This form results from bites of infected fleas or from handling an infected animal. Yersinia pestis, a zoonotic bacteria, usually found in small mammals and their fleas and it is transmitted between animals from their fleas. Occasionally, other species become infected, causing an outbreak among animals, called an epizootic. A downloadable version pdf icon[PDF – 1 page] is also available. Patients develop fever, chills, extreme weakness, abdominal pain, shock, and possibly bleeding into the skin and other organs. yersinia pestis 1) disease 2) source of infection 3) mode of transmission from animal to human 4) replication in host. Humans are usually infected through bites from rodent fleas that carry the disease. Plague is transmitted between animals and humans by the bite of infected fleas, direct contact with infected tissues, and inhalation of infected respiratory droplets. Many types of animals, such as rock squirrels, wood rats, ground squirrels, prairie dogs, chipmunks, mice, voles, and rabbits can be affected by plague. CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Clin Infect Dis. Most human cases in the United States occur in two regions: Over 80% of United States plague cases have been the bubonic form. It occurs in both men and women, though historically is slightly more common among men, probably because of increased outdoor activities that put them at higher risk. Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous. If the disease has progressed to the pneumonic form, humans can spread the bacterium to others by coughing, vomiting, and possibly snee… Protect health workers. Rats 2. If the patient is not treated with the appropriate antibiotics, the bacteria can spread to other parts of the body. The disease can also result by inhaling contaminated aerosols or from direct contact with infected animal tissue. Scientific studies have suggested that epizootics in the southwestern United States are more likely during cooler summers that follow wet winters. Isolate patients with pneumonic plague. Find and stop the source of infection. Squirrels 4. Cats are particularly susceptible to plague, and can be infected by eating infected rodents. Yersinia pestis can be transmitted by fleas within a few days after taking a blood meal from a highly bacteremic host, termed early-phase or mass transmission; and again after it forms a dense biofilm in the foregut of its vector that can eventually block blood feeding. Plague is a serious illness. In the bubonic form there is also swelling of lymph nodes, while in the septicemic form tissues may turn black and die, and in the pneumonic form shortness of breath, cough and chest pain may occur. In the case of plague pneumonia, transmission can occur via inhalation of the cough droplets from another infected individual. As an animal disease, plague is found in all continents, except Oceania. It is this third that is the root cause of all three instances of plagues going global causing humongous human and economic damage. From 2010 to 2015 there were 3248 cases reported worldwide, including 584 deaths. The flea lives on a rat and gives the rat the sickness, but it doesn't affect the rat. Lymph node aspirate: An affected bubo should contain numerous organisms that can be evaluated microscopically and by culture. Institute vector control, then rodent control. If these Yersinia pestis bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Prompt treatment with the correct medications is critical to prevent complications or death. Presently, human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia. While the most common form of Yersinia pestis transmission is the flea, it is possible to become infected if you eat an infected mammal or come into contact with the body fluids of dead plague victims or partially resistant infected animals. Currently, the three most endemic countries are the Democratic Republic of the Congo, Madagascar, and Peru. Rare infection may have caused death of Chicago scientist. In parts of the developing world, plague can sometimes occur in urban areas with dense rat infestations. There are two main clinical forms of plague infection: bubonic and pneumonic. The organism is transmitted to humans who are bitten by fleas that have fed on infected rodents or by humans handling infected animals. Depending on the mode of transmission (flea bite or aerosol droplets), Y. pestis can precipitate bubonic or pneumonic plague infections (35, 53). Plague then spread from urban rats to rural rodent species, and became entrenched in many areas of the western United States. These organisms multiply in the flea and block the flea's proventriculus. J Pediatr. Between 2010 and 2015, there were 3,248 cases reported worldwide. Plague has occurred in people of all ages (infants up to age 96), though 50% of cases occur in people ages 12–45. Victims of septicemic