2022-01-27 ศัพท์ น่าสับสน - Set – C - contagious & infectious

Revision C

2022-01-27

ศัพท์ น่าสับสน - Set – C - contagious & infectious

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ความหมาย อาจผันแปร ตาม ตำแหน่ง/หน้าที่ ในประโยค

 

Dictionary.com:

ออกเสียง contagious = “kuhn-TEY-juhs”

ออกเสียง infectious = “in-FEK-shuhs”

 

Dictionary of Problem Words and Expressions:

contagious & infectious

These words have precise scientific meanings, 

but in everyday usage they are often confused. 

 

As for illness, a contagious disease 

is one communicated or transferred by contact: 

aninfectious disease is not necessarily contagious.

 

Contagious emphasizes the speed 

with which contagion (contact, communication, medium) spread: “Contagious fear ran through the audience.” 

 

Infectious suggests the powerful or irresistible quality 

of the source of contagion:

“Mark Twain’s infectious humor stimulated prolonged laughter and applause.”

 

The A-Z of Correct English Common Errors in English Dictionary

contagious & infectious 

Both refer to diseases passed to others. 

Strictly speaking, 

CONTAGIOUS means passed by bodily contact, 

and INFECTIOUS means passed by means of air or water. 

 

Used figuratively, the terms are interchangeable: 

INFECTIOUS laughter, 

CONTAGIOUS enthusiasm.

 

Dictionary.com:

SYNONYM STUDY FOR CONTAGIOUS

Contagious, infectious 

are usually distinguished in technical medical use. 

Contagious, literally “communicable by contact,” 

describes a very easily transmitted disease 

as influenza or the common cold. 

Infectious refers to a disease involving a microorganism 

that can be transmitted from one person to another 

only by a specific kind of contact; 

venereal diseases are usually infectious. 

In nontechnical senses, 

contagious emphasizes the rapidity with which something spreads: 

Contagious laughter ran through the hall. 

 

Infectious suggests the pleasantly irresistible quality of something: 

Her infectious good humor made her a popular guest.

 

Dictionary.com:

“Contagious” vs. “Infectious”: The Difference Can Be Important

Published July 5, 2020

by John Kelly, Senior Research Editor at Dictionary.com

 

Whether it’s flu season, chickenpox at your kid’s school, 

concerns about measles in your town, 

or the coronavirus pandemic, 

the words contagious and infectious often

come around in news and social media, 

in casual conversations and government communications.

 

While these two terms get used interchangeably, 

knowing the difference between them can, in some cases, be life-saving.

 

To bring you clarity and comfort, we’re diving deep into these

—and many other—terms that come up within the topic of disease.

 

Here’s the big takeaway. 

All contagious diseases are infectious, 

but not all infectious diseases are contagious. 

 

Contagious diseases are infectious diseases 

that are easily spread through contact with other people.

 

But how did we get to this distinction? 

Let’s begin by zooming out from contagious and infectious 

to look at a bigger picture of disease. Stay with us.

 

What is the difference between communicable vs. noncommunicable?

There are many different ways to classify diseases. 

One broad classification is whether the disease is communicable or noncommunicable.

Let’s start with noncommunicable diseases,

sometimes abbreviated as NCDs. 

Noncommunicable literally means “not communicable.”

 

Yes, we know it might seem more logical to start by defining 

what something is as opposed to what it is not. 

But hear us out: 

we think this approach can help make these challenging terms and concepts a little easier to follow.

 

So, a noncommunicable disease isn’t communicable. 

That means these diseases are not transmitted through contact with an infected or afflicted person. 

Noncommunicable diseases are, instead, 

caused by various genetic, physiological, environmental, and behavioral factors.

The World Health Organization (WHO) identifies four main types of noncommunicable diseases:

• cancer
• cardiovascular diseases (e.g., heart attacks and stroke)
• chronic respiratory diseases (e.g., asthma and chronic obstructive pulmonary disease)
• diabetes

According to the WHO, these diseases account for 71% (41 million) of all deaths globally each year.

Because these diseases are noncommunicable, 

a person with cancer or diabetes can’t spread it to someone else by touching them, for instance, or through the air or water.

