Immunity

What causes illness? Most illnesses are caused by one of three types of germs (antigens): Bacteria Viruses Fungi

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

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

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

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)

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

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

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

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

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

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

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

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