The story is harrowing - and familiar to many in Cambodia. HIV infection rates in the country of 12 million people are just under 3 per cent, the highest in Asia. Outside, the dusty yard is checked with bright, white squares of noon sun and blocks of black shade full of mosquitoes. Old women sell hard-boiled eggs and dried fish. The toilets reek of stale urine. Inside, patients line the corridor of the clinic.

Each clutches an orange binder with their notes. They sit very still and wait. Nhem Sokunthea, 24 years old and four months pregnant, sits on a bench near the door with her palms folded over her swollen belly and her eyes on the floor. She has put on her best clothes - and borrowed the bus fare - for the visit to the hospital. Her story is harrowing - and familiar to many in Cambodia.

HIV infection rates in the country of 12 million people are just under 3 per cent, the highest in Asia. Almost everyone sitting in the clinic corridor has the virus. Sokunthea was infected by her husband. 'I got married a year ago and after four months discovered I had HIV,' she says softly. 'My husband said 'sorry, I am very sorry'.

He told me that before we were married, when he was working on fishing boats in the south, he had sex with a prostitute.' When Sokunthea fell pregnant last year, she paid for an unsupervised abortion, fearing that the child would be HIV positive. Now she is pregnant again and, although scared once more, the couple have no money. 'My husband is too weak to work now. I used to earn money selling vegetables but can't now. We have nothing.

I know I will die, but I am here to save my child,' she said. Mother-to-child transmission is one of the primary ways in which HIV is spreading. The women are usually infected by husbands who have had sex with prostitutes - something that is relatively socially acceptable. By 2005 the United Nations estimates that more than 100,000 children are likely to have been orphaned by Aids.

Many more will be infected themselves. In fact, the doctors at the clinic, which is run and funded by the aid agency Médecins Sans Frontières, say that there is only a one in three chance that Sokunthea will infect her child. 'I just want my baby to be free of Aids,' Sokunthea sobbed quietly. 'I have no hope now.

All my family are praying to the Lord Buddha.' The MSF clinic is in Takeo, a provincial town in the southwest of Cambodia, 60 miles from Phnom Penh, the capital. Bart Janssen, the agency's medical co-ordinator, said the project was part of an effort to provide healthcare to the sufferers of chronic diseases in rural areas.

'HIV has affected everybody,' Janssen said. 'Many farming communities have been hit very badly.' Only one in five of the 25,000 Aids sufferers in Cambodia who are likely to die within 12 months receives palliative care. 'Most just rot to death,' one HIV worker said. With regulation weak, pharmacies sell the drugs over the counter. Traditional medicine, according to one western Phnom Penh-based specialist, is 'organised theft'.

Mother-to-child transmission is one of the primary ways in which HIV is spreading. The women are usually infected by husbands who have had sex with prostitutes - something that is relatively socially acceptable. By 2005 the United Nations estimates that more than 100,000 children are likely to have been orphaned by Aids. Many more will be infected themselves.

And, although a massive effort by the government and international agencies has reduced levels of infection from a peak in 1997, the prevalence of HIV threatens to knock the fragile recovery of Cambodia off course. Last week saw political ferment as the king of more than 60 years, Norodom Sihanouk, resigned, designating his virtually unknown 51-year-old son, a former ballet dancer living in Paris, as his successor. Though a crisis threatened, a clash between royalists and the Prime Minister, Hun Sen, was avoided.

The country is still recovering from the damage done by the US-backed coups of the early Seventies, the Khmer Rouge genocide of the late Seventies and the Vietnamese communist regime that followed. One in three children dies before the age of five from preventable diseases, life expectancy is in the mid-50s and the Aids epidemic is a massive drain on resources. In the main Norodom Sihanouk hospital in Phnom Penh the sheer volume of HIV sufferers means that many are selected for treatment by lottery.

'There were three people in this bed,' said Isa Wang, 35. 'I won the draw, so kept it. I don't know what happened to the others.' Initiatives to combat the epidemic vary. British funds have helped the development of a racy new soap opera which will tackle controversial health issues. Others rely on more traditional networks. Cambodia's venerated monks are playing a valuable role, particularly in more conservative rural areas. Sitting in his saffron robes beside a pagoda, monk Munth Chhuoen, 41, described how he tells people that, if they follow Buddhist teaching, they will avoid HIV.

'I say that if you seek a lot of money you will use it in the wrong way and have a lot of sex and then you will die,' he said. Such teaching is of little relevance to eight-year-old Khon Phitun, who has HIV and is unlikely to live much longer. Last week he lay on a bed in the children's ward in the Takeo clinic, too weak to speak or move his wasted, scabrous limbs. 'He is my youngest son. I have sold everything I have to care for him. And I have five other children,' said his father, a landless labourer who suffers from HIV himself, stroking the boy's hair. 'I do not think about the future. There is nothing to say.'