 

But a communicable disease, in contrast, is one that can be spread from one organism to another. 

This includes the spread from person to person, or 

(when it is a zoonotic disease) animal to humans. 

Communicable diseases claim millions of lives each year, 

though considerably fewer than their noncommunicable counterparts.

OK, word break. What’s up with the word communicable? 

Another term for spread is communicate, 

hence communicable (capable of being communicated). 

Most of us probably use the word communicate for the various ways 

we share thoughts, feelings, information, and so on through talking and writing. 

But in medical and scientific contexts, communicate can mean 

“to give to another, impart, transmit,” as a disease. 

Communicable diseases are also referred to as transmissible.

 

Still with us so far?
So, communicable diseases can be spread. 

But, how such a disease is spread is at the heart of the 

technical difference between the terms contagious and infectious.

 

What does infectious mean?

To drill down, it helps to begin with the term infectious.

Infectious means “communicable by or causing infection.” 

Hey, we don’t want to take any terms for granted here, 

so let’s break this down some more. 

Infection refers to “the process or state of being infected with a disease.” And to infect means “to affect or contaminate someone or something with disease-producing germs.”

 

So, with infectious diseases, it’s all about spreading germs. 

Let’s get even more technical.

An infectious disease is caused by pathogenic microbial agents, 

such as viruses, bacteria, or other microorganisms. Pathogenic 

means “disease-producing.” 

 

Microbial refers to microbes, or microorganisms that can produce disease. 

Viruses are sometimes referred to as microbes because, like microbes, 

they are microscopic and can cause disease.

 

Put simply, an infectious disease happens 

when bad germs get into the body in some way, spread, 

and make you sick by affecting the way your body normally works.

 

Examples of infectious diseases:

• chickenpox
• cholera
• common cold
• coronavirus, including COVID-19
• Ebola
• flu (influenza)
• hantavirus
• hepatitis A & B
• HIV/AIDS
• Lyme disease
• malaria
• measles
• meningitis
• MRSA
• polio
• pneumonia
• smallpox
• STDs (sexually transmitted diseases)
• tuberculosis
• West Nile virus
• Zika

Some of these diseases are common, like the cold and flu. 

Others are rare or have been effectively eliminated in many parts of the world.

 

Facts about the word infectious:

• Infectious is first recorded around 1535–45.
• Infectious, infection, and infect all go back to the Latin infectus,  

past participle of the verb inficere, “to dip, dye, tint; infect, stain, poison, corrupt.”

• The root of the Latin verb inficere is facere, “to do, make,” 

and is a source of a great number of English words, from fact to affection.

 

How do infectious diseases spread?

Infectious diseases can be spread in a variety of ways. 

Some infectious diseases spread in more than one way. 

Major ways include:

• direct contact with an infected person, animal, or their discharges
• direct contact with a contaminated object
• contaminated food and water
• disease-carrying insects

 

There are many types of discharges. They include secretions, 

such as saliva, and body fluids, such blood, urine, and semen.

Another type of discharge is respiratory droplets. 

These are expelled when a person coughs and sneezes, and often 

when they talk, laugh, or just breathe. 

These droplets are sometimes referred to as aerosols.

 

What does airborne mean?

Some of these general ways of spreading have earned special names 

that feature the word borne, a past participle form of the verb bear 

(“carry, transmit”).

A blood-borne pathogen, such as HIV and some types of hepatitis,

is transmitted by the blood or other body fluids. 

A food-borne illness, such as salmonella, is transmitted by food. An airborne disease, like tuberculosis, is spread through the air; 

airborne is especially used to describe diseases spread by germs that can survive in the air for hours.

 

❗ Update: 

The World Health Organization hasn’t technically considered COVID-19 an airborne disease like tuberculosis, as it concluded that the virus particles generally don’t linger in the air very long and can’t travel very far, the conventional hallmarks of an airborne disease. However, in early July 2020, a growing body of scientists were urging public health officials to consider the transmission of COVID-19 as airborne and revise their health and safety recommendations.

