Eight new human H7N9 bird flu cases were reported in three provinces in China yesterday, ahead of a ban on live poultry trading set to come into force in several cities, including Shanghai.

The eastern province of Zhejiang reported four new cases — a 43-year-old woman in Hangzhou, an 81-year-old man and a 63-year-old woman in Huzhou, and a 57-year-old man in Ningbo.

The new cases brought the number of infections in the province this year to 53, the provincial health and family planning commission said.

Three more new cases were reported in the southern city of Shenzhen, according to Guangdong Province’s health and family planning commission. The cases were women aged 43, 41 and 31. Another case, a 53-year-old man, was reported in Huai’an City in east China’s Jiangsu Province.

So far this year, the virus has killed 20 people in China out of 96 known infections, Xinhua news agency reported. The deaths were in Shanghai, its neighboring Zhejiang Province and Guangdong in the south.

Most cases have been linked to contact with live poultry.

The jump in cases comes during the 40-day travel period around Chinese New Year, a period that concerns health authorities because of the volume of people traveling in crowded trains and buses, often with live chickens on board.

Chinese people are expected to make more than 3.6 billion trips as families get together. The holiday, which officially starts on Friday, also falls during the winter months when flu typically rages.

The World Health Organization says there is no evidence of sustained human-to-human transmission, but has recommended close monitoring given the holiday travel and the potentially unpredictable behavior of flu viruses.

Shu Yuelong, director of the Chinese National Influenza Center, said a large-scale H7N9 epidemic is unlikely during the Spring Festival holiday, as no H7N9 virus mutation that could affect public health has been identified so far.

On Monday, Hong Kong suspended live chicken sales — halting imports from the Chinese mainland — for three weeks after poultry imported from Guangdong tested positive for the H7N9 virus.

Yesterday, Hong Kong authorities were culling 20,000 birds, mostly chickens, at the territory’s wholesale market.

Shanghai will halt live poultry trading for three months from Friday. The city has reported eight infections and four deaths this year.

Live poultry trading will also be halted from February 15 in some cities in Zhejiang, where 49 people have been infected and 12 people have died this year, the Zhejiang Daily reported.

Hangzhou is planning to close live poultry trading markets permanently and promote frozen poultry products instead, Zhang Hongming, acting mayor of the Zhejiang provincial capital, told Xinhua.

With bird flu cases increasing on a daily basis, China has stepped up vaccine research.

Hualan Biological Engineering Inc said earlier this month that the H7N9 vaccine developed by its subsidiary, Hualan Biological Bacterin Co Ltd, had passed an initial examination by the food and drug watchdog in central China’s Henan Province.

It is not yet known when it will be approved for production.

Chicken has been a requisite dish on dining tables for centuries during Spring Festival.

Farmers have traditionally raised chickens using free range methods, especially in the countryside, which has been deemed by experts as a potential risk for spreading bird flu.

Improved surveillance methods and networks have increased the possibility of confirming new cases, but this does not mean a more rapid transmission of the virus, said Zhong Nanshan, director of the Guangzhou Institute of Respiratory Diseases in Guangdong. “It deserves high attention when the infection cases increase by dozens or hundreds of times. Currently, public panic is unnecessary given the slow transmission speed,” he added.

The General Administration of Quality Supervision, Inspection and Quarantine has intensified H7N9 bird flu virus monitoring at borders to prevent cross-border transmission.

Customs staff will measure body temperatures, conduct medical inspections and report on the health of passengers.

The National Health and Family Planning Commission has also urged local health departments to strengthen prevention and control measures.

At the weekend, health authorities in the eastern Jiangxi Province confirmed a second human case of H10N8, a new strain of bird flu known to affect humans. A 55-year-old woman is in a critical condition. The first case was confirmed in December after the death of a 73-year-old woman.