London School of Hygiene & Tropical Medicine researchers, led by James Hargreaves, found HIV infections appear to be concentrating among the least educated Africans, reversing previous patterns that saw higher levels of infection among the most educated. The scientists also found HIV prevalence sometimes increased among the less educated, even while it fell among the overall population.

"These results are partly good news," said Hargreaves. "They confirm that HIV prevalence is falling, sometimes quite steeply, in some groups of people. This is probably at least partly because of the global response to the epidemic so far.

"But our new study also indicates … HIV is increasingly becoming concentrated among the most vulnerable members of society. We conclude that more needs to be done to encourage educational achievement across the whole of society if we are to stem the tide of HIV infection in sub-Saharan Africa."

The study appears in the journal AIDS.