A 64-year-old woman from Shaoyang in Hunan province was diagnosed with H7N9 bird flu yesterday, sparking fears that the virus might soon emerge in Guangdong and Hong Kong.
The provincial health department said the woman's case was the first confirmed in Hunan, Xinhua reported.
Meanwhile, a 54-year-old man who sells pork in Jiangxi province, and who was admitted to hospital in Hunan, was also diagnosed with the H7N9 strain yesterday.
China National Radio said the latest cases raised the number of people infected with the virus to 121, of whom 23 have died.
Cases in the past week in the southern provinces of Hunan, Jiangxi and Fujian - which all border Guangdong - suggest that the virus might surface in Guangdong.
Officials in Dongguan yesterday ordered the closure and sterilisation of the local poultry markets. Other areas in Guangdong have also stepped up inspections and virus tests in poultry markets.
In the academic arena, a fast-tracked study, published in medical journal The Lancet, by University of Hong Kong microbiologist Professor Yuen Kwok-yung and Zhejiang University found that further adaptation of the virus could lead to less severe symptoms and more efficient person-to-person transmission.
Zhejiang University's Professor Li Lanjuan, who collaborated in the research, said the H7N9 virus was only a step away from human-to-human transmission. Researchers have already identified three of the four gene mutations required to make the virus spread more easily among humans.
Hunan's health department said the 64-year-old woman had physical contact with poultry four days before she developed a fever on April 14. She tested positive for the virus on three occasions, including twice on Thursday and once yesterday.
It said she had been stabilised with integrated treatment including antiviral therapy and respiratory support. Forty-one people who have had close contact with her were put on medical observation and appeared to be healthy.
Xinhua said the Jiangxi pork vendor developed fever on April 15 and was treated in a local hospital two days later.
He was transferred to a hospital in Liuyang in Hunan and later admitted to the Centre for Public Health in the provincial capital of Changsha on Monday.
He tested positive for the H7N9 virus yesterday. Fifty-one people who have had close contacts with him in Jiangxi also appeared to be healthy.
View H7N9 map in a larger map
Click on each balloon for more information on individual patients infected: blue, patients infected with the H7N9 virus under treatment; red, those infected with H7N9 who have died; yellow, those who have fully recovered; and pink, those infected other types of the Influenza A virus, including H1N1.