Infectious and Epidemic Disease in History

Department of History
University of California, Irvine
 Instructor:    Dr. Barbara J. Becker

Lecture 4.  The Black Death (1347):  Aftermath.

"...a vast and dreadful silence..."

In 1347, the plague that became known as the Black Death moved into Europe from Asia traveling quickly along well-trafficked trade routes.  In fact, the deadly disease had reached the Crimea on the northern coast of the Black Sea by September 1345.  Italian merchants had a number of trading colonies there.  One story tells of a seige of the city of Kaffa by Janibeg Khan whose army had been stricken by plague.  The Khan ordered bodies of the plague victims to be catapulted into the city walls.  Genoese merchants who escaped the city returned home carrying the disease with them.

Reports reached Europe in 1346 that India had been depopulated and that Tartary, Mesopotamia, Syria and Armenia were covered with dead bodies.  In some areas rumor had it that no one had been left alive.

Later, people would recall other portents of the coming plague:

  • unusual weather
    • heavy mists and clouds
    • falling stars
    • hot wind from the South
    • column of fire stood above the papal palace at Avignon
    • ball of fire seen in skies above Paris
    • earthquake in Venice chimed the bells of St. Mark's
    • earthquakes in Naples, Rome, Pisa, Bologna, Padua
  • unusual events
    • a stranded whale
    • an outstandingly good crop of hazelnuts
    • blood fell from bread when taken from the oven
    • mysterious bloodstains found on men's clothes
    • wine in the casks had become turbid (proof that changes causing a decomposition of the atmosphere had taken place

Illuminated manuscript (c. 1410) from St. Augustine's City of God (MS 45-65-1 fo. 115v.) in the Philadelphia Museum of Art's Philip S. Collins Collection.

The plague stopped first near Consantinople in 1347.  By October it reached Messina, Sicily.  Ten years after the fact, Michael of Piazza, a Franciscan friar recorded that the disease arrived in Messina on twelve Genoese galleys.  Plague broke out within days of the ships' arrival.  Citizens turned on the sailors and forced them and their ships to leave the port. 

But it was too late.  As illness spread and deaths increased, frightened Messinese fled into the countryside carrying the disease with them.  When refugees began arriving in the city of Catania, they were welcomed until the residents realized what was happening.  Officials in Catania instituted strict control over the movement of people.  The Messinese viewed the Catanians as callous and evil while the Catanians viewed their actions as a matter of simple self-preservation. 

Michael of Piazza recounted a wondrous tale of the archbishop of Catania's failed attempt to rid Messina of the plague through divine intervention.  It is reminiscent of an account of St. Francis of Assisi's (1181-1226) fabled expulsion of demons from the city of Arezzo that would have been familiar to his readers:

The Expulsion of the Devils from Arezzo (1297-1299) by Giotto di Bondone (1266-1337).

According to Michael of Piazza, relics of St. Agatha, the patron saint of Catania, were dipped in water by the archbishop.  He carried the water to Messina, but when he arrived:

there appeared demons transfigured into the shape of dogs, who wrought grievous harm upon the bodies of the citizens; so that men were aghast and dared not go forth from their houses.  Yet by common consent and at the wish of the Archbishiop, they determined to march devoutly around the city reciting litanies.  While the whole population was thus processing around the streets, a black dog, bearing a drawn sword in his paws, appeared among them, gnashing with his teeth and rushing upon them and breaking all the silver vessels and lamps and candlesticks on the altars, and casting them hither and thither....  So the people of Messina, terrified by this prodigious vision, were all strangely overcome by fear.

From Sicily, the plague spread to Tunis, Corsica, Sardinia, the Balearics, the Iberian peninsula and to southern Italy, arriving in Genoa and Venice around January 1348.

More than you ever wanted to know about bubonic plague....

The microbe:  Yersinia pestis

Identified in 1894 by Swiss-born French bacteriologist, Alexandre Yersin (1863-1943) 

Three natural varieties, all toxic to man:
    -variety most often found today 
    - responsible for most recent pandemic 
      (Far East, end of 19th c) 

    - probable cause of Black Death

   - exists around great lakes in Central Africa
   - probable cause of plagues of antiquity

How Yersinia pestis bacilli cause illness:

  • produce toxin lethal to host cells
  • when ingested by white blood cells, they continue to multiply
  • progeny disseminate throughout the body
  • bacilli accumulate in blood stream and clog capillaries
  • capillaries become distended and burst
  • blood-filled fluid infiltrates and swells lymph nodes
  • swollen lymph tissue squeezes nerves causing excrutiating pain
  • secondary infections cause large abscesses

Lifespan of Yersinia pestis bacilli outside of living host:

  • in frozen cadavers (years)
  • in putrefying cadavers (a few days)
  • in ground (dies rapidly)
  • in micro-climate of rodent warrens (several months years)

Three forms of the disease:

  • microbe enters body through skin
  • untreated, death occurs 5-8 days after onset
  • 60-70% fatality rate
  • microbe enters body through lungs
  • untreated, death occurs 1-3 days after onset
  • 100% fatality rate
  • rare form and poorly understood
  • untreated, death occurs within hours after onset
  • 100% fatality rate
Transmitted by:
  • flea bite
  • ingested flea feces
  • bites from bedbugs and lice
  • direct contact with live, or recently dead victim's body fluids
  • inspired airborne flea feces
  • inspired airborne droplets from victim's sneeze or cough
  • mode of transmission uncertain
Course of disease after exposure:
1-6 days of incubation

