When the United Nations Children’s Fund started its campaign to eradicate polio in 1988, the crippling disease was endemic in 125 countries.

There are now only about 1,000 cases of polio worldwide.

That’s the good news. The bad news is that for every success in bettering the lives of children, there’s a daunting new challenge apart from the perennial standbys of poverty and armed conflict: HIV-AIDS.

In its annual report on the state of the world’s children being released today, Unicef says the human immunodeficiency virus and AIDS, the disease it can cause, are among the most devastating scourges affecting the world’s children.

The devastation caused by HIV-AIDS is most clear among the 15 million children who have been left orphans. But the effects are felt long before a parent’s death, the report says.

“Because of the parent’s inability to work, many children, especially girls, are forced to drop out of school to work or care for their families, and are in particular danger of being exploited through hazardous labour.”

David Agnew, president of Unicef Canada, said in an interview that while the world is “on the cusp” of eradicating polio, and while great strides have been taken in reducing childhood deaths from diarrhea, children are threatened by a new stalker.

“AIDS is the new factor in the last decade or so on the block and it is having a vicious effect in some countries,” Mr. Agnew said in an interview. AIDS is now the single largest killer of people 15 to 49.

Twice as many children survived to age 5 in 2002 as in the 1960s, and most countries have had significant decreases in under-five mortality. But childhood mortality has risen sharply in regions, such as sub-Saharan Africa, where AIDS is prevalent.

“There is absolutely no question that in some countries, we are going backwards, and those are countries that are affected by intense and enduring conflict - or the majority of them are the ones that have the highest HIV infection rates and AIDS death rates,” Mr. Agnew said.

Deprivation caused by poverty, war and AIDS, Mr. Agnew said, is causing misery for half the world’s two billion children. About 700 million of them lack two or more of the following: adequate shelter, sanitation, safe water, information, health care, education and enough food.

Last year, 10.6 million children died before the age of 5. That number of dead represents 1.5 times the number of Canadian children.

Since the 1989 enactment of the United Nations Convention on the Rights of the Child, the most widely adopted international human-rights treaty, there have been successes among the grim child-survival statistics, Mr. Agnew said.

In another report released yesterday, the UN said the world is losing the battle against hunger, with the number of malnourished people in developing countries growing to more than 800 million people and rising.

The report by the Rome-based UN Food and Agriculture Organization makes an eight-year-old pledge by governments to halve the number of the world’s hungry by 2015 seem difficult to reach - the number in the developing world is just nine million lower than in 1990-92. But the report proposed a combination of programs to help boost agricultural productivity and direct food aid to achieve the 2015 target.

Although the number of hungry people in developing countries fell in the early 1990s, that trend was later reversed, the report - the agency’s annual update on world hunger - said. By 2000-02 the figure stood at 815 million, just nine million below the estimate of a decade earlier. The global total in 2000-02 stood at 852 million.