plague are usually covered with black patches due to hemorrhages throughout the skin, leading to its “Black Death” nickname. Pneumonic plague, or lung-based plague, is the most virulent form of plague. This type of spread has not been documented in the United States since 1924, but still occurs with some frequency in developing countries. Rodents are the primary hosts of the bacteria, which is spread through fleas. Proc Natl Acad Sci USA 1995 15;92(17):7609-11. Plague is caused by infection with the bacterium Yersinia pestis, usually found in small mammals and their fleas. In order to effectively and efficiently manage plague outbreaks it is crucial to have an informed and vigilant health care work force (and community) to quickly diagnose and manage patients with infection, to identify risk factors, to conduct ongoing surveillance, to control vectors and hosts, to confirm diagnosis with laboratory tests, and to communicate findings with appropriate authorities. If bubonic plague is untreated, Yersinia pestis bacteria invade the bloodstream and spread rapidly, causing septicemic plague, and if the lungs are seeded, secondary pneumonic plague. The organism that causes plague, Yersinia pestis, lives in small rodents found most commonly in rural and semirural areas of Africa, Asia and the United States. Dogs and cats may also bring plague-infected fleas into the home. Chipmunks 7. During the first week after being taken up by a flea in a blood meal, the bacteria multiply in the … Yersinia pestis is a zoonotic bacteria that causes plague or the Black Death during medieval times, that is most commonly transmitted through fleas that feed on infected rodents. Since that time, plague has occurred in rural and semi-rural areas of the western United States, primarily in semi-arid upland forests and grasslands where many types of rodent species can be involved. Human infections with the bacterium Yersinia pestis are often secondary sequelae to expansion phases of sylvatic rodent plague foci (17, 24).Expansion events occur in response to conditions that facilitate the dispersal of the infectious agent or to the population dynamics of animal reservoirs (), the flea vector (), and human hosts (8, 52). Plague epidemics have occurred in Africa, Asia, and South America; but since the 1990s, most human cases have occurred in Africa. The mice, which carried Yersinia pestis, were being studied at the Public Health Research Institute as part of a vaccine experiment. Plague is infamous for killing millions of people in Europe during the Middle Ages. Footnote: All recommended antibiotics for plague have relative contraindications for use in children and pregnant women; however, use is justified in life-threatening situations. Transmission to People. Plague is a highly virulent disease believed to have killed millions during three historic human pandemics. Direct person-to-persontransmission does not occur except in the case of pneumonic plague, whenrespiratory droplets may transfer the infection from the patient to others inclose contact. Yersinia pestis, the bacterial agent of bubonic and pneumonic plague, is one of the most virulent human bacterial pathogens and is well known historically for its ability to cause devastating pandemics.Plague remains an international public health concern and periodically re-emerges in the form of sudden large outbreaks. Obtain specimens which should be carefully collected using appropriate infection, prevention and control procedures and sent to labs for testing. Symptoms, on top of those found in the other two forms, include a severe cough, bloody sputum, chest pains, confusion, cyanosis, shock and eventual death. The bacteria that cause plague, Yersinia pestis, maintain their existence in a cycle involving rodents and their fleas. In Madagascar cases of bubonic plague are reported nearly every year, during the epidemic season (between September and April) 4). Remove brush, rock piles, junk, cluttered firewood, and possible rodent food supplies, such as pet and wild animal food. The bacteria multiply in the lymph node closest to where the bacteria entered the human body. A person with pneumonic plague may experience high fever, chills, cough, and breathing difficulty and may expel bloody sputum. During plague epizootics, many rodents die, causing hungry fleas to seek other sources of blood. Plague ecology in the United States. Localization and adherence of the biofilm to the flea foregut is essential for transmission. by unblocked fleas was viewed as anomalous and thought to occur only by mass action. Prairie dogs 6. Being that a rat is a bigger organism and … Yersinia pestisadopts a unique life stage in the digestive tract of its flea vector, characterized by rapid formation of a bacterial biofilm that is enveloped in a complex extracellular polymeric substance. In the case of plague pneumonia, transmission can occur via inhalation of the cough droplets from another infected individual. Not widely available in the United States. Active long-term surveillance of animal foci, coupled with a rapid response during animal outbreaks has successfully reduced numbers of human plague outbreaks. Flea bite exposure may result in primary bubonic plague or septicemic plague. Yersinia Pestis. Ensure safe burial practices. Antibiotic treatment is effective against plague bacteria, so early diagnosis and early treatment can save lives. Workers in direct contact with pneumonic plague patients must wear standard precautions and receive a chemoprophylaxis with antibiotics for the duration of seven days or at least as long as they are exposed to infected patients. yersinia enterocolitica 1) disease 2) source of infection 2. There are only a handful of sporadic cases in the US every year and are concentrated in the desert southwest. Transmission of these droplets is the only way that plague can spread between people. Global distribution of natural plague foci as of March 2016, Figure 3. Recommended antibiotic treatment for plague. Although the majority of patients with plague present with a bubo, some may have nonspecific symptoms. Yersinia pestis can be transmitted by fleas within a few days after taking a blood meal from a highly bacteremic host, termed early-phase or mass transmission; and again after it forms a dense biofilm in the foregut of its vector that can eventually block blood feeding. Occasionally, other species become infected, causing an outbreak among animals, called an epizootic. Scientists think that plague bacteria circulate at low rates within populations of certain rodents without causing excessive rodent die-off. Yersinia pestis, which causes bubonic plague, forms biofilms in fleas, its insect vectors, as a means to enhance transmission. The three most endemic countries are the Democratic Republic of Congo, Madagascar, and Peru. In urban areas or places with dense rat infestations, the plague bacteria can cycle between rats and their fleas. Plague is infamous for killing more than 50 million people in Europe during the fourteenth century. Bacteriostatic, but effective in a randomized trial when compared to gentamicin. Killing rodents before vectors will cause the fleas to jump to new hosts, this is to be avoided. The pneumonia may cause respiratory failure and shock. Washington (DC): National Academies Press (US); 2008. In the urban and sylvatic (forest) cycles of Y. pestis, most of the spreading occurs between rodents and fleas. Typically this requires direct and close contact with the person with pneumonic plague. Boulanger LL, Ettestad P, Fogarty JD, Dennis DT, Romig D, Mertz G. Gentamicin and tetracyclines for the treatment of human plague: Review of 75 cases in New Mexico, 1985–1999. Use repellent if you think you could be exposed to rodent fleas during activities such as camping, hiking, or working outdoors. PATHOGENESIS Yersinia pestis is primarily a rodent pathogen, with humans being an accidental host when bitten by an infected rat flea. Yersinia pestis possesses a unique gene (pla) encoding coagulase and fibrinolysin which is implicated in the transmission of plague by fleas. Appropriate diagnostic samples include blood cultures, lymph node aspirates if possible, and/or sputum, if indicated. Septicemic and pneumonic plague may also be primary manifestations. Yersinia pestis, the etiological agent of the zoonosis plague, is transmitted from diseased rodents to humans by the bite of infected fleas. Plague was the cause of some of the most-devastating epidemics in history. Man to man transmission. The conclusions from studies comparing how efficiently fleas transmit plague after becoming infected have been inconsistent, possibly because a variety of rodent blood sources have been used. Diagnosis. Rodents are the primary hosts of the bacteria, which is spread through fleas. Reduce rodent habitat around your home, work place, and recreational areas. Several cases of human plague have occurred in the United States in recent decades as a result of contact with infected cats. The Gram-negative bacterium Yersinia pestis is responsible for deadly plague, a zoonotic disease established in stable foci in the Americas, Africa, and Eurasia. Now, the pathogenesis of Yersinia pestis consists of two components - the transmission of bacteria from fleas and the host response to the bacteria. Humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. Blood smears taken from suspected bubonic plague patients early in the course of illness are usually negative for bacteria by microscopic examination but may be positive by culture. There are only a handful of sporadic cases in the US every year and are concentrated in the desert southwest. Many types of animals, such as rock squirrels, wood rats, ground