BEIJING (Reuters) - China has found two more cases of human bird flu infection, bringing this week’s total to three and stoking fears the deadly virus could spread at a time when other Asian nations are battling to control outbreaks of the disease.

Workers wearing protective suits cull ducks after some tested positive for H5 bird flu at a poultry farm in Aomori, northern Japan, in this photo taken by Kyodo November 29, 2016. Mandatory credit Kyodo/via REUTERS/File Photo

Health officials in nearby South Korea and Japan have been scrambling to contain outbreaks of different strains of bird flu, with the poultry industry there bracing for heavy financial losses.

A man diagnosed with the H7N9 strain of bird flu is being treated in Shanghai, after traveling from the neighboring province of Jiangsu, the Shanghai Municipal Commission of Health and Family Planning said on its website on Wednesday.

Shanghai is China’s most populated city with more than 24 million residents.

The local government in Jiangsu is looking into the origin of the infection, the provincial health authority said on Thursday.

In Xiamen, a city in China’s eastern Fujian province, local authorities ordered a halt to poultry sales from Thursday in the Siming district, after a 44-year-old man was diagnosed with H7N9 flu on Sunday, state news agency Xinhua reported late on Wednesday.

The patient is being treated in hospital and is in stable condition, Xinhua said, citing Xiamen’s diseases prevention and control center. The city has a population of about 3.5 million.

The latest incidents come after Hong Kong confirmed an elderly man was diagnosed with the disease earlier this week.

CHICKEN DEMAND AT RISK?

The cases come as South Korea and Japan have ordered the killing of tens of millions of birds in the past month, fueling fears of a regional spread.

Bird flu is most likely to strike in winter and spring and farmers have in recent years increased cleaning regimes, animal detention techniques and built roofs to cover hen pens, among other steps, to prevent the disease.

In the past two months, more than 110,000 birds have been killed following bird flu outbreaks, according to the Ministry of Agriculture. They did not lead to human infection.

Each year, China slaughters 11 billion birds for consumption.

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Authorities have not culled any birds as a result of this week’s episodes, which appear to be isolated.

Still, farmers worry the virus could spread, hurting demand for chicken as the Chinese prepare for peak demand during Lunar New Year celebrations at the end of January.

Amid recent outbreaks elsewhere, the Chinese are feeding their flocks more vitamins and vaccines and ramping up hen house sterilization to protect their birds.

On Wednesday, authorities said they would ban imports of poultry from countries where there are outbreaks of highly pathogenic bird flu. It already prohibits imports from more than 60 nations, including Japan and South Korea.

The last major bird flu outbreak in mainland China in 2013 killed 36 people and caused about $6.5 billion in losses to the agriculture sector.

Delegations from Japan, South Korea and China gathered in Beijing last week for a symposium on preventing and controlling bird flu and other diseases in East Asia, according to China’s agriculture ministry website.