Across Africa, hospital wards are filling with military casualties. The cause is not another African conflict, but AIDS.

More deadly than any of Africa's wars, AIDS is hitting at the continent's ability to defend itself at a time when its countries are shouldering a growing share of the peacekeeping burden.

"HIV and other diseases represent a readiness challenge to militaries throughout the world, and security for us all demands that we pay attention to this," U.S. Deputy Assistant Secretary of Defense Theresa Whalen told a recent gathering of African military health officers.

South Africa, which has more people infected with HIV than any other country, has responded with a groundbreaking clinical research program in partnership with the United States that is investigating how best to manage the virus in a military setting and providing treatment to hundreds of infected members and their families.

Few of its neighbors, however, have the funding, expertise or infrastructure to do likewise.

Sub-Saharan Africa is home to some 25 million of the world's nearly 40 million HIV-infected people.

"Members of the armed forces are in many ways at the [forefront] of the HIV and AIDS epidemic," South African Deputy Defense Minister Mluleki George said at the military health officers' conference in Cape Town. Their age, mobility and access to casual sex put them at a higher risk of catching and spreading the virus.

Few African militaries have even tried to produce reliable figures, but their infection rates are estimated to be up to twice those in the wider population, according to the Pretoria-based Institute for Security Studies.

The South African National Defense Force says 23 percent of its 75,000 members are infected, on par with the adult civilian rate of infection. Seven out of every 10 military deaths are AIDS-related, according to figures presented to lawmakers in 2002, the most recent year for which statistics are available.

AIDS is also the biggest killer in the Ugandan armed forces, said Lt. Col. Kenneth Ochen, a military doctor in Kampala who said he lost 200 patients to the disease last year.

"They are dying. Oh, they are dying," he lamented.

While most militaries screen recruits for HIV, many soldiers are spending weeks, even months, on sick leave, disrupting unit cohesion, availability for deployment and chains of command.

In Sierra Leone, at least four U.N. peacekeepers died and 10 others were sent home because of AIDS-related illnesses. Two officers deployed to Sudan as peacekeepers by the African Union, a regional bloc, died of similar causes.

The disease hits hardest at people in their late twenties and thirties, many of whom hold important positions. Their care places a burden on already stretched military budgets.

South Africa's military has been at the forefront of efforts to address the virus in the continent's armed forces. It first approached the United States for help setting up AIDS drug trials in 2002, long before the life-prolonging medicines became available through the public health system. The five-year collaboration began in 2003.

Members of the U.S. National Institute of Allergy and Infectious Diseases are now working with their South African counterparts at five clinics, with one more on the way.

Two years into Project Phidisa -- meaning "prolong life" in Sesotho, a South African language -- the military is reporting progress in getting critically ill members back to fighting fit.

More than 2,900 people have been tested. Those with HIV are monitored, while those with full-blown AIDS are put on one of four widely used combinations of drugs to compare their effectiveness, side effects and compliance levels.

The study will eventually consider the role of nutritional supplements and traditional medicines in delaying progression of the disease.

President Thabo Mbeki's government has drawn criticism for its sluggish response to the AIDS epidemic, and despite government promises to provide treatment to all, AIDS drugs still are not widely available.

Phidisa is providing the drugs to 834 force members and their dependents. An additional 232 are getting medicine through separate U.S. funding until the military can provide them.

Sgt. Philisiwe Ntshangase, 36, was in and out of the hospital for months. She lost weight, started drinking and became suicidal. Now she is the picture of health. Her main worry: how to shed those extra pounds she put on since starting her AIDS medicine.

"The medication made me a different person," said Ntshangase, a former anti-apartheid guerrilla who advises other soldiers with HIV. "It reminded me what was my mission in the defense force: to take care of my beloved country."

This is of strategic importance to the South African government in view of the leading peacekeeping role it is playing, said George, the defense official. South Africa has some 1,250 troops in Burundi and 1,350 in Congo.

Now some of its neighbors are also increasing treatment. The Zambian military has more than 1,000 people on AIDS drugs. But the stigma still associated with HIV is keeping more soldiers from seeking treatment.

Many countries are also struggling to train staff members to care for their infected troops. The few with the skills are leaving for better paying jobs overseas. Others are infected and dying.

Mozambique is still recovering from years of civil war and lacks even basic diagnostic equipment, said Maj. Agostinho Afonso, a physician at the military hospital in Maputo. It has just 200 people on treatment and must concentrate on prevention.

"We need more help," he said.

Project Phidisa, meaning "preserve life," tests blood samples and provides AIDS drugs to African military members and their dependents.