However, the expected disease dynamics have not been found in any rodent. In the western United States, several species of rodents are thought to maintain Y. In the steppes, the natural reservoir is believed to be principally the marmot. Several species of rodents serve as the main reservoir for Y. If the disease has progressed to the pneumonic form, humans can spread the bacterium to others by coughing, vomiting, and possibly sneezing. Transmission to humans is usually through the bite of infected fleas. pestis can spread from the urban environment and back. In the sylvatic cycle, the rodent is wild, but in the urban cycle, the rodent is primarily the brown rat ( Rattus norvegicus). pestis, most of the spreading occurs between rodents and fleas. In the urban and sylvatic (forest) cycles of Y. ![]() pestis is regurgitated into the wound, causing infection. pestis biofilm when the flea attempts to feed on an uninfected host, Y. pestis bacterium, which appears as a dark mass in the gut: The foregut ( proventriculus) of this flea is blocked by a Y. Oriental rat flea ( Xenopsylla cheopis) infected with the Y. The analysis focused on the transition to a growth condition mimicking growth in host cells. Proteome Ī comprehensive and comparative proteomics analysis of Y. pseudotuberculosis, differing only in the presence of specific virulence plasmids. pestis is thought to be descended from Y. Among other things, these virulence factors are required for bacterial adhesion and injection of proteins into the host cell, invasion of bacteria in the host cell (via a type-III secretion system), and acquisition and binding of iron harvested from red blood cells (by siderophores). Together, these plasmids, and a pathogenicity island called HPI, encode several proteins that cause the pathogenesis for which Y. pPla codes for a protease, Pla, that activates plasmin in human hosts and is a very important virulence factor for pneumonic plague. pFra codes for a phospholipase D that is important for the ability of Y. It also hosts two other plasmids, pPCP1 (also called pPla or pPst) and pMT1 (also called pFra) that are not carried by the other Yersinia species. Some strains are non-pathogenic, such as that of strain 91001, whose sequence was published in 2004. In 2006 the genome sequence of a strain of biovar Antiqua was completed. orientalis, obtained from a clinical isolate in the United States). medievalis), and strain CO92 (of biovar Y. Several complete genome sequences are available for various strains and subspecies of Y. Its closest relatives are the gastrointestinal pathogen Yersinia pseudotuberculosis, and, more distantly, Yersinia enterocolitica. Similar to other Yersinia species, it tests negative for urease, lactose fermentation, and indole. pestis is a non-motile coccobacillus, a facultative anaerobic bacterium with bipolar staining (giving it a safety pin appearance) that produces an antiphagocytic slime layer. 3.3 In humans and other susceptible hosts.The plague also has a detrimental effect on non-human mammals in the United States, these include the black-tailed prairie dog and the endangered black-footed ferret. The plague is now commonly found in sub-Saharan Africa and Madagascar, areas that now account for over 95% of reported cases. A five- to six-fold increase in cases occurred in Asia during the time of the Vietnam War, possibly due to the disruption of ecosystems and closer proximity between people and animals. With proper antibiotic treatment, the prognosis for victims is much better than before antibiotics were developed. However, Yersin actually linked plague with a bacillus, initially named Pasteurella pestis it was renamed Yersinia pestis in 1944.Įvery year, between one thousand and two thousand cases of the plague are still reported to the World Health Organization. Kitasato Shibasaburō, a Japanese bacteriologist who practised Koch's methodology, was also engaged at the time in finding the causative agent of the plague. Yersin was a member of the Pasteur school of thought. pestis was discovered in 1894 by Alexandre Yersin, a Swiss/French physician and bacteriologist from the Pasteur Institute, during an epidemic of the plague in Hong Kong. Yersinia pestis is a parasite of its host, the rat flea, which is also a parasite of rats, hence Y. Plague takes three main forms: pneumonic, septicemic, and bubonic. It causes the disease plague, which caused the first plague pandemic and the Black Death, the deadliest pandemic in recorded history. It is a facultative anaerobic organism that can infect humans via the Oriental rat flea ( Xenopsylla cheopis). pestis formerly Pasteurella pestis) is a gram-negative, non-motile, coccobacillus bacterium without spores that is related to both Yersinia pseudotuberculosis and Yersinia enterocolitica. ![]() (Lehmann & Neumann, 1896) The Netherlands, 1920
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |