The Causitive Agent of Rocky Mountain Spotted Fever
The Bacteria
Rickettsia rickettsii is the small, aerobic gram-negative bacterium that is the cause Rocky Mountain spotted fever in humans (and other vertebrates). They are obligate, intracellular bacteria that range in size form 0.2x0.5 µm to 0.3x2.0µm. Rickettsia belong to the phylum alpha-protobacteria, which are capable of growing in low levels of nutrients, and have a long generation time relative to other gram negative bacteria such as Escherichia coli. In humans rickettsiae preferentially reside in the nucleus or cytoplasm of cells lining small to medium size blood vessels.
Rickettsia enter host cell by inducing phagocytosis, then immediately escape the phagosome to grow and reproduce within the cytoplasm (or nucleus)of the host cell. The host cell will normally lyse eventually, causing the release of new organisms. The host cell is also harmed by the toxic effect of the cell wall. (CDC)
Van Kirk et al have done studies showing that actin-based motility (ABM) is a mechanism for intercellular spread. R. rickettsii is the only Rickettsia species that utilizes ABM. Findings suggest that ABM is a major factor in causing infection; after a host cell becomes infected the polymerization of the actin of the host cell forms a filamentous actin comet tail. The actin tail aids the pathogen in moving through the cytosol and into membrane protrusions of the host cell, where it can be engulfed by neighboring cells and can initiate a new infectious cycle.
The Vector
Rocky Mountain spotted fever (RMSF) is classified as a zoonosis (diseases of animals that can be transmitted to humans), and requires a vector for transmission. The vectors (and reservoirs) for RMSF are tic...
... middle of paper ...
...G. Marshall, Anita M Kelsey, MD. “What’s Your Diagnosis?” Consultant August 1996:1729-1735
Niebylski, Mark L., Mort G. Peacock, and Tom G. Schwan. “Lethal Effect of Rickettsia rickettsii on Its Tick Vector (Dermacentor andersoni)” Applied and Environmental Microbiology Feb 1999: p 773-338.
Rahman, M. Sayeedur, Jason A. Simser, Kein R. Macaluso, and Abdu F. Azad. “Molecular and Funcional Analysis of the lepB Gene, Encoding a Type I Signal Peptidase from Rickettsia rickettsii and Rickettsia typhi.” Journal of Bacteriology August 2003 (2003 American Society for Microbiology):4578-4584.
Van kirk, Levi S., Stanley F. Hayes, and Robert A. Heinzen. “Ultrastructure of Rickettsia rickettsii Actin Tails and Localization of Cytoskeletal Proteins.” Infection and Immunity (August 2000). Abstract. 16 September 2004. <http://iai.asm.org/cgi/content/abstract/68/8/4706>.
This extremely pathogenic zoonotic virus is now understood to travel from bat species, to equine intermediate hosts, to humans.[8, 10] The Hendra virus is listed as a Bio-Safety Level (BSL)-4, and can only be studied at a few adequately equipped laboratories worldwide due to its virulence.[1, 2] Case fatality rates
Francisella tularensis is a bacteria that is commonly referred to as Rabbit Fever. This microorganism is often known as this because the bacteria resides in mammals such as rabbits, squirrels and mice (UPMC Center for Health Security, 2013). There are many different components to this bacteria that make it unique. The microorganism F. tularensis is one that has very unique characteristics that make it responsible for being the kind of bacteria that it is. It is a gram-negative bacteria that occurs in coccobacillus form. It is a non-motile bacteria that is commonly found in water, mud, and decaying animal carcasses. (Center for Infectious Disease Research and Policy, 2013). Because of these characteristics, F. tularensis is able to live in these conditions for weeks (UPMC Center for Health Security, 2013). For all of these reasons, this microorganism can be potentially harmful to humans.
Studies have shown pertactin, a 69kDa non fimbrial outer membrane protein, facilitates attachment of the bacteria to ciliated respiratory cells. Experiments conducted on humans to test the role of pertactin have shown no significant effect except with the results from Bassinet (4). Furthermore, filamentous haemagglutinin confers infection by attaching to the host cells in the lower respiratory tract. It is about 2nm wide, and 50n...
You woke up a week ago feeling odd. You were not sure what was wrong, but your body was full of aches, you felt hot to the touch, and you kept vomiting. Your mother told you to lay down and rest, hoping it was just a cold. After a few days, you began to feel better, well enough that you wanted to return to the river to watch the trade ships come in. Now, unfortunately, your symptoms have come back with a vengeance – your fever is back along with intense abdominal pain, your mouth is bleeding without being wounded, and every time you vomit, it appears black in color. Also, when you look in the mirror, your skin has changed from the sun-kissed color you have always been to a dull yellow hue. The doctor comes in to examine you; he makes many “tsk tsk” noises and hurries out of the room with a cloth over his face. The doctor mumbles to your mother that he believes you have Yellow Jack and there is nothing more he can do, you are going to die. Your mother weeps uncontrollably yet you cannot react because another horrendous pain in your head has doubled you over. Soon, as you stop shaking and begin to relax, the sounds of the doctor and your mother become white noise and your surroundings begin to dull until you prove the doctor right; another person fell victim to the infectious Yellow Fever virus.
