LONDON (Reuters) -- The foundation set up by billionaire Microsoft Corp. founder Bill Gates and his wife Melinda is working toward global health fairness, its top executive said Friday.

The Bill & Melinda Gates Foundation is the world's largest foundation. It has already donated $1.7 billion to attack diseases such as tuberculosis, malaria and AIDS that pose the greatest danger to people in the developing world.

"The Foundation really has a three-word objective: Global Health Equity," William Foege, the director of the foundation's newly formed Global Health Program, told The Lancet medical journal.

Foege and Gordon Perkin, the executive director of the foundation, said they intend to keep it small, efficient and focused to maximize its aims of preventing and eradicating diseases that afflict people living in the world's poorest countries.

So far most of their efforts have been aimed at providing vaccines for children around the globe. It spends $500 million of a $21.8 billion endowment each year on health projects.

The Gates couple have so far focused on biggest killers and improving childhood and maternal health, but Perkin said they are willing to invest substantial amounts of money in "long shots" or high risk investments which have the potential to do great things.

Perkin said the foundation prefers to focus on tools such as vaccines that have permanent value. "You only have to develop such tools once and then they're going to benefit many people far into the future," he added.

It also provides start-up funds for projects that will attract other investors such as the development of a vaccine against AIDS.

Because it is small, the foundation is interested in working with international agencies such as the World Health Organization, UNICEF and the World Bank.

"The Gates Foundation is basically putting global health back on the world's agenda, where it really wasn't for much of the last decade," Perkin added.

From http://www.cnn.com/200/HEALTH/07/07/health.gates.reut/index.html