Hong Kong (CNN) -- Hong Kong is on high alert after an Indonesian domestic helper contracted the city's first human case of H7N9 avian flu, the city's government says.
The 36-year-old maid is in hospital in a critical condition, Ko Wing-man, Hong Kong's secretary for food and health said in a statement.
The woman had recently traveled to Shenzhen, the mainland Chinese city nearest to Hong Kong, where she bought, slaughtered and ate a chicken, Ko added. Her close contacts have also been isolated in hospital.
Ko said that Hong Kong had raised its level of preparedness for an influenza pandemic to "serious."
Human infections from the H7N9 strain of bird flu first emerged in Shanghai in March this year and within weeks more than 100 cases were confirmed, according to the World Health Organization.
However, the number of cases dropped dramatically after the closing of live poultry markets in affected areas, the WHO said. So far, there is no evidence of sustained human-to-human transmission, it added.
As of November 6, the WHO said it had been informed of a total of 139 laboratory-confirmed human cases of the H7N9 virus, including 45 deaths.
Ko said Hong Kong said it had suspended the import of live chickens from three farms in Shenzhen and would inspect Hong Kong chicken farms and poultry wholesale markets.
Hong Kong takes the threat of new disease extremely seriously after Severe Acute Respiratory Syndrome or SARS first emerged in the city in 2003. The outbreak went on to infect 8,096 people and kill 744 worldwide.
On Monday, Shanghai said it will suspend live poultry trading from January 31 until April 30 to prevent a recurrence of this year's bird flu outbreak, according to state-run news agency Xinhua.