H7N9 harder to track but less likely to cause disease
New avian flu strain is more deadly to humans than birds, scientists say, as third death reported
The H7N9 bird flu virus is less likely to cause disease than the H5N1 virus that has killed hundreds of people worldwide, scientists say.
But tracking the new virus is harder, as it seems to spread quietly among poultry.
While the spread of H5N1 has been halted by culls of chickens, this will not work with the H7N9 virus, as it is not known to have caused widespread deaths among birds or other animals, says Professor Yuen Kwok-yung, a microbiologist at the University of Hong Kong.
Though symptoms are mild in animals infected with H7N9, the virus seems to be more deadly to humans, having killed three of the nine people infected so far and left the others critically ill.
"These avian viruses are not well adapted to humans, so they cause much more of a problem," Yuen said.
These avian viruses are not well adapted to humans, so they cause much more of a problem
Since culling is ineffective, the remaining preventive measures are screening tests and vaccination. Some Western countries have developed a vaccine against the H7 virus but its efficacy on H7N9 is unknown.