 

Sometimes waterborne is used to refer to diseases like cholera, 

which can spread through contaminated water.

Malaria (transmitted by mosquitos) is an insect-borne disease, 

and Lyme disease is tick-borne.

Sexually transmitted diseases (STDs)

—also called venereal diseases

—are transmitted through sexual contact. 

Blood and other body fluids are often the vehicle through which STDs spread.

 

A note on the word vector, which often comes up in the context of infectious diseases. 

A vector can refer to an insect or other organism that transmits a pathogenic fungus, virus, bacterium, and so on. 

In the case of malaria, the mosquito is the vector.

 

So, what is a contagious disease?

Recap time. Communicable diseases are infectious diseases. 

An infectious disease is contagious when it spreads through direct, 

bodily contact with an infected person, their discharges, or an object 

or surface they’ve contaminated.

 

Some key points: this transmission is typically very easy 

and results from close, casual contact.

Malaria is an infectious disease caused by a parasite, 

but it is not contagious because you don’t get it just by being around 

or coming into contact with an infected person. 

It’s usually transmitted by a mosquito bite, which transfers the parasite from the mosquito into your blood.

 

Tetanus is an infectious disease, but it’s not contagious because 

you don’t get it by shaking hands with someone who has the infection. 

Like malaria, it has to enter your bloodstream, 

such as by getting cut by a rusty nail, 

where the tetanus-causing bacteria can breed.

 

Food poisoning is an infectious, if short-lived (acute, not chronic), disease. It’s not discussed as contagious because it is spread by eating contaminated food, not by sitting across from someone who has food poisoning.

 

Facts about the word contagious:

• Contagious and its related noun, contagion, are first recorded around 1350–1400.
• Both go back to the Latin contāgiō, “touching, contact; infection.”
• The origin of the word contact is also related to contāgiō.
• A contagious disease is spread by contact.

 

Is the coronavirus contagious?

Let’s apply what we’ve learned.

1. We know COVID-19 is a disease caused by an infection from a virus, a new type of coronavirus.
2. This infection very easily spreads by direct and casual contact with a person, droplets, and infected surfaces.
3. So, we can say COVID-19 is indeed a contagious disease.

 

That’s why we are staying at home and social-distancing the best we can! It’s also why washing your hands is so important—not only for COVID-19, but for other contagious and infectious diseases, as well as for your general health and hygiene.

 

Why is the word contagious important?

In everyday settings, the distinction between contagious and infectious often breaks down. 

Oftentimes, that’s just fine: contagious and infectious, very generally, 

can refer to a disease that tends to spread from one person to another.

We use the terms figuratively, too. Contagious laughter might spread across a classroom after the class clown cracks a perfectly timed joke. 

Or, low morale might be said to be contagious in an office after layoffs have been announced. 

If someone has an infectious smile, it’s simply irresistible. 

Infectious, in its metaphorical sense, 

tends to have a positive connotation. 

Contagious can be positive or negative, 

though it might skew toward the latter.

 

But, if contagious and infectious are sometimes used interchangeably, why do we need to make a distinction between them at all?

In some instances, especially in public health emergencies, 

it’s important we call out that a disease isn’t just infectious, 

but that it is contagious. 

 

Calling a disease contagious highlights the fact that 

it is very easily spread by being around people and public places

—in our very normal life circumstances. 

This can help influence and guide behaviors to help prevent ourselves 

and others from getting infected, 

whether it’s getting a yearly flu shot or practicing social distancing.

 

THE AMERICAN HERITAGE® SCIENCE DICTIONARY:

USAGE

A contagious disease is one that can be transmitted from one 

living being to another through direct or indirect contact. 

Thus the flu, which can be transmitted by coughing, and cholera, 

which is often acquired by drinking contaminated water, are contagious diseases. 

Although infectious is also used to refer to such diseases, 

it has a slightly different meaning in that it refers to diseases 

caused by infectious agents-agents such as viruses and bacteria that are not normally present in the body and can cause an infection. 

 

While the notion of contagiousness goes back to ancient times, 

the idea of infectious diseases is more modern, 

coming from the germ theory of disease, 

which was not proposed until the later nineteenth century. 

