H7N9 avian flu
The influenza A (H7N9) virus is one subgroup among the larger group of H7 viruses that normally circulate among birds. A number of human infections of the H7N9 virus have been reported in eastern China, mostly in the Yangtze River Delta region since late March 2013. Some of the patients have died of severe pneumonia brought on by the virus.
Bird flu a reminder of things we dare not forget
Ten years after Sars, the city faces two timely reminders of the need for vigilance and preparedness against the threat of another outbreak of deadly disease. In the latest, the first reported cases of human infection by a lesser-known strain of bird flu, H7N9, have resulted in the deaths of two men in Shanghai, while five people are in a critical condition in Anhui and Jiangsu provinces.
Mainland authorities say there is no evidence of human-to-human infection, but the virus seems to have mutated and the circumstances are worrying. Two sons of one of the dead men contracted pneumonia and one died, although H7N9 was not found in either of them. The World Health Organisation says it is too early to rule out a link with dead pigs found floating in the Huangpu river, even if tests have not found it.
Hong Kong's secretary for food and health, Dr Ko Wing-man, says it remains important to find out if there has been human-to-human transmission. Tests showing the three did not infect each other raise the possibility of more than one infection source and he says it is also important to look out for epidemics among animals. Health officials have held an emergency meeting and the city is now on high alert for two potential threats - H7N9, and a deadly new Sars-like infection, novel coronavirus. The latter has killed 11 of 17 known victims since emerging recently in the Middle East. Researchers at the University of Hong Kong have found that it is potentially more deadly than Sars and able to infect more animal species that can pass it on to humans. It does not appear as infectious, but mutation could soon make it so.
Video: As Hong Kong marks 10 years since the outbreak of the deadly SARS virus, health experts say the city is now well prepared for coping with highly infectious diseases but warn that constant vigilance is required.
It took a month and three weeks before we learned of the deaths of the two men with H7N9. In light of the lack of information which left Hong Kong unprepared for Sars, this has prompted questions about the notification system set up to avoid a similar situation. Ko has explained that diagnosis of the first cases of human infection usually take a long time. We trust the system now works as it is supposed to.
As Sars fades in the collective memory, complacency is only human, especially after the swine-flu scare a few years ago became another seasonal flu. But Hong Kong stands at a crossroads of business and transport and is therefore vulnerable to contagion through an infected traveller. It can never afford to relax its world-standard surveillance system for infectious diseases.