Transcript Pathogens - 12biolcsc

Pathogens
Disease causing agents
Plague!
17th
Century:
Europe
Bubonic
plague
outbreak, kills
tens of
millions.
People tried
to prevent
catching it by
filling nosecovers with
fragrance
1997 – 2004:
worldwide
1900:
Sydney
2009: worldwide
Bubonic plague:
rats were killed
to prevent the
movement of
the disease
Avian influenza: particular
strain (H5N1) infects
humans. Technology used
to notify of changes in
immigration of humans
and animals. Relenza
(drug) used to treat human
patients
H1N1 influenza
virus (swine flu).
Most common
human flu in 2009.
Antiviral drugs like
Zanamir used to
treat patients
Disease
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Anything that harms an individual.
Inherited: genetic disorders (Unit 4)
Deficiencies: not enough of a particular
nutrient
Infectious disease: caused by pathogens
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Non-cellular (prions/viruses)
Cellular (microorganisms like bacteria or fungi)
Pathogens
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Are any parasites (organisms living off
another) that cause harm or damage to the
host.
Usually contagious (spread by person to
person contact) or infectious (spread via the
air)
Prions
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Non-cellular pathogens (not alive in their own right)
Abnormal proteins – slightly warped or twisted
Abnormal protein has the ability to change the
shape and function of normal protein in neurons
Not affected by agents such as enzymes
Not killed by cell – eventually cause lysis and are
free to infect other cells
Animation: prions
http://www.1lec.com/Microbiology/Prion/index.html
The discovery of prions
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1913: Dr Creutzfeld examines the body of a
patient that died during an odd breakdown
which involved shaking and jerking. There is
extensive damage to her brain cells.
1957: New Guinea: natives are observed
jerking, shaking and with uncontrollable facial
tics. Disease locally called “laughing death”.
Funeral rites included eating bodies of the
dead. Brain cell damage was found in bodies.
This disease is known as Kuru.
Continued…
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1960s-80s: human growth hormone
harvested from pituitary gland of cadavers
and given as a fertility drug. Women who
received treatment sometimes got disease
described by Dr Creutzfeldt
1985: UK: people observed with similar
symptoms. Have eaten beef, containing
prions. Mad Cow Disease.
Viruses
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Also non-cellular
Must infect a host cell to reproduce
Source: http://www.csa.com/discoveryguides/avian/images/virus.jpg
Different viruses infect different cells
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Humans and mammals (flu, measles, cold
sores… hundreds more)
Birds
Reptiles
Plants
Even bacteria (bacteriophage)
In fact, all living things are susceptible to
some kind of viral infection
Classification of viruses
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Classification may include:
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Required host
Kind of nucleic acid contained (DNA or RNA)
Structures on protein coat
Life Cycle of a Bacteriophage
Source: http://www.nature.com/nrmicro/journal/v4/n5/images/nrmicro1393-i1.jpg
Life Cycle of a human virus
Source: http://www.ifpma.org/fileadmin/templates/influenza/images/replication_cycle.jpg
Papilloma virus (warts)
Warts are spread by direct contact
The “normal”
manifestation of
the wart virus
Papilloma virus
contains DNA, not
RNA like the flu
virus
Picture sources:
http://www.pharmas.co.uk/blog/wp-content/uploads/2010/02/hpv_1.jpg
http://www.femalegenitalwarts.org/wp-content/uploads/2009/08/Human-Papillomavirus-hpv-300x225.jpg
http://www.geekologie.com/2008/04/16/tree-man-2.jpg
The “tree man” is a result
of the Papilloma virus
attacking someone who is
immuno-compromised.
His body could not control
the effects of the virus, so
it took over.
Measles/ Rubella
Also known as German Measles,
Rubella manifests itself as
painful red spots on the host’s
skin.
Pregnant women who catch the
virus are at risk of passing a
variety of illnesses to their
unborn child
In Australia and many other parts
of the world, Rubella is controlled
by vaccination programs where
children are given deactivated
viruses to promote immunity
against infection.
Picture sources:
http://php.med.unsw.edu.au/embryology/images/thumb/2/2a/Infant_rubella_virus.jpg/400p
x-Infant_rubella_virus.jpg
http://wholefoodusa.files.wordpress.com/2009/03/vaccine__disease_decline.png?w=366&h=400&h=400
Poliomyelitis (polio)
Polio has been effectively
eradicated in Australia, due to
rigorous vaccination programs.
It used to be common that children
in particular would contract the polio
virus, and muscles would weaken.
In order to stay alive, some had to
have a machine called and Iron
Lung breathe for them.
The poliovirus only causes the disease if it
enters the bloodstream. If not, it is
asymptomatic. This is why vaccination must
continue!!
Picture sources:
http://wholefoodusa.files.wordpress.com/2009/03/vaccine__disease_decline.png?w=366&h=400&h=400
Polio is spread oral-oral or intestinal-oral
http://www.thegeminigeek.com/wp-content/uploads/2009/06/polio.gif
Pest control (Rabbit Calicivirus)
Rabbits have become a pest species in most regions of Australia. As a
result, we have had to find an effective way of controlling their numbers.
The most successful has been the introduction of lethal rabbit viruses,
the most recent called Calici Virus (introduced in 1996).
Treatment of viruses
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Many are fought by the body efficiently, so
medication is not required (flu/cold)
Some are not efficiently fought by body, nor is
medication available (Human Immunovirus)
Antiviral drugs available for some:
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May act to inhibit particular enzymes involved in disease
progress
Relenza = anti-flu drug
Cells may produce interferon when infected: blocks viral
protein synthesis in neighbouring areas
Plant viruses
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“mosaics” – differential coloured splotches on
plants
Usually transmitted via insect vectors
Pepino Mosaic Virus infection (PepMV).
PepMV is a highly contagious agricultural
pest causing significant destruction of
plants in tomato production. Symptoms
consist of distorted leaf development,
mosaic, bubbling of the leaf surface and
some chlorosis (loss of chlorophyll).
Source: http://www.sciencephoto.com/images/download_wm_image.html/C0015943Tomato_plant_infected_with_mosaic_virus-SPL.jpg?id=670015943
Viroids
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Naked RNA
Only identified as pathogenic to plants
Completely dependent on host cell for all
functions