7 pages/≈3850 words
Biological & Biomedical Sciences
Discuss Into Detail Cholera As A Disease. Use Sources (Research Paper Sample)
discuss into detail cholera as a disease. use at least five sourcessource..
Vibrio cholerea is a member of the Vibrionaceae, a facultative anaerobic, Gram-negative, non-spore forming, curved rod which has a single polar flagellum. It is highly motile and can tolerate alkaline media (Bergey’s Manual, 1986).
Microbe biodiversity Cholera is an infectious disease that causes severe watery diarrhea which may lead to dehydration or even death if the case is not treated. It is caused by a bacterium called Vibrio cholerae.
Cholera toxin activates the adenylate cyclace enzyme in cells of intestinal mucosa leading to increased level of intracellular cAMP; and the secretion of water, sodium ions, potassium ions, chloride ions and hydrogen carbonate ions into the lumen of the small intestine.
The worldwide distributions of cholera have been alarming and in some cases causing death since precautions are not taken to prevent it. Donald G McNEIL Jr in his article to the New York Times, Promise is seen in an inexpensive cholera vaccine July 8,2015, gives an account of how cholera has spread in some parts of the world, Donald argues, Cholera, which causes severe diarrhea kills about 91,000 people a year, most of them children. It is endemic in over 50 countries, mostly in Asia and Africa. When the infection unexpectedly spreads to a new country where no one has immunity — as it did after Haiti’s 2010 earthquake, and in Zimbabwe in 2008 — it can overwhelm health systems and kill thousands within months.
In Haiti, cholera is presumed to have been introduced by United Nations peacekeepers from Nepal; it sprang up near sewage leaks from their compound. The disease is widespread in Nepal. If the vaccine had been used as routinely there as it was in this study, experts said, the bacteria might never have reached the Caribbean and many lives would have been spared. (Donald; NYT 2015). Medical researchers have put forth that there is an estimated 1.4 -4.4 million cases and 28000- 142000 deaths worldwide due to cholera ever year (WHO).
In the past 200 years there have been 8 main cholera pandemics with the disease most common in tropical and sub tropical areas. Most of the cases have been in the Indian sub continents and Africa; in 2002 WHO estimated that 90% of cases were reported in Africa.
Cholera is typically spread by consumption of water that is contaminated with infectious feces, infected raw fish and sea food. The aquatic environmental reservoir is critical to long-term maintenance of epidemic V. cholerae. These reservoirs constitute complex biological systems, with modulation of V. cholerae populations by environmental conditions (the local microenvironment as well as global macro environmental factors, such as the El Niño/Southern Oscillation[); by predatory bacteriophage populations; and by fluctuations in populations of copepods and zooplankton (which can, in turn, be driven by predation by fish), binding to chironomid egg masses, water hyacinth, carriage by birds and mammals, and a host of other variables.(Glenn Morris 2010)
Most cholera cases in developed countries are as a result of transmission by food that is fecally contaminated whereas in developing world it is more often transmitted by water infected with sewage. When the bacteria is consumed, most do not survive the acidic conditions of the human stomach, the few surviving bacteria conserve the energy and stored nutrients during the passage through the stomach by shutting down much protein production.
The natural reservoir for V. cholerae was thought to for along time to be humans but evidence now supports that the reservoir is the aquatic environment.
There are several characteristics of pathogenic V. cholera that are important determinant of the colonization process. They include; Adhensis, Neuraminidase, Motility, Chemotaxis and Toxins. If the bacteria are able to survive the gastric secretions and low pH the stomach, they are well adapted to survival in the small intestine.
V. cholera is resistant to bile salts and can penetrate the mucus layer of the small intestine by secretion of Neuraminidase and proteases (mucinases). They evade the propulsive gut motility by their own swimming by the aid of the flagellum and chemotaxis directed against the gut mucosa.
The bacterium adheres to the intestinal mucosa by the aid of a long filamentous fimbriae that form bundles at the poles of the cells. The fimbriae are termed as Tcp pili ( toxin coregulated pili), because expression of these pili genes is coregulated with the expression of the cholera toxin genes. Much is not know about interaction of Tcp with host cells and the host cell receptors for these fimbriae have not been identified.
Two other adhensis in V. cholerae are surface proteins that agglutinates red blood cells (haemagglutinin) and a group of outer proteins that are products of the accessory colonization factor( acf) genes.acf mutants have been proved top reduce the ability to colonize the intestinal tracts.
V. cholerea produces a protease called mucinase that degrades different types of proteins including fibronectin, lactoferrin and cholera toxin itself. It is also believed that the mucinase might contribute to detachment rather attachment; possibly the bacteria would need to detach from cells that are sloughed off to reattach to newly formed mucosal cells. ( Todas 2008-2012)
Treatments, Vaccination, Prevention
Treatment involves rapid intravenous replacement of the lost fluids and ions. Following these replacements, administration of isotonic maintenance solution should continue until the diarrhea ceases.Glucose is added to the maintenance solution that may be administered orally which eliminates the need for sterility and intravenous administration. Most antibiotics and chemotherapeutic agents have no value in cholera therapy, even though a few e.g. tetracycline may shorten the duration of diarrhea and fluid loss. Up to 80% of people can be treated successfully through prompt administration of oral dehydration salts (WHO/UNICEF ORS standard sachet).
Currently there are 2 WHO pre-qualified oral cholera vaccines (OCVs)-DukoralR and ShancholR. both vaccines have been used with WHO’s support.
DukoralR is administered to adults and children aged above 6 years in two doses and to children aged above 2 years and below 6 years in three doses. Protection can be expected one week after the last dose. Field trials have shown that this vaccine is safe and confers 85% protection for 4-6 months in all age groups. However, this vaccine is not licensed for use in...
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