The risk of sporadic human infection is high after three samples collected from live-poultry markets in the southern city of Shenzhen tested positive for the H7N9 avian influenza virus, the Chinese government said.
The Guangdong province health authority examined 70 samples from 13 live poultry markets in Shenzhen, it said in a statement yesterday. Shenzhen is an hour’s train ride from downtown Hong Kong and a popular day-trip destination for shopping and dining.
Hong Kong has stepped up surveillance of travellers with fever after finding two cases of a new strain of bird flu that killed at least 45 people in China. The first case is a 36-year-old Indonesian woman who traveled to the Chinese city to buy and slaughter a chicken, and the second is an 80-year-old man who was hospitalised in Shenzhen last month before moving to Hong Kong.
“Visiting a live poultry market in Shenzhen was the likely source of infection for at least one of the two Hong Kong cases,” said Ben Cowling, an associate professor of infectious disease epidemiology at the University of Hong Kong’s school of public health. “It’s likely that H7N9 virus infection among poultry in live markets may be more widespread in Shenzhen.”
Samples that tested positive for the virus were found in two live poultry markets, the Guangdong health authority said yesterday. One sample came from chicken feces, one from a defeathering machine and the third from a chopping block, according to the statement.
The novel avian influenza strain is often lethal to humans, though it doesn’t transmit easily from person to person.
Human cases of H7N9 in China date to February and surged in April, before agriculture authorities temporarily closed live poultry markets and quarantined farms to limit exposure. The WHO counted 139 laboratory-confirmed cases as of Nov. 6.
“We know from patterns in other influenza viruses that transmission tends to increase during the winter months when the weather is cooler,” said Cowling. “If H7N9 follows this pattern, then we only expect an increase in H7N9 transmission in the coming one or two months, particularly around Chinese New Year.”
Chinese New Year is on Jan 31.
Last year, Hong Kong residents departed from the Lo Wu check point 35.4 million times, according to the census and statistics department. The city had 7.2 million people in mid-2013, according to a government estimate.