How did John Snow contribute towards germ theory? Starter: Collect your photography which shows a street in Glasgow in the 19th Century. Around it, identify anything that suggests why disease was widespread. In this lesson, we will: Explain why cholera was so widespread in 19th Century Britain. Describe how John Snow made his discovery.

Buildings closely built together, means lack of ventilation or sunlight. Allows mould to grow quickly. Water tap right next to the privy. Would often become clogged with human excreta. Human waster will seep into water pipes. Privy to service entire tenement/flat. Often overflows, causing sewage to spill out. ‘Night soil collectors’ empty it without gloves.

How was Britain changing during this period? Technology developments had launched Britain into an industrial revolution. Massive cities began to grow in Manchester, Belfast, Glasgow etc. Populations grew by 260% as workers moved for work. Cities became overcrowded, polluted and full of new disease like tuberculosis, typhus, smallpox and cholera. Ideas like the Four Humours had been completely discarded in the Renaissance. Better quality microscopes could now see clearly microbes on decaying matter. New ideas were put forward to explain these microbes, such as spontaneous generation.

How did cholera effect 19th Century Britain? Cholera caused diarrhoea and sickness that would kill a victim by dehydration within 6 days. The blood would become thicker, rupturing blood vessels under the skin which turned the skin pale blue. Mostly affected the poor and would spread quickly through slums, workhouses, prisons and asylums. Between 1831 and 1866, cholera killed 109, 650 people in England and Wales. It was believed that miasmata and rotting waste caused the disease.

Checkpoint: Can you explain why cholera was so widespread in 19th Century Britain? To the right are small images. For each: Identify the cause of cholera. Explain clearly how it caused cholera to spread. Stretch challenge: To what extent could we blame the British government for the outbreaks of cholera during this period?

Privies/public toilets Most houses had no bathroom, instead people shared an outside toilet. Each privy was built above a cesspit. These pits would be emptied by nightmen who would dump it into the rivers or leave it piled up on streets. Cesspits would leak into waterpipes, so people would be drinking contaminated water.

Overcrowding/cramped spaces In the big cities, sometimes 10-12 people would share one room. This meant flats had poor ventilation and disease could spread quickly. People shared bed sheets, cooking and eating utensils, so cholera bacteria could spread very quickly. So many people lived in a block of flats, people would collect faeces in buckets in their rooms and then dump it out the window. This caused cholera to spread even quicker.

Lack of knowledge No one believed in germs, so their hygiene was terrible. Night men would empty cesspits without gloves and would not wash their hands. When someone caught cholera, their clothing would be burned as they believed in miasmic theory. This did nothing to stop the disease spreading.

The work of Dr John Snow John Snow had become well known as an anaesthetist in London, having given Queen Victoria chloroform in 1851. Snow disagreed with the idea that miasmata caused cholera. Between 1848 and 1849, he wrote ‘On the Mode of Communication of Cholera’ with his ideas. Cholera couldn’t be transmitted by miasma, because it affected the guts not the lungs. Drinking water was being contaminated by the faeces being disposed in the city’s drains. He put two and two together to suggest cholera was caused by dirty drinking water. https://www.youtube.com/watch?v=753XHXPLrn4

Checkpoint: Can you describe how John Snow proved cholera was spread by water? Targets 8-7 Snow’s work had immediate impact. Argue for and against this statement. For each word below, write a sentence describing its connection to Snow’s work: Broad Street Interviewed Map Water pump Remove Targets 6-4 Explain why John Snow’s work was such a turning point in ideas about disease. Targets 3-1 How did Snow’s work change things in Britain? Explain

When Cholera broke out in Broad Street, London in 1854, Dr John Snow set out to prove water caused cholera. Snow interviewed people living in Broad Street, asking them about the disease and how many people were infected. He wrote all of this down in his notebook, as well as the ages and sex of each victim. Using this data, Snow plotted all cases on a map. This map was published in his report ‘On the Communication of Cholera’ Snow’s map showed that all victims used the same water pump on Broad Street. Using his data, Snow convinced the local authority to remove the handle for the pump which ended the outbreak.

How did Snow’s work change things in Britain? Explain Yes – Broad Street pump was removed, cholera epidemic disappeared in London. No – Took a while to make impact, wasn’t until publication of germ theory by Pasteur and Koch that his finding were accepted. Targets 8-7 Snow’s work had immediate impact. Argue for and against this statement. Targets 6-4 Explain why John Snow’s work was such a turning point in ideas about disease. Changed some people’s attitudes that disease was caused by germs and not miasmata. First step towards scientific understanding of germs and bacteria. Use of statistics and research to back up theories. Paved the way for germ theory, Public Health Acts etc. Targets 3-1 How did Snow’s work change things in Britain? Explain Broad Street pump removed, saved lives, had a small impact on the government passing the Public Health Acts 20 years later.