China’s latest human bird flu infection is worrying as it indicates that the H5N1 virus may have mutated and become as infectious in warm months as it is in cooler ones, Hong Kong’s health minister said on Friday.
The H5N1 virus thrives in lower temperatures and is more infectious in the cooler months between October and March in the northern hemisphere.
Separately, a 14-year-old Indonesian boy who died this week has tested positive for bird flu, a Health Ministry official said on Friday, citing local tests.
If confirmed by a World Health Organization laboratory, the boy from south Jakarta will be the 39th bird flu death in Indonesia, a sprawling archipelago where the virus has killed millions of fowl.
Samples of the boy’s lung fluid have been sent to a WHO laboratory in Hong Kong for confirmation, Nyoman Kandun, a director general at the ministry, told a news conference. Local tests are not considered definitive.
China’s confirmation on Thursday that a 31-year-old truck driver in the southern city of Shenzhen had been infected by the disease has brought uneasiness.
“Is this because the virus has changed, so that it can be highly infectious all year round? Or, if it is happening in summer, winter would be even worse?” Health Secretary York Chow told reporters. “We will have to monitor further.”
The truck driver was admitted to hospital and is critically ill. He visited a wet market where live poultry was sold and ate a chicken before he fell ill, but he is not known to have had any other close contact with poultry.
He is the 19th person in China to be infected, 12 of whom have died. But, like most of the other cases, it is a mystery how he came to be infected because there was no known outbreak of the disease in poultry in the area where he lived.
The official Xinhua news agency said on Friday that the government has not found the disease in Shenzhen poultry farms.
'Asymptomatic' poultry
Experts in Hong Kong, including Chow, have highlighted the possibility that the human infections in China may have been due to contact with infected poultry which were not taken ill by the disease, which are described as “asymptomatic”.
A recent study of fecal samples taken from healthy poultry in markets found that one percent were infected with the virus.
Lo Wing-lok, an infectious disease expert in Hong Kong, said China must explain how the truck driver came to be infected when it claimed there were no H5N1 outbreaks in birds in the area.
“They ought to come up with a reasonable explanation how this man came to be infected. Blanket denials don’t help at all. When they deny we have to think twice about accepting,” Lo said.
He recalled an incident in late January when a chicken that was smuggled into Hong Kong from Shenzhen was found with H5N1.
“It took only one tiny bird to show that the virus is there (in Shenzhen),” Lo said, adding that China should disclose how it conducts disease surveillance in poultry.
“I don’t know if there is insufficient surveillance or if the data is too frightening to be disclosed,” he said.