Beijing: Scientists are seriously concerned about a new bird flu virus that is causing severe disease in China, killing a fifth of all those it infects.
So far, the virus, known as H7N9, is being transmitted only to humans from chickens, but there are worries that it could mutate into a form that could be passed from one person to another. Five mutations are known to be necessary for that to happen — H7N9 already has two of them. If that occurred, it could spread worldwide with lethal effect.
According to the World Health Organisation, there have been 126 cases of H7N9 bird flu, all but one of which were diagnosed in China, with the other in Taiwan in a man who had travelled from China. So far 24 people had died from the disease.
“The cases are going up daily — about 20 percent have died, 20 percent have recovered and the rest are still sick,” said Prof John McCauley, director of the WHO Collaborating Centre for Influenza at the MRC National Institute for Medical Research in London. “The WHO considers this a serious threat. We’re on an alert and we’re developing diagnostics and vaccines specifically against the virus.”
The first comprehensive genetic analysis of the virus is published in the Lancet medical journal yesterday. It suggests the virus might have originated from the mixing of viruses from as many as four different origins, including ducks. “Extensive global surveillance is needed,” say the authors.
One of the biggest problems is that the virus does not cause illness in chickens, so it is impossible to know which are infected and which are not.
In the past, China has slaughtered flocks to eradicate bird flu viruses, but H7N9 is now known to be present in chickens in all 31 provinces of China. The first human cases were notified over the Easter weekend. “Whenever an influenza virus jumps across from its animal host to human, it is cause for concern,” said Prof Jeremy Farrar, director of the Wellcome Trust major overseas programme in Vietnam.
“This particular one has to be taken calmly, but seriously.” There is concern about the swift rise in cases - and there may be more undetected cases if some people suffer less severe illness which does not get reported, he said, speaking by telephone from Vietnam to a scientific briefing on H7N9 in London.
The virus has not been in the human population before. Unlike swine flu, it is affecting small children and the elderly alike, so the oldest generation does not have any inherited immunity to it.
Public health experts are most concerned about the possibility of human-to-human spread.
Guardian News
