A sanitation worker retrieves dead pigs from the Huangpu. (Photo/Xinhua)
The new strain of bird flu that has already killed two people and left another critically ill in eastern China could be linked to the thousands of dead pigs found floating in a Shanghai river last month, according to a Hong Kong expert in infectious diseases.
China's Ministry of Health and the National Health and Family Planning Commission announced on Sunday the world's first reported cases of the H7N9 virus, a new subtype of avian influenza. The virus has already killed two men, aged 87 and 27, from Shanghai, while a 35-year-old woman from Anhui province remains in critical condition.
Health authorities said there is insufficient data to suggest that the new strain could be passed between humans, especially as 88 close contacts of the three had tested negative for the virus. A vaccine is not yet available.
Ho Pak-leung, director of the Infectious Disease Center at the University of Hong Kong, said the H7N9 cases could be related to the more than 10,000 pig carcasses that have been pulled out of Shanghai's Huangpu river since early March. Local media reports attributed the mass dumping to a swine epidemic earlier in the year.
While there is no concrete evidence to suggest a definitive link between the two, the fact that the 27-year-old victim sold pork means health departments should collect samples of the dead pigs to see if they have been affected by the same virus, Ho said.
The previous outbreak of the highly pathogenic bird flu that first struck China in 2003 belonged to the H5 subtype, Ho said. This time the human infection appears to be different and suggests that this strain might be evolving.
Ho is not the only person to draw a link between the new bird flu and the pig carcasses. Yuen Kwok-yung, a professor in the microbiology department at the University of Hong Kong, told reporters that while the H7N9 subtype should not be highly pathogenic, the virus could have mutated after infecting the pigs. Yuen urged the public not to panic until all necessary tests have been carried out.
Many of China's internet users have also drawn a direct relationship between the flu and the pigs, with some saying it is obvious that birds passed the virus to pigs, which were then consumed by humans.
Huang Li-min, the director of infection in children at National Taiwan University Hospital in Taipei, said the recent deaths in China are not a coincidence and that the fatality rate could be high if the virus turns out to be highly pathogenic. The virus does not necessarily have to go from bird to pig to human; it is possible that the virus may be transmitted directly from birds to humans, Huang said, adding that at this stage the disease should be controllable as long as it is not spread from human to human.
Ho Pak-leung 何栢良
Yuen Kwok-yung 袁國勇
Huang Li-min 黃立民