In the year 1664, a terrible disease appeared in Europe. It reached London, England in 1665. People called it the plague. They didn’t know where it came from or how it spread so fast. Some thought it came from dirty air and some said it was from farm animals. We now know that black rats carried the disease. Tiny insects called fleas bit the rats and then bit humans, and this is how the disease spread. The plague was a horrible illness. It started with a headache and a temperature, then a stomachache. Marks appeared on people’s bodies and they started coughing. People with any of these signs couldn’t leave their houses, and all their family members needed to stay inside too, even when they were perfectly healthy. People in these houses put a red cross on the front door. The worst thing about the plague was that people that caught it usually died within a day or two. The first death in London occurred in April 1665. By May, 43 people were dead from the plague. By the time the disease disappeared from the city, the total number of deaths was about 100,000 – a quarter of London’s population. So what stopped the Great Plague? During the winter of 1665 to 1666, the weather was very cold. This killed the fleas that lived on the rats and stopped them spreading the plague. There weren’t a lot of cases of the plague in 1666. Then, in September, the Great Fire of London destroyed a third of the city and ended the Great Plague completely. As we can see, even though the people of London didn’t understand the plague and they didn’t have any medicine to cure it, they still tried their best to stop it. Sick people stayed in their houses and healthy people didn’t go outside unless they really needed to. These are useful ways to stop disease spreading, even today, and can still save lives.