Welcome To the Department of microbiology Tansian University: Microbial

Infections and its occurence

Infection is a process in which bacteria, 
viruses, fungi or other organisms enter 
the body, attach to cells, and multiply. To 
do this, they must evade or overcome the 
body's natural defenses at each step. 
Infections have the potential to cause 
illness, but in many cases the infected 
person does not get sick.
KEYWORDS
for searching the Internet and other 
reference sources.
Antibiotics
Immunization
Infection
Inflammation.
HOW DOES INFECTION OCCUR?
Organisms that can cause illness are all 
around us: in air, water, soil, and food, 
as well as in the bodies of animals and 
other people. Infection occurs when 
some of them get past a series of natural 
defenses. Those defenses include:
*  Skin: The skin physically blocks germs, 
but may let them in if it is cut or 
scraped. 
*  Coughing deeply: This expels germs from 
the lungs and breathing passages but 
may be less effective for weak, sick, or 
injured people. 
*  Bacteria: Called "resident flora," harmless 
bacteria normally are present in some 
parts of the body. They compete with 
harmful germs and crowd them out. But 
they can be weakened or killed by 
medications, allowing harmful germs to 
thrive and cause illness. 
Inflammatory response: This is produced 
by the body's immune system. Certain 
kinds of white blood cells—including 
macrophages and neutrophils—surround 
and destroy or otherwise attack any kind 
of germs, often causing fever, redness, 
and swelling. 
*  Antibodies: These are proteins produced 
by the immune system. Some are 
targeted to attack specific microbes. This 
response is also called humoral 
immunity. Usually these antibodies are 
produced after a person is infected by or 
exposed to the microbe. 
The immune system's responses may fail 
if the germs are too numerous, or if they 
are too virulent. "Virulent," from the 
Latin for "poisonous," describes germs 
that are particularly good at countering 
the body's defenses. For instance, some 
microbes can prevent antibodies from 
forming against them. Another 
important factor is the functioning of the 
immune system. If it is damaged— 
weakened, for instance, by age or illness 
—infection is more likely. Babies tend to 
get more infections because their 
immune systems have not yet learned to 
recognize and attack some microbes.
WHERE DOES INFECTION OCCUR?
Localized infections
Localized infections remain in one part 
of the body. Examples include a cut on 
the hand that gets infected with bacteria, 
but does not cause problems anywhere 
else. Localized infections can be very 
serious if they are internal, such as in 
the appendix (appendicitis ) or in the 
heart (endocarditis ).
Systemic infections
Most serious infections, however, occur 
when the microorganisms spread 
throughout the body, usually in the 
bloodstream. These are called systemic 
infections, and they include flu, malaria, 
AIDS, tuberculosis, plague, and most of 
the infectious diseases whose names are 
familiar.
How Do Infections Lead To Illness?
The major causes of infection are 
viruses, bacteria, fungi, and parasites, 
including protozoa (one-celled 
organisms), worms, and insects such as 
mites (which cause scabies) and lice. 
Bacteria can release toxins, or poisons. 
Viruses can take over cells and prevent 
them from doing their normal work. 
Bacteria and fungi—and larger infective 
agents like worms or other parasites— 
can multiply so rapidly that they 
physically interfere with the functioning 
of the lungs, heart, or other organs. The 
immune response itself—which can 
bring fever, pain, swelling, and fatigue— 
often is the major cause of the sick 
feelings an infected person gets.
Do Infections Always Cause Illness?
No, often they do not. Of people infected 
with tuberculosis bacteria, for instance, 
only about one in ten will ever get sick. 
Some viruses and parasites, too, can 
remain in the body a lifetime without 
causing illness. In such cases, called 
latent infection, people usually get sick 
only if the immune system weakens.
How Do Infections Spread?
The organisms that cause infections may 
spread through water, soil, food, or air; 
through contact with an infected 
person's blood, skin, or mucus ; through 
sexual contact; or through insect bites. 
Most germs spread by a couple of these 
routes; no one microbe spreads in all 
these ways. In addition, many disease- 
causing microbes can spread from a 
pregnant woman to her fetus. When this 
happens, we say the baby is born with a 
congenital infection.
What Are The Symptoms Of Infection?
The symptoms vary greatly depending on 
the part of the body and type of 
organism involved. The first sign of 
bacterial infection is often 
inflammation : fever, pain, swelling, 
redness, and pus. By contrast, viral 
infections less commonly cause 
inflammation but may cause a variety of 
other symptoms, from a runny nose or 
sore throat to a rash or swollen lymph 
nodes * .
What Is The Treatment For Infection?
The main treatment is usually 
medication: antibiotics for bacterial 
infections; antiviral drugs for some 
viruses (for most there is no treatment); 
antifungal medications for fungus 
infections; and antihelmintic drugs for 
worms. In some cases of localized 
infection, as when an abscess or 
collection of pus forms, surgery may be 
necessary to drain the infected area.
How Are Infections Prevented?
Disinfecting wounds
When a wound occurs, infection may be 
prevented by washing and covering the 
wound, using antibacterial ointment or 
spray, and getting medical attention if 
the wound is serious.
Immunization
Many systemic infectious diseases can be 
prevented by immunization. Among 
them are chickenpox, cholera, 
diphtheria, hepatitis A and hepatitis B, 
influenza, Lyme disease, measles, 
mumps, pertussis (whooping cough), 
pneumococcal pneumonia, polio, rabies, 
rubella (German measles), tetanus, 
typhoid fever, and yellow fever. 
Hygiene, sanitation, and public health 
Many other systemic infections can be 
prevented by having a clean public 
water supply and a sanitary system for 
disposing of human wastes; by washing 
hands before handling food; by cooking 
meats thoroughly; by abstaining from 
sexual contact; and by controlling or 
avoiding ticks and mosquitos.
* lymph nodes are round masses of tissue 
that contain immune cells to filter out 
harmful microorganisms. During 
infections, lymph nodes may become 
enlarged.
See also 
Bacterial Infections 
Fungal Infections 
Immunodeficiency 
Parasitic Diseases 
Viral Infections 
Worms

