causes

• by 1900's the Germ Theory had been around for 40 years - microbes = clear link to outbreak of disease
• no miasma, 4 humours or supernatural
• 1900 - diagnosis= doctor and patient
• 20th century -> diagnosis = laboratory testing, medicine and examining samples - blood testing
• beginning of 1900 - X-rays developed - see inside the body
• therefore, diagnosis changed so instead if being based off symptoms and the experience of doctors and knowledge of doctors it was based of Medical Testing