Transcript Slide 1

MICROBES AND DISEASES
A microbe is anything too small to
be seen without a microscope
Microbes are in the water you drink, the
food you eat, and the air you breathe they are everywhere.
About 95% are good for us.
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MICROORGANISMS THAT CAUSE
DISEASES
These are called PATHOGENS.
They include:



Viruses
Bacteria
Fungi
The body’s natural barriers:
• The skin stops microorganisms getting into the body
• Sweat forms an extra protective layer over the skin
• Tears contain chemicals that can kill bacteria
• Stomach acid can kill bacteria in food and water
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MICROBES CAN CAUSE DISEASES
viruses
bacteria
fungi
influenza (flu)
food poisoning
ringworm
mumps
sore throats
athlete’s foot
chickenpox
tuberculosis (TB)
smallpox
tetanus
polio
cholera
rabies
typhoid
German measles
whooping cough
viral
meningitis
bacterial
meningitis
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SYMPTOMS–SIGNS OF A DISEASE
(ILLNESS) NOT NORMAL
These can be caused by cell damage or by
toxins (poisons)
A rash Fever Swelling Vomiting Diarrhoea
www.germancarzone.com
www.somerset.gov.uk
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MORE SYMPTOMS
Cough
Dizziness Pain Breathing problems
Sneezing
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They infect cells and use
them to make many more
viruses. They cannot reproduce
by themselves.
Once inside the cell, viral DNA
replicates (makes an identical
version of) itself 1000’s of times.
They then burst out of the host
cell into the bloodstream,
destroying the cell.
Examples: cold, flu, measles,
mumps, rubella, HIV.
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VIRAL DISEASES
These diseases are caused by infections of
viruses.
 These infections cannot be cured by
antibiotics e.g. penicillin.

www.medem.com
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MUMPS
www.mullhaven.co.uk
www.immunizationed.org
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MUMPS

Mumps Virus


news.bbc.co.uk


Mumps is an infectious disease caused by the
mumps virus.
Mumps normally affects children, but can occur
at any age.
Immunisation is offered to all children in
the UK. It is part of the MMR (Measles,
Mumps and Rubella) vaccine. Two doses are
usual - the first aged 15 months and the
second about three years later.
MMR vaccine gives very good protection, and
so mumps is now rare in the UK.
Possible complications – infertility in males
over the age of 12 and miscarriage in 12-16
weeks of pregnancy.
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MEASLES
Measles rash
www.uspharmacist.com
www.historyforkids.org
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MEASLES
Measles virus
www.wales.nhs.uk
Measles is one of the most
contagious (it goes from one person to
another easily) of all human viruses.
Measles causes rash, cough, and
fever, and can lead to ear infection,
pneumonia, conjunctivitis, diarrhoea,
brain damage, and death.
Any doctor who suspects that a patient
has measles is required by law to report
it.
Measles infection can be prevented
by a highly effective and safe vaccine
which is part of the measles-mumpsrubella (MMR) immunisation.
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RUBELLA

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Symptoms are a rash and fever
for two to three days.
Complications - Birth defects if
acquired by a pregnant
woman.
Spread by contact with an
infected person, through
coughing and sneezing
commons.wikimedia.org

Vaccine - Rubella vaccine
(contained in MMR vaccine)
can prevent this disease.
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CHICKENPOX
health.nytimes.com
•Chickenpox is caused by a virus.
•Chickenpox is a mild, but highly
infectious disease that most
children catch between 2-8 years of
age, although you can develop
chickenpox at any age.
•You are infectious from about two
days before the rash appears until
roughly five days after, when all of
the blisters have fully crusted over.
•Once you have had chickenpox,
you will very rarely catch
chickenpox for a second time.
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MORE VIRAL DISEASES
Cold Sore
/www.lipclear.com
Warts
Shingles
Polio
www.healthcentral.com
Verruca
commons.wikimedia.org
www.nytimes.com
www.sorefeet.co.uk
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BACTERIA
•Single celled organisms
that can multiply rapidly.
They are bigger and more
complex than viruses and
can reproduce by
themselves.
www.braintree.gov.uk
www.associatedcontent.com
•Attack tissues in host
(person infected) and
release toxins (poisons).
•Examples: food
poisoning, cholera and
whooping cough.
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BACTERIAL INFECTIONS

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These diseases are caused by infections of
bacteria.
These infections can be cured by antibiotics e.g.
penicillin (unless resistant).
Antibiotics are substances that harm
bacteria. Some antibiotics
stop the bacteria reproducing
and others kill the bacteria.
www.irishhealth.com
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ANTIBIOTIC RESISTANCE IN BACTERIA
Many bacteria have resistance to antibiotics
(they are not killed by the antibiotic), so we
need a range of antibiotics to fight diseases.
We must use the best one for the job.
 To slow down more antibiotic resistance
developing in pathogenic bacteria we need to
avoid over-using antibiotics or only use them
when really necessary and always finish the
course.
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TUBERCULOSIS
Tuberculosis bacteria
www.nlm.nih.gov

Tuberculosis (T.B.)is
usually a disease of the
lungs.

