George W. Bush was president of the United States from 2001 to 2009.

Some 25,000 delegates are gathering in Washington this week for the 2012 International AIDS Conference. This is a moment of exceptional promise. Gains in AIDS treatment are remarkable — and continuing.

One of the saddest tragedies in the world is for people to die of HIV/AIDS when lifesaving medicines are available. Just a decade ago, that tragedy was playing out across Africa. Thanks to the generosity of the American people, this is no longer the case today. Through the President’s Emergency Plan for AIDS Relief (PEPFAR) and the Global Fund to Fight AIDS, Malaria and Tuberculosis — working with committed governments, faith-based and community organizations, and the private sector — treatment and prevention have advanced at an almost unimaginable pace. This month, the Joint United Nations Program on AIDS (UNAIDS) announced that 6.2 million people are on lifesaving antiretroviral AIDS drugs in sub-Saharan Africa — up from just 100,000 in 2003. This is more than a vast statistic. It is a series of real people’s names — those of nurses, doctors, civil servants, farmers, students, entrepreneurs and parents who did not leave orphans behind. It is proof of what many in Africa call the Lazarus effect: Communities once given up for dead have been brought back to life, and millions of men, women and children are alive to build their futures.

An important byproduct of this massive effort on HIV/AIDS has been the improvement of African health systems. PEPFAR and other programs have helped raise professional standards and improve infrastructure. This has raised an exciting prospect: to extend the gains on AIDS to other diseases.

It is heart-wrenching to save a woman from AIDS, only to watch her die from cervical cancer, which is more prevalent in women with HIV. So Laura and I, along with the Bush Institute and partners from the public and private sectors, started Pink Ribbon Red Ribbon to save women from breast and cervical cancer, two of the leading causes of cancer death in Africa. Like PEPFAR, the success of Pink Ribbon Red Ribbon depends on a broad alliance of private companies, nonprofit organizations and governments. The Bush Institute is working with the Obama administration, UNAIDS, Susan G. Komen for the Cure and private-sector partners. Secretary of State Hillary Clinton has been a consistent champion of this effort.

We launched Pink Ribbon Red Ribbon in Lusaka, Zambia, in December 2011 and returned to Africa this month to expand the program to Botswana. During our trip, Laura and I went back to Zambia and spent four days helping refurbish a women’s health clinic in Kabwe, two hours north of the capital. As soon as we cut the ribbon, the clinic started screening women who had lined up to be tested for cervical cancer. It was a joy to see the relief on the first patient’s face when she left with a clean bill of health. And it is heartening to know that those diagnosed with early signs of cancer will have access to treatment and a good chance of beating it.

During the past decade, millions of lives have been saved and changed. This has been a global effort. It would be a sad and terrible thing if the world chose this moment to lose its focus and will. Other countries and local governments in Africa can do more in providing resources and increasing funding — as the new government of Zambia is doing. But to continue the momentum in the fight against AIDS, America must continue to lead. Having seen the need and accepted the challenge, we can’t turn our backs now.