Researchers say the rapid rise in H7N9 bird flu cases, which made the jump from infecting chicks and ducks to infecting humans last year, could be attributed to the winter season and preparations for the Chinese New Year. The World Health Organization has asked nations to continue strengthening their flu surveillance and maintains that the data does not "support sustained human-to-human transmission."
Gregory Hartl, a spokesperson for WHO, said the virus spread is higher in the cold winter months. He did say that they will be monitoring celebration around the Chinese New Year, which will involve a lot of people traveling, some with birds.
"We need to remain vigilant, but so far the virus does not seem to have mutated in any way," he said.
These new cases take the total number of H7N9 cases to 219, including 55 deaths. Apart from a few cases of the virus spreading within a family, the virus has shown no sustained human-to-human transmission.
"There's still no evidence of human-to-human transmission or mutations to make it closer to a pandemic," said Wendy Barclay, a flu researcher at Imperial College of London.
The range of the virus has spread beyond the Guangdong province, further south and east, but the virus doesn't seems to have mutated to the point it can travel across the globe and pose a global health hazard.