The Bubonic Plague Essay, Research Paper
Since the reign of Emperor Justinian in 542 A.D., man has one unwelcome
organism along for the ride, Yersinia pestis. This is the bacterium
more commonly know as the Black Death, the plague. Plague is divided
into three biotypes, each associated with one of three major pandemics
occurring in history. Each of these biotypes are then divided into three
distinct types, classified by method of infection.
The most widely know is bubonic, an infection of plague that resides
in the lymph nodes, causing them to swell. The Black Death of the 14th
century was mainly of this type. Bubonic plague is commonly spread
through fleas that have made a meal from an infected Rattus rattus.
The most dangerous type of plague is pneumonic. It can be spread through
aerosol droplets released through coughs, sneezes, or through fluid
contact. It may also become a secondary result of a case of untreated
bubonic or septicemic plague. Although not as common as the bubonic
strain, it is more deadly. It has an untreated mortality rate on nearly
100%, as compared to 50% untreated mortality for bubonic plague. It
attacks the respiratory track, furthering the cycle.
The third type of plague is septemic. It is spread by direct bodily
fluid contact. It may also develop as a secondary result of untreated
bubonic or pneumonic plague.
A LITTLE HISTORY
As mentioned before, the most known incidence of bubonic plague was in
14th century Europe. In 1346 reports of a terrible pestilence in China,
spreading through Mesopotamia and Asia Minor had reached Europe, but
caused no concern until two years later. In January of 1348 the plague
had reached Marseille in France and Tunis in Africa. By the end of the
next year the plague had reached as far as Norway, Scotland, Prussia,
Iceland, and Italy. In 1351 the infection had spread to include Russia.
The plague was an equal opportunity killer. In Avignon nine bishops
were killed, King Alfonso XI of Castile succumbed, and peasants died
wherever they lay. Though the plague had, for the most part, ceased
less than ten years after it started, it killed nearly one third of the
European population. In many towns the dead outnumbered the living. Bodies
piled in the streets faster than nuns, monks, and relatives could bury
them. Many bodies were interred in mass graves, overflowing with dead,
or dumped into nearby rivers. Domesticated cats and dogs, along with
wolves, dug dead out of shallow graves, and sometimes attacked those
still living. Many animals did either from plague or lack of care. Henry
Knighton noted more than 5,000 dead sheep in one field alone.
The death of a very large portion of the work force aided those that
were still living. The sheer scarcity of workers enabled the remainder to
make demands of higher wages and better conditions. Farms located on poor
soil were abandoned because the demand for grain had decreased, enabling
fewer farms, located on the better tracts of land to feed the population.
There have been a few encounters with bubonic plague in modern times. In
the American and Canadian west, from Texas and Oklahoma in the east
to the Pacific Ocean in the west, it is most often transmitted from
species of squirrels. The last occurrence of transmissions from rats to
people, or people to people in the United States occurred in 1924 in
Los Angeles. In that epidemic there were 32 cases of pneumonic plague
with 31 fatalities. Since then there have been around 16 cases a year
in the United States, most connected with rock squirrels and its common
flea Oropsylla montana.
In the years of World War II the Japaneese army formed a special
biological warfare division. This unit worked on developing a method to
deliver the plague bacteria to the civilian population of China. They
tested the effectiveness of the plague as a weapon of war first on
prisoners of war, then on unsuspecting civilians. In their first tests
they confined a small group of prisioners in a room with thousands of
plague infested fleas. The moratlity rate in these experiments were
somewhere in the neighborhood of 50-60 percent.
The next step was to release the plague on the general population of
Manchuria. This was accomplished by planes flying over cities and villages
and releasing huge amounts of plague infested fleas over the town. When
this proved to be an inaccurate way of spreading the disease, and would
periodiocally result in the infection of the air crew, another method was
devised. The infected fleas were packed into the shell of a conventional
bomb and dropped, exploding just over the targeted towns. While exact
figures are not know, it is known that these attacks killed many people
and caused wide-spread terror in the towns.
How is the disease transmitted?
Plague is caused by an infection with Yersian pestis, which is a
bacterium carried by rodents and transmitted by fleas found in parts
of Asia, Africa, and North and South America. The Oriental Rat flea
(Xenopsylla cheopis) is the most efficient carrier of plague, but other
species of fleas (ex. Nosopsyllus fasciatus, Xenopsylla brasiliensis,
Pulex irritaus) can also pass the disease on to humans. Overall, 100
species of fleas are known to be infected by the plague bacillus. Plague
is transmitted to humans in two ways:
-Mostly by being bitten by an infected flea
-Sometimes from exposure to plague infected tissue
Plague is normally enzootic, (present in an animal community but occurring
in only a small number of cases), among rodents. However, with certain
environmental conditions plague reaches an epizootic scale (affecting
many animals in any region at the same time). It is after a significant
amount of the rodent (usually rats) population dies out, that hungry,
infected fleas seek other sources of blood, increasing the risk to humans
and other animals. the incubation period of bubonic plague is 2 to 6
days after exposure. Between disease outbreaks, the plague bacterium
exists among certain burrowing rodent populations without causing much
illness. These animals act as long-term reservoirs of infection.