"We need to assist poor countries to train more health staff, provide commensurate salaries to enable them to live better lives and carry out their work," Moses Massaquoi, medical coordinator with Medecins Sans Frontieres in Malawi, told Reuters at a global AIDS conference in Mexico City.

The shortage of medical staff leaves HIV patients untended, to die without drugs that can keep them alive and healthy even if they do not offer a cure. Treating AIDS patients requires dedicated training, and most countries with a huge burden of the disease simply do not have enough of such professionals.

Peter Piot, executive director of the U.N. AIDS agency UNAIDS, echoed Massaquoi's comments at the conference, where international agencies, health officials, scientists, pharmaceutical companies and nongovernmental groups will discuss ways to stop the epidemic over the coming week.

"Three million people (globally) have access to drugs, but six million do not. AIDS is far from over," Piot said.

"There is a need to expand treatment to those who do not yet have treatment."

In Malawi, where 12 percent of the population of 12 million is infected with HIV, a nurse who cares for AIDS patients earns $3 a day.

Massaquoi said it was little wonder why half of those who need treatment, or 141,000 people, have not been able to get drugs.

"These people are uncared for because of the terrain of the country, and there are not enough resources to provide services," he said.

In Lesotho, 54 percent of nursing posts in public clinics and 30 percent in hospitals are vacant, while nearly a quarter of its 1.8 million people are infected with HIV. Malawi has fewer than 100 trained AIDS doctors, while it needs up to 400.

Dr. Pheello Lethola, an HIV and tuberculosis specialist in Lesotho, said international agencies and donors tend not to see healthcare workers as being essential factors in the effort to stop the spread of AIDS.

"You need healthcare workers to administer the drugs. Without healthcare workers, drugs are useless," she said.

Over the past 10 years life expectancy in Lesotho has fallen from over 50 to 35, Lethola said.

"Average life expectancy in Malawi has fallen from 62 to 39 mainly due to AIDS. With fewer staff, it also means that people with other diseases are also not being taken care of," Massaquoi said.

UNAIDS says 33 million people are infected with the human immunodeficiency virus that causes AIDS, and 2 million die of it each year.