Infections and its occurence

Infection is a process in which bacteria, viruses, fungi or other organisms enter the body, attach to cells, and multiply. To do this, t...

Microbial

MICROBES CAN CAUSE DIFFERENT KINDS OF INFECTION. 
  
Some disease-causing microbes can make you 
very sick quickly and then not bother you again. 
Some can last for a long time and continue to 
damage tissues. Others can last forever, but you 
won’t feel sick anymore, or you will feel sick only 
once in a while. Most infections caused by 
microbes fall into three major groups:
* Acute infections 
* Chronic infections 
* Latent infections
ACUTE INFECTIONS 
Acute infections are usually severe and last a 
short time. They can make you feel very 
uncomfortable, with signs and symptoms such as 
tiredness, achiness, coughing, and sneezing. The 
common cold is such an infection. The signs and 
symptoms of a cold can last for 2 to 24 days 
(but usually a week), though it may seem like a 
lot longer. Once your body’s immune system has 
successfully fought off one of the many different 
types of rhinoviruses or other viruses that may 
have caused your cold, the cold doesn’t come 
back. If you get another cold, it’s probably 
because you have been infected with other cold- 
causing viruses.
CHRONIC INFECTIONS 
Chronic infections usually develop from acute 
infections and can last for days to months to a 
lifetime. Sometimes people are unaware they are 
infected but still may be able to transmit the 
germ to others. For example, hepatitis C, which 
affects the liver, is a chronic viral infection. In 
fact, most people who have been infected with 
the hepatitis C virus don’t know it until they have 
a blood test that shows antibodies to the virus. 
Recovery from this infection is rare—about 85 
percent of infected people become chronic 
carriers of the virus. In addition, serious signs of 
liver damage, like cirrhosis or cancer, may not 
appear until as long as 20 years after the 
infection began.
LATENT INFECTION
Latent infections are “hidden” or “silent” and may 
or may not cause symptoms again after the first 
acute episode. Some infectious microbes, usually 
viruses, can “wake up”—become active again but 
not always causing symptoms—off and on for 
months or years. When these microbes are active 
in your body, you can transmit them to other 
people. Herpes simplex viruses, which cause 
genital herpes and cold sores, can remain latent 
in nerve cells for short or long periods of time, or 
forever.
Chickenpox is another example of a latent 
infection. Before the chickenpox vaccine became 
available in the 1990s, most children in the United 
States got chickenpox. After the first acute 
episode, usually when children are very young, the 
Varicella zoster virus goes into hiding in the body. 
In many people, it emerges many years later when 
they are older adults and causes a painful disease 
of the nerves called herpes zoster, or shingles. 
Researchers are studying what turns these 
microbial antics off and on and are looking for 
ways to finally stop the process

