How the World Keeps Diseases from Spreading

1. How the World Keeps Diseases from Spreading A look at the history of etiological frameworks

2. The Bubonic Plague • Swept through Europe in the 14th century (1348-1351). • Caused fever, swollen and oozing nodes, red rash, necrosis, dehydration, and death. • Killed approximately 200 million people.

3. Discussion Question • Why do you think the bubonic plague persisted for so long? (4 consecutive years) and killed so many people?

4. The Bubonic Plague • We now understand that the plague is caused by the bacterium Yersinia pestis that is transmitted through fleas. • But this etiological framework was unknown in the 14th century.

5. What “they” thought about the bubonic plague Proposed causes: • Atmospheric alterations resulting from a rare conjunction of planets • Divine punishment for the sinners and morally corrupt • Miasma theory • The poor

6. Miasma Theory • Miasma or “bad air” was considered to be a poisonous vapour or mist filled with particles from garbage that caused illnesses. • The “bad air” was detected by foul smells (i.e. the smell of garbage) • Abiding by this notion, physicians and the rich wore masks that contained fragrant herbs so that they could not smell the “bad air”.

7. Ring around the Rosie Ring around the Rosie,A pocketful of posies.ashes, ashes.We all fall down!. • Some think it is written about the bubonic plague • The symptoms of the plague included a rosy red rash in the shape of a ring on the skin (Ring around the Rosie). • Pockets and pouches were filled with sweet smelling herbs (or posies) which were carried due to the belief that the disease was transmitted by bad smells. • The term "Ashes Ashes" refers to the cremation of the dead bodies!

8. Miasma Theory • Although the reasoning (foul smell) was wrong, the miasma theory was correct with the observations that disease was associated with poor sanitation. • This caused public health reforms and to an extent encouraged cleanliness, but most of all it promoted the idea of isolation. • Their solution, isolate the sick, dirty poor from the healthy rich!

9. Miasma theory and tactics of isolation dominated for the next 500 years, until it was finally replaced by the Germ Theory in 1860! • What is Germ Theory?

10. How do you think the germ theory has impacted public health measures?

11. After the Germ Theory • We have causation, Vaccines, Antiseptics, Antibiotics, and Antivirals • But this does not mean we are immune to epidemics. Recurring waves of Influenza • Spanish Flu 1918 • Swine Flu 1931 • Asian Flu 1957 • Avian Flu 2006 • Swine Flu 2009

12. Influenza remains the biggest and unconquered acute threat to human health, inflicting damage and death far beyond familiar notification data. The impact of influenza A is particularly severe during periodic pandemics owing to novel antigenic variants which override immunity from experience of earlier subtypes. N.R Grist

13. Important Points • Public Health measures are the product and legacy of prior epidemics. • Legislated controls are influenced by current notions of disease transmission and can incorporate social prejudice.

14. Homework • What is the miasma theory of disease? • What is the germ theory of disease? • What public health measures were based on the above two theories?