Immunity

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Immunity
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What causes illness?

• Most illnesses are caused by one of three types
  of germs (antigens)
• Bacteria
• Viruses
• Fungi

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Bacteria

• Streptococcus causes sore throats
• Tetanus (muscles become locked in place (also
  called lockjaw)
• Tuberculosis
• Leprosy
• Syphilis
• Salmonella
• Anthrax
• Cholera
• All of these can be treated with antibiotics

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Cholera

• This is a third world disease caused by drinking
  dirty water
• It reacts with the small intestine and causes
  massive diarrhoea
• It can be fatal if not treated
• Without fluids somebody could die within 18 hours
• The fluids are usually intra venous

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Viruses

• Antibiotics do not work on viruses (it is a bad
  idea to take too many as your body builds up a
  resistance to them).
• You need to be vaccinated against viruses
• Viruses include
• The common cold and flu
• Chickenpox
• Cold sores
• Ebola
• AIDS

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Smallpox

• This is very important in the history of medicine
  as Edward Jenner developed the first vaccine for
  this disease
• The virus loves blood capillaries and from there
  will cause skin rashes, then blisters
• It killed 300-500 million in the C20th
• Due to vaccination it was eliminated by 1979
• It was caught through spit, sneezing or touch
• Currently there are two places where smallpox can
  be found one in a lab in USA and one in Russia
  (these are kept for future vaccines)

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Pandemics

• The Spanish Flu started in March 1918 and lasted
  to June 1920
• This mutant flu virus killed young healthy adults
  (rather than children and the elderly)
• Current upper estimates of the mortality rate are
  around 100 million (5 times more than all the
  deaths from the Great War(WW1)
• This was 5 of the population
• 20 suffered from Spanish flu
• 25 million died in the first 25 weeks

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The Aztecs and Incas

• When the Spanish (Hernan Cortez) landed in Mexico
  in 1518 the population was 20 million
• By 1568 this had fell to 3 million (destroying
  the Aztecs)
• This was due to the introduction of smallpox,
  measles and typhus
• In 1532 General Pizarro kidnapped Atahualpa the
  Inca leader in Peru
• They had 168 men against 80,000 Incas
• The Inca culture was wiped out by 1572

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The Black Death

• It is caused by bacteria commonly called the
  Bubonic Plague
• The Black Death killed 75 million in total across
  Europe between 1347 and 1353
• The disease lasted between the 1300s up to the
  C18th
• The Great Plague of London was between 1665 to
  1666
• This is where the rhyme ring a ring of roses
  comes from

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Ebola

• Also called haemorrhagic fever
• It is highly contagious
• It kills 50 to 89 of the people who contract it
• It can be caught through contact with bodily
  fluids or by touching objects used by the patient
• The worst symptoms include vomiting blood, bloody
  faeces and blood coming out of the nose, mouth
  and red eyes
• Death comes from multiple organ failure

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Fungi

• Athletes foot is caused by fungus
• Fungi love wet and warm conditions (like those
  between your toes)
• A mould grows on the skin surface, but this
  penetrates the skin
• It causes scaling, flaking, itching leading to
  pain and inflammation
• Antibiotics are needed

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Protections Against Diseases

• You body tries to keep harmful germs out of your
  blood in a variety of ways
• Your skin is a physical barrier
• Your stomach is full of HCl
• You eyes produce tears to wash away dirt
• You have an immune system

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What is the Immune System?

• The body makes white blood cells and antibodies
  to detect and fight germs
• These are made in the bone marrow
• The move in the lymph vessels and fight disease
  in the lymph nodes
• These are found under your neck, armpits and in
  your groin

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White blood cells

• There are different types
• Phagocytes attack germs
• They eat them or use enzymes to kill them
• Lymphocytes make antibodies
• Each different germ needs its own antibody to
  recognize it (like a key for a door)
• When they find the right antibody lots are made
• This builds up immunity to the disease the next
  time you catch it