シャドーイング練習: Understanding Malaria: Causes Of Malaria - YouTubeで英語スピーキングを学ぶ
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the developed world today,
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the bite of a mosquito might at worst mean an irritating interruption to a warm summer's evening on the porch.
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If you happen to live in a more tropical climate,
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however, that itch could be the start of something far worse.
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In fact, as much as half of the world's population are at risk of a deadly infection called malaria,
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due to the bite of this blood-sucking menace.
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The disease isn't actually caused by the mosquitoes.
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They're what we call a vector.
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These buzzing little pilots are the vehicles for the actual killer,
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lurking inside the mosquito's salivary glands.
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A microscopic single-celled organism called Plasmodium is what's really responsible for the symptoms of weakness,
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aches, intense fever, and for an unlucky percentage who don't receive treatment, even death.
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There are five species of Plasmodium that infect humans,
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but the most dangerous is called Plasmodium falciparum,
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which is the cause of 90% of all malaria deaths.
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All these parasite species spread the same way.
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Mosquitoes pick up Plasmodium by biting a previously infected person who has the parasite in their blood.
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Later, the same mosquito delivers the parasite to another host the host through its saliva.
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The dangerous microbes quickly find their way inside red blood cells,
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where they breed in such numbers that the cells swell up and eventually explode.
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Luckily not all mosquitoes make for a suitable carrier.
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In fact just one genus will do for this picky parasite,
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a type of mosquito called Anophilus.
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Even then, it's only the female mosquito who feeds on human blood to nourish her young.
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Males prefer to dine on nectar.
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There are still more than 40 species of this particular mosquito across the world,
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which can be found on every continent except for Antarctica.
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They are all capable of carrying malarial parasites,
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yet not all countries have cases of malaria.
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Why not?
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Plasmodium microbes have no tolerance for the cold.
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The deadliest species, for example,
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can't reproduce if the temperature falls to far below 20 degrees Celsius.
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On the other hand, at 27 degrees,
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the microorganisms thrive and multiply with staggering speed.
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Colin Sutherland is a professor of parasitology at the London School of Hygiene and Tropical Medicine.
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According to him, that speed makes a tremendous difference.
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The mosquito, after it picks up the parasite by feeding on the blood of a person with the infection,
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then needs 15 to 20 days for the parasite to fully mature inside and it needs to expand inside the mosquito.
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Now if you think about the lifespan of the average mosquito,
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20 days is pushing it.
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So the mosquito has to survive that period of time.
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Now there's a problem for the parasite,
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which is in colder regions, it develops slower.
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So it's a race between the parasite getting ready to go to another person and the mosquito dying.
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And in colder places, and we used to have some malaria in southern England,
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but it's much easier to control because it's right on the edge of that temperature that's required.
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Mosquitoes also need moisture, and a lot of it.
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These insects lay their eggs in pools of stagnant or slow-moving water,
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where they hatch into larvae.
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The adults' delicate bodies are also susceptible to drying out,
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meaning they prefer humid atmospheres.
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These conditions tend to rule out cool, dry countries.
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But for some 90 countries spread around the equator,
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both Anopheles and Plasmodium have the perfect conditions to thrive,
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warm enough for the parasite to grow quickly and wet enough for the mosquito to spread it.
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You might not want to get too comfortable though.
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As the world continues to warm, climates will change.
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This tropical humid zone could expand,
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opening the way for Anopheles mosquitoes to breed in more environments.
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And just maybe, malaria will move with it.
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If you're lucky enough to live in a more developed part of the world,
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there are already ways to keep malaria at bay.
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We've known about some of them for centuries.
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Ancient texts on how to plan cities describe the importance of avoiding noxious wetland areas,
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such as swamps and marshes.
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The word malaria itself comes from the old Italian words meaning bad air.
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It's easy to see why.
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Before people knew much about the transmission of parasites,
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foul air near stagnant pools were considered responsible for causing illness.
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While the smell might be relatively harmless,
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stagnating warm water makes for the perfect mosquito breeding ground.
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In many parts of the world,
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humans have done a good job of eradicating mosquitoes by fumigating,
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clearing away rubbish and draining wetlands as cities expand.
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In other areas, human activity has encouraged mosquitoes to breed.
