1. How to Diagnose a Medieval Disease

2. Modern Plague

3. The Third Plague Pandemic Previous Pandemics – First Pandemic: The Plague of Justinian (6 th – 8 th c.) – Second Pandemic: The Black Death (1346-1353) – Third Pandemic: 1855-1959 (esp. China and India) Research in Hong Kong, 1894 – Pre-antibiotics (discovered in 1929) – Alexandre Yersin – Bacillus Pasteurella pestis (renamed Yerinia pestis and commonly called Y. pestis)

4. Yersinia pestis Bubonic Plague – Lympathic System – Animal to Human Septicemic Plague – Blood Steam – Flea happens to inject bacteria directly into blood steam or Plague infection spreads to blood Pneumonic Plague – Respiratory System – Primary Infection – Inhale Bacteria (Human to Human) – Secondary Infection – Plague infection spreads to lungs

5. Common Symptoms – Fever, weakness, fatigue, headache Bubonic Plague – Incubation Period: 7-20 days – Chills, buboes (esp. groin, armpit, neck), muscle aches, petechiae (subcutaneous bleeding) Septicemic Plague – Incubation Period: 1-6 days; 100% fatal without treatment – Chills, abdominal pain, subcutaneous bleeding, diarrhea, vomiting, bleeding from mouth/nose/rectum, petechiae (subcutaneous bleeding, gangrene, shock Pneumonic Plague – Incubation Period: 1-3 days – Coughing, coughing up bloody or watery mucus, nausea, dizziness, vomiting, shortness of breath, chest pain, pneumonia, respiratory failure, shock. – Symptoms can appear very similar to influenza ( שפעת ), anthrax ( גחלת ), Q fever (Q קדחת ), tularemia ( קדחת הארנבות \ טולרמיה )

6. From: http://gentlemint.com/tack/153967/

7. Bubonic Plague: Buboes (Swelling of Lymph Nodes)

8. Plague: Petechiae (Spots Caused by Broken Blood Vessels )

9. Septicemic Plague Gangrene

10. Agent of Spread Tropical Rat Flea Xenopsylla cheopis פרעוש הדבר

11. Identifying Medieval Plague: Problems

12. Graham Twigg (1984) Entomologist Read English accounts Seasonality

13. Death Rates The Problem – Modern Plague has a death rate of roughly 14% Possible Explanations (Not Plague) – Anthrax (Twigg) – Hemorrhagic fever (similar to Ebola) (Scott & Duncan) – Don’t know, but not plague (Cohn) Possible Explanations (Plague) – A combination of plague and typhus ( טיפוס ) (Shrewsbury) – Many secondary deaths

14. Seasonality The Problem – Bubonic Plague should be active mainly in Summer and Fall. Pneumonic plague mainly in winter when people are cooped up. – The medieval plague peaks in Fall and doesn’t seem to have a rest period. – The tropical rat flea cannot survive Fall temperatures, especially in northern regions like England Possible Explanations – A different disease? – A different type of flea? (see next slide)

15. Rats The Problem – Where are all the rats? Not mentioned in medieval sources – The medieval “black rat” (Rattus rattus, חולדה מצויה ) tends to avoid humans – The rats would have to die before rat fleas would jump to humans Possible Explanations – More than 30 species of flea can carry the plague, including the human flea, pulex irritans ( פרעוש האדם )

16. Symptoms The Problem – Many sources don’t mention buboes at all; others place them all over the body (instead of just at the groin, armpit, and neck) – In general, the descriptions of symptoms are too vague for a definitive identification “In a sense, Preclinical disease was socially constructed. People reduced all illnesses with common symptoms into a single diagnosis.” --Theilmann and Cate

17. Spread The Problem – A study on 19 th century China shows spread of only a few miles per year

18. The Question of Immunity The Problem – Humans do not develop immunity to Y. pestis. – The Plague kept returning, but it never did as much damage as the first time, suggesting acquired immunity. Possible Explanations – There is debate over the premise that humans cannot develop immunity to Y. pestis.

19. DNA Evidence

20. Polymerase Chain Reaction (PCR) 1998 Study (Marseille Team) – Plague Cemeteries from 1590 and 1722 – Teeth – Y. pestis found in 50% of plague teeth and none of control sample 2000 Study (Marseille Team) – Begins using PCR testing – Found Y. pestis in a 14 th century site Sharp Criticism of the Methods and Results of the 1998 and 2000 Study 2003 Study (Munich Team) – Replicated the earlier methodology and found Y. pestis in a sixth- century site as well (part of First Pandemic, 6 th -8 th century) 2004 and 2007 Studies (Marseille Team) – Confirmed Y. pestis in sixth-century sites

21. F1 Antigen Test 2004 Study (Tübingen Team) – Skeletons from a mortuary chapel (17 th c.) 12 Bodies covered with lime ( סיד ) (presumably plague victims) – 10 out of 12 tested positive for Y. pestis antigens 12 Bodies not covered with lime Also used PCR 2009 Study (Turin Team) – Confirmed Y. pestis antigens in sixteenth and seventeenth century sites

22. Criticism of DNA Evidence What is the value of the DNA Evidence if they don’t explain anything about the differences between modern and medieval plague? (Cohn)

23. Recent Studies 2010 (Mainz Team) – 5 Sites all around Europe (England, France, Germany, Netherlands, Italy), 14 th -17 th centuries – F1 Antigen analysis showed Y. pestis in all sites – PCR analysis showed Y. pestis in three sites – Found two different strains of Y. pestis 2010 (International Team) – Attempt to sequence the history of Y. pestis – Concluded that it originated in China 2011 (Marseille Team) – Used both methods and found Y. pestis in Venice

24. Hypotheses: Biological Factors Genetic alteration in fleas may have made it easier to transfer to humans Iron deficiency in humans increases susceptibility to the plague Other infections, such as salmonella and other Yersinia bacteria prevent infection of Y. pestis. There are at least 4 major strains of Y. pestis. The one studied in modern outbreaks (Y. pestis orientalis) is not the same as the Black Death strain (Y. pestis medievalis). – How many active during the Black Death?