HANGZHOU - Chinese health authorities on Wednesday disclosed details of a family of three infected with H7N9 bird flu in East China's Zhejiang province.

A 49-old-man in Hangzhou City was confirmed on January 20 to have been infected with the virus. His wife and daughter who accompanied him to the hospital, were later confirmed to also have flu, according to the provincial health and family planning commission. The man has since died, his daughter is in a serious condition and his wife is comfortable.

Experts have reached no firm conclusion on how the virus spread between the family members. They all may have had contact with poultry, or the father may have transmitted the flu to his wife and daughter.

Even if the case is confirmed as person-to-person transmission, there is no need to panic, said Li Lanjuan, an academician at the Chinese Academy of Engineering and a specialist in H7N9 prevention.

"So far there have not been any cases in which one person transmits the flu to another, and the latter transmits the virus to a third person," said Li.

In this year's epidemic, transmission has been limited to a second person, who does not transmit the virus to a third. H7N9 is not likely to be spread in schools, workplaces or at gatherings, said Chen Zhiping, deputy head of the provincial disease control and prevention center.

The probability of continuous person-to-person transmission is very slim, said Feng Zijian, deputy head of the Chinese Center for Disease Control and Prevention.

Three new human H7N9 cases were reported in Zhejiang on Wednesday, bringing the number of infections in the province this year to 56. All three are in a critical condition.

In neighboring Fujian Province, a two-year-old child tested positive for bird flu, according to the provincial health commission. The patient  is now recovering.

South China's Guangxi Zhuang Autonomous Region also reported one new  case on Wednesday. A 56-year-old woman showed flu symptoms for a week before she tested positive for bird flu and is now critical, according to local health authorities. It is the first human H7N9 case in the region.

The National Health and Family Planning Commission said on Wednesday that live poultry markets would close if a case of H7N9 was detected.

In places where no H7N9 cases have been reported, the commission suggested that live poultry markets be cleaned every day and disinfected once a week.

Chicken has been a required dish on Chinese dining tables for centuries during Spring Festival, which begins this Friday.

Chinese farmers have traditionally raised chickens using free range methods, especially in the countryside, which is seen by experts an additional risk.

Live poultry trading has been halted in the cities of Hangzhou, Ningbo and Jinhua in Zhejiang, with the most human H7N9 cases of any province. The province has launched emergency surveillance of poultry farms, parks, and migratory bird haunts, and has halted the flying of domestic pigeons.