科學家揭祕爲何冬季多發流感

Scientists discover why flu strikes in winter

It is a mystery that has baffled doctors for decades.

But experts believe they have now finally solved the tricky question of why winter is notoriously known as the flu season.

According to new research, the influenza virus coats itself in a protective fatty shield that is tough enough to withstand cold temperatures.

The butter-like material only melts when it hits the respiratory tract, leaving the virus free to infect cells - a process scientists say is like an M&M melting in the mouth.

However, in warmer outdoor temperatures, the protective coating melts before it reaches a person or an animal, killing the germs before they can infect someone.

Joshua Zimmerberg, from the National Institute of Child Health and Human Development (NICHD), in the US, which led the study, said: 'Like an M&M in your mouth, the protective covering melts when it enters the respiratory tract.

'It's only in this liquid phase that the virus is capable of entering a cell to infect it.'

In the past scientists have worked on theories that flu is more common in winter because people spend more time inside or the radiation from the sun in summer kills off germs.

But no research has successfully explained the spread of the disease.

Researchers have already claimed that the report, which is published in the journal Nature Chemical Biology, could lead to new ways to prevent and treat flu.

Duane Alexander, the director of NICHD, said: 'The study results open new avenues of research for thwarting winter flu outbreaks.

'Now that we understand how the flu virus protects itself so that it can spread from person to person, we can work on ways to interfere with that protective mechanism.'

Influenza and other respiratory viruses are spread in small droplets broadcast by coughing, sneezing and talking and which can also settle onto surfaces, to be picked up on fingertips.

爲何冬季爲多發流感？

這可是困擾了醫生們幾十年的一個謎。

不過，專家們現在終於解開了這個難題。

一項最新研究發現，流感病毒表面包有一層脂肪保護外殼，這種外殼十分堅硬，能抵禦嚴寒。

這種油狀物質在進入呼吸道後纔會融化，病毒被釋放後即會感染細胞。科學家稱這一過程如同M&M巧克力豆在嘴裏融化。

然而，在溫度較高的環境下，這層保護殼在進入人體或動物體內之前就會融化，因此病毒在感染細胞之前即被殺死。

研究負責人、美國兒童健康與人類發展研究所的約瑟華•茲姆博格說：“這層保護殼在進入呼吸道時即會融化，就像放入口中的M&M巧克力豆一樣。”

“而就在這一液態階段，病毒才得以入侵併感染細胞。”

科學家們過去一直在研究冬季易發流感的原因，一些理論稱這是因爲冬季人們多在室內活動，或是因爲夏季的陽光輻射會殺死細菌。

但沒有一項研究能真正解釋流感傳播的原因。

研究人員們稱，這項研究成果能爲防治流感提供新辦法。研究報告將在《自然化學生物學》期刊上發表。

美國兒童健康與人類發展研究所主任杜安尼•亞歷山大說：“研究結果爲控制冬季流感爆發開闢了新途徑。”

“現在我們明白了流感病毒是如何保護自己並在人際間傳播的，因此我們可以研究如何‘干擾’這種保護機制。”

流感及其他呼吸道病毒主要通過咳嗽、打噴嚏或說話時散播的飛沫傳播，它也會附着在物體表面，通過被污染的手指接觸傳染。