Yersinia pestis
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. In the past, Y. pestis has caused devastating epidemics during three periods of modern history; the Justinian Plague spread from the Middle East to the Mediterranean during the 6th-8th centuries AD and killed approximately 25% of the population below the Alps region. Perhaps the most famous incidence of any disease was the devastating Black Plague of 8th-14th century Europe that eradicated 25 million people (nearly 25% of the population) and marked the end of the Dark Ages. The third endemic began in 1855 in China and was responsible for millions of deaths.
Microbiological Characteristics
Yersinia pestis is a Gram-negative, bipolar-staining coccobacillus member of the Enterobacteriaceae family, and is an obligate intracellular pathogen that must be contained within the blood to survive. It is also a fermentative, motile organism that produces a thick anti-phagocytic slime layer in its path.
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. Once internalized, the bacteria will continue to reproduce until a large blockage is formed in the midgut of the flea, causing digestion and other gastrointestinal functions to cease. When the flea attempts to feed on humans, the blockage inhibits any blood from entering the stomach cavity; instead, portions of the blockage, often containing 11,000-24,000 bacilli, are regurgitated into the mammalian host.
Virulence Factors
Yersinia pestis encodes two antigenic molecules: Fraction 1 (F1) capsular antigen, and VW antigen. Both of these molecules are needed for pathogenicity, and are not expressed at temperatures lower than 37°C. This requirement is the main reason why Yersinia is not virulent in fleas, since their body temperature normally levels around 25°C. Yersinia is a model for studying Type III Secretion Systems (TTSS) that inject bacterial proteins into a host cell. In Y. pestis, it is the translocation of Yersinia outer proteins (Yop’s) that blocks the host cell’s ability to communicate with immune system cells and down-regulates the response of phagocytic host cells to infection.
Table 6 shows the results of the biochemical tests. The isolate can obtain its energy by means of aerobic respiration but not fermentation. In the Oxidation-Fermentation test, a yellow color change was produced only under both aerobic conditions, indicating that the EI can oxidize glucose to produce acidic products. In addition to glucose, the EI can also utilize lactose and sucrose, and this deduction is based on the fact that the color of the test medium broth changed to yellow in all three Phenol Red Broth tests. These results are further supported by the results of the Triple Sugar Iron Agar test. Although the EI does perform fermentation of these three carbohydrates, it appears that this bacterium cannot perform mixed acid fermentation nor 2,3-butanediol fermentation due to the lack of color change in Methyl Red and Vogues-Proskauer
The Black Death (also called the "plague" or the "pestilence", the bacteria that causes it is Yersinia Pestis) was a devastating pandemic causing the death of over one-third of Europe's population in its major wave of 1348-1349. Yersinia Pestis had two major strains: the first, the Bubonic form, was carried by fleas on rodents and caused swelling of the lymph nodes, or "buboes", and lesions under the skin, with a fifty-percent mortality rate; the second, the pneumonic form, was airborne after the bacteria had mutated and caused fluids to build up in the lungs and other areas, causing suffocation and a seventy-percent mortality rate.
For the disease to occur, Bordetella pertussis evades the host immune system and is disseminate in the lower respiratory tract. Inhaled bacteria droplets then attach to the ciliated epithelial cells in the nasal-pharynx and trachea. It is at this point that Bordetella pertussis produces virulent factors that are classified into two; adhesins and toxins. Adhesins mediate bacterial attachment to the epithelial cells while toxins that mediate the host immune system. Adhesins include; filamentous haemagglutinin, fimbriae and pertactin while toxins include pertussis toxin, tracheal cytotoxin and adenylate cyclase toxin(1). To understand the role of these virulence factors in whooping cough disease, a mouse model has been used (2).
Bloodborne Pathogens are pathogenic microorganisms that can eventually cause disease. They are found in human blood and other bodily fluids such as synovial fluid, semen, vaginal secretions, cerebrospinal fluid and any other fluid that mixes or has contact with blood. The bloodborne pathogens are pathogenic, which means they are disease causing, and they are also microorganisms, which means that they are very small so the human eye cannot see them.
The most common way this disease is transmitted from one animal to the next is through mosquitoes. A mosquito carrying infective heartworm larvae bites a dog and transmits the infection to them. The larvae grow, develop, and migrate in the body over a period of 6 to 7 months, in which time they become sexually mature male and female worms. this is the prepatent period. The worms then reside in the heart, lungs, and associated blood vessels. The worms begin to mate and release microfilaria into the blood stream. When a mosquito bites an infected dog it takes in some of the microfilaria in the blood. After 10 to 30 days there is larvae in the mosquito’s salivary gland which can then be passed on to the next dog the mosquito bites.
Disease and parasitism play a pervasive role in all life. Many of these diseases start with microparasites, which are characterized by their ability to reproduce directly within an individual host. They are also characterized by their small size, short duration of infection, and the production of an immune response in infected and recovered individuals. Microparasites which damage hosts in the course of their association are recognized as pathogens. The level of the interaction and the extent of the resultant damage depends on both the virulence of the pathogen, as well as the host defenses. If the pathogen can overcome the host defenses, the host will be damaged and may not survive. If on the other hand the host defenses overcome the pathogen, the microparasite may fail to establish itself within the host and die.
