WU LIANGLIANG went to hospital on March 1st with a tickly cough. After a number of hours hooked up to a saline drip, the 27-year-old pork butcher went home. When he still felt poorly a few days later Mr Wu returned to hospital and was diagnosed with a pulmonary infection. But then instead of recovering, as was expected for a man his age, Wu’s condition worsened rapidly. On March 10th, he became the second person known to have been killed by H7N9, a novel strain of avian flu not previously seen in humans. There are now nine identified human cases of H7N9 in the Yangzi delta region, which includes Shanghai, three of which have been fatal. The most recent death reported, announced on April 3rd, was a 38-year-old chef, surnamed Hong, who died in late March. Mr Hong worked in Jiangsu, the province next to Shanghai where four of the other people who contracted H7N9 live (a nearly real-time map endeavours to track the cases). The remaining cases are all in critical condition, but in general they have not deteriorated as swiftly as Mr Wu did. A 35-year-old woman in Anhui province is still alive 22 days after she first became ill.

Many questions surround H7N9’s origin, pattern of infection and treatment (there is no vaccine). Early analyses of the genetic sequence of the virus, which the Chinese authorities have shared with the world, suggest that a familiar strain of avian flu has mutated. Previously infectious only to birds, H7N9 appears now to be able to bind with mammalian cells, making it possible to jump from chickens to animals such as pigs. The World Health Organization (WHO) maintains that that there is no evidence of ongoing human-to-human transmission. If the virus were well adapted to jump between humans, the thinking goes, clearer evidence of transmission would already have emerged among the victims’ close contacts.

Anne Kelso, director of a research centre that collaborates with the WHO in Melbourne, said that while it is too early to make a comprehensive risk assessment, the overall picture of H7N9 is unlike any bird-flu virus previously examined.

“In particular, apart from the H7 and N9 components [the proteins it wears on its outer shell], the other six components of the virus are from a very different source”, Ms Kelso said. She calls the phenomenon “reassortment”: “There has been a mixing of at least a couple of other viruses previously, to create this new virus.” Unlike other strains that ravage poultry, such as H5N1, which has also killed 360 people worldwide since 2003, H7N9 seems to be imperceptible in its animal hosts. China’s ministry of agriculture is yet to find the strain, either in birds or other livestock.

In the absence of a known source, speculation is rife among Chinese citizens, who tend to be especially sensitive about the risk of pandemic since SARS (Severe Acute Respiratory Syndrome) broke out, ten years ago. On Sina Weibo, China’s largest microblog network, millions are talking about it. After it became known that Mr Wu was a pork butcher, users drew parallels to the 16,000 dead pigs that were found floating in tributaries of Shanghai’s Huangpu river in recent weeks. One user, Fen1234, told his 44,881 followers that

Shanghai’s hygiene and disease-control departments had 20 days to detect the virus and claim the announcement was not delayed, but just one day to prove there is no connection to the pigs floating in the Huangpu.

In contrast to plodding management at the time of the SARS crisis, while 349 people in mainland China died of the disease, the government has been relatively forthcoming with information about H7N9, ever since the announcement of the first human cases on March 31st. Experts, too, are in effect soothing public fears that there could be an outbreak on the SARS scale. Zhong Nanshan, a director of the Chinese Medical Association and a hero from the time of SARS, said that the two viruses are “very different”.

At Jingchuan wet market in Shanghai, Wu Desen, the father-in-law of the second H7N9 fatality, leans against his shuttered pork stall. On April 3rd, the wet market—so called because of the live, sometimes splashing, produce—is bustling with locals haggling over pork ribs and trotters.

The elder Mr Wu hasn’t opened the stall where his son-in-law once worked since the family learned the truth about his death. For 20 days they thought Wu Liangliang died of simple pneumonia. They only learned it was H7N9 watching the news on television.

Mr Wu says he won’t fight the Fifth People’s Hospital over the misinformation. But he is adamant that Wu Liangliang picked up H7N9 at the hospital, despite the municipal government’s conclusion (in Chinese). Mr Wu claims that his son-in-law was treated in the same department as the first known H7N9 case, an 87-year-old man surnamed Li. “[Wu Liangliang] was hospitalised in the morning of March 4th, on the same floor as the family whose father [Mr Li] died of the virus that afternoon,” he says.

Mr Li first visited Fifth People’s on February 14th with his two sons. All exhibited flu-like symptoms. Since Mr Li’s death, one son, a 55-year-old, has since died and the other recovered. At the time H7N9 wasn’t identified as the cause of illness in either of the two younger men, but their cases are now being reinvestigated.

(Picture credit: AFP)