 This decision may have affected the length of the epidemic since those animals could have helped keep in check the rat population carrying the fleas which transmitted the disease.Thinking bad air was involved in transmission, the authorities ordered giant bonfires to be burned in the streets and house fires to be kept burning night and day, in the hope that the air would be cleansed.Tobacco was thought to be a prophylactic and it was later said that no London tobacconist had died from the plague during the epidemic.