 

Contagious and infectious are also used to refer to people

 who have communicable diseases at a stage 

at which transmission to others is likely.

 

THE AMERICAN HERITAGE® SCIENCE DICTIONARY:

an infectious disease.

Usage 

A contagious or communicable disease is one that can be transmitted 

from one living being to another through direct or indirect contact. 

Thus the flu, which can be transmitted by coughing, and cholera, 

which is often acquired by drinking contaminated water, 

are contagious (or communicable) diseases. 

Modern medicine also uses the word infectious to refer to such diseases. 

Infectious has a slightly different meaning. 

It refers to diseases caused by infectious agents—agents such as viruses and bacteria that are not normally present 

in the body and can cause an infection. 

 

While the notion of contagiousness goes back to ancient times, 

the idea of infectious diseases is more modern, coming from 

the germ theory of disease, which was not proposed 

until the later 19th century.

 

Merriam-Webster Dictionary:

Usage Notes

Is That Cold 'Contagious' or 'Infectious'?

You can ponder the distinction while you wash your hands

What to Know

Contagious diseases are spread by contact, 

while infectious diseases are spread by infectious agents. 

Something "contagious" is by default "infectious" 

because contact exposed you to the infectious agent, 

but something infectious isn't always contagious. 

You can be infected with food poisoning, which itself is not contagious.

 

Flu season descends annually, and we wonder whether our coworkers 

who come down with it are going to pass it along to us. 

If they do, is it because they're contagious?

Or because they're infectious? What exactly is the difference?

 

Contagious vs Infectious

The crux of the distinction is this: contagious diseases are spread 

by contact, while infectious diseases are spread by infectious agents.

So, if contact with your sniffling coworker results in 

your developing the sniffles, your coworker's sniffles are contagious. 

(If your coworker's sniffles are caused by allergies, 

you can't catch them because allergy symptoms aren't contagious.)

 

But here's the thing: your coworker's contagious sniffles 

are also infectious.

Huh? Yup. 

Infectious sniffles are sniffles that are spread by infectious agents; 

an infectious agent is the thing that gets you sick, 

usually a virus or a bacteria.

 

Anything contagious is always automatically infectious: 

if you can catch it from someone, 

it's being passed to you via an infectious agent.

 

But the reverse isn't true. Just because something is infectious 

does not mean it's contagious. 

Food poisoning is a good example of something infectious 

but not contagious: food can be contaminated 

with a bacteria that makes you sick, 

but you can't give your food poisoning to someone else 

just by shaking their hand or even giving them a kiss.

 

Figurative Use of Contagious and Infectious

Both these words are also used figuratively, often in much happier contexts. Your sniffling coworker might also have a contagious laugh 

or an infectious enthusiasm. 

While both words are used of both pleasant and unpleasant things, 

contagious is more often chosen for the unpleasant, 

as in "grumpiness that's contagious."

 

Merriam-Webster Dictionary:

What is the Difference Between contagious and infectious?

The words contagious and infectious can be confusing 

because they do not designate wholly distinct categories; 

something is not either contagious or infectious.

 

Essentially, infectious diseases and contagious diseases are 

caused by disease-producing agents such as bacteria and viruses, 

but they differ in that contagious diseases can be spread to 

other people by direct or indirect contact.

 

Anything contagious, such as the flu, is always automatically infectious: 

if you can catch it from someone, 

it's being passed to you via an infectious agent, which is the thing 

that gets you sick—usually a virus or a bacteria.

 

The reverse, however, isn't true. Just because something is infectious 

does not mean it's contagious. 

Food poisoning, for example, is infectious but not contagious: 

food can be contaminated with a bacteria (an infectious agent) 

that makes you sick, but you can't give your food poisoning 

to someone else by shaking their hand or even giving them a kiss.

 

Both contagious and infectious are also used figuratively, 

often in much happier contexts: laughter can be contagious; 

someone's enthusiasm can be infectious. 

 

While both words are used figuratively of both pleasant 

and unpleasant things, 

contagious is more often chosen for the unpleasant, 

as when it's grumpiness or fear that seems to be spreading.