the poorest nations, but also the health, development, and security of all in an interdependent world.

Sub-Saharan Africa is the worst off, according to the findings. It has only one tenth the number of nurses and doctors for its population that Europe has. The report says countries need a minimum of one health worker for every 400 people, but about 75 nations with nearly one third of the world's population fall below that level.

Ironically, the report comes at a time when, as it acknowledges, money is beginning to flow from donor nations and organizations, and when drugs, vaccines, and medicines are far cheaper and more widely available than just a few years ago. But the experts note that people, not just technology, prevent illness and administer cures.

They blame chronic underinvestment in human resources as a major cause of the severe health worker shortage. To boost collapsing health systems, the world needs four million more people in the medical professions. The top priority of the report's authors is to get one million more in sub-Saharan Africa alone, three times its current number.

The report urges governments to develop workforce plans to ensure that every family has access to a skilled and supported health care professional. They should also increase investments in education and retention in such professionals. In addition to national plans, the experts call for a global plan to designate $400 million a year to help countries train and retain health workers.

The report says what we do - or fail to do - will shape the course of global health over the coming century.