Here is something of interest and goes along with the article BRD posted...During medieval times, superstitious beliefs about witchcraft led to the killing of large numbers of cats, which allowed the Bubonic Plague to spread unchecked.
Certain religious leaders had been casting aspersions on cats for quite some time before the Black Plague hit. Pope Gregory IX told people that domestic cats were diabolical in 1232, fueling anti-cat sentiment, and this prejudice worsened over the years. Cats were not subservient and tended to be noisy at night, which caused them to be viewed with suspicion. Many superstitious people began to associate them with the devil Large numbers of cats and their owners were executed after being accused of witchcraft in the years leading up to the Black Plague, and for hundreds of years thereafter. Totals vary widely from one historian to the next for both “witches” and cats killed. However, it is safe to say that a large proportion of Europe’s domestic cats were slain, either on suspicion of being Satan’s familiars or as part of the mass animal killings that people undertook in a desperate attempt to control the Plague later on. Dogs were also slain in these mass killings, which removed another of the rat’s natural predators. Most of those murdered on suspicion of witchcraft were poor peasant women who kept pets for companionship, and thus were easy scapegoats. The impoverished, the elderly, and the eccentric were convenient targets for witchcraft accusations, and they were executed along with their pets. Overall, from 1230 to 1700, starting with the Inquisition, millions of cats were murdered...
The persecution had depleted the supply of domestic cats dramatically, leaving human grain stores unprotected when merchants brought the Plague from Asia to Europe in the form of ship rats with infectious fleas. Rats took over Europe, gobbling the grain and providing homes for the fleas that carried the Black Plague. Without the protection of domestic cats, the rat population multiplied exponentially. As a result, the Black Death spread rapidly, decimating Europe’s population. Additionally, many people suffered food poisoning due to rat droppings in their food supplies. Overall, people paid dearly for the slaughter of cats...Although the persecution of cats was not the only cause of the Black Plague's rapid spread, it certainly contributed. Historical events such as these underscore the importance of all animals within a given ecosystem, and the dangers inherent in removing a single predator from the equation...
Lehr, L.J. (2006). “Cats, People, and the Black Plague: Those Who Kept Cats Survived.
PBS.org. (2002). “Mystery of the Black Death.” Secrets of the Dead series