Around the mid 1300's, a great plague hit Europe. The black rat, also known as Rattus Rattus (rather a lack of imagination in the rodent naming office - must have been late on a friday afternoon...) is thought to be the prime suspect. The plague, or Black Death, was caused by a bacterial infection, Pasteurella Pestis. This bacteria lived on fleas and some of the fleas were carried by the rat.

Now, does this make the rat public enemy number 1?

We think not. Sure, the rat was a stowaway on the ships that sailed into European waters but the bacteria was just as much a stowaway. The men that crewed the ships were infected with the plague before they left the east and they could have just as easily caused the spread of the plague on their own, without any rats being on board. Even their food stocks or their cargo would have carried the bacteria - indeed, it could live for weeks without a live host.

To add to the spread of the disease, living conditions in england were rather less than sanitary. Open sewers alongside the streets were the norm and humans shared their living quarters with their livestock. Perfect conditions for the spread of disease and pestilence.

So was the rat responsible for the Plague? Well, to a degree it helped it on its way but even if the rat had not existed the plague would likely have happened anyway.