NOTE: Free essay sample provided on this page should be used for references or sample purposes only. The sample essay is available to anyone, so any direct quoting without mentioning the source will be considered plagiarism by schools, colleges and universities that use plagiarism detection software. To get a completely brand-new, plagiarism-free essay, please use our essay writing service.
One click instant price quote
I. The Bacteria- Borrelia Burgdorferi Lyme disease is caused by Borrelia burgdorferi, a spiral-shaped bacterium that is frequently carried by deer ticks of the genus Ixodes. Borrelia burgdorferi is named after its discoverer, Willy Burgdorfer, PhD. When the deer tick bites a human being, the bacteria are transmitted to the human bloodstream, where it travels throughout the body. Because the bite of the deer tick is usually painless and does not itch, most people do not recall the bite and so cannot trace the origin or the time of onset of the infection.
Borrelia burgdorferi is a spirochete. Spirochetes are a group of phylogenetic ally-distinct procaryotes that have a unique mode of motility by means of axial filaments. Spirochetes are widespread in viscous environments and they are found in the intestinal tracts of animals and the oral cavity of humans. The spirochetes have a unique cell surface which accompanies their unique type of motility. The axial filaments are contained within the periplasmic space between a rigid peptidoglycan helix and a multi-layer, flexible outer membrane sheath. When the filaments rotate within this space, the spirochetes move in cork-screw fashion.
This mode of motility in spirochetes is thought to be an adaptation to viscous environments such as aquatic sediments and the intestinal tracts of animals. Spirochetes are usually much longer than they are wide. Hence, most spirochetes cannot be viewed using conventional light microscopy. Dark-field microscopy must be used to view spirochetes. Dark field microscopy utilizes a special condenser which directs light toward an object at a angle, rather than from the bottom. As a result, particles or cells are seen as light objects against a dark background.
The spirochetes are not classified as either Gram-positive or Gram-negative. When Borrelia burgdorferi is Gram-stained, the cells stain a weak Gram-negative by default, as safranine is the last dye used. Borrelia, like most spirochetes, does have an outer membrane that contains an LPS-like substance, an inner membrane, and a periplasmic space which contains a layer of peptidoglycan. Therefore, it has a Gram-negative bacterial type cell wall, despite its staining characteristics. II.
The Disease-Lyme Disease Lyme disease first appeared in Lyme, Connecticut, in October 1975. Several people complained to their doctor of feeling fatigued, having pain in their joints, and noticing an unusual rash on their body. Also, several children were reported to have come down with juvenile rheumatoid arthritis. Dr. Allen C. Steere, a rheumatologist at the Yale University Medical School, was dispatched to Lyme to investigate.
He found thirty-nine reported cases of juvenile rheumatoid arthritis. He knew something was wrong, and he proceeded to interview the victims of the disease. In all cases symptoms first developed during the summer months, when people would be outdoors. Lyme was also a rural town, with many heavily wooded areas. Dr.
Steere concluded that the disease was transmitted by some type of arthropod. He gave it the name Lyme Disease, after the town in which it was first observed. Dr. Steere then studied the blood of the lyme disease victims in an attempt to identify the causative agent, which he suspected to be a virus.
He was not successful. In 1981 Willy Burgdorfer, an international authority on tick borne diseases, was called in. He examined the contents of the digestive tract of Ixodes using a technique called dark-field microscopy and found it to be teeming with a senior corkscrew-shaped microbe. The causative agent was not a virus but a bacterium-a spirochete. The Lyme disease spirochete was small and delicate, difficult to see and difficult to grow. It was a member of the genus Borrelia but unlike any Borrelia previously observed.
In 1984, in honor of its discoverer, it was given the name Borrelia burgdorferi. Lyme Disease is most commonly transmitted by a tick bite (usually painless). The tick vectors include Ixodes scapular is (Deer Tick), Amblyomma american (Lone Star Tick) and Ixodes pacific. Ixodes damning was thought to be the only species responsible for transmission until it was shown to be the same as Ixodes scapular is in 1993. The ticks prefer to live in wooded areas, low growing grassland, seashores and yards. Depending on the location, anywhere from less than 1 % to more than 90 % of the ticks are infected with spirochetes.
The Deer tick has a 2 year life cycle and must feed 3 times. The symptoms of Lyme disease in humans occur in three stages: Stage one (early infection): The early stage of Lyme disease is often characterized by a distinctive, expanding red rash that usually develops at the site of the tick bite. This rash, known as erythema migrant, is seen in 60 - 80 % of infected individuals. Spirochetes can be isolated from the leading edge of the rash. Erythema migrant is a red circular patch that appears usually 3 days to 1 month following the bite of the tick.
The patch then expands, often to a large size and develops a characteristic "bull's eye" appearance. However, not all rashes that occur at the site of a tick bite are due to Lyme disease. An allergic reaction to tick saliva often occurs at the site of a tick bite. This rash can be confused with the rash of Lyme disease.
Allergic reactions to tick saliva usually occur within hours to a few days after the tick bite, usually do not expand, and disappear within a few days. Erythema migrant persists longer, but usually subsides within 3 - 4 weeks. Stage two (dissemination stage): Occurs days to weeks following infection. At this stage the spirochetes spread hematogenous ly to additional body tissues. One or more of the following symptoms and signs may be noted: fatigue chills and fever headache muscle and joint pain swollen lymph nodes secondary annular skin lesions Stage three (persistent infection): Some symptoms and signs of Lyme disease may not appear until weeks, months, or years after a tick bite. Stage three typically involves intermittent episodes of joint pain.
Common clinical manifestations at this stage may include meningitis, Bell's palsy, cardiac involvement, and migratory pain to joints, tendons, muscle and bone: Arthritis is most likely to appear as brief bouts of pain and swelling, usually in one or more large joints, especially the knees. Treatments for Lyme Disease: Antibiotics are the standard treatment for Lyme disease in its early stages. For adults, doctors may recommend such antibiotic drugs as doxycycline, tetracycline or amoxicillin. For children, antibiotics may include amoxicillin, erythromycin or penicillin G. (Children shouldn't be given doxycycline or tetracycline because either can cause permanent discoloration of teeth. ) Treatment with these drugs for 3 weeks usually cures the infection and prevents complications. For treatment to be most successful, it's important to take the full course of medications. Don't discontinue taking these drugs prematurely.
If the disease progresses to a later stage, the brain, nerves, heart or joints may be affected. Hospitalization may be necessary in some cases. Treatment will then likely include penicillin G or a drug called ceftriaxone, which is administered intravenously. These treatments are usually effective and may make your symptoms disappear. If a relapse occurs, additional therapy may be recommended. Research is also being done on a topical antibiotic cream that could stop the infection from spreading immediately following a bite.
References - Killer Germs - web - web - web - web - web Microsoft Encarta Encyclopedia 98
Free research essays on topics related to: stage three, lyme, rheumatoid arthritis, gram negative, lyme disease
Research essay sample on Lyme Disease Rheumatoid Arthritis
