Bird flu strain has begun to mutate into form 'more likely' to cause human pandemic
Warning comes days after authorities in China announced they had identified cases of H7N9Flu experts are currently picking through DNA data of victims to assess severity of the strainVirus needs a 'very close eye kept on it' say experts
16:59 GMT, 3 April 2013
16:59 GMT, 3 April 2013
A deadly strain of bird flu previously unknown in people has begun to mutate into a form more likely to cause a human pandemic, scientists say.
Just days after authorities in China announced they had identified cases of H7N9, flu experts in laboratories across the world are picking through the DNA sequence data of samples isolated from patients to assess its severity.
One of the world’s top flu experts, Ab Osterhaus, from the Erasmus Medical Centre in The Netherlands, says the sequences show some genetic mutations that should put authorities on alert and entail increased surveillance in animals and humans.
'The virus has to a certain extent already adapted to mammalian species and to humans, so from that point of view it’s worrisome,' he said.
A deadly strain of bird flu previously unknown in people has begun to mutate into a form more likely to cause a human pandemic, say scientists
'Really we should keep a very close eye on this.'
China’s National Health and Family Planning Commission confirmed that three people had been infected with the new H7N9 flu, with two deaths of men in Shanghai aged 87 and 27 who fell sick in late February.
Chinese authorities have in the past two days confirmed another six cases, including another fatal one.
The World Health Organisation (WHO) says the cases of H7N9 are 'of concern' because they are the first in humans.
'That makes it a unique event, which the World Health Organization is taking seriously,' the Geneva-based United Nations health agency said today.
Other strains of bird flu, such as H5N1, have been circulating for many years and can be transmitted from bird to bird, and bird to human, but not from human to human.
So far, this lack of human-to-human transmission also appears to be a feature of the H7N9 strain.
Other strains of bird flu, such as H5N1 (pictured), have been circulating for many years and can be transmitted from bird to bird, and bird to human, but not from human to human
Flu viruses are classified based on two types of protein found on their surface, haemagglutinin and neuraminidase, which are abbreviated to H and N.
Although it is very early days, scientists says initial analysis also suggests H7N9 does not appear to make birds particularly ill – in other words it is what is known as a low pathogenic avian influenza, of LPAI.
Unfortunately, this doesn’t necessarily mean it will be mild in humans, says Wendy Barclay, a flu virology expert at Britain’s Imperial College London.
Its mildness in birds could also mean H7N9 is a 'silent spreader' – harder to detect than highly pathogenic flu strains such as H5N1 that can wipe out entire flocks of wild birds or domestic poultry and are therefore far more visible.
In 2003, China initially tried to cover up an epidemic of Severe Acute Respiratory Syndrome (SARS), which emerged in China and killed about a tenth of the 8,000 people it infected worldwide.