Singapore: The H7N9 Avian Influenza virus that had killed 45 people and infected 138 others in May has now resurfaced in China. The country has confirmed the fourth human case in a matter of three weeks. A woman from Zhejiang was admitted in a critical condition and scientists are now saying that it would be too early to predict whether a major outbreak is likely following these cases.

The Center for Health Protection in Hong Kong had been notified by the National Health and Family Planning Commission about the 64-year-old woman who caught the virus and fell ill on October 30, 2013.

The health commission has further notified the World Health Organization (WHO) about the human cases. "We expect to continue to see a small number of sporadic cases. To date, there is no evidence of sustained human-to-human transmission. Whether the H7N9 virus could actually cause a pandemic was unknown, although in principle, it carries a risk," said Dr Bernhard Schwartlander, WHO representative in China.

Previously, the third new human H7N9 bird flu case of a three-year-old boy in Dongguan was confirmed as having contracted the virus. Since he did not develop fever, he is said to be in a stable condition and is expected to be discharged from the hospital soon.

Doctors said that the child had gone to a wet market with poultry stalls but did not come in contact with the fowl. The health department has put the 63 people, who were in close contact with the patient, in quarantine for a week.

"It is too early to say if there would be a major outbreak during the flu season this winter," said Mr Ben Cowling, associate professor at the University of Hong Kong's school of public health in a statement. He has further published a paper in the medical journal, The Lancet, stating that H7N9 may follow a similar seasonal pattern to H5N1 bird flu, and predicted that it would reappear this autumn and potentially cause a major epidemic this winter.

"No significant genetic mutation had been detected in the virus, there is a very low chance of a community-wide outbreak or human-to-human transmission. It is possible that there would be sporadic cases in the winter flu season," Professor Xu Xiaoyuan of Peking University's department of infectious diseases added in the statement.