2021-05-19
ศัพท์ น่าสับสน ชุด – B – bacteria & bacterium & virus
แนะนำการใช้ ตามที่ส่วนใหญ่ใช้ แต่ละท้องถิ่น
ความหมาย อาจผันแปร ตาม ตำแหน่ง/หน้าที่ ในประโยค
Dictionary.com
ออกเสียง bacteria = ‘bak-TEER-ee-uh’
ออกเสียง bacterium = ‘bak-TEER-ee-uhm’
ออกเสียง virus – ‘VAHY-ruhs’
Dictionary.com
“Virus” vs. “Bacteria”: What’s The Difference?
It’s easy to confuse viruses and bacteria.
They are both extremely tiny, for one thing,
and, depending on what kind of bug you get, they can make you sick.
OK, “extremely tiny” and “make you sick”?
We do have technical words for these things.
Viruses and bacteria are microscopic,
meaning they are too small to see with the unaided eye.
And pathogens are“disease-producing agents,”
especially virusesand certain kinds of bacteria.
But, there aremany differences between viruses and bacteria too
—and they’re not just important to know toace your science exams.
These differences can be vital to your health and safety.
What is a virus?
Here’s our full, formal definition of virus:
A virus isan ultramicroscopic (20 to 300 nm in diameter), metabolically inert,
infectiousagent that replicates only within the cells of living hosts, mainly bacteria, plants, and animals:
composed ofan RNA or DNA core, a protein coat,
and, in more complex types, a surrounding envelope.
Virus,explained in everyday words,
is an extremely tiny particle that causes an infectious disease.
It is generally made up of some RNA or DNA coated in protein.
It can only multiply inthe cell of hosts that are alive.
That means, technically, viruses are not themselves living.
In informal contexts,
virus is also commonly used to refer to the disease caused by thevirus.
And of course,
virus has another special meaning when it comes to computers.
Where does the word virus come from?
The word virus entered English around 1590–1600.
It comes directly from the Latin vīrus, meaning “slime, poison.”
The adjective virulent isalso ultimately derived from the Latin vīrus.
In medicaland scientific settings,
virulent specifically means “highly infective”
or “causing clinical symptoms.”
More generally,
virulent can mean
“actively poisonous,”
“violently hostile,” or
“intensely bitter.”
What does bacteria mean?
Our full, formal definition of bacteria:
Bacteria are ubiquitous
one-celledorganisms, spherical, spiral, or rod-shaped
and appearing singly or in chains,
comprisingthe Schizomycota,
a phylum of the kingdom Monera
(in some classification systems the plant class Schizomycetes),
various speciesof which are involved
in fermentation, putrefaction, infectious diseases, or nitrogen fixation.
Bacteria explained ineveryday words:
One-celled organisms that sometimes cause infectious diseases
but, very often, areessential to keeping us healthy or are harmless.
They come in three shapes, resembling a sphere, spiral, or rod.
We generally refer to bacteria justlike that: bacteria.
But note that bacteria istechnically
the plural form of the singular bacterium.
(You can blame that on Latin.)
You might need to use bacterium
when discussing the specific kind of bacteria
that causes a disease,
such as: Yersinia pestis, which causes the plague.
Where doesthe word bacteria come from?
Bacteria isfirst recorded in English around 1905–10.
Bacterium isolder, evidenced by 1840–50.
Both words ultimately come, via Latin,
from the Greek baktēría, meaning“staff.”
Remember how we mentioned that bacteria comein three shapes?
The Greek baktēría is related to the Latin word bacillus,
a name for rod-shaped bacteria.
Sphere-shaped bacteria are also referred to as coccus (cocci in the plural; again, thanks Latin).
You may have encountered coccus in streptococcus,
which can cause strep throat.
What are some otherdifferences between a virus and bacteria?
As we noted in the intro,
a pathogen is an agent thatcan cause a disease,
especially a virus or bacterium.
Some fungi and algae can be pathogenic, too.
Viruses cause infection,
and thoseinfections very often result in disease.