Being a gram-negative bacterium, L. pneumophila has lipopolysaccharides (LPS) that act as endotoxin within a human host. The presence of a flagella is thought to mediate adherence to human lung cells, thereby causing infection, since flagella-less strains do not cause disease. Once attached to human cells, the organism is engulfed by a macrophage where is utilizes the internal environment to multiply.
As this book points out, and what I found interesting, the therapeutic relationship between therapist and client, can be even more important than how the therapy sessions are conducted. A therapists needs to be congruent. This is important because a client needs a sense of stability. To know what is expected from him or her while being in this transitional period of change. In some cases this congruency may be the only stability in his life, and without it, there is no way of him trusting in his t...
This disease may be on the brink of being eradicated entirely but that doesn’t stop it from being one of the grossest things that anyone has ever seen. The parasite enters the body via unsafe drinking water. When people drink water infected with water fleas that have have been hosting the larvae of the parasite. There are no symptoms, to begin with, but about one year later, blisters on the feet or legs begin to develop and then the adult fully developed worm crawls out of the host body over a period of a few weeks. It’s said that the pain is intense and can incapacitate a person for weeks at a time. The pain can also continue for months after the infection. The parasite needs to infect a person at least once a year in order to continue. There were an estimated 3.5 million cases in 1986 but the disease has been greatly reduced over time and only 22 cases were reported in 2015. This disease will probably be the first parasitic disease to be completely eradicated in humans.
Kirsten I. Bos, Verena J. Schuenemann, et al, “A draft genome of Yersinia pestis from victims of the Black Death,” Nature, 7370, (2011): 506-510
Sweeping through Western Europe during the fourteenth century, the Bubonic Plague wiped out nearly one third of the population and did not regard: status, age or even gender. All of this occurred as a result of a single fleabite. Bubonic Plague also known as Black Death started in Asia and traveled to Europe by ships. The Plague was thought to be spread by the dominating empire during this time, the Mongolian Empire, along the Silk Road. The Bubonic Plague was an infectious disease spread by fleas living on rats, which can be easily, be attached to traveler to be later spread to a city or region. Many factors like depopulation, decreasing trade, and huge shifts in migrations occurred during the Bubonic Plague. During Bubonic Plague there were also many different beliefs and concerns, which include fear, exploitation, religious and supernatural superstition, and a change of response from the fifteenth to eighteen century.
In Shirley Jackson’s “The Lottery,” the theme of the story is dramatically illustrated by Jackson’s unique tone. Once a year the villagers gather together in the central square for the lottery. The villagers await the arrival of Mr. Summers and the black box. Within the black box are folded slips of paper, one piece having a black dot on it. All the villagers then draw a piece of paper out of the box. Whoever gets the paper with the black dot wins. Tessie Hutchinson wins the lottery! Everyone then closes in on her and stones her to death. Tessie Hutchinson believes it is not fair because she was picked. The villagers do not know why the lottery continues to exist. All they know is that it is a tradition they are not willing to abandon. In “The Lottery,” Jackson portrays three main themes including tradition, treason, and violence.
Understanding the components of building an effective helping relationship is fundamental. The therapeutic alliance evolves from an effective helping relationship. In family therapy the alliance, exist among the individuals, subgroups, and whole family. It is imperative for the family and clinician to have a positive relationship in order progress towards resolution of the presenting problem. In the alliance, the clinician and family work as a team. The alliance can have an impact on the outcome of therapy. Positive alliances increase the likelihood of resolution and positive outcome in therapy. A negative alliance will yield a less than expectable outcome. The therapeutic alliance hinges on the bond that is created between the client and clinician. Having a positive therapeutic alliance and solid theoretical rationale a family therapist can join hands with his or her client(s) and together can achieve goals.
Deforestation is a widely used term, but one with different meanings. Disturbance deforestation refers to all man made disturbances that alter a forest, these are the most common. This argumentative essay discusses the positive and negative aspects of deforestation. In the first part of the essay the pro arguments of deforestation will be discussed. For example, the issue of Global population and how forests are being used, land use and the ways forests contribute, wood use, forest growth, destruction and the reasons for cutting down the trees. The second half of the essay will cover the issues that are harmful to the environment because of deforestation. Many environmental issues take place everyday; a big question that arises, is if the global economy will ever finds middle on the issue of forest thinning. If deforestation was used only in the most crucial of times, the world might become a better place.
The group decided to do the lottery so; we had to make our own interpretation of the story. We started by each member brainstorming ideas for how to adapt the play. Rhonda and Lisa came up with the majority of the ideas. They decided to focus on the central characters of the play and give it an alternative ending. Everyone also contributed similar ideas from seeing the YouTube video adaption of the story. From the original story our group kept Tessie and Bill Hutchison, Mr. Summers, and Old Man Warner. We changed Mrs. Delacroix name to Cynthia Delacroix and added a narrator for the prologue. Also every character was given more lines to say in our adaptation.