危機四伏:H7N9病毒已構成"嚴重"威脅

The new H7N9 bird flu virus, which has infected 126 people in China and killed 24 over the past month, poses a “serious” threat to world health, virologists said yesterday.

病毒學家表示，新型H7N9禽流感病毒對世界健康造成了“嚴重”威脅。上個月，中國有126人感染這種病毒，24人死亡。

“The World Health Organisation considers this to be a very unusual event,” said John McCauley, director of the WHO Collaborating Centre for Influenza at the UK National Institute for Medical Research. “With a 20 per cent mortality rate it is serious but we don’t know whether it is going to spread from human to human.”

英國國家醫學研究院(UK National Institute for Medical Research)世界衛生組織(WHO)流感合作中心的主任約翰•麥考利(John McCauley)說：“世界衛生組織認爲這是一次非同尋常的事件。20%的死亡率非常嚴重，但我們不確定這種病毒是否會人傳染人。”

Genetic analysis shows that H7N9 has two of the five mutations believed to be required for a flu virus to spread easily through the air between people, said Wendy Barclay, professor of influenza virology at Imperial College London.

倫敦帝國理工學院(Imperial College London)流感病毒學教授溫迪•巴克利(Wendy Barclay)指出，一般認爲，一種流感病毒易於通過空氣在人際間傳播要求具備五種變異，而基因分析顯示，H7N9病毒具備其中的兩種。

But intensive surveillance in China has not provided clear evidence of spread between people – everyone infected so far could have picked up the virus from domestic poultry or wild birds.

但在中國的密切監控還沒有提供明顯證據證明人際傳染，目前爲止感染的人可能都是從家禽或者野生鳥類染上病毒的。

Diagnosis has proved difficult because the virus does not kill infected poultry, although detailed blood studies showing its absence in humans who have had contact with infected patients suggests it is not transmitting easily or to large numbers.

診斷比較困難，因爲這種病毒不會讓感染的禽類致死。但詳細的血液研究顯示，與感染病毒患者接觸過的人沒有染上病毒，表明這種病毒不會輕易或者大規模在人際間傳播。

The biggest difference between H7N9 and H5N1 – the virulent avian flu strain that has infected 628 people and killed 374 over the past 10 years without transmission between humans – is its effect on birds.

H7N9和H5N1的最大區別就體現在對禽類的影響上，後者十年來共導致628人感染、374人死亡，但沒有出現人際傳播。

H5N1 has been easier to track because it causes severe disease in domestic poultry, while H7N9 has little or no effect on birds.

H5N1更容易追蹤，因爲它會導致家禽患上嚴重疾病，而H7N9對禽類影響微乎其微，甚至沒有影響。

Jeremy Farrar, the flu expert who runs the Wellcome Trust Overseas Programme in Vietnam and takes over as head of the Wellcome Trust in October, said: “H7N9 has been found in birds in all 31 Chinese provinces . . . This has to be taken seriously but calmly.”

維康信託基金會海外項目(Wellcome Trust Overseas Programme)越南負責人、去年10月開始執掌維康信託基金會的流感專家傑里米•法拉( Jeremy Farrar)說：“在中國所有31個省都發現禽類攜帶H7N9病毒。這需要嚴肅對待，但也要保持鎮定。”

“What a difference it has been working with China on this, compared with Sars 10 years ago,” Prof Farrar added.

“與10年前的非典相比，與中國在這方面的合作有了很大的不同。”

“Their openness in sharing data and samples has been a huge tribute to them.”

“中方在分享數據和樣本方面的開放性值得讚賞。”

Chinese researchers published yesterday in the Lancet the first comprehensive genetic analysis of the origins and evolutionary history of H7N9. This shows the complex way flu viruses rearrange themselves in birds and animals.

中國研究人員近日在《柳葉刀》(Lancet)雜誌上發佈了關於H7N9來源和演變歷史的首個綜合基因分析。其中涉及流感病毒在禽類和動物身上自我重組的複雜方式。

H7N9 probably evolved from at least four viral components in ducks and chickens – and has already split into two lineages during the past few months, the Lancet paper says.

H7N9可能是從鴨和雞中的至少四種病毒成分演變而來，在過去的幾個月已經分成兩個世系。

Human victims of H7N9 range in age from two to 89, though people affected tend to be primarily middle-aged and elderly men, in contrast to the 2009 H1N1 swine flu pandemic that mainly affected younger people – suggesting that there is no immunity in the population from previous exposure to similar flu viruses. The symptoms are mainly respiratory though in severe cases the patient’s immune system can go into overdrive, causing death.

H7N9人類感染者從兩歲到89歲不等，但以中老年人爲主，而2009年H1N1豬流感主要感染較爲年輕的人。這表明之前接觸類似流感病毒的人羣沒有形成免疫力。症狀主要表現在呼吸系統，但在嚴重情況下，患者免疫系統會出現超負荷，導致死亡。

H7N9 is sensitive to Roche’s Tamiflu, the most widely used anti-flu drug. But many patients have sought medical help too late for the medicine to work and the main weapon, if the virus starts circulating between people, is likely to be a new vaccine, which will have to be developed.

H7N9對羅氏(Roche)達菲這種被廣泛用於抗流感的藥比較敏感。但很多患者在求醫的時候，這種藥物已經無法起效。如果這種病毒開始出現人際傳播，主要的武器或許會是一種有待開發的新疫苗。