Bacteria can sometimes causeinfectious disease, too,
but a great deal ofbacteria are completely harmless or even beneficial.
(Think of all those good bacteria you’re supposed to get from yogurt.)
Because viruses aren’t technically alive,
they also aren’t technically microorganisms.
A microorganism is“any organism too small to be viewed
by the unaided eye, asbacteria, protozoa,
and some fungi and algae.”
Another word for a microorganism is a microbe.
However, microbe is often used specifically to refer to pathogenic
(disease-causing) bacteria.
And because viruses aremicroscopic and infectious,
they are alsosometimes referred to as microbes.
An everyday term for microbes is germs.
Yeah, we know it’s confusing. Language—just as life—can get messy.
Vaccine vs. antibiotics
Another area of difference
between viruses and bacteria concerns what treats them.
Both vaccines and antibiotics areused to treat infectious diseases.
There are vaccines that workagainst both viruses and bacterias.
Antibiotics,however,
only work againstbacteria and other microorganisms.
What does vaccine mean?
A vaccine isany preparation used as a preventive inoculation
to confer immunity againsta specific disease,
usuallyemploying an innocuous form of the disease agent,
such as killed or weakened bacteria or viruses,
to stimulate antibody production.
What does antibiotic mean?
An antibiotic is any of a large group of chemical substances,
as penicillin or streptomycin,
produced byvarious microorganisms and fungi,
having the capacityin dilute solutions to inhibit the growth
of or to destroy bacteria and other microorganisms,
used chieflyin the treatment of infectious diseases.
What are different types of viruses?
COVID-19 isthe disease caused by the novel coronavirus.
Coronavirus isa family of viruses that includes SARS and MERS.
The flu is also caused by viruses, but the novel coronavirus is not the flu.
There are many types of flus.
Different strainsof what’s known as the H1N1 virus
have caused some particularly lethal pandemics,
including the 2009 swine flu and 1918 pandemic flu,
commonly referred to as the Spanish flu.
There are many types of other viruses
that you have probably heard of, notably hantavirus and HIV.
Some diseases caused by viruses
include chickenpox, Ebola, polio, and smallpox.
Seasonal flus and, yes, the common cold are viral infections, too.
What does flu mean?
The word flu is short for influenza
—borrowed from Italian and from the same Latin root
that gives English the word influence.
Formally defined,
influenza isan acute, commonly epidemic disease,
occurringin several forms.
It is causedby numerous rapidly mutating viral strains
and characterized by respiratory symptoms and general prostration.
General prostration?
That’s another way of saying “I just can’t get out of bed.”
And on that note, stay safe, stay at home when you can, and wash your hands.
That will help you, and others, avoid general prostration—or worse.
Dictionary.com
HOMEWORK HELP
What is a virus?
A virus isan ultramicroscopic agent
that can only reproduce inliving cells and is spread through infection.
Many viruses cause diseasesas part of their reproduction process.
Viruses are only 20 to 300 nanometers
—so small that even microscopes can’t seethem.
Viruses are also very simple.
They consist of a core made of DNA or RNA,
a protein coat that surrounds the core,
and sometimes an envelope that surrounds the core.
A virus can’t reproduceon its own.
Instead, it will infecta living cell
and force itto make more copies of the virus.
When the virus does this,
it stops the cell from whatever it was doing before
and, eventually, kills the cell.
Viruses are infectious,
meaning they often cause symptoms
that allow fluidswith copies of the virus to spread to otherorganisms.
For example,
if you have the flu and cough on another person,
your virus-containing saliva and mucus
will enterthe other person’s body
and allow the virus toinfect their cells.
Because viruses remaininside living cells,
it is often impossibleto kill the virus without also killing the cell.
Usually, your immune system
is the only thing that can safely fight a virus.
Why is virus important?
Viruses areresponsible for some of the most deadly,
incurablediseases we have today.
In 2019, a new type of coronavirus
(a family of viruses thatoften cause respiratory illnesses)
was the cause of a deadly disease known COVID-19
(short for coronavirus disease 2019), which became a worldwide pandemic.
