The world’s AIDS epidemic has hit a plateau, with 2.7 million people becoming newly infected each year for the last five years, according to the annual report released Monday by U.N.AIDS, the United Nations agency fighting the disease.

Almost seven million people are receiving treatment — more than half of them thanks to American taxpayers — and that number has been steadily rising. But it is still not close to catching up to the new infection rate: Last year, 1.35 million got on treatment for the first time, meaning 200 people were newly infected for each 100 newly treated.

That is an improvement over two years ago, when 250 were infected for each 100 treated.

And, in a development that augurs badly for the future, donor funds dropped about 10 percent last year as the worldwide economic crisis made some countries cut their donations.

Whether the world’s generosity is producing a triumph or a failure depends on what yardstick is used. The seven million receiving treatment represent about half the people sick enough to need immediate treatment under World Health Organization guidelines. But the figure falls far short of reaching the ambitious new “test and treat” goal adopted last year by U.N.AIDS and endorsed this month by Secretary of State Hillary Rodham Clinton in her speech calling for an “AIDS-free generation.” To reach that, all 34 million infected people in the world would have to be found — a Sisyphean task in itself — and then put on antiretroviral drugs immediately so they would stop passing the virus on.