The Black Death

Hunter-gatherers

Industrialization

Agriculture

Human Population

• Crowd diseases: – Parasites, e.g. schistosomiasis– Contagious diseases, e.g. measles

• Epidemics

• Domesticated animals

Rinderpest Measles

• Endemic disease, Epidemics and Pandemics

• The Three Great Pandemics

The Biology of Plague

6th and 7th Centuries AD

The Medieval Pandemic

The Modern Pandemic

The Biology of Plague

• Bacillus: Yersinia pestis

The Biology of Plague

• Rattus rattus (Black Rat)

The Biology of Plague

• Flea: Xenopsylla cheopis

Types of Plague

• Primary Bubonic– Transmitted by fleas

– Buboes

– 60-90% mortality

Types of Plague - 2

• Primary bacteraemic (septicaemic)

• Secondary bacteraemic

• Primary pneumonic• Secondary pneumonic

– Transmitted by air-borne droplets

– Not too infectious

The Black Death

• Origins in Central Asia, ca. 1331-1332

• Slow rate of spread

• Importance of Mongol Empire

• Spreads from Tatars to Genoese colony of Caffa

• From there to Europe in September 1347

How Many People Died?

How Many People Died?

Death Rates of English Parish Priests

Diocese

York Lichfield

Bath/W

ells

Ely E

xeterWinchesterNorw

ich

Pe

rcen

tag

e

0

10

20

30

40

50

60

70

80

90

100

Burials at Givry, 1334-1348

0

100

200

300

400

500

600

700

1335

1337

1339

1341

1343

1345

1347

Year

Bur

ials

How Many People Died?: Conclusion

• Ca. one-half of population dies

• Population declines until ca. 1425, when stabilizes at one-third level of that of 1300

• Remains at this low level until ca. 1475

• Returns to level of 1300 around 1600

But Was It Plague?

But Was It Plague?

• Two types of rat needed

• Rattus norvegicus (brown rat) did not reach England until 1700s

But was it plague?

• Plague a disease of open steppes, and/or warm countries, but

• Spreads to Iceland and Greenland

• No reports of dead rats

• 40 day disease cycle, as opposed to 7-10 days for plague

Or a Viral Hemorrhagic Fever?

• Characterized by bleeding and vomiting of blood

• Generalized necrosis• Affected domestic

animals• Spread from human to

human

Population Movement at Prato

Consequences

• Western Europe: “Golden Age” of the Peasantry– Rents decline– Wages rise– Serfdom disappears in W. Europe

Population Movements: England

Consequences - 2

• Intensifies political and social conflict– “Seigneurial reaction”– Peasant revolts/urban worker revolts– Increased competition among aristocrats for

control of shrinking numbers of peasant, leading to

• Increased civil war

• Increased inter-state war