BEIJING — With confirmation that a sixth person has died from a mysterious avian-borne virus, Chinese officials escalated their response Friday, advising people to avoid live poultry, dispatching virologists to chicken farms across the country and slaughtering more than 20,000 birds at a wholesale market in Shanghai where the virus, known as H7N9, was detected in a pigeon.

News of the outbreak dominated China’s main Internet portals. There were photographs of workers in white coveralls carrying out the culling in Shanghai and recommendations that people take banlangen, an herbal cold remedy that is a mainstay of Chinese households.

Anxious residents have been crowding emergency rooms at the first sign of respiratory problems. And at a KFC restaurant in Beijing, employees stood idle as mounds of fried chicken went largely unsold.

“They say it’s OK to eat cooked chicken, but I’d rather not take the chance,” Zhang Minyu, 41, a housewife, said as she coaxed her young son to instead order a soft-serve ice cream.

Roughly 10 years after Severe Acute Respiratory Syndrome, or SARS, began here and spread across the globe, infecting more than 8,000 people and killing nearly 800, the deadly influenza outbreak is testing a government known for its lack of transparency and reluctance to divulge damaging news.

Although some critics have questioned why it took so long for officials to publicly announce the outbreak of the H7N9 virus, public health experts have so far commended the government for responsiveness and transparency in the five days since officials identified the first victims.

“It was the Ministry of Health and Family Planning that first came to us and volunteered the information,” said Gregory Hartl, a spokesman for the World Health Organization in Geneva. “Their response has been excellent.”

Health officials around the world are nervously monitoring the outbreak, which has killed nearly half of the 14 people in whom the virus has been diagnosed. What they fear most is that the disease will mutate so that it can spread from human to human.

In the United States, federal health officials Thursday said they had begun working on a vaccine for H7N9.

At the U.S. Centers for Disease Control and Prevention’s first news conference about the H7N9 outbreak, its director, Dr. Thomas Frieden said there was close cooperation between his organization and its Chinese counterpart.