Name: What Is Outbreak Science? Crash Course Outbreak Science #1
Uploaded: 2022-02-04T05:50:41.000Z
Duration: 11 min 31 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

You are part of one of the world's greatest endeavors: the effort to stop infectious disease.

Like other animals, infectious diseases have been with us since the dawn of our species,

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from herpes virus that infected our common ancestors in Africa

to the Covid-19 pandemic that struck the whole world.

The effort to understand these diseases has been going on for some time, too.

As far back as 400 BCE, civilisations in different parts of the world tried to work out

Since then, we've come a long way in understanding what diseases are and how they spread.

And that knowledge is vital to stopping them.

But it's not only doctors and scientists who can act on what we know.

so everything from the way you and I go about our everyday activities

to the way we organise whole societies all influence how an outbreak evolves –

I'm Pardis Sabeti, a professor of genetics at Harvard University,

In this series, we're going to take a deeper look at disease outbreaks,

from the microbiology and genetic factors behind them to healthcare systems,

social structures and people who tackle them, including you!

Welcome to Crash Course Outbreak Science!

The study of outbreaks is a little different from your garden variety science.

Not everything about an outbreak can be studied experimentally.

Outbreaks are complex situations involving real people in their environments,

so we can't perfectly measure and control all the variables.

It would also, you know, be highly unethical to release an infectious disease into a population

though, sadly, that hasn't stopped people from doing just that.

Even so, it helps to be specific about what we're talking about when using words like

The American Public Health Association's Control of Communicable Diseases Manual

– yes, there's a handbook for this! –

“The occurrence, in a defined community or region, of cases of an illness

with a frequency clearly in excess of normal expectancy.”

In other words, an epidemic is when many more people in a group than usual develop a particular illness.

We can also use the word “outbreak”, usually when the region we're talking about is relatively small.

That might all seem straightforward, but there's a question hidden here.

What counts as a “usual” amount of illness?

It turns out, it depends on the community.

For example, in the 1990s there was an outbreak of cholera in Latin America.

Cholera is a bacterial disease that attacks the intestines,

usually contracted from contaminated water, and nearly a million people were infected.

Those kinds of numbers for cholera cases hadn't been seen on the continent in over a century,

But near the Ganges delta between Bangladesh and India,

cases of cholera are an unfortunate and persistent fact of life because of the environment.

When a disease has roughly the same incidence in a place over an extended period of time,

The word endemic is derived from the ancient greek words “en” meaning “in”

and “demos” meaning “people”, like, diseases that reside in a group of people.

That's opposed to “epidemic”, which is derived from “epi” meaning “on”,

as in, diseases that act on a group of people.

Similarly a pan-demic draws on the greek word “pan” meaning “all”,

as in an epidemic that spreads across borders into many countries,

affecting the whole world if left unchecked.

What really distinguishes an epi-demic, or outbreak,

is that the number of cases of illness are much higher than they normally are within

Which means words like “normal” and “usual” have to be taken in the context of particular groups of people,

It doesn't mean that the cases of cholera were more or less important in South America

But it means we might approach the two situations differently.

Outbreaks are evolving situations where the disease could become more widespread.

So the goal is to stop the disease spreading even further, as well as treating those who have it.

It also means having organizations and systems in place that can handle the social changes

What's key to tackling those challenges is understanding the nature of an infectious

When it comes to diseases, different scientists have different ways of thinking about them.

For example, microbiologists consider diseases in terms of their biological cause.

One of the most important scientific discoveries in history is that tiny organisms that enter the human body

are what's often responsible for us contracting infectious diseases.

The most commonly known pathogens are microorganisms like bacteria, viruses, protozoa and fungi.

The science behind pathogens is pretty broad,

so we'll be looking at them in closer detail next episode!

The take-away is that microbiologists tend to characterize diseases by the pathogens that cause them.

Epidemiologists meanwhile think about diseases in terms of the bigger picture,

focusing on how it spreads and what its source is.

Unfortunately for us, there are lots of ways pathogens can infect people.

They might be spread from person to person through contact with skin

or through droplets in the air from someone's sneezes or coughs.

They might be eaten in contaminated food or injected by an insect like a mosquito.

Even if the pathogens might be different,

an epidemiologist would think of diseases in terms of these transmission routes.

They also consider when a community is regularly coming into contact with the same source of

Sometimes, a reservoir is a group of infected people,

but it could also mean a local population of animals carrying diseases like rabies.

The reservoir might be soil which contains certain kinds of fungi or contaminated water.

The kind of reservoir also determines who might be at the most risk from an outbreak,

Finally, there are medical scientists and doctors,

who tend to think of diseases by their clinical symptoms.

Clinical symptoms might be familiar things like fever or difficulty breathing but also

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