Cholera Disease Research Report Essay
Karla Obasi HEA 341 Disease Research Report December 9, 2010 CHOLERA Disease Defined Cholera is an infection of the small intestine that causes a large amount of watery diarrhea. Cholera is a bacterial disease (caused by the bacterium Vibrio cholerae) usually spread through contaminated water. The bacteria, which are found in fecal-contaminated food and water and in raw or undercooked seafood, produce a toxin that affects the intestines causing diarrhea, vomiting, and severe fluid and electrolyte loss.
This overwhelming dehydration is the outstanding characteristic of the disease and is the main cause of death. Cholera has a short incubation period (two or three days) and runs a quick course. In untreated cases the death rate is high, averaging 50%, and as high as 90% in epidemics, but with effective treatment the death rate is less than 1%. Historical Perspective During 1883, cholera was epidemic in Egypt. A German physician and bacteriologist, Robert Koch traveled with a group of German colleagues from Berlin to Alexandria, Egypt in August, 1883.
Following necropsies, they found a bacillus in the intestinal mucosa in persons who died of cholera, but not of other diseases. He reasoned that the bacillus was related to the cholera process, but was not sure if it was causal or consequential. He stipulated that the time sequence could only be resolved by isolating the organism, growing it in pure culture, and reproducing a similar disease in animals. He was not able to obtain such a pure culture, but did try to infect animals with choleraic material. None became infected.
His thoughts and early findings were sent in a dispatch to the German government and shared with the German press. On January 7th 1884, Koch announced in a dispatch that he had successfully isolated the bacillus in pure culture. One month later he wrote again, stating that the bacillus was not straight like other bacilli, but “a little bent, like a comma. ” He also noted that the bacillus was able to proliferate in moist soiled linen or damp earth, and was susceptible to drying and weak acid solutions. Finally, e pointed out that the specific organisms were always found in patients with cholera but never in those with diarrhea from other causes, were relatively rare in early infection, but were extensively present in the characteristic “rice water stools” of advanced cholera patients. He was, however, still unable to reproduce the disease in animals, reasoning correctly that they are not susceptible. In May, 1884 Koch and his colleagues returned to Berlin where they were treated as national heroes. Epidemiology Cholera is a disease that occurs in low income regions of the world where sanitation, food and water hygiene are inadequate.
Imported cases occasionally occur in travelers returning from endemic areas. In areas without clean water or sewage disposal (as may occur after natural disasters or in displaced populations in areas of conflict), cholera can spread quickly and have a case fatality rate of as high as 50% in vulnerable groups with limited medical care. The World Health Organization (WHO) reports the emergence of new strains of Vibrio cholerae which now predominates in parts of Africa and Asia, and the emergence and spread of antibiotic resistant strains.
Annual global figures (2009) reported to WHO included 221,226 cases and 4,946 deaths from 45 countries. The majority of cases (98%) were reported from Africa where an outbreak, that started in 2008 and lasted for almost a year, spread to South Africa and Zambia. By the end of July 2009, over 98,000 cases and 4,000 deaths were reported in this outbreak. Asia reported an 82% decrease in cases in 2009 compared to 2008, however, reports of acute watery diarrhea, many of which may be cholera, were not included.
When cholera first appears in epidemic form in an unexposed population, it can affect all age groups. In contrast, in areas with high rates of endemic disease, most of the adult population have gained some degree of natural immunity because of illness or repeated asymptomatic infections. In this setting, the disease occurs primarily in young children, who are exposed to the organism for the first time, and in the elderly, who have lower gastric acid production and waning immunity. The poor are at greatest risk because hey often lack safe water supplies, are unable to maintain proper hygiene within the home, and may depend on street vendors or other unregulated sources for food and drink. Recent epidemiologic research suggests that an individual’s susceptibility to cholera (and other diarrheal infections) is affected by their blood type: those with type O blood are the most susceptible, while those with type AB are the most resistant. Between these two extremes are the A and B blood types, with type A being more resistant than type B. Signs and Symptoms Dry mucus membranes or mouth * Dry skin * Excessive thirst * Glassy or sunken eyes * Lack of tears * Lethargy * Low urine output * Nausea * Rapid dehydration * Abdominal cramps * Watery diarrhea * Rapid pulse * Vomiting The usual incubation period is 2 to 5 days, although it can be as short as several hours. Severe cholera is characterized by a sudden onset of profuse, watery diarrhea accompanied by nausea and vomiting. If left untreated, this can rapidly lead to serious dehydration, electrolyte imbalance and circulatory collapse.
Over 50% of the most severe cases die within a few hours? with prompt, effective treatment, mortality is less than 1%. Cholera may be asymptomatic or mild in healthy individuals, with diarrhea as the only symptom. Etiology/Pathophysiology Most of the Vibrio cholerae bacteria in the contaminated water consumed by the host do not survive the highly acidic conditions of the human stomach. The few bacteria that do survive conserve their energy and store during the passage through the stomach by shutting down protein production.
