Chinese authorities were slaughtering birds at a poultry market in the financial hub Shanghai on Friday (April 5th) as the death toll from a new strain of bird flu rose to six, spreading concerns domestically and overseas.

The Huhuai market for live birds in Shanghai had been shut down and birds were being culled after authorities detected the H7N9 virus in samples of pigeons in the market.

All of the 14 reported infections from the H7N9 bird flu strain have been in eastern China and at least four of the dead are in Shanghai, a city of 23 million people and the showpiece of China's vibrant economy.

Cages of live chickens still remained outside the wet market as of Friday (April 5) afternoon.

Despite the current measures taken by local authorities, who the official Xinhua news says are working closely with the World Health Organization to monitor the cases, the latest death caused by the H7N9 virus occurred in Shanghai's Huashan hospital on Thursday (April 4th).

In Hangzhou, official television CCTV reported on Thursday that one patient, a retiree surnamed Yang, remains in the intensive care unit of the First Affiliated Hospital of Zhejiang University hanging between life and death.

According to an interview conducted by CCTV, Sheng Jifang, director of the hospital's infectious disease department, said that the patient's condition had only worsened in the past few days. Shanghai has suspended poultry sales at two other markets and ordered thorough disinfection of the premises.

Samples of the virus have been shared with World Health Organization (WHO) collaborating centres in Atlanta, Beijing, London, Melbourne and Tokyo. Scientists were analysing them to identify the best candidate to be used for the manufacture of a vaccine if it becomes necessary.

Presented by Adam Justice