Viruses have also been responsible for other serious diseases,
such as HIV (short for human immunodeficiency virus),
that causes AIDS,
a disease in which the immune system gradually breaks down
and often leads to cancer.
Because viruses are so hard to kill
and some can make you very sick,
we try to prevent viruses frominfecting us in the first place.
Washing your hands,not breathing on people,
and staying home when you are sick witha virus
all help preventthe virus from spreading.
Vaccines are used to train your immune system
to better fight specific viruses.
Sometimes, antiviral medications
can interferewith the virus’s ability to take over a cell
or treat the symptoms of the virus rather than attackthe virus itself.
Dictionary.com
What Are Antibodies, And Do They KillViruses?
Terms and concepts to understand coronavirus antibody testing
by John Kelly, Senior Research Editor at Dictionary.com
Testing continues to be a major story
—and concern—amid the COVID-19 pandemic.
This includes diagnostic testing
to determine if one is infected with the virus that causes COVID-19.
It also includes serological tests todetermine
if a person has antibodies thatcan signal immunity to COVID-19.
But what does serological mean,
and what are antibodies, for that matter?
As the coronavirus pandemic evolves,
we know that vocabularyand concepts evolve with it.
Continuing our mission to keep you informed and up-to-date,
we’re providing a primer to very complicated topics,
and terms, in immunology
—complete with a handy glossary to all thingsantibodies at the end
and some checkmarks () to help you digest the key takeaways along the way.
What is immunity?
Before we can discuss antibodies,
we need to take a big-picture look at the immune system.
The immune system is an incredibly complex network of cells
that identifyand defend against foreign substances in your body.
It includes the thymus, spleen, lymph nodes
and lymph tissue, stem cells, white blood cells, antibodies, and lymphokines.
One major type offoreign substances
the immune system fends off are pathogens:
infectious agents, especially viruses and bacteria, that cause disease.
Your body has immunity whenit is resistant to a particular disease.
This immunity is usually indicated
by the presence of a critical part of the immune system: antibodies.
Antibodies vs. antigens
Antibodies arespecial protein molecules
that the immune system produces in response to antigens.
And antigens are substances that can
stimulate the body’s production of antibodies.
Now, there are differenttypes of antigens,
but, for our purposes here, let’s zoom in
on foreign, disease-causingantigens.
These are harmful substances
that come from outside the body,
such as fromviruses or bacteria.
The body wants to fight antigens off,
So, it recognizes these substances and starts makingantibodies.
Antibodies are able to latch onto the antigens
using a unique binding site, which then disables the invaders.
Put simply,
the body makes antibodies to fend off germs
and other harmful substances.
And this process is part of the body’s immune response.
How antibodies work
Antibodies are produced by B cells, also called B lymphocytes,
which are made in bone marrow
and found in the blood and lymph.
Antibodies have a distinctive Y shape, which is key to how they work.
At the tips of antibodies arethe unique sites
where they bind with a matching site onantigens
—and destroy them.
Abbreviated as Ab, antibodies are
also referred to as immunoglobulins, abbreviated as Ig.
Specifically,
immunoglobulins arethe special proteins that function as antibodies.
They are found in plasma (theliquid part of blood and lymph),
other body fluids, and in the membrane of certain cells.
There are five classes of immunoglobulins,
which can be described by
wherethey are found and what their function is:
- 1. IgA (immunoglobulin A):
found in breathing and digestive passages
as well as in saliva, tears, and blood, among other places;
helps protectsurfaces
thatare exposed to foreign substances
from outside the body
- 2. IgD (immunoglobulin D):
found in cellsin tissues in the chest and belly;
function asreceptors; least understood of the immunoglobulins
- 3. IgE (immunoglobulin E):
found in lung, skin, and mucous membranes;
helpexpel parasites in the intestines and
are involvedin allergic reactions
- 4. IgG (immunoglobulin G):
found in all body fluids;
critical to fighting infections from viruses and bacteria;
only antibodies
that canpass over the placenta from mother to fetus;
most common but smallestantibody
- 5. IgM (immunoglobulin M):
found in blood and lymph fluid;
firstantibody to respond to an infection; largest antibody
IgG and IgM are two of the key players in your body
when it comes to warding off infectious diseases.
