5. Famous for killing roughly half the population of Europe during the 14th century, bubonic plague has not disappeared and recent years have seen an increasing number of cases reported in the United States
Entering the body via a flea bite, bubonic plague remains one of the most notorious diseases in history. Causing the body’s lymph nodes to swell and the patient to develop severe fevers and vomit profusely, the condition is most famous for eradicating between 25 to 60 percent of the European population, more than 50 million people, in the mid-14th century. Not the first occurrence of the bubonic plague, appearing during the 6th century to kill between 25 and 50 million people, the condition returned in the mid-19th century. Regarded as the first modern pandemic, the late-19th and early-20th centuries saw more than 10 million people die in India alone whilst modern transportation trafficked the condition throughout the globe.
No vaccination exists that effectively combats the disease, but with managed medical care mortality rates can be lowered to between 1 and 15 percent; in contrast, if left untreated mortality lingers between 40 and 60 percent. Despite advances in the developed world, the developing world continues to suffer from the bubonic plague, with more than a thousand cases reported each year in central Africa. Recent years have even seen a return of the disease to North America, with at least 1,036 cases reported between 1990 and 2015 in the United States – a number rising in frequency over time.