Secret of what made 1918 Spanish flu 疫病／流行性の that killed 50 MILLION the fastest in history

• Deadly flu ウイルス attacked more than one-third of the world's 全住民
• Pandemic ウイルス arose の直前に 1918
• 緊張する developed when a human H1 ウイルス which had been 広まる in the human 全住民 since about 1900 選ぶd up genetic 構成要素 from a bird flu ウイルス
• 研究員s say this left people 異常に 攻撃を受けやすい
  

By 示す Prigg

Published: 19:12 BST, 29 April 2014 | Updated: 09:11 BST, 30 April 2014

研究員s believe they have 暴露するd the mystery of the how the 1918 flu 疫病／流行性の which killed 50 million people was so 破滅的な.

The say （危険などに）さらす to an earlier, いっそう少なく dangerous 緊張する の中で children 原因（となる）d the 1918 緊張する to spread so quickly.

The deadly flu ウイルス attacked more than one-third of the world's 全住民, and within months had killed more than 50 million people ? three times as many as the World War I ? and did it more quickly than any other illness in 記録，記録的な／記録するd history.

Nurses care for 犠牲者s of the 1918 Spanish influenza 疫病／流行性の outdoors まっただ中に canvas テントs in Massachusetts. 研究員s now say （危険などに）さらす to an earlier 緊張する left people 攻撃を受けやすい to the pandemic 緊張する, making it 異常に 効果的な.

HOW THE STRAIN EMERGED

The 研究員s discovered that the pandemic ウイルス arose の直前に 1918, when a human H1 ウイルス, which they infer had already been 広まる in the human 全住民 since about 1900, 選ぶd up genetic 構成要素 from a bird flu ウイルス (pictured, a 2004 swine flu ウイルス).

The Human influenza A ウイルス usually sees higher mortality 率s for 幼児s and the 年輩の, but the pandemic ウイルス 原因（となる）d 広範囲にわたる deaths in people ages 20 to 40, まず第一に／本来 from 第２位 bacterial infe ctions, 特に 肺炎.

The authors 示唆する this was because many young adults born from about 1880 to 1900 were exposed during childhood to a H3N8 ウイルス 広まる in the 全住民, which had surface proteins that were very different from those of the H1N1 ウイルス.

In contrast, most individuals born earlier or later than 1880-1900 would have had better 保護 because they were more likely to have been exposed a ウイルス variant more 類似の to the 1918 ウイルス.

However, until now, the origin of the 1918 pandemic flu ウイルス and its unusual severity have baffled health 専門家s.

A new 熟考する／考慮する led by Michael Worobey, professor in the University of Arizona Department of 生態学 and Evolutionary Biology, within of the College of Science, not only sheds light on the 破滅的な 1918 pandemic, but could also 改善する ワクチン接種 戦略s, and pandemic 予防 and preparedness.

'If our model is 訂正する, then 現在の 医療の 介入s, 特に 抗生物質s and ワクチンs, against several 肺炎-原因（となる）ing bacteria, could be 推定する／予想するd to 劇的な 減ずる mortality, if we were 直面するd today with a 類似の 始める，決める of pandemic 成分s,' Worobey said.

'Ever since the 広大な／多数の／重要な flu pandemic of 1918, it has been a mystery where that ウイルス （機の）カム from and why it was so 厳しい and, in particular, why it killed young adults in the prime of life,' Worobey 追加するd.

'It has been a 抱擁する question whether there was something special about that 状況／情勢, and whether we should 推定する／予想する the same thing to happen tomorrow.'

Worobey and his 同僚s developed an 前例なく 正確な 'molecular clock' approach to untangle the origins of the 1918 pandemic H1N1 influenza A ウイルス, the classical swine H1N1 influenza ウイルス, and the po st-pandemic seasonal H1N1 lineage that 循環させるd from 1918 until 1957.

A molecular clock is a technique used in evolutionary biology to 再建する family trees of organisms ? or ウイルスs ? based on the number of genetic 突然変異s 蓄積するing over time.

The 研究員s discovered that the pandemic ウイルス arose の直前に 1918, when a human H1 ウイルス, which they infer had already been 広まる in the human 全住民 since about 1900, 選ぶd up genetic 構成要素 from a bird flu ウイルス.

In particular, Mr Gates 恐れるs a Spanish flu-like 疫病／流行性の 類似の to the one that killed more than 65 million people in 1918 could decimate 全住民s in a 事柄 of months. In this image, 患者s of the Spanish flu 嘘（をつく） in Influenza 区 No. 1 in a French hospital as doctors 戦う／戦いd the ウイルス and the 影響s of the War

The Human influenza A ウイルス usually sees higher mortality 率s for 幼児s and the 年輩の, but the pandemic ウイルス 原因（となる）d 広範囲にわたる deaths in people ages 20 to 40, まず第一に／本来 from 第２位 bacterial 感染s, 特に 肺炎.

