The Black Death had been endemic to Asia, but came to Europe by means of ships landing in Italy which originated in Asia. The bacterium responsible for the Black Death, yersenia pestis only survived on a certain type of flea that only survived on Asian black rats. European brown rats were not a suitable host.The rats were transmitted to Europe by means of ship, and thereby carried the disease to Europe. A ship which landed in Messina in October, 1347 is widely suspected as the first to transmit the rats to Europe. Town officials would not allow the ship to offload, as the sailors were either dead or dying; yet in the time the ship was docked, the Asian rats left the ship and made their way inland. Fleas from the rats often infested the bedding and clothing of people of the European Middle Ages and bit their human hosts, thereby inflicting them with the plague. The clothes of the deceased were often passed on to others who were also bitten by the fleas. Numerous remedies, including inhaling vapors from urinals, were attempted to stop its spread, all to no avail.
The plague, known as astra mors (dreadful death) but later "black Death had two phases: bubonic, which could only be transmitted by flea bites, and pneumonic which could be transmitted from human to human. The plague seldom reached the pneumonic phase, as victims normally died during the bubonic stage. An often misunderstood fact is that the Plague did not descend on Europe as a blanket but rather as a cascading wave. Much of the panic caused by the plague was in towns and villages where it had not yet struck; but whose inhabitants saw it coming and could do nothing other than wait. Plague normally passed through a given area within two weeks, yet it left unprecedented death in its wake.
Plague finally passed when the European Brown rats drove off their black rivals; but before it ended, fully one fourth the population of Europe had died as a result.
The biological mechanism for the spread of the Black Death was fleas that were carried by rats and then transferred themselves onto human hosts. Humans could also pass some forms of the Black Death to one another through bodily fluids.
The rats and fleas spread across Eurasia with human migration and with trade. Some of the movement was caused by upheaval in human populations as wars and famines caused people to move around. Black Death spread over truly long distances (for example, to Europe) through trade. Rats on ships are seen as the main means of getting the Black Death to Europe.
The Black Death also called the Bubonic Plague, was caused by fleas carried by rats that were common to the towns and cities. The Black Death was able to spread very quickly due to the fact that people lived very close together and knew nothing about contagious diseases. Also, because of the crude disposal of infected bodies, it helped spread the disease much faster, as those who handled the bodies did not protect themselves in any way.