What is serum?
Among other proteins, blood serum contains antibodies,
which, as we saw above, indicate immunity to a specific disease.
Serum is a clear, pale-yellow liquid
that separates outfrom the clot when blood is coagulated.
When antibodies areidentified
in the blood serum of animals with an immunity to a disease,
the serum may be injected into other animals
in an efforttotransfer that immunity.
Word break:
where does the word serum come from?
Serum derives directly from the Latin serum, meaning “whey.”
Blood serumwas originally likened to whey,
the watery liquid that isseparated out from curds
in the cheese-making process.
The adjective form of serum is serous
—not to be confused with serious,
though serum is indeed a serious matter.
What is a serological test?
Now, the combining formof serum is sero–,
which appears ina number of intimidating-seeming words
that frequently come up in discussions of infectious disease.
Serology (literally, “study of serum”)
is the science dealing with
the immunological properties and actions of serum.
Its adjective is serological, and a specialist in serology is a serologist.
One major job ofserologists is to test serum for antibodies.
A serological test,also called an antibody test,
detects antibodies in the blood
when the body’s immune system is responding to a specific infection.
Serological tests determine your serostatus:
whether or not you have
detectableantibodies against a particular antigen.
Your serodiagnosis can be seropositive
(your serum tests positive for detectable antibodies against the antigen)
or seronegative (your serum tests negative for detectable antibodies against the specific antigen).
Seropositive, in everyday terms,
means you havethe antibody to fend off a particular disease.
Now, when a person developsthose specific antibodies
when they were notpreviously detectable,
that process is known as seroconversion.
Seroconversion happensas a result of infection or immunization,
which leads us to our final important distinction.
For more serological terms,
see the definitions of seroprevalence, seroprotection, serosurvey, and serosurveillance
from the World Health Organization included in our glossary.
Active immunity vs. passive immunity
Quick review:
your body has immunity when it is resistant to a specific disease.
Now, there are two ways the body develops this all-important immunity:
passive immunity and active immunity.
Passive immunity
provides moretemporary protection from the injection of antibodies
(or certain lymphocytes) from other immune organisms.
One of the most common sourcesof passive immunity in humans
is the transfer of antibodies through the placenta to infants.
Active immunity
is protection resulting from your own immune system.
It is much longer lasting, and sometimes lasts for a person’s entire life
—making it much more advantageous.
There are two ways to gain active immunity to a specific disease:
- Surviving infection with the actual disease (natural immunity)
- Getting a vaccine of a killed or weakened form of the disease (vaccine-induced immunity)
Passive immunity results from
when a persoฝn is given antibodies to a disease.
Active immunityresults from
when a person producestheir own antibodies
through exposureto the disease.
Both vaccines andantibiotics are used to treat infectious diseases.
There are vaccinesthat work against both viruses and bacterias.
Antibiotics, however,
only work againstbacteria and other microorganisms.
Vaccines stimulate antibody production in the body.
Antibiotics inhibit the growth of
or destroy bacteria or other microorganisms.
Antibodies andcoronavirus treatment
So, what does this all mean forCOVID-19?
Serological tests for antibodies to COVID-19 areimportant.
As the Food and Drug Administration explains:
“Experience with other viruses suggests that
individuals whose blood contains antibodies
associated with SARS-CoV-2 infection
—provided they are recovered and notcurrently infected with the virus
—may be able to resume work and other daily activities in society.
They may also be eligible to serve
as potential donors of convalescent plasma.”
Serological testscan also greatly help
the medical community understand immune responseto COVID-19.
But, current tests have limitations
(none have been validated for diagnosing infection with COVID-19,
for instance),
and there are concerns about their reliability
(some have yielded false positives).
