A policeman stands guard as Chinese health workers collect the bags of dead chickens at Huhuai wholesale agricultural market in Shanghai, April 5, 2013.

China Slaughters Chickens as H7N9 Bird Flu Strain Spreads

Bird flu strain mutates, human infections begin.

A policeman stands guard as Chinese health workers collect the bags of dead chickens at Huhuai wholesale agricultural market in Shanghai, April 5, 2013.

A policeman stands guard as health workers collect bags of dead chickens at an agricultural market in Shanghai on April 5, 2013.

By + More

A market in Shanghai was the scene of carnage Friday morning as authorities killed 20,536 chickens, ducks, geese and pigeons. The entire market was disinfected before 6 a.m. local time Friday, the Xinhua News Agency reports, as authorities worked to prevent a breakout of the H7N9 strain of bird flu in China's largest city.

As of Friday China has confirmed 14 H7N9 human infections — six in Shanghai and eight in neighboring provinces. Six people have died of the flu.

The marketplace slaughter was undertaken after a pigeon sample tested positive for H7N9.

According to Xinhua, Chinese authorities have pledged to be transparent and to cooperate with the World Health Organization. There are currently no confirmed cases of human-to-human transmission.

[READ: How Bad Is the New H7N9 Bird Flu Strain?]

During a 2011 bird flu scare in China the price of chicken meat rose dramatically, Xinhua reported. It's possible that similar price hikes will happen if poultry continues to be disposed of as a precaution.

The U.S. Centers for Disease Control and Prevention is working on a vaccine for the new virus, CNN reported Friday.

"There are lots of things happening at CDC to prepare for this virus," Joseph Bresee, chief of the Epidemiology and Prevention Branch in CDC's Influenza Division, told CNN.

[RELATED: Supercomputers Identify Bird Flu Drugs]

There are already vaccines available for the better-known and more widely spread H5N1 bird flu strain. In a statement on its website, the FDA notes the H5N1 in some ways resembles standard flu viruses, "but people quickly become seriously ill and pneumonia, difficulty breathing, and multi-organ failure have been common [symptoms]."

In a Wednesday press briefing WHO spokesman Gregory Hartl said, "We believe that the virus, this H7N9 virus, has mutated to a form which makes it easier to infect humans." There were just seven confirmed cases — all unlinked — as of the briefing, Hartl noted. "We're a long ways away from thinking about a pandemic," he said.

More News: