As early as the thirteenth century, man has had one unwelcome organism along for the ride, Yersinia pestis. This is the bacterium more commonly known as the Black Death or the plague. Plague is a word that has struck fear in the hearts of man since the earliest of times. It has also led to some of the greatest historical events and stories of our time.
            
             Plague is divided into three distinct types, classified by method of infection. The most common is bubonic, with a mortality rate of 30-75%. An infection resides in the lymph nodes (around arm pits, neck, and groin), causing them to swell. Symptoms took from 1-7 days to appear and consisted of headaches, nausea, vomiting, aching joints, fever of 101-105 degrees, and a general feeling of illness. The disease also causes the skin to turn black. Fleas, rats, and humans serve as hosts for the bubonic plague. Black rats carried the fleas, which the bacteria multiplied inside of, who in turn would bite a human infecting them.
            
             The second most common form of the Black Death is the pneumonic plague, with a mortality rate of 90-95%. Even though this is not the most common, it is the most dangerous type of plague. The lungs are infected causing slimy sputum (saliva mixed with mucus exerted from the respiratory system) tinted with blood. This can lead to an attack on the respiratory track, furthering the cycle. Symptoms took 1-7 days to appear. It can be spread through aerosol droplets released through coughs, sneezes, or through fluid contact.
            
             The third type of plague is septemic, with a mortality rate of close to 100%. This type of plague often caused disseminated intravascular coagulation (DIC), which caused a high fever and the victims skin to turn a very dark purple. Transmission occurs in the same way as the bubonic plague. Death usually occurred the same day the symptoms appeared. Because this is the most rare form of all even toda...