Officials throughout Asia are implementing measures to protect people from a new strain of bird flu - H7N9 - that has so far infected dozens of people in China, killing more than 12.

These are the first human infections and deaths to have been recorded from this virus strain worldwide. China’s neighbours have reacted by boosting hospital capabilities and disease surveillance, strengthening border control, issuing reminders to ban illegal poultry imports, and more vigorously testing what is imported. 

Shigeru Omi, a regional director of the World Health Organisation, said: “With the virus so widespread within poultry, it will have many opportunities to alter its form and become transmissible between humans.”

He said the simultaneous outbreak of bird flu in ten Asian countries was “unprecedented”.

Dr Omi, WHO’s Western Pacific director, added: “There is always potential for this kind of outbreak to result in a serious global pandemic which involves not hundreds, but could kill millions of people.”

Following a mass poultry culling on 5 April in Shanghai - one of the Chinese cities affected - pandemic expert and virologist Yi Guan from the University of Hong Kong told IRIN he expects human cases to “drop or stop”. But he added that experts still have much to learn about the disease. 

The virus has proved to be a “low-pathogenic” virus in infected land-based birds, so it is not clear why the virus has been so severe in humans, he noted. The true spread of the disease is also still unknown. 

“We have a knowledge gap and do not know the full picture. There may be people with minor infections or who are asymptomatic among [the] population as a result of H7N9,” said Yi. 

Experts have not been able to learn how or why the 21 persons became infected. While some people had contact with animals or their habitats, and infections are suspected to originate in poultry, the virus’s host and source have not been lab-confirmed. 

The UN Food and Agriculture Organization has noted that knowing what species is responsible for the fatal outbreak is “essential to target response actions accordingly, including trade restrictions”. 

Since the H5N1 bird flu virus first appeared in 2003, there have been 622 laboratory-confirmed human cases globally, 371 of them fatal, according to the World Health Organization (WHO). Indonesia has seen the largest number of deaths from H5N1: 160. 

“We face a similar situation to China because the high risks of the animal-human interface, and inadequate bio-security among many poultry farmers. That’s why [holding a] public awareness campaign is important, and we continue to closely monitor genetic mutations of the bird flu virus,” said Emil Agustiono, the head of Indonesia’s National Zoonosis Committee. 

He said no “special measures” have been enacted as the country does not import live poultry from China. 

The WHO has not advised any travel restrictions or any special screenings linked to the flu outbreak. 

Tjandra Yoga Aditama, director general for disease control and environmental health at Indonesia’s Health Ministry, told IRIN the call for “intensive surveillance” has been made to local health departments. They have also been called upon to immediately respond to “any cases of influenza-like illness and severe acute respiratory infection, which may be found in communities, hospitals and other health care providers, seaports and airports.” 

Vietnam, which does import live poultry from China, issued a government directive on 4 April reminding officials working near the border with China to be vigilant about keeping out illegal poultry imports and about inspecting all legal imports before distribution. 

Vietnam’s health ministry has designated laboratories to analyse blood samples of suspected cases. 

The Institute for Tropical Diseases in the capital, Hanoi, has ready 8,000 doses of Tamiflu (reported by Chinese authorities to be effective in treating the infection at early stages), 23 respirators and two dialysis machines. On 5 April, the Health Ministry promulgated an action plan in the case of an H7N9 outbreak. 

Local media reported that Hong Kong government officials have cautioned against panic-buying and confirmed the availability of 1,400 hospital beds to quarantine any patients infected with H7N9. 

Following his visit to a local poultry market on 8 April, Hong Kong’s secretary for food and health, Ko Wing-man, told reporters that officials in Hong Kong and mainland China are collaborating to boost surveillance of all poultry imports. All poultry are to receive rapid tests for H5N1 virus as well as H7N9 before being released to the markets for sales in Hong Kong. 

Meanwhile, genetic analysis of a bird flu strain responsible for at least nine human deaths in China suggests it could evolve to adapt to human cells, researchers say.

A study led by researchers from Japan’s National Institute of Infectious Diseases with colleagues at the University of Wisconsin-Madison examined the genetic sequences of the H7N9 pathogen from four of the human victims as well as samples derived from birds and the environs of a Shanghai market.

“The human isolates, but not the avian and environmental ones, have a protein mutation that allows for efficient growth in human cells and that also allows them to grow at a temperature that corresponds to the upper respiratory tract of humans, which is lower than you find in birds,” UW-Madison researcher Yoshihiro Kawaoka said.

Although it is too early to predict its potential to cause a pandemic, Kawaoka said, signs the virus is adapting to mammalian and, in particular, human hosts are unmistakable.

Avian influenza rarely infects humans but can sometimes adapt to people, posing a significant risk to human health, the researchers said.

“These viruses possess several characteristic features of mammalian influenza viruses, which likely contribute to their ability to infect humans and raise concerns regarding their pandemic potential,” Kawaoka and his colleagues reported.

Last weekend a Chinese military official has blamed the US government for the new strain of bird flu affecting China, calling it a secret biological attack.

People’s Liberation Army Senior Colonel Dai Xu said America released the H7N0 bird flu virus into China, in an act of biological warfare, in a blog on Saturday.

Writing on Sina Weibo, a Chinese microblogging site similar to Twitter, Dai alleged the new bird flu strain had been designed as a weapon, similar to severe acute respiratory syndrome (SARS), that affected the country in 2003 and which he claims was also developed as a US bio-weapon.

The US has dismissed the claims. State Department spokesman Jason Rebholz told the Washington Free Beacon: ‘There is absolutely no truth to these allegations.’

Dai’s post suggests the new outbreak of bird flu should not be a cause for concern.

He wrote: ‘The national leadership should not pay too much attention to it, or else it’ll be like in 2003 with SARS!

 At that time, America was fighting in Iraq and feared that China would take advantage of the opportunity to take other actions. This is why they used bio-psychological weapons against China.’

He said the country fell into turmoil, which he claimed is what the US had wanted, and now they were using the ‘same old trick’.