Shanghai closing all live poultry markets…

HONG KONG (CNN) —Chinese authorities have killed more than 20,000 birds from a live-poultry trading zone in Shanghai after an unusual strain of bird flu that has so far killed six people in the country was found in pigeons on sale in the city, state-run media outlet Xinhua reported Friday.

Details of the slaughter of chickens, ducks, geese and pigeons come as the city prepares to temporarily close all its live poultry markets. It wasn’t clear how long the market closures — announced Friday on the Shanghai Municipal Government’s microblog account — would last.

By Friday morning, authorities in Shanghai had already closed the Huhai agricultural market, where the H7N9 avian flu virus had been found in pigeons, Xinhua reported. The virus had not previously been found in humans until a series of cases were reported in China this week.

The cull at the Shanghai poultry trading zone came as researchers in the United States said they had started work on developing a vaccine for H7N9.

The Chinese Minister of Agriculture said Thursday an analysis showed a strong genetic overlap between the strain found in the Huhai market pigeons and the one detected in infected humans.

At the Huhai market, Shanghai authorities were disinfecting the area and objects that came into contact with the birds, Xinhau reported.

Officials are trying to track where the infected pigeons came from.

A growing number of cases

A 64-year-old man died Thursday night in Huzhou, Zhejiang province, the provincial health bureau said Friday. He died hours after doctors had confirmed he had been infected with the H7N9 virus, it said.

He is one of the 14 human cases of H7N9 reported so far — all of them in the coastal area of eastern China. Authorities there began reporting the first cases on Sunday. Four of the deaths happened in Shanghai, the two others in Zhejiang