GREG HOY, PRESENTER: Chinese and international health experts continue to be puzzled by the latest strain of bird flu, which they describe as one of the most lethal they've seen.
They say more sporadic cases are likely, even after the closure of live poultry markets which have been a major source of infections.
The big concern for authorities is whether there's a chance of direct transmission between humans.
China correspondent Huey Fern Tay reports from Beijing.
HUEY FERN TAY, REPORTER: The man who runs this restaurant has seen Beijing panic in an epidemic. That was a decade ago when the capital was gripped by SARS (Severe Acute Respiratory Syndrome).
This time the 7 year old girl, who reportedly became the first person in Beijing to contract the virus, lives just around the corner. But while Wang Hongliang isn't using disinfectants any more, district officials have ordered him to do something else.
WANG HONGLIANG, RESTAURANT MANAGER (translation): Local authorities have told us to stop selling poultry for the time being.
HUEY FERN TAY: We entered the area unsure if we would find the girl who contracted the disease and her migrant worker parents who sell poultry to the small community.
We could not find her at first. She had recovered after being in hospital for seven days. People we spoke to said the area was being disinfected twice a day.
FEMALE RESIDENT (subtitled): The vegetable markets have been moved indoors. Poultry sellers aren't allowed to come here.
HUEY FERN TAY (Subtitled): Since when have they not been allowed to come?
FEMALE RESIDENT (subtitled): Since that poultry [seller's daughter got sick].
HUEY FERN TAY (subtitled): Do you still eat chicken?
FEMALE RESIDENT (subtitled): No, I don't eat it. What if you get bird flu? It's best to wait a while.
HUEY FERN TAY: We soon realised not everyone was comfortable with our presence.
MALE (off camera, subtitled): Hello.
HUEY FERN TAY (subtitled): Hello.
MALE (off camera, subtitled): Show me your ID.
(Footage of outside of family home is shown)
HUEY FERN TAY: It became obvious where the family was living. There was a heavy security presence outside their home.
(Footage of young girl in hospital is shown)
Not much is known about the strain of bird flu this girl has recovered from. More than 100 people have been diagnosed with the H7N9 virus that first detected in Shanghai and other provinces along the Yangtze River Delta more than three weeks ago.
It's made some people very sick. Around a fifth of those have died, most of them elderly.
Liu Qingquan is a member of the taskforce the Chinese government has form to battle the virus.
LI QINGQUAN, BEIJING TRADITIONAL CHINESE MEDICINE HOSPITAL (translation): Earlier the girl's body was so hot it was like heated charcoal. In traditional Chinese medicine we believe that the heat in your body will only dissipate when you begin to perspire.
That happened to this patient three and a half hours after taking Chinese medicine. She began to perspire on her chest and back. Her body temperature then gradually declined from 39.8 degrees Celsius to 38 to 37. It stabilised by the sixth hour.
HUEY FERN TAY: More than 10 people who have been diagnosed with this strain of bird flu have been successfully treated with a combination of western and traditional Chinese medicine. Health experts stress that early intervention is very important.
But crucial questions remain, such as where is the virus coming from besides live poultry markets? How is it crossing from birds to humans? And how virulent could it become?
KEIJI FUKUDA, WORLD HEALTH ORGANISATION: This is definitely one of the most lethal influenza viruses we've seen so far.
But I want to give you a caveat or give you a little bit of context. We really at the beginning of our understanding of this virus and right now we may just be seeing most serious infections and it may be possible that there are people who have mild infections. We don't really know that right now.
HUEY FERN TAY: Chinese officials have repeatedly emphasised that they have been transparent about the outbreak of this strain of bird flu since the very beginning. They have also won the backing of the WHO (World Health Organization).
But the Chinese are waging a war against public scepticism because people remember the time when officials initially tried to cover up the SARS epidemic 10 years ago.
LIANG WANNIAN, CHINESE GOVERNMENT H7N9 TASK FORCE (translation): There are many unknown factors in the source of the virus: the mutation of the virus, the pathogenicity, the virulence, the migration, the clinical symptoms, and the epidemiological situation of the virus. So we need to study a lot. There are so many things that remain to be studied and learnt.
HUEY FERN TAY: Despite official assurances that it is safe to eat chicken if it's cooked properly, many people have stopped eating it, dealing a significant blow to businesses like KFC which has reported a drop in sales in China.
And for the poultry sector overall the virus is estimated to have cost more than $1 billion in lost sales.
Health experts on the fact finding mission in China say the closure of live poultry markets was very effective in controlling the spread of the virus, but more sources and more sporadic cases could be detected in the months ahead.