Yellow fever is a horrible disease for those who begin to show symptoms, and while that number is low, of those who do become ill 50% die; only after having two rounds ...
Treponema pallidum is a Gram-negative bacterium that has a spiral shape (1). They are about 6 to 20um in length and 18-20um in diameter (1). Treponema pallidum can only survive within a host which makes them obligate internal parasites, meaning that outside a host this organism will die due to the absence of nutrients, exposure to oxygen and heat. Also since this organism can’t be grown on a culture medium, animal models are used to study T. pallidum (1). Treponema pallidum bacteria consist of an inner and outer membrane with a thin peptidoglycan cell wall lacking liposaccharides (1). They have a distinctive corkscrew motility with the aid of 6 endoflagellas (2). The specific classifications of Treponema pallidum are the following: Scientific name- Treponema pallidum, Common name- Syphilis. Treponema causes syphilis, yaws, and spinta. Borrelia causes Lyme disease and relapsing fever and Leptospira causing leptospirosis (5). What makes this microorganism special to the human population is that it causes infection to its host by entering the body through microscopic skin or mucous abrasions via direct personal contact with the lesions (sexual or kissing), blood transfusions, accidental bacterial inoculation, and transplacental passage (2). According to the CDC website there are 55,400 people diagnosed with Syphilis every year and 322 reported cases of congenital Syphilis in 2012 (6).
The perspective the author gives to this book is a unique. Smallpox according to most histories does not play the role of a major character, but a minor part. In my opinion smallpox was a major factor during the Revolutionary War, and Feen focuses on several key areas which allows us to see just how bad this epidemic was and the grip it had not only on the soldiers, but the colonist as well.
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.
The 1878 yellow fever epidemic in Memphis proved to be fatal, killing almost all who got infected. The disease traveled up from New Orleans infecting and killing many on its way. Memphis was going through reconstruction and was becoming the center for merchants and travelers. Furthermore, Memphis began to become overly populated only increasing the devastation that would be caused by the yellow fever. This was a confusing period were even medical professionals did not know where the disease came from or how they could to stop it. The epidemic caused panic and challenged the state government of Tennessee and made changes to it that are still in effect today.
”Attacks implemented by cyber terrorists via information systems to (1) significantly interfere with the political, social or economic functioning of a critically important group or organization of a nation, or (2) induce physical violence and/or create panic. We define hackers as individuals who (1) wish to access/modify data, files, and resources without having the necessary authorization to do so, and/or (2) wish to block services to authorized users. Cyber terrorists are individuals or groups who utilize computing and networking technologies to terrorize. In this paper, we study the behaviors of two groups of hackers: cyber terrorists and common hackers" (Hua & Bapna 2013).
Armando Rendon in his landmark 1970 wrote the book I am a Chicano. This book is about how activist in the Chicano movement pointed to an empty monolog of the word Chicano. Chicano means an activist. Chicanos describes themselves it was a form of self-affirmation; it reflected the consciousness that their experiences. Chicanos means, nations, histories, and cultures. This book talks about how Mexican American also used the term of Chicano to describe them, and usually in a lighthearted way, or as a term of endearment. In a text it talks how Chicanos haven’t forgotten their Mexican origins, and how they become a unique community. The book talks about how Mexican American community’s long-suffering history of racism and discrimination, disenfranchisement, and economic exploitation in the United States. The
Throughout the 1970s, the ability of any one person to work hard enough to transcend social stratification in the United States became difficult due to various domestic challenges. The reality Americans begun to see during the ‘70s was bleak, this being contributed in great part to ecopolitical events. In the year 1974, a recession begun that has continued to affect the United States economy to this very day. Harold Meyerson, a writer and journalist for the Washington Post and The American Prospect in the article “The 40-Year Slump” notes “The middle-income jobs of the nation’s postwar boom years have disproportionately vanished. Low-wage jobs have disproportionately burgeoned. Employment has become less secure. Benefits have been cut. The dictionary definition of “layoff” has changed, from denoting a temporary severance from one’s job to denoting a permanent severance” (1). It is important to consider this point because it really lays the foundation of the 1970’s; one of little hope, and one shaken by what became known as the 1973-1975 Recession. This recession affected practically every person living in the U.S, and changed the perception of the workplace. Through low-economic growth and high inflation, the economic term “stagflation” came about, and negatively influenced the success of countless Americans. Alejandro Reuss, co-editor for the magazine Dollars & Sense in the article “That ‘70s Crises” asserts "The economy seemed trapped in the new nightmare of “stagflation,” so called because it combined low economic growth and high unemployment (“stagnation”) with high rates of inflation” (1). This is a valuable point to consider, as this term is still used to this day, and has affected all aspects of life for many Americans. Mic...
Paisley. "The Impact of a Cyber War." Defense Tech RSS. N.p., 16 Jan. 2008. Web. 21 Nov. 2013. (Source H)
“India and Pakistan: Tense Neighbours.” BBC. N.p., 16 Dec. 2001. Web. 15 May 2011. .
Whether the partition of these countries was wise and whether it was done too soon is still under debate. Even the imposition of an official boundary has not stopped conflict between them. Boundary issues, left unresolved by the British, have caused two wars and continuing strife between India and Pakistan.