H7N9 Virus adapting

Virus adapting



Xinhua-Global Times | 2014-1-20 19:53:01
By Xinhua – Global Times

As the world's largest annual human migration begins ahead of Chinese Lunar New Year, containing the spread of the latest H7N9 bird flu faces extra challenges from a more virulent, infectious strain.

Health authorities are concerned by the resurgent strain, with about 30 new cases reported in the first 18 days of 2014, mostly in eastern coastal regions like Zhejiang, Guangdong and Fujian provinces.

Two H7N9 avain flu patients, including a doctor, died in Shanghai on Monday after they were confirmed on Sunday to have been infected with the disease.

So far about 150 cases of H7N9 bird flu have been confirmed on the Chinese mainland since the first human cases of H7N9 avian influenza virus emerged in late March near Shanghai.

After the summer lull, the virus is expected to become more active in winter and spring, and popular public transportation like coaches, trains and aircraft could create favorable circumstances for the epidemic to spread, according to Li Lanjuan of the Chinese Academy of Engineering.

Li is China's leading bird flu researcher and a member of the H7N9 prevention and control group. The virus might be spread by migrants returning to their rural homes from developed eastern regions, she warns.

Travel rush

During the 40 days of Chunyun around the lunar new year, about 3.62 billion trips will be made, according to a National Development and Reform Commission press release on Tuesday.

"We're worried about the risk brought by massive numbers of people gathering together in confined spaces," said Liang Weifeng of the medical college at Zhejiang University.

H7N9 cases have been reported in two consecutive weeks in Zhejiang. As of Sunday, the eastern province had reported a total 23 cases, including one death. Zhejiang was also the site of China's first confirmed human-to-human transmission in November last year, when a man was infected while caring for his father-in-law.

More alarming still, Guizhou Province in the southwest of the country confirmed its first H7N9 death on Saturday - a migrant worker who returned home from Zhejiang on January 4.

The latest case of both a father and daughter being confirmed infected on Sunday in Guangzhou, Guangdong Province, added to concerns the virus might be transmitted between humans.

Since both father and child had been to the poultry market and had contact with other people in the market, yet only the two of them were infected, it's hard to conclude that the H7N9 virus was transmitted through human contact, said a statement released by the Guangzhou health and family planning commission on Saturday.

Mutant strain

A variation of an amino acid on the H7 gene has made the H7N9 strain more infectious to mammals, according to research by a Chinese team published in the Lancet in April 2013.

"We have found another variation in a key amino acid," Liang said. "If we get one more variation of a specific amino acid then human-to-human transmission will become much more likely."

The team recently identified a new partial variation of the virus, demonstrating its capacity to adapt to its environment.

"It increased the risk of human-to-human transmission and brought more difficulty in treatment," Liang said.

"In spite of this, there's no reason to panic," said a member of the team drafting a thesis on the new results. "We can confirm that the H7N9 flu virus has not shown scaled variation and human-to-human transmission."

The National Health and Family Planning Commission said on Friday that an epidemic was unlikely.

"Current cases are scattered, and no mutation of the virus has been identified so far that could affect public health," said a statement from the commission.

"The virus is still spreading from birds to humans, and the chances of a large human H7N9 outbreak are slim," the statement said. Cases will keep coming as the country's urban and rural fowl markets are scattered, the commission noted, while transport and trade of poultry will intensify around the lunar new year.

The commission urged local health departments to strengthen monitoring and step up treatment of patients while carrying out detailed prevention and control measures and timely risk evaluations.

Live poultry concern

Spring Festival is the peak season for sales and consumption of poultry in China. The Chinese have a tradition of eating fresh ingredients at important feasts and family reunions.

People like to buy live chickens and ducks and slaughter them at home for fresh and festive atmosphere. Despite the government ban, live poultry markets are reemerging in some regions.

Zhejiang and other provinces are cranking up inspections and quarantine measures wherever live birds are sold.

Poultry is easily infected by H7N9, and the risk cannot be contained simply by closing live poultry markets, Li Lanjuan said.

"Some deaths were caused by delays in seeking medical advice, as the virus quickly attacks the lungs," said Li, urging people to mind their health during the holidays and go to hospital if they have a fever or a cough.