Bubonic plague has had a major impact on the history of the world. Caused by the bacterium, Yersinia pestis, and transmitted by fleas often found on rats, bubonic plague has killed over 50 million people over the centuries. Burrowing rodent populations across the world keep the disease present in the world today. Outbreaks, though often small, still occur in many places. The use of antibiotics and increased scientific knowledge first gained in the 1890s have reduced the destruction of plague outbreaks. In Medieval times, with the unknowing help of humans, bubonic plague exploded into a pandemic. Known as the ³Black Death², it decimated Europe in 1350, killing 1/3 of the population. It disrupted government, trade, and commerce. It reshaped people¹s perspectives on life and Christianity, and found expression in many works of art. Bubonic plague¹s influence and effects have shaped events of the past and part of our world today. What is the name of the disease?
Bubonic plague came by its name because of the symptoms of the disease. Bubonic plague causes very painful, swollen lymph nodes, called buboes. These swollen lymph nodes are often first found in the groin area, which is "boubon" in Latin. This disease became associated with the term "plague" because of its widespread fatality throughout history. Bubonic plague was also known as the "Black Death" in Medieval times. This is because the dried blood under the skin turns black. What is/are the causative agent(s)?
Bubonic plague is caused by the bacterium, Yersinia pestis. It is also known as Pasteurella pestis. Other Pasteurella bacillus cause diseases such as tuberculosis. 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. What happens (biologically) to people who get the disease and why? Once the bacterium, Yersinia pestis, enters the bloodstream, it travels to the liver, spleen, kidneys, lungs, and brain. The incubation period is commonly 2 to 6 days after exposure. Early symptoms include: -shivering
-intolerance to light
-pain in the back and limbs
-white coating on tongue
Eventually, pain occurs in the groin, armpit, and neck (all the areas that contain lymph nodes). Later, there is painful swelling of the lymph nodes called "boboes", hard lumps that begin to appear on the inner thigh, neck, and armpit. Blood vessels then break, causing internal bleeding. Soon, dried blood under the skin begins to turn black. Yersinia pestis, in autopsies, has been found in the periodical sac, spleen, liver, lymph nodes, and bone marrow. If untreated, plague mortality is very high (up to...
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