Furthermore, the WHO reports:
“There is currently no evidence
that people who have recovered from COVID-19
and have antibodies are protected from a second infection.”
For health, safety, and medical emergencies
or updates on the novel coronavirus pandemic,
please visit the CDC (Centers for Disease Control and Prevention) and WHO (World Health Organization).
For more words related to the coronavirus,
see our full glossary and our dictionary updates.
Merriam-Webster Dictionary
Is bacteria singularor plural?: Usage Guide
In its established and uncontroversial uses,
bacteria isthe plural of bacterium.
Although the singular use of bacteria
is often identified as an error to be avoided,
it is common in published writing.
The plural form bacterias isalso seen but is relatively rare.
The bacteria seems to prefer living in water
and is more resistant to chlorine
and elevated water temperatures than other bacterias. — Allan Bruckheim
Merriam-Webster Dictionary
Usage Notes
'Virus' vs. 'Bacteria'
The key differences between two common pathogens
What to Know
While both can cause disease,
viruses are notliving organisms, whereas bacteria are.
Viruses are only "active" within host cells which they need to reproduce,
while bacteria are single-celled organisms
that produce their own energy and can reproduce on their own.
Bacteria serve many vital roles innature outside of being infectious.
The two most common causative agents
of infectious disease are the virus and bacterium.
Both of these pathogens areinvisible to the naked eye,
allowing for their stealthy transfer fromperson to person
during an outbreak of a contagious disease.
While they rightly share a nasty reputationas disease agents,
their properties apart from the harm they cause are quite dissimilar.
What is the Differencebetween Viruses and Bacteria?
Living or Not
Viruses are notliving organisms, bacteria are.
Viruses only grow and reproduceinside of the host cells they infect.
When found outside of these living cells, viruses are dormant.
Their “life” therefore
requires the hijackingof the biochemical activities of a living cell.
Bacteria, on the other hand, are living organisms that consist of single cell that can generate energy, make its own food, move, and reproduce (typically by binary fission).
This allows bacteria to live in many places
—soil, water, plants, and the human body
—and serve many purposes.
They serve many vital roles in nature
by decomposing organic matter
(maybe not that vital to anyone
who's forgotten leftovers in the back of the fridge)
and by converting nitrogen, through nitrogen fixation,
to chemicals usable byplants.
Bacteria even know how to work as a team
through something called quorum sensing.
Size
Bacteria aregiants when compared to viruses.
The smallest bacteria are about 0.4 micron (one millionth of a meter)
in diameter
while viruses range in size from 0.02 to 0.25 micron.
This makes most viruses submicroscopic,
unable to be seen in an ordinary light microscope.
They are typically studied with an electron microscope.
Mode of Infection
Their mode ofinfection is different.
Because of their distinct biochemistry,
it should come as no surprise that bacteria and viruses differ
in how they cause infection.
Viruses infect a host cell and thenmultiply by the thousands,
leaving the host cell and infecting other cells of the body.
A viral infection will therefore be systemic,
spreading throughout the body.
Systemic diseases caused by viral infection include influenza, measles, polio, AIDS, and COVID-19.
Pathogenic bacteria have a more varied operation
and will often infect when the right opportunity arises,
so called opportunistic infection.
The infection caused by pathogenic bacteria
is usually confined toa part of the body,
described asa localized infection.
These infections may be caused by the bacteria themselves
or by toxins (endotoxins) they produce.
Examples of bacterial disease
include pneumonia, tuberculosis, tetanus, and food poisoning.
How VirusesInteract with Bacteria
Viruses can infectbacteria.
Bacteria are not immune to viral hijackers
which are known as bacteriophages
—viruses that infect bacteria.
We don’t want to judge,
but this may be one morereason
to put viruses one notchhigher in the nasty germs hierarchy.
American Heritage® Dictionary of the English Language,
bacterial adjective
Usage
It is important to remember that
bacteria is the plural of bacterium,
and that saying a bacteria is incorrect.
It is correct to say
The soil sample contains millions of bacteria,
and Tetanus is caused by a bacterium.