The risk factors for
getting TB include poor
diet and hygiene, closecontact situations,
alcohol and drug abuse,
certain diseases and
occupations (e.g.
health-care workers).
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SALMONELLA (FOOD POISONING)
Salmonella bacteria

www.associatedcontent.com

Salmonella is a type of
bacteria. It is usually found in
chicken, eggs, fish, meat and
water.
The salmonella bacteria attack
the stomach and intestines.
The bacteria attack all age
groups and both sexes.
Children, the elderly and
people who are already ill are
much more likely to get a
serious infection.
Symptoms include vomiting,
diarrhoea, strong stomach
pain and fever.
www-structmed.cimr.cam.ac.uk
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GANGRENE
Gangrene is caused by a
bacterial infection.
www.anaesthetist.com
Gangrene can happen when a
cut or surgical wound
becomes infected with
bacteria. The bacteria can
spread under the skin or through
the blood to cause a total body
infection.
Some of these bacteria make
poisons (toxins) that flow into the
body, destroying tissues and
causing severe illness or death.
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FUNGAL INFECTIONS
These diseases are caused by infection by
fungi.
 These infections can be cured by fungicides

www.harmonytoronto.com
www.beliefnet.com
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ATHLETES FOOT
Athlete's Foot is a fungal
infection. It is common in
athletes or those taking
part in sports regularly.
http://toenailbuddy.com
shopping.msn.com
 It is normally caught in
changing rooms or showers
because the fungus likes a
moist (wet) environment.
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RINGWORM
The fungi that cause
ringworm generally enter the
body through a break in the
skin.
Animals can have ringworm
and can pass it on to humans.
Children who come into close
contact with their pets, farmers
and people who work with
animals, are more at risk.
aboutringworm.info
Ringworm can also be
caught through person-toperson contact.
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IMMUNITY
= the body’s ability to resist infection
The immune system’s job is to kill any
organisms that enter the body
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WHITE BLOOD CELLS DEFEND THE BODY!
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White blood cells are always used
in fighting off microbes and are
responsible for building up
immunity to disease.
www.regentsprep.org
One type of white blood cell attacks
anything that is ‘foreign’ or not
meant to be there. It surrounds the
microbe and digests (eats)it.
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Another type of white blood cell attacks only
certain microorganisms.
Every pathogen has unique molecules (antigens) on its
surface; when white blood cells don’t recognise these
antigens, they start to produce antibodies, which lock onto
and kill the pathogens.
www.web-books.com/
Once a white blood cell recognises the antigens on a pathogen, it divides
quickly to make more antibodies to fight the infection. Some of these cells stay
in the blood and ‘remember’ the antigens, so that they can quickly produce
lots of antibodies if the body gets infected again – that’s why you are usually
immune to most diseases you have had in the past.
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VACCINES
A vaccine is usually made of the same or
similar cells that could make you sick, but
they are weak or inactive.
 When a vaccine goes into the body, the
immune system responds the same way it
would to any germ. The vaccine is easier to
fight than the illness you’re being vaccinated
against and it won’t make you sick while your
immune system fights it.
Once the immune system works out how to
fight and kill the antigens, it remembers what
works against them and protects your body in
future.
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VACCINATION – GOOD OR BAD?
Advantages
 It prevents disease
 Big outbreaks of a disease
(epidemic) can be prevented
if many people have been
vaccinated
 Some diseases have been
stopped completely
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VACCINATIONS
Disadvantages
They cannot be completely safe for
everyone.
 Some people have side effects e.g. painful
arm for a short time, high temperature
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SOME PEOPLE MAY NOT WANT TO DO
WHAT IS BEST FOR SOCIETY
Some people are worried about possible side
effects and refuse to let their children be
vaccinated – even though getting the disease
may be worse than the side effects
 There must be enough people who are
vaccinated to control the disease – people who
refuse vaccination benefit because everyone
else has been vaccinated. Is this fair?
 Should people be forced to have vaccinations
for the good of everybody?

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