Microbial

MICROBES CAN CAUSE DIFFERENT KINDS OF INFECTION. Some disease-causing microbes can make you very sick quickly and then not bother you a...

What Are Microbes?

Microbes are single-cell organisms so tiny that millions can fit into the eye of a needle. 
 They are the oldest form of life on earth. Microbe fossils date back 
 more than 3.5 billion years to a time when the Earth was 
covered with oceans that regularly reached the boiling point,
 hundreds of millions of years before dinosaurs roamed the 
earth. Without microbes, we couldn’t eat or breathe. Without us, they’d probably be just fine. Understanding microbes is vital to understanding the past and the future of ourselves and our planet.
 
Microbes <my-crobes> are everywhere. There are more of them on a person's hand than there are people on the entire planet!

Microbes are in the air we breathe, the ground we walk on, the food we eat—they're even inside us!

We couldn't digest food without them—animals couldn't, either. 
 Without microbes, plants couldn't grow, garbage wouldn't decay and 
there would be a lot less oxygen to breathe.

In fact, without these invisible companions, our planet wouldn't survive as we know it!

<h3>
Our Challenge: How are we going to solve the case of what a microbe is when they're so small they're invisible to us?</h3>
Microbe is a term for tiny creatures that individually are too small 
 to be seen with the unaided eye. Microbes include <a href="http://www.microbeworld.org/types-of-microbes/bacteria?id=138" title="Bacteria">bacteria</a> (back-tear-ee-uh), <a href="http://www.microbeworld.org/types-of-microbes/archaea?id=149" title="Archaea">archaea</a> (are-key-uh), <a href="http://www.microbeworld.org/types-of-microbes/fungi?id=127" title="Fungi">fungi</a> (fun-jeye) and <a href="http://www.microbeworld.org/types-of-microbes/protista?id=117" title="Protists">protists</a> (pro-tists).
 You've probably heard of bacteria and fungi before. Archaea 
are bacteria-like creatures that have some traits not found 
in any true bacteria. Protists include primitive algae (al-gee), amoebas (ah-me-buhs), slime molds and protozoa (pro-toe-zoh-uh). We can also include <a href="http://www.microbeworld.org/types-of-microbes/viruses?id=108" title="Viruses">viruses</a> (vye-rus-is)
 as a major type of microbe, though there is a debate as to 
whether viruses can be considered living creatures or not.

To solve the case of what a microbe is, we have to use tools such as 
 high-power microscopes. Let's zoom in on some microbes and 
see what a few of these strange creatures look like.

As you can see, microbes come in many varieties. They may live as individuals or cluster together in communities.

<h3>
So how small are microbes?</h3>
<img alt="baseball" height="60" src="http://www.microbeworld.org/images/stories/whatisamicrobe/baseball.gif" style="float: left; margin: 5px;" width="163" />Well, let's say we could enlarge an average virus, the smallest of all microbes, to the size of a baseball.

<img alt="baseballmound" height="50" src="http://www.microbeworld.org/images/stories/whatisamicrobe/baseballmound.gif" style="float: right; margin: 5px;" width="97" />An average bacterium would then be the size of the pitcher's mound.

<img alt="baseballpark" height="75" src="http://www.microbeworld.org/images/stories/whatisamicrobe/baseballpark.gif" style="float: left; margin: 5px;" width="84" />And just one of the millions of cells that make up your body would be the size of the ballpark!

Continue reading the other parts of this section of the site to find 
out more about the different types of microbes and what they 
do.

What Are Microbes?

Microbes are single-cell organisms so tiny that millions can fit into the eye of a needle. They are the oldest form of life on...