Another type of plague, called pharyngeal, resembles acute tonsillitis. Periodic outbreaks of the plague occur naturally in rodent populations, which may result in a high death rate. Fleas that have lost their usual hosts pursue alternative sources of blood. When this happens, the risk to humans and other animas is increased. Epidemics of plague in humans commonly involves house rats and their fleas. The disease is passed on to humans and other animals when they are bitten by a flea that has bitten an infected rat or other living thing. Animals prone to be carriers in the United States include the rock squirrels, prairie dogs, and other burrowing rodents. During 1924