It causes the deadly disease named plague. Yersinia pestis bacteria Plague.
The plague disease, caused by Yersinia pestis, is enzootic (commonly present) in populations of fleas carried by ground rodents, including marmots, in various areas including Central Asia, Kurdistan, Western Asia, Northern India and Uganda.  Yersinia pestis bacteria -- the organism responsible for plague -- can grow with or without oxygen. Yersinia pestis are the bacteria that cause plague. Approximately 10 to 20 people in the United States develop an infection each year from flea or rodent bites. Yersinia pestis are the bacteria that cause plague. This is a Gram-negative bacteria that can grow with or without oxygen (a quality called facultative anaerobic). Yersinia pestis bacteria are responsible for the various types of plague, such as bubonic plague. Yersinia pestis are the bacteria that cause plague. They can infect humans, rodents, and ectoparasites (such as fleas and lice). Once infection with Yersinia pestis bacteria has been confirmed, the patient is hospitalized, isolated, and treated with antibiotics. Yersinia pestis are the bacteria that cause plague. They can infect humans, rodents, and ectoparasites (such as fleas and lice). The plague bacteria can be transmitted to humans in the following ways: Flea bites. Plague bacteria are most often transmitted by the bite of an infected flea. During plague epizootics, many rodents die, causing hungry fleas to seek other sources of blood. People and animals that visit places where rodents have recently died from plague are at risk of being infected from flea bites. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Typically this requires direct and close contact with the person with pneumonic plague. Transmission of these droplets is the only way that plague can spread between people. Scanning electron micrograph of Yersinia pestis, which causes bubonic plague, on proventricular spines of a Xenopsylla cheopis flea. NIAID. Yersinia pestis (sometimes spelled Yersina) is the name of the bacteria that causes the bubonic plague. Y. pestis is primarily the cause of disease in a wide variety of rodents, including marmots, ground squirrels, gerbils, and prairie dogs, and, most famously, rats, specifically the black rat (Rattus rattus) (and almost certainly not the brown rat (R. norvegicus), despite what you might have heard). Yersinia pestis. By: Katia Sutyak. Life History Yersinia pestis is the causative agent of the systemic invasive infectious disease often referred to as the plague. The Y. pestis is an extremely virulent pathogen that is likely to cause severe illness and death upon infection unless antibiotics are administered. Transmission. Y. pestis has the ability to cause disease in rodents, insects and humans. The primary carriers of the pathogen are the Oriental rat flea, Xenopsylla cheopis, and infected rodents. The path of transmission to humans usually involves a flea feeding on an infected rodent and becoming a carrier of infection. Yersinia pestis (formerly Pasteurella pestis) is a Gram-negative, rod-shaped coccobacillus, a facultative anaerobic bacterium that can infect humans and animals. It causes the deadly disease named plague. Y. pestis is a nonmotile, rod-shaped, facultative anaerobe with bipolar staining (giving it a safety pin appearance). Similar to other Yersinia species, it tests negative for urease, lactose fermentation, and indole. Transmission occurs most often through the bites of infected fleas or rodents -- symptoms tend to appear one to six days later. Yersinia pestis are the bacteria that cause plague. They can infect humans, rodents, and ectoparasites (such as fleas and lice). Once infection with Yersinia pestis bacteria has been confirmed, the patient is hospitalized, isolated, and treated with antibiotics. Yersinia pestis are the bacteria that cause plague. They can infect humans, rodents, and ectoparasites (such as fleas and lice). Ecology. The bacteria that cause plague, Yersinia pestis, maintain their existence in a cycle involving rodents and their fleas. In urban areas or places with dense rat infestations, the plague bacteria can cycle between rats and their fleas. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Typically this requires direct and close contact with the person with pneumonic plague. Transmission of these droplets is the only way that plague can spread between people.
https://en.wikipedia.org/wiki/Black_Death http://plague.emedtv.com/yersinia-pestis/yersinia-pestis.html http://plague.emedtv.com/yersinia-pestis/yersinia-pestis-bacteria.html http://www.cdc.gov/plague/transmission/index.html http://archaeology.about.com/od/Ancient-Medicine/fl/Yersina-pestis.htm http://web.uconn.edu/mcbstaff/graf/Student%20presentations/Y.%20pestis/Yersinia%20pestis.html https://en.wikipedia.org/wiki/Yersinia_pestis http://plague.emedtv.com/yersinia-pestis/yersinia-pestis-bacteria.html http://www.cdc.gov/plague/transmission/index.html
what causes yersinia pestis