By Holly Williams
The Chinese public has finally been let in on the secret - a new disease is spreading to provinces across the country.
The Chinese authorities have finally admitted that Sars is a problem
After months spent enforcing a near media blackout, in the last few days the Chinese Government seems to have had a change of heart.
Severe Acute Respiratory Syndrome - or Sars - is now the lead headline on China's state-controlled television news.
Reporters don face masks to interview doctors working in badly-hit hospitals, while newsreaders advise viewers to open their windows wide and wash their hands thoroughly.
But the message is predictably sanitised.
"Thanks to the hard work of the health authorities, the disease has been effectively controlled", parrot the announcers night after night.
There is no mention of the widespread speculation that authorities are still under-reporting the numbers of people dead and infected.
Nor is there any word of the World Health Organization's criticism of the government's slow reaction to the outbreak.
For people living on the frontline of Sars - in Guangdong Province, in China's deep south - the lack of information can be frightening.
Wang Ping gave birth to her daughter about four months ago, around the same time that rumours of a deadly new form of pneumonia began to surface in Guangzhou, the provincial capital.
Worried for her baby's health, Wang Ping searched state-owned papers for information. But the government had told journalists not to report the disease.
The people of Guangzhou were desperate for information
In desperation, Wang Ping turned to her mobile phone.
"We learnt about Sars in a mobile phone text message from a friend," said Wang.
"It said that people were dying, including some doctors. We were very frightened.
"After a few days there was an announcement on TV, but all it said was 'don't panic'. It didn't explain anything at all," she said.
Even before the Sars outbreak, text messaging was hugely popular with the country's 200 million mobile phone users.
During this year's Spring Festival - the most important family gathering of the Chinese calendar - more than six billion digital greetings flew across the country.
But a frightening illness, accompanied by official silence, has given text messaging an important new role.
In Guangdong, messages on Sars, its symptoms and the rising death toll spread faster than the disease itself.
The government reaction was swift.
In February, Xinhua, the state-run news agency, published a report saying that mobile phone text messaging may pose a threat to state security.
Many Chinese mobile phone users now find they can no longer receive messages sent from overseas.
China telecom consultant Duncan Clark believes the government may take further steps to block the free exchange of messages.
"Any popular mass medium which is outside the government's control will be considered a threat by default. Everything has to be regulated here at some point," he said.
But one mobile phone user who does not want to be regulated is political dissident Xu Yonghai.
A member of the underground Christian church and an anti-corruption campaigner, Mr Xu has been in the government's bad books for years.
But he finds the idea that text messages could be used to undermine government rule laughable.
"We have much better ways of threatening state security than using mobile phones," he said.
Mr Xu admitted, however, that he and other dissident friends do use their mobiles to "swap political humour".
It does not seem like the kind of thing that might bring down a government.
But for an authoritarian regime it is a frightening concept - ordinary people circumventing state-controlled media, and using new technology to reach out to each other.
In China, even health advice and political humour can be dangerous.