The Black Death came from China. The Mongolians wanted to keep expanding their empire and their armies travelled along the Silk Road, carrying the disease with them.
They started the siege of Caffa (now part of Ukraine) in 1347. The army catapulted dead bodies infested by the plague over the walls to spread the disease. The survivors of the attack fled and carried the disease with them, this is what sparked the Black Death in Europe.
The disease is called the bubonic plague and it is caused by the bacteria Yersinia pestis. Yersinia pestis is an enterobacteriaceae; it is gram negative and rod shaped.
The carriers of the disease are fleas and wild rodents (often rats). They are immune to it so are not killed by it. When a flea is infected it causes the flea to become more hungry; therefore more likely to spread the disease. Urban rats are not immune to Yersinia pestis so if they are infected they will die. This means that fleas will no longer have them to feed on, so they start to bite humans and infect them instead.
If it is not treated with antibiotics within about a day then it is extremely likely to cause death.
Bubonic plague is one form that the disease can take, but it can also lead to septicemic plague or pneumonic plague. Pneumonic plague can spread from human to human unlike the other forms, and is one reason why it spreads so quickly. It is estimated that 75 million people died from the Black Death.
They started the siege of Caffa (now part of Ukraine) in 1347. The army catapulted dead bodies infested by the plague over the walls to spread the disease. The survivors of the attack fled and carried the disease with them, this is what sparked the Black Death in Europe.
The disease is called the bubonic plague and it is caused by the bacteria Yersinia pestis. Yersinia pestis is an enterobacteriaceae; it is gram negative and rod shaped.
The carriers of the disease are fleas and wild rodents (often rats). They are immune to it so are not killed by it. When a flea is infected it causes the flea to become more hungry; therefore more likely to spread the disease. Urban rats are not immune to Yersinia pestis so if they are infected they will die. This means that fleas will no longer have them to feed on, so they start to bite humans and infect them instead.
If it is not treated with antibiotics within about a day then it is extremely likely to cause death.
Bubonic plague is one form that the disease can take, but it can also lead to septicemic plague or pneumonic plague. Pneumonic plague can spread from human to human unlike the other forms, and is one reason why it spreads so quickly. It is estimated that 75 million people died from the Black Death.
