ROME (Reuters) Jun 12 - Winning the war on hunger is vital to reducing the spread of HIV/AIDS in hardest hit sub-Saharan Africa, a senior AIDS expert said.

"If you are able to provide food to people, that in itself will contribute to prevention of the epidemic," Marcela Villarreal, leading expert and spokeswoman on HIV/AIDS at the Rome-based United Nations Food and Agriculture Organisation (FAO), said late on Tuesday.

"A person who is not hungry will not have to sell her body that day to be able to eat," Villarreal told Reuters in an interview on the sidelines of a World Food Summit aimed at reviving enthusiasm to reach a goal to halve hunger by 2015.

Some 95% of the estimated 40 million HIV/AIDS sufferers live in developing countries, most of them in sub-Saharan Africa, the UN says.

In the 25 hardest hit countries in Africa, seven million agricultural workers have died of AIDS since 1985 and 16 million more deaths are expected in the next two decades.

CHILD PROSTITUTION

Villarreal said she had returned this month from a trip to Kenya where she saw orphaned girls, aged around nine, prostituting themselves in Bondo district in the western province of Nyanza in the basin of Lake Victoria.

She said young people had to sell their bodies just to get from one meal to the next.

Bondo district is one of the worst hit by HIV/AIDS in Kenya, Villarreal said.

"Here the prevalence (infection) rate--about 30% of adults--is twice the national rate," she said.

"In some of the communities it is even higher--there was one community where all adults were tested, and 50% were found to be HIV positive."

With 14% of the total adult population believed to be HIV positive, and around 2.1 million people living with HIV, Kenya is the ninth most affected country in the world, Villarreal said in a report after her trip.

The FAO hopes the four-day summit will encourage rich nations to open their purse strings and work harder to halve the number of hungry people around the world to 400 million by 2015.

Sub-Saharan Africa is one of the world's worst hunger spots. One in four people in the region are malnourished, aid agency officials say.

Almost 13 million people in six southern African states--Zimbabwe, Malawi, Zambia, Mozambique, Lesotho and Swaziland--are at risk of famine unless they receive food aid, according to the United Nations.

Two successive years of poor harvests caused by drought, floods and frost, coupled with economic and political crises, have slashed food availability and caused prices of the staple food maize to skyrocket, it says.

The severe food shortages in the six southern African states raised risks of the spread of HIV/AIDS there, Villarreal said.

"Part of people's vulnerability to HIV/AIDS is due to hunger itself and to poverty," she said.

James Morris, Executive Director of the UN World Food Programme (WFP), the world's largest food aid agency, said HIV/AIDS was a serious drain on household incomes.

"Families afflicted with AIDS have higher health expenses and funeral expenses," he told journalists at the summit.

"You end up with many AIDS orphans--children who are simply left for an extended family to care for them, or families who are led by very young children."

The United Nations estimates that there are around 13.2 million AIDS orphans around the world whose parents have died from the disease. Most of them live in sub-Saharan Africa.