Gao left China and moved to the United States in August last year in order to be able to complete the books without government interference. Close to completion, they contain material she has written and collected since 1996, when she came across her first Aids patient, who contracted the deadly illness through a blood transfusion.

She's also updating her autobiography and thinking about what will come next.

'I don't want to die in the United States but I don't think I'll be able to go back to China,' Gao said. 'I want to book a flight back to China and die on the plane.'

A respected gynaecologist when she retired in the 1980s, Gao was 67 when she took on a new career, helping and campaigning for mainland HIV carriers and Aids patients, after learning about the 'plasma economy'. She found that illegal blood collection stations and shoddy transfusion practices in rural areas had kick-started an Aids epidemic,

Gao has spent millions of her own money supporting Aids orphans and printing Aids awareness information. She has already published more than 20 books on Aids and other sexually transmitted diseases, but her last three promise to be her strongest yet.

In recent months Gao has been struggling with her own illness - spreading thrombosis, which makes it difficult to walk without support. But she still spends at least four hours a day working on finalising her books.

'Yesterday after I wrote for four hours, my fingers all turned black,' Gao said of her declining health.

She received the final draft copy of the second of the three new books, China's Aids Plague, from her editors earlier this month. She's already gone through the 300,000-word book, marking errors here and there, with at least 100 pages flagged with notes.

She outlined the main points: illegal blood collection stations have gone underground, and officials have been using money, gifts, job promotions, threats and even criminal detention and mental institutions against those wanting to speak out.

The first of the three new books, China's Aids Plague: 10,000 Letters, a rewrite of a much-censored version published in China five years ago, was published in December and she's finished writing the third, 100 cases of Epidemics, and is waiting for it to be published in Hong Kong. Now, she is onto her final assignment: an updated edition of her 2008 autobiography, The Soul of Gao Yaojie.

Gao decided to leave the mainland in May last year when Sichuan teacher Tan Zuoren , who documented the number of children who died in collapsed schools during the earthquake that hit the province a year earlier, was arrested for subversion. Tan was jailed for five years in February for 'inciting subversion of state power'.

'I did similar things to what he did: speaking for the weak, but I was doing it on a much broader scale, and making an international impact,' Gao said. At the same time, the French offered her a human rights award. Sensing that government control was tightening, Gao left her Zhengzhou home abruptly one afternoon with help from friends, without time to even close the window or finish her lunch.

Gao had been subjected to constant government interference since starting to research the mainland's Aids epidemic. She concluded that contaminated blood was the main cause of the spread of Aids on the mainland, rather than sex and drugs as the government claimed, and that the government was covering up the real number of those with HIV.

There were four surveillance cameras in her flat in the Henan capital, and her phone was tapped and sometimes cut off.

In 2007, after being invited to Washington to receive a women's leadership award, she was put under house arrest for two weeks and guarded by more than 50 policemen. The central government allowed her to make the trip in the end, bowing to international pressure, and many in the US urged Gao to stay. She said no at the time, thinking that all her work and patients were in China.

But in May last year she realised that if she did not leave the country she might not be able to finish her books. She worried that if she was locked up, she would never get out.

Gao first travelled to Beijing and then stayed in Guangdong for two months, where volunteers helped her type and scan the material for her new books. In August, when she boarded the plane to the US, she carried with her only a small bag with a computer disk inside.

Asked why she has devoted herself to Aids work, Gao replies that it's one of the biggest health problems on the mainland, but the government is running away from the truth.

'It affects a large number of people, and several generations of a family,' she said

For 13 years she visited hundreds of villages all over the country, and saw too many heartbreaking scenes of Aids patients struggling in inhumane circumstances. She also collected grass-roots data showing that transmission through sex and drugs was low on the mainland compared to those who contracted HIV through blood sales and blood transfusions.

'The biggest problem right now is a government cover-up,' she said. 'The local government's interest is tied in with such illegal blood sales due to bribery and a face-saving mentality. But fundamentally it's because these officials simply don't care about the lives of the people.

'The government's propaganda claims that HIV in China today is mainly spread by sex and drugs have also contributed to severe discrimination in society against HIV carriers and Aids patients.'

Premier Wen Jiabao told a UN poverty summit in New York on Wednesday, looking at progress towards meeting the world body's Millennium Development Goals (MDG), that Beijing would continue a 'tireless campaign' against Aids around the world.

He said it had been a 'tough and protracted battle, yet we have never shown fear or backed down'.

'The fast spread of HIV/Aids in China has been basically brought under control,' Wen said. 'We are confident that we will meet the MDG on HIV/Aids [halting and beginning to reverse their spread] by 2015.'

According to the latest official figures, made available yesterday, there were 370,522 confirmed HIV and Aids cases in China by the end of last year, while the estimated number of people living with HIV and Aids on the mainland was 740,000.

However, Gao says the number is more like 10 million. She also disputes claims that the rate of HIV cases turning into full-blown Aids is 5 per cent, saying that based on her data the rate should be 30 to 40 per cent.

Photos on her laptop computer show scenes ranging from a long queue outside a blood station in Guangdong in 2005 to young children she has sponsored. She points them out one by one, recalling their names and how they contracted HIV, almost invariably ending the description with 'now dead'.

Gao says she has also persisted with her Aids work because the disease mainly affects the poor and leaves behind thousands of Aids orphans, who need financial and psychological support from the government and society at large.

Earlier books told how her Aids work and government persecution led her own children to distance themselves from her and she is reluctant to talk about her own family. Gao said her children did not say much when she decided to move to the US, but they now stay in contact from time to time through three layers of relatives and friends.

'I didn't want to bring them further trouble,' she said.

She is used to the loneliness. 'I was on my own most of the time at home too,' she said. 'My daughter brought me some food once during my house arrest in 2007, and two police cars followed her around for days after. With the four surveillance cameras, who would want to come near me?'

Gao's late husband, the only family member who supported her Aids work, died in 2006. In New York, a Chinese volunteer helps take care of her daily needs.

Despite being so far from home, Gao keeps in touch with news about Aids and activists on the mainland, recounting her meetings with HIV-infected activist Tian Xi , who went on trial in her home province this week. He is accused of intentionally destroying property worth 4,000 yuan (HK$4,600) during an argument with an official in a hospital office, and she wishes she could write something about it.

Tian, now 23, was infected via a blood transfusion in the same hospital when he was nine years old, and has repeatedly sought and been denied compensation. He now faces up to three years in jail if convicted.

Gao also recalled three conversations with another young Aids activist, who got kicked out of university one year short of graduation for organising Aids rights work. She tried to persuade him to tone down his activism in order to finish his degree.

'One must strengthen oneself first, before one can help others,' she says.