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Plague!17th Century: Europe
Bubonic plague
outbreak, kills tens of
millions. People tried to prevent
catching it by filling nose-covers with fragrance
1900: Sydney
Bubonic plague: rats were killed to prevent the movement of the disease
1997 – 2004: worldwide
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
2009: worldwide
H1N1 influenza virus (swine flu). Most common
human flu in 2009. Antiviral drugs like Zanamir used to
treat patients
Disease
Anything that harms an individual. Inherited: genetic disorders (Unit 4) Deficiencies: not enough of a particular
nutrient
Infectious disease: caused by pathogens Non-cellular (prions/viruses) Cellular (microorganisms like bacteria or fungi)
Pathogens
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
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
The discovery of prions
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…
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
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 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
Classification may include: 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
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.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
Measles/ RubellaAlso 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/400px-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!!
Polio is spread oral-oral or intestinal-oral
Picture sources:
http://wholefoodusa.files.wordpress.com/2009/03/vaccine_-_disease_decline.png?w=366&h=400&h=400
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
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: 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
“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/C0015943-Tomato_plant_infected_with_mosaic_virus-SPL.jpg?id=670015943