The authors 示唆する that this likely was because many young adults born from about 1880 to 1900 were exposed during childhood to a putative H3N8 ウイルス 広まる in the 全住民, which had surface proteins that were very different from those of the H1N1 ウイルス.

In contrast, most individuals born earlier or later than 1880-1900 would have had better 保護 because they were more likely to have been exposed a ウイルス variant more 類似の to the 1918 ウイルス.

'You can picture the flu ウイルス as a tiny サッカー ball studded with lollipops,' Worobey explained.

'The candy part of the lollipop is by far the most potent part of the flu ウイルス, against which our 免疫の system can make antibodies.

'If antibodies cover all the lollipop 長，率いるs, the ウイルス can't even 感染させる you.'

For example, a person exposed to a flu 緊張する studded with blue candy lollipops would have antibodies 保護するing it from 未来 感染s with that f lu ウイルス.

THE 1918 FLU OUTBREAK - THE WORLD THE WORLD HAS EVER SEEN

欠如（する）ing a reliable cure, public health groups concentrated on 予防?

The deadly flu ウイルス attacked more than one-third of the world's 全住民, and within months had killed more than 50 million people ? three times as many as the World War I ? and did it more quickly than any other illness in 記録，記録的な／記録するd history.

Most influenza 突発／発生s 不均衡な kill juvenile, 年輩の, or already 弱めるd 患者s; in contrast the 1918 pandemic predominantly killed 以前 healthy young adults.

To 持続する 意気込み／士気, 戦時 censors 最小限に減らすd 早期に 報告（する）／憶測s of illness and mortality in Germany, Britain, フラン, and the 部隊d 明言する／公表するs.

However, newspapers were 解放する／自由な to 報告（する）／憶測 the 疫病／流行性の's 影響s in Spain, creating a 誤った impression of Spain as 存在 特に hard 攻撃する，衝突する - and 主要な to the pandemic's 愛称 Spanish flu.

The の近くに ４半期/4分の1s and 大規模な 軍隊／機動隊 movements of World War I 急いでd the pand emic and probably both 増加するd 伝達／伝染 and augmented 突然変異, 研究員s believe.

The 全世界の mortality 率 from the 1918/1919 pandemic is not known, but an 概算の 10% to 20% of those who were 感染させるd died, with 見積（る）s of the total number of deaths 範囲ing from 50-100 million people.

However, if 直面するd with a different 緊張する 含む／封じ込めるing red candy, that same person would get sick because the “anti-blue” antibodies would not 認める the red lollipops, 許すing the ウイルス to slip through the 団体／死体’s 免疫の 弁護s 無傷の.

'We believe that the mismatch between antibodies trained to H3 ウイルス protein and the H1 protein of the 1918 ウイルス may have resulted in the 高くする，増すd mortality in the age group that happened to be in their late 20s during the pandemic,' Worobey said.

Worobey said the new 視野 適用するs not only to the pandemic of 1918, but might also explain patterns of seasonal flu mortality and the mysterious patterns of mortality when humans are 感染させるd by 高度に pathogenic avian-origin H5N1 and H7N9 ウイルスs, 一般的に known as 'bird flu'.

H5N1causes higher mortality 率s in young people, and H7N9 原因（となる）s higher mortality in the 年輩の.

In both 事例／患者s, the 研究員s 設立する that the more susceptible age groups were exposed 最初, as children, to ウイルスs with a mismatched HA, and may 苦しむ 厳しい consequences 類似の to young adults 直面するd with a mismatched ウイルス in 1918.

Members of the Red Cross モーター 軍団, all wearing masks against the その上の spread of the influenza 疫病／流行性の, carry a 患者 on a 担架 into their 救急車 in Saint Louis, Missouri, October 1918.

The authors 示唆する that immunization 戦略s mimicking the often impressive 保護 供給するd by 初期の childhood （危険などに）さらす to influenza ウイルス variants 遭遇（する）d later in life might 劇的な 減ずる mortality 予定 to both seasonal and novel IAV 緊張するs.

Earlier this year, Worobey and his 協力者s published a 熟考する／考慮する in the 定期刊行物 Nature 供給するing the most 包括的な 分析 to date of the evolutionary 関係s of flu ウイルス across different host 種類 over time.

The results 明らかにする／漏らすd a 早い, 全世界の 交替／補充 of the 遺伝子s in the avian flu ウイルス 同時に起こる／一致するing closely with a horse flu 突発／発生 in the 1870s that 手足を不自由にする／（物事を）損なうd the economy.

They also challenged the 受託するd 知恵 of wild birds as the major 貯蔵所 harboring the flu ウイルス, from where it jumps to 国内の birds and other 種類, 含むing humans.

Instead, the 研究員s 設立する a very strong 指示，表示する物 of spillover from 国内の birds to wild birds.