The Plague!

It's big (well, actually microscopic...), it's bad, it caused a pandemic in medieval europe...IT'S YERSINIA PESTIS!!!!! This nasty little bacterium, also referred to as "plague", "the bubonic plague", "pneumonic plague" and "septicemic plague". The bubonic plague impacts lymph nodes, the pneumonic plague impacts the lungs, and the septicemic plague infects the blood.                                                  The bacterium itself is shaped like a rod, making it "Bacillus". It is described as having a "safety pin" appearance. The bacterium has a nucleoid and no nuclear membrane. The cell wall is made up of phospholipids and several other components that we have not yet studied in Biology. There is a capsule surrounding the cell. This capsule is described as "lumpy" looking. It protects the bacterium, stores nutrients, and assists in spreading disease. It's components are polysaccharides and lipids. The cell also has tiny appendages referred to as "needles" which are pili. These allow the bacterium it to "attack" its host and infect the cell. They also help the bacterium latch onto other bacteria and cells. They are composed of protein. 

All of the variations are spread by rodents such as rats, squirrels, rabbits, prairie dogs, and chipmunks . Rodents infected by the disease are found in every continent save Australia. The fleas that live on an infected rodent will bite the rat, then they to become infected. The fleas can hop off of the rat and onto a human being, then bite that human being and transferring the disease. Once a person has contracted the disease they can spread it to others when they cough. After an invalid coughs, tiny droplets will fly out of the person's mouth and become airborne. These droplets can be inhaled by other people nearby, who in turn contract the disease. After a human has contracted bubonic or septicemic plague, they usually begin to show symptoms two to ten days later. If they have pneumonic plague, they will show symptoms in several hours, and will typically be dead within two days.

Here are some typical symptoms of each type of plague:

 Bubonic Plague                                      

1. Fever    
2. Headache      
3. Seizures                                  
4. Swelling of lymph nodes, which can reach the size of eggs and turn black. These are found in armpits and neck

5. Chills

6. A tired and ill feeling                                            

                                                                                                  

 Pneumonic Plague

1. Breathing is hard

2. Excessive coughing

3. coughing up a bubbly and bloody substance, which comes from the lungs

4. High fever

5. Nausea and vomiting

6. Debility

Septicemic Plague

1. Stomach pain and nausea

2. Fever

3. Diarrhea

4. Organ failure

5. Low blood pressure

6. Vomiting

7. Discoloration of the skin to  a dark purple, the cause being blood coagulation.

8. Bleeding from the mouth, nose and under the skin

9. Shock

A person who has contracted a strain of the plague must receive treatment within one day of the incident. Doctors give patients antibiotics including, but not limited to, streptomycin, gentamicin, doxycycline, and ciprofloxacin. Most patients also require additional oxygen, and an IV. Those who are suffering from the plague must be completely isolated. Even with treatment, the patient has a 50% chance of death.

The most famous incident of the plague was in the Middle Ages. The bubonic plague, then referred to as "the black plague" or "the black death". This outbreak killed one out of every four people living in Europe at the time within the course of three years. This was the last large-scale outbreak of the plague. In America, the number of plague cases today is negligible, although there have been a few infections in California, Utah, Arizona, Nevada, and New Mexico. 

Sources:
https://health.google.com/health/ref/Plague
http://www.wisegeek.com/what-is-the-black-plague.htm
http://www.mayoclinic.com/health/plague/DS00493/DSECTION%3Dsymptoms
http://www.mayoclinic.com/health/plague/DS00493/DSECTION=symptoms
http://www.mayoclinic.com/health/plague/DS00493/DSECTION=causes
http://en.wikipedia.org/wiki/Yersinia_pestis#General_characteristics
http://www.rkm.com.au/PLAGUE/index.html
http://newsinfo.iu.edu/asset/page/normal/7343.html
and my notes from bio class!

Image courtesey of:
http://www.google.com/imgres?imgurl=http://library.thinkquest.org/05aug/00639/en/images/yersinia_pestis.jpeg&imgrefurl=http://library.thinkquest.org/05aug/00639/en/w_biological_bacteria.html&usg=__q7lHLrycWp27qnCe4BaM_I2-44o=&h=500&w=505&sz=42&hl=en&start=1&zoom=1&um=1&itbs=1&tbnid=4SszfYWxwZiXfM:&tbnh=129&tbnw=130&prev=/images%3Fq%3Dyersinia%2Bpestis%26um%3D1%26hl%3Den%26client%3Dsafari%26rls%3Den-us%26tbs%3Disch:1