squirrels, prairie dogs, chipmunks, mice, voles, and rabbits can be affected by plague. If these bacteria-containing droplets are breathed in by another person they can cause pneumonic plague. Todd SR, Dahlgren FS, Traeger MS, Beltrán-Aguilar ED, Marianos DW, Hamilton C, McQuiston JH, Regan JJ. FDA approved based on animal studies but limited clinical experience treating human plague. The pneumonic form is invariably fatal unless treated early. Prairie dogs 6. However, recovery rates are high if detected and treated in time (within 24 hours of onset of symptoms). Bactericidal. Its persistence in the environment relies on the subtle balance between Y. pestis-contaminated soils, burrowing and nonburrowing mammals exhibiting variable degrees of plague susceptibility, and their associated fleas. The deduced evolutionary pathway involved sequential steps of increased flea digestive tract colonization and transmissibility. Ecology. Pneumonic plague is the most serious form of the disease and is the only form of plague that can be spread from person to person (by infectious droplets). Patients should be isolated so as not to infect others via air droplets. This zoonotic pathogen can be transmitted directly by infectious droplets or by contact with contaminated fluid or tissue or … Transmission Fleas are natural vectors (carriers) of Y. pestis , and the bacteria are typically transmitted to and among rodents via flea bite. Plague can take different clinical forms, but the most common are bubonic, pneumonic, and septicemic. Yersinia pestis is a zoonotic bacteria that causes plague or the Black Death during medieval times, that is most commonly transmitted through fleas that feed on infected rodents. Yersinia pestis, responsible for causing fulminant plague, has evolved clonally from the enteric pathogen, Y. pseudotuberculosis, which in contrast, causes a relatively benign enteric illness. Y. pestis Principal réservoir : les rongeurs (souris, rat, mulot, écureuil…) Principal vecteur : la puce L’homme est un hôte accidentel, il développe la forme bubonique suite à une piqûre de puce. The infection exists in three major plague forms: bubonic, septicemic, and pneumonic. In the bubonic form there is also swelling of lymph nodes, while in the septicemic form tissues may turn black and die, and in the pneumonic form shortness of breath, cough and chest pain may occur. People always focus on the genetic changes between Y. pestis and Y. Epizootics are most likely in areas with multiple types of rodents living in high densities and in diverse habitats. Sputum: Culture is possible from sputum of very ill pneumonic patients; however, blood is usually culture-positive at this time as well. Plague can be a very severe disease in people, particularly in its septicemic and pneumonic forms, with a case-fatality ratio of 30%-100% if left untreated 2). After being taken up by macrophages, the bacteria proliferate in the affected lymph nodes, causing inflammation and swelling to occur, i.e., buboes. Yersinia pestis is an obligate parasite, meaning that it cannot reproduce without a host. Yersinia Pestis starts by a rodent flea picking up Yersinia Pestis in unclean environments. Dogs and cats may also bring plague-infected fleas into the home. Recommended antibiotic treatment of pregnant women for plague. Contact your local health department if you have questions about disposal of dead animals. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. At present, the third pandemic has become largely quiescent, with hundreds of human cases being reported mainly in a few impoverished African countries, where zoonotic plague is mostly transmitted to people by rodent-associated flea bites. People and animals that visit places where rodents have recently died from plague are at risk of being infected from flea bites. This is called the enzootic cycle. Duration of treatment is 10 to 14 days, or until 2 days after fever subsides. The acquisition of flea-borne transmission is a recent event in the evolution of Yersinia pestis. Make your home and outbuildings rodent-proof. The last urban outbreak of rat-associated plague in the United States occurred in Los Angeles in 1924-1925. Buboes are often so painful that patients are generally guarded and have restricted movement in the affected region. If cultures yield negative results, and plague is still suspected, serologic testing is possible to confirm the diagnosis. Scientists think that plague bacteria circulate at low rates within populations of certain rodents without causing excessive rodent die-off. Post-exposure prophylaxis is indicated in persons with known exposure to plague, such as close contact with a pneumonic plague patient or direct contact with infected body fluids or tissues. PEP should be given only when the benefits outweigh the risks.

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