Abrupt onset with 

  • fever (102-104° F)
1-3 days of incubation

Abrupt onset with

  • fever (102° F) 
  • high pulse rate:  90-120 bpm
Virtually no incubation period

Abrupt onset


1-2 days after onset:
  • headache 
  • general feeling of weakness
  • aches and chills
  • white coating on the tongue
  • rapid pulse
  • slurred speech, confusion
  • fatigue, apathy and staggering gait
  • blackish pustule (plague carbuncle) at point of inoculation (usually a flea bite somewhere on leg)
1-3 days after onset:
  • back and side pain
  • cough
    • at first moderate with some sputum
    • then violent with blood
  • choking
    • victim must sit up to breathe
  • death


Man with bubo in armpit.  Physician lancing a bubo on woman's neck.

3 days after onset:
  • lymph nodes near bite swell (usually in groin, but can also affect nodes in armpit and/or neck) 
  • heart flutters rapidly as it tries to pump blood through swollen, suffocating tissues
  • hemorrhaging under the skin causes purplish blotches

4-5 days after onset:

  • collapse of nervous system causes severe pain and bizarre neurological disorders
    • sense of wild anxiety and terror
    • sense of resignation
  • skin blackens
  • death for many victims
  • Bursting of buboes
    • extremely painful,
    • nevertheless viewed as a good sign (?!)
[half of plague victims had already died by this stage, so those who lasted this long had a better than even chance of survival!]
8-10 days after onset:
  • disease takes turn for better and patient recovers, or
  • generalized septicemia causes failure of vital organs
    • temperature can reach 104-108° F
    • more pustules, more boils, spontaneous hemorrhages, large bruises, digestive trouble, mental disturbances
  • death
Primary Plague Bacillus Vector: 
  • always in motion
  • travels from one warm body to another
  • able to jump 150X its body length
  • prefers rats, but not choosy
    • will immediately abandon dead rat
    • will adopt any substitute host
    • can survive weeks without feeding
  • attracted to color white
  • repelled by certain smells
    • common herd animals (horses, cows, sheep, goats...)
    • some cooking oils (nuts and olives)
  • optimal living conditions
    • 62-70° F (cooler temperatures limit activity)
    • 90-95% humidity (can live up to a year)
    • 80% humidity (can live 7-8 days)
    • 70% humidity (cannot survive)
Rat flea,  Xenopsylla cheopis

Plague Infection Cycle 
  • flea ingests plague bacillus by biting infected rat 
  • bacillus multiplies in host flea's digestive tract
  • bacilli clog flow of nutrients to host flea's body
  • host flea becomes voraciously hungry 
  • host flea bites more frequently
  • if flea's gut is clogged, previously ingested bacilli will be regurgitated into next fleabite victims
Primary flea vector:  burrowing wild rodents
  • marmots of central Asia
  • rats indigenous to lake regions of central Africa
  • black rat
  • ground squirrels of western North America

Wild rodent life cycle:

  • late spring
    • rodents begin estivation period
    • dig tunnels
    • live on reserves accumulated in warrens
  • summer
    • some rats succumb to plague
    • some infected fleas survive
    • most plague bacilli survive
  • fall, after end of rainy season
    • surviving rodents emerge
    • invade nearby vacant, infested warrens
    • become hosts to infected fleas
    • field rodents that move to populated areas bring disease to village rodents
    • humans become infected through fleabites

Black rat (Rattus rattus)

  • adaptable to urban environments
    (roof rat, house rat, ship rat)
    • resilient
    • can scale walls, and fall 50 ft without injury
    • can jump 2 ft vertically and 4 ft horizontally
    • prefers grain, but will eat meat, and even manure
    • can squeeze through holes the size of a quarter
    • can swim for days
    • can gnaw its way through almost anything 
    • can harbor some plague bacillus without ill effects

Why?  Searching for explanations....

Why did some people fall ill and not others?

Why did some victims recover while others died?

Why did some die suddenly even though they did not show any symptoms?

Why now?

Why here?

Some modern explanations based on archaeological, historical, and physiological evidence:

  • Environmental changes in Asia -- westward migration of the black rat
  • Marmot fur trade -- sale of furs infested with bacilli and/or fleas
  • Rat population in seaports along Black Sea and on ships -- increased East-West sea trade

Why US?

To learn about some contemporary explanations, see the documents in this week's readings listed below.

The Aftermath
  • manorial system continued to erode as serfs became freeholders, leaseholders, sharecroppers and wage-workers
  • some of these individuals prospered from the reduction of population
    • opportunity for those at bottom to gain economic advantage and social freedom
    • towns loosened citizenship requirements
    • guilds made it easier to become an apprentice and move up through the system
  • old certainties were lost
    • wrath of God seemed to be turned on all of mankind
    • no one, not even village priests or other authoritative figures, had the slightest notion of how the world would turn out
  • contemporary authorities called into question
    • renewed interest in antiquity; ancient world seemed an age of light compared to recent past
    • movement launched to "rescue" works of the ancients from ravages of translation; return to original Greek sources
Go to:
  • The Pardoner's Tale, from The Canterbury Tales (c. 1390) by Geoffrey Chaucer (c.1340 - 1400)
Weekly Readings
Lecture Notes