13. Plague Fleas
Few insect infestations have done as much damage as the plague fleas that started the waves of the Black Death throughout Europe. While people living at the time had no way of knowing it was the tiny fleas on rats, not the rats themselves, that were causing the plague, we now know the full devastation that unnaturally high populations of plague-infected fleas had throughout Europe.
Research of the periods of the Black Death indicate that plague years tended to occur after a warm, wet summer in the areas in which the fleas were endemic throughout the Middle East and northern Africa. The fleas then reached Europe through merchant vessels and began to infect a population with no natural resistance to the disease.
Plague fleas can actually still be encountered in the American Southwest, and the likelihood of running into one may be increasing with climate change. Campers in some Southwestern national parks are given warnings on how to avoid attracting fleas to their camps to reduce the risk of exposure. Thankfully, the plague is now a treatable disease, but that’s of little comfort to the hundreds of thousands who died thanks to medieval Europe’s flea infestation.