Plague, was a term that was used in the

Middle Ages to describe all fatal epidemic diseases, but now it is only
applied to an infectious, contagious disease of rodents and humans. In
humans, plague occurs in three forms: bubonic plague, pneumonic plague,
and septicemic plague. The best known form is the bubonic plague and it
is named after buboes, or enlarged, inflamed lymph nodes, which are characteristics
of the plague in the groin or neck or armpit. Bubonic plague can only be
transmitted by the bite of any of numerous insects that are normally parasitic
on rodents and that seek new hosts when the original host dies. If the
plague is left untreated it is fatal in thirty to seventy five percent
of all cases. Mortality in treated cases is only five to ten percent.

The origin of the bubonic plague is unknown
but it may have started in Africa or India. Colonies of infected rats were
established in Northern India, many years ago. Some of these rodents had
infected traders on the route between the Middle East and China. After

1330 the plague had invaded China. From China it was transferred westward
by traders and Mongol armies in the 14th century. While these traders were
travelling westward they followed a more northerly route through the grasslands
of what is now Russia, establishing a vast infected rodent population there.

In 1346 the disease reached Crimea and
found its way to Europe in 1347. The outbreak in Europe was a devastating
one, which resulted in more than 25 million deaths-about twenty five percent
of the continent\'s whole population. After that the plague reappeared in
many European cities until the early 18th century, when it suddenly stopped
there. No explanation has ever been given for the plague\'s rapid disappearance.

The first symptoms of the bubonic plague
are headache, vomiting, nausea, aching joints and a feeling of ill health.

The lymph nodes of the groin or of the armpit or neck suddenly start to
become swollen and painful. The pulse and respiration rate of a bubonic
plague victim is increased, and the victim will become listless and exhausted.

The buboes will swell until they are approximately the size of a chicken
egg. If a case is nonfatal than the temperature will begin to fall in about
five days, and returnt to normal in about two weeks, but in fatal cases
death will probably occur within four days.

Yersinia Pestis, an infectious, round and
rod shaped agent is the cause of the Bubonic Plague. Yersina Pestis is
a bacteria, which means the cells lack the internal organization of eukaryotic
cells. These bacteria cells would contain the membrane but they would not
be able to subdivide the inside of the cell. These bacteria cells do not
have a nucleus so instead they have a nucleiod that contains genetic material.

The two types of bacteria cells are gram-negative and gram-positive. Yersina

Pestis is gram negative and that means that antibiotics are less effective
on the plague because of a lipopolysaccharide layer over their walls that
adds extra protection.

The bubonic plague has a major impact on
the lymphatic system. The lymphatic system is made up of lymph nodes, lymphatic
vessels, lymphoid organs and circulating lymphocytes. Plague victims tend
to have large bumps on their bodies which are called "buboes". These are
actually swollen lymph nodes filled with puss. The spread of the infection
causes the lymph nodes to become hard and painful.

The lymph nodes are heavily concentrated
in the neck, armpits, and groin. When a person becomes ill these areas
will begin to swell because the body needs to make a vast amount of white
blood cells to fight off whatever pathogen has entered the body.

Many preventive measures can be used to
reduce the spread of the plague (sanitation, killing of rats, prevention
in transport of rats). Individuals who contract the disease are isolated,
fed fluids and put to bed. During World War II, scientists using sulfa
drugs were able to produce cures of plague.

Since it is a bacteria, the bubonic plague
can be treated with antibiotics. Tetracyline, Streptomycin, and Chloramphenicol
are three of the antibiotics used to prevent plague. Sometimes, they are
even mixed together. The plague can almost always be cured when it is recognized
fast enough.

Since the late 19th century bubonic plague
vaccinations have been in use. There is a vaccine that can be taken in
a six to month installment period, but there is a element of risk to this
vaccination. This vaccination has been proven to be ineffective with people