THE BUBONIC PLAGUE

Rana Kundu



Introduction



Plague, was a term that was applied in the Middle Ages to all fatal epidemic diseases, but now it is only applied to an acute, infectious, contagious disease of rodents and humans, caused by a short, thin, gram-negative bacillus. 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.



History Of The Bubonic Plague



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, thus 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 irregularly 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.



Symptoms and Causes



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 approaches normal in about two weeks, but in fatal cases death will probably occur within four days.

Yersinia Pestis, an infectious 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.



Lymphatic System



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.

To make all parts of the body function properly the "electron transport chain" is needed. Yersina pestis releases a toxin into the body that obstructs this function from occurring.



Prevention and Treatment



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