When the surviving bacteria exit the stomach and reach the small intestine, they need to propel themselves through the thick mucus that lines the small intestine to get to the intestinal wall where they can thrive. The bacteria start up production of the protein flagellin to make flagella so that they can propel themselves through the mucus of the small intestine. StoIn some animals, including vertebrates, echinoderms, insects and molluscs, the stomach is a muscular, hollow, dilated part of the alimentary canal which functions as the primary organ of the digestive tract.
It is involved in the second phase of digestion, following mastication . The stomach is… Once the cholera bacteria reach the intestinal wall, they do not need the flagella propellers to move any longer. The bacteria stop producing the protein flagellin, thus again conserving energy and nutrients by changing the mix of proteins which they manufacture in response to the changed chemical surroundings. On reaching the intestinal wall, Vibrio cholerae start producing the toxic proteins that give the infected person a watery diarrhea.
This carries the multiplying new generations of the bacteria out into the drinking water of the next host if proper sanitation measures are not in place. Diagnostic Methods Cholera is diagnosed by the stool sample and it keeps out the bacteria, which can cause cholera. Cholera needs immediate action because of watery diarrhea, so the health centre can begin lack of fluids treatment before a final diagnosis is made. A number of tests have been performed to check cholera: * A doctor confirms a diagnosis of cholera by recovering the bacteria from fresh stool sample or from rectal swabs. A dark-field atomic test of fresh feces shows quick moving bacilli allows for a quick, cautious analysis. * Cholera can be established only by the separation of the contributory organism from the diarrheic stools of infected persons. Clinical symptoms are profuse watery diarrhea. “Cholera cots”, cots with openings to allow fecal output into a bucket, are used to measure volumes of stool loss and fluid replacement needs. Lab tests include stool gram stain (gram negative rods) culture, dark field microscopy or stool PCR. People must begin treatment even before diagnostic work-up. Treatment
Methods The objective of treatment is to replace fluid and electrolytes lost through diarrhea. Depending on your condition, you may be given fluids by mouth or through a vein (intravenous). Antibiotics may shorten the time you feel ill. The World Health Organization (WHO) has developed an oral rehydration solution that is cheaper and easier to use than the typical intravenous fluid. This solution of sugar and electrolytes is now being used internationally. Oral rehydration therapy (ORT) involves the replacement of fluids and electrolytes lost during an episode of diarrheal illness.
Diarrheal illnesses are pervasive worldwide, and they have a particularly large impact in the developing world. Children under the age of five are the major victims and account for over 3 million deaths a year due to dehydration associated with diarrheal illness. The World Health Organization (WHO) estimates that over one million deaths are prevented annually by ORT. An oral rehydration solution (ORS) is the cornerstone of this treatment. Between 90 and 95 percent of cases of acute, watery diarrhea can be successfully treated with ORT. Prognosis
Most infections are not severe, with about 75% to 80% of infected people not showing any symptoms. These individuals continue to shed the bacteria back into the environment, potentially infecting others with the disease. Because of severe dehydration, fatality rates are very high (25% to 65%) when untreated, especially among infants, young children, older individuals and people with a compromised immune system. Death can occur with adults within hours of infection, but those who recover usually have long-term immunity against reinfection. Prevention and Control Methods
The first cardinal rule in preventing cholera and other infectious diseases is routine hand washing. A safe and clean supply of water is the key to cholera prevention. Adequate chlorination of public water supplies and, in some cases, the distribution of chlorine tablets to households with instructions for their proper use are often effective measures. If chemical disinfection is not possible, people can be instructed to boil water before drinking it, but this may be difficult to accomplish, especially in poor countries where fuel may be expensive or unavailable.
Measures for the prevention of cholera mostly consist of providing clean water and proper sanitation to populations who do not yet have access to basic services. Health education and good food hygiene are equally important. Communities should be reminded of basic hygienic behaviors, including the necessity of systematic hand-washing with soap after defecation and before handing food or eating, as well as safe preparation and conservation of food.
Appropriate media, such as radio, television or newspapers should be involved in disseminating health education messages. Community and religious leaders should also be associated to social mobilization campaigns. Among people developing symptoms, 80% of episodes are of mild or moderate severity. The remaining 10%-20% of cases develop severe watery diarrhea with signs of dehydration. Once an outbreak is detected, the usual intervention strategy aims to reduce mortality – ideally below 1% – by ensuring access to treatment and controlling the spread of disease.
To achieve this, all partners involved should be properly coordinated and those in charge of water and sanitation must be included in the response strategy. Recommended control methods, including standardized case management, have proven effective in reducing the case-fatality rate. The main tools for cholera control are: * proper and timely case management in cholera treatment centers * specific training for proper case management, including avoidance of nosocomial infections * sufficient pre-positioned medical supplies for case management (e. g. iarrheal disease kits) * improved access to water, effective sanitation, proper waste management and vector control * enhanced hygiene and food safety practices; improved communication and public information Today, no country requires proof of cholera vaccination as a condition for entry and the International Certificate of Vaccination no longer provides a specific space for recording cholera vaccinations. The International Health Regulations do not provide a legal basis for countries to require travelers to have proof of cholera vaccination as reference to uch requirements was removed from the Regulations in 1973. WHO does not consider that proof of vaccination plays any useful role in preventing the international spread of cholera and therefore represents an unnecessary interference with international travel.
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