Despite the rush by scientists to decipher the nature of the latest outbreak of bird flu, the virus and its relatives have been under the radar of a local research team for more than a decade.
Months before the emergence of H7N9, Malik Peiris, virologist at the University of Hong Kong and leader of the institution's bird flu research team, warned that the virus could cause the next major disease outbreak in Hong Kong.
"Bird flu viruses are very efficient in mixing their genes and changing, so they are really one of the best experts in jumping from animal to human," Peiris said.
Since the outbreak of H5N1 in 1997, his team has been focusing on research into avian influenza and other diseases that jump from animals to humans, such as Sars.
"It is these emerging diseases that suddenly come out of nowhere that cause the biggest impact," he said, adding that about 70 per cent of newly emerging diseases come from animals, most of them being viruses.
Though the H7N9 virus that recently emerged on the mainland was new to the scientific world, it has the "engine" of H9N2 - a disease well established in poultry - since six of its genes are from that virus.
Peiris' team has been studying the mutations of H9N2 that allowed it to transmit to humans. One of these mutations was found in H7N9, but further study is needed to understand the full process.
"Many of the things we have been using to study avian influenza, we're using them to study this new H7N9," he said.
The new H7N9 is a hybrid from poultry and wild birds, but he believes the virus is more likely to have originated from the former than the latter. The pattern of infection seems to have a strong relationship with exposure to wet markets, and is not in line with wild birds' migration patterns.
H7 viruses have the capacity to mutate from having lowdisease-causing abilities to being high pathogenic, as seen in previous outbreaks of H7N2 and H7N3 in poultry in several countries. The current H7N9 is still low pathogenic to birds, Peiris says.
Peiris expects that sooner or later a H7N9 human case will appear in Hong Kong but that "it will not be a major concern as long as there is no human-to-human transmission".
In summer, the H7N9 virus may become less active and the number of cases may go down, but he does not think that it will totally disappear like Sars.
View H7N9 map in a larger map
Click on each balloon for more information on individual patients infected: blue, patients infected with the H7N9 virus under treatment; red, those infected with H7N9 who have died; yellow, those who have fully recovered; and pink, those infected other types of the Influenza A virus, including H1N1.