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Septicemic (or septicaemic) plague is one of the three main forms of plague. It is caused by ''Yersinia pestis'', a gram-negative species of bacterium. Septicemic plague is a life-threatening infection of the blood, most commonly spread by bites from infected fleas. Like some other forms of gram-negative sepsis, septicemic plague can cause disseminated intravascular coagulation, and is almost always fatal when untreated (the mortality rate in medieval times was 99-100 percent). However, it only occurs in a minority of cases of ''Yersinia'' infection, so that fewer than 5,000 people a year acquire the disease. It is in fact the rarest of the three plague varieties; the other forms are bubonic and pneumonic plague.〔 == Septicemic plague in animals == Septicemic plague is a zoonosis, a disease that generally is acquired by humans from animals, such as rodents and carnivores. Goats, sheep and camels also may carry the bacteria. Cats rarely develop clinical signs but can be infected. Areas west of the Great Plains of North America are one region where plague-infected animals commonly occur. Animals that commonly carry plague bacteria are largely rodents and Leporidae, but carnivores sometimes also become infected by their prey. Prey animals are not immune to the disease, and outbreaks of various strains of plague, such as sylvatic plague, have on occasion devastated populations of black-tailed prairie dogs and black-footed ferrets. Plague has been active in black-tailed prairie dog populations for the past 40–50 years. In the United States outbreaks only occur in the western States and they are devastating, with mortality rates near 100% because the animals have no immunity to the plague. Survivors are the ones that happened not to become infected and colonies that recover from a plague outbreak remain at risk. Because black-footed ferrets prey on black-tailed prairie dogs, wild ferret populations also fall victim to sylvatic plague. An outbreak can kill nearly 100% of ferrets in a population, and surviving ferrets commonly face starvation because the prairie dogs are their main prey. Spray-and-vaccinate campaigns have aimed at preventing the spread of the plague among these animals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「septicemic plague」の詳細全文を読む スポンサード リンク
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