LONDON – Young children and certain other people with the AIDS virus should be started on medicines as soon as they are diagnosed, the World Health Organization says in new guidelines that also recommend earlier treatment for adults.

The advice will have the most impact in Africa, where nearly 70 percent of people with HIV live. Many rich countries already advocate early treatment. WHO’s new guidelines were released Sunday at the International AIDS Society meeting in Kuala Lumpur, Malaysia.

About 34 million people worldwide have HIV, the virus that causes AIDS. HIV attacks key infection-fighting cells of the immune system known as T-cells. When that count drops to 200, people are considered to have AIDS. In the past, WHO recommended countries start treating people with HIV when their T-cell count fell to 350; a normal count is between 500 and 1,600.

The new recommendations say to treat earlier, when the T-cell count hits 500.

In addition to children under 5, WHO says several other groups should also get AIDS drugs as soon as they’re diagnosed with HIV: pregnant and breast-feeding women, people whose partners are uninfected and those who also have tuberculosis or hepatitis B.

The new guidelines mean an additional 9 million people in developing countries will now be eligible for treatment.