Rats did not start plague—starving fleas did
Yersinia pestis still causes roughly 600 reported cases a year, mostly in places like Congo, Madagascar, and Peru. Antibiotics cut death risk to about 10% from roughly 70% untreated. The real vector story centers on blocked fleas—and, in one English village study, mostly people infecting people.
Plague is infection with the bacterium Yersinia pestis. Fever, weakness, and headache usually begin one to seven days after exposure. Bubonic plague swells lymph nodes; septicemic plague invades the blood; pneumonic plague hits the lungs and can spread person to person through infectious droplets. Lab confirmation looks for the organism in lymph fluid, blood, or sputum. Typical treatment combines antibiotics such as gentamicin with a fluoroquinolone, plus supportive care; vaccines are reserved for people at especially high exposure risk.
A popular myth blames rats as direct starters of bubonic outbreaks. The pathogen mainly rides fleas—especially Xenopsylla cheopis—that first sicken rodents. Bacteria multiply into a stomach plug that starves the flea; frantic feeding then regurgitates infected blood into a new bite. Reservoirs persist among rodents on every continent except Australia, between about 55 degrees north and 40 degrees south. A study of the 1665 Eyam outbreak in Derbyshire estimated that about three-quarters of cases were likely human-to-human, often within families—far more than older models assumed.
Without treatment, septicemic plague is usually fatal, though early antibiotics can cut mortality to roughly 4 to 15 percent. Untreated pneumonic plague approaches 100 percent mortality and may kill within one to six days after a short incubation of hours to a few days. Waldemar Haffkine made the first plague vaccine in 1897; an estimated 26 million doses left Bombay between 1897 and 1925, cutting mortality by about 50 to 85 percent in that program. The fourteenth-century Black Death killed more than 50 million people in Europe. Today's CDC guidance still limits routine vaccination to select lab and field workers facing antimicrobial-resistant or aerosol risks.
Source: Plague (disease)