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From digging up the earth for mines,
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to leaving buildings to crumble,
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abandoning tyres and other rubbish,
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to having inadequate drainage where predator-free puddles form.
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Mosquito eggs can hatch in peace and quiet.
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Moving populations can also create the right conditions for malaria to spread,
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not just by carrying the parasite with them,
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but by changing the landscape to suit breeding mosquitoes.
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Caroline Maxwell works for the charity group Malaria No More.
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According to her, as people are forced to move into unplanned settlements,
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the environment can change with them.
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One of the biggest challenges around malaria control is things like urbanisation or people moving to spontaneous settlements such as shantytowns.
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And often when this is done in a very rapid way,
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it's not in a controlled fashion at all.
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So you get poor drainage systems,
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you get stagnant water, and that again can increase the breeding for mosquitoes.
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And so it's really important that governments or town planners come together
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and ensure that things are done in a very systemised way,
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that irrigation projects, drainage and
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so on are done in a very controlled fashion to reduce people being exposed to the mosquito that carries malaria.
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Destroying natural environments is also increasing the risk of bringing more people into contact with this deadly disease.
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Dr Sutherland describes another example where humans moving into new areas can increase the risk of disease.
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There's a kind of malaria that is at home in the monkeys of Southeast Asia,
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mainly live in the forests and rarely have interaction with humans.
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But as the environment is being changed and forests are being cleared for plantations and human habitation,
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the monkeys are forced to live close to the humans.
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Now the mosquitoes that bite those monkeys are biting humans who are getting this kind of malaria which the monkeys have.
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So that's been an increasing problem only in a few countries in Southeast Asia.
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So that's an example of where humans have changed the environment and malaria risk has gone up.
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With enough money, countries might be able to afford better sanitation,
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efficient waste disposal programmes, or ways to keep their environment free of pooling water,
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wiping out mosquitoes before they can even breed.
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Governments can designate land as national reserves,
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preventing it from being cleared.
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Wealthy nations can also afford treatments to clear the illness from human populations,
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driving Plasmodium to extinction with preventative medications.
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Not all nations have such resources, unfortunately.
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In less economically developed countries,
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individuals' poverty might mean they can't afford these treatments
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or don't complete their prescription to keep some drugs on hand for next time,
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which increases the parasite's resistance to the medication.
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If we're to ever have hope of controlling and wiping out malaria,
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we need to consider how to work together in this fight.
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There's an acceptance that it takes a global level of effort
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from partnership between many countries and many organisations to make a difference.
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And it's taken that level,
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a global level of effort,
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to push back this disease locality by locality.
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You know, it's step by step and reducing malaria at the most vulnerable places first and then moving on.
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このレッスンについて
このレッスンでは、マラリアについての基本的な理解を深めることを目的としています。特に、マラリアの原因やその感染経路について詳しく学ぶことができます。この内容を英語で学ぶことで、医学的な語彙やフレーズを増やし、リスニングとスピーキングのスキルを向上させることができます。
重要な語彙とフレーズ
- malaria - マラリア
- mosquito - 蚊
- parasite - 寄生虫
- salivary glands - 唾液腺
- Plasmodium - プラスモディウム
- Anophilus - アノフィレース（蚊の一種）
- temperature - 温度
- infection - 感染
練習のヒント
動画を視聴する際には、英語シャドーイングの技法を用いて練習しましょう。シャドーイングは、話者の声に合わせて声を出す練習方法であり、特にこの動画ではゆっくりとしたアクセントと明瞭な発音が特徴です。まずは、動画の音声をよく聞き、内容を理解した後、再生を一時停止し、短いフレーズを繰り返すことから始めましょう。
また、動画のスピードが比較的速くないので、リズムに合わせて声に出すことが容易です。英語の発音やイントネーションを模倣しながら、shadowspeakやshadow speechの技術を使うことで、自分自身のスピーキングスキルを高めることができます。特に、専門的な語彙を習得しながら練習することで、より自然な英語を話せるようになるでしょう。
定期的にこのようなコンテンツを使って練習することで、英語力は着実に向上します。他のリソースやshadowing siteを利用し、異なるテーマの資料でも練習を続けましょう。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。