Briar Gosvenor
McGuire
Microbiology
March 28, 2018
Vibrio Cholerae
Vibrio cholerae, or more commonly known as cholera, is a deadly bacterial disease that causes severe diarrhea, that can lead to extreme dehydration and possibly death if left untreated. Vibrio cholerae is typically found in contaminated water, and is transmitted through drinking said contaminated water. This makes the disease extremely prevalent in individuals that do not have access to clean, purified water, especially after a natural disaster. Vibrio cholerae is also found in organisms such as shellfish found in contaminated water are carriers for the disease.
Causes of Disease
Vibrio cholerae is found in contaminated organisms, like shellfish, and water containing the bacteria. This particular bacteria attacks the digestive system, after being ingested; typically through eating or drinking the contaminated organisms and water. Interestingly enough, the digestive system has its’ own defense against cholera; the acid in the stomach can kill small amounts of the bacteria. However, if the bacteria travel to the small intestine, then the illness begins. Vibrio cholerae cause the body to lose copious amounts of salt and water, in the form of watery diarrhea. This is the major symptom of cholera, with symptoms such a vomiting and leg cramps being secondary symptoms. The loss of bodily fluids can lead to shock, and possibly death, within a few hours if left untreated. (ShareCare)
History
Vibrio cholerae was discovered by Filippo Pacini in 1854. While typically, credit goes to the scientist Robert Koch, Pacini discovered cholera approximately thirty years before Koch received credit. Pacini, after the bacteria made its’ way from Asia to Italy, wanted to find what was causing the illness. Pacini performed numerous autopsies on the infected who had already passed; specifically looking at the mucosa of the intestines. In them, he found the comma-shaped bacteria, now called Vibrio, and published his findings in a paper. Unfortunately, he gained no recognition for this breakthrough. (Arnold)
Robert Koch essentially did the same investigation; only thirty years later. He, too, examined the bodies of the deceased and found the bacteria in the mucosa. He attempted to grow pure cultures of Vibrio cholerae and infect animals with it. However, Koch found, through a series of trials, that animals were immune to cholera; it was only able to infect humans. (Arnold)
Morphology
Vibrio cholerae is a comma-shaped, gram-negative bacteria. The bacterium has a flagella on one end, in addition to pili on the outside of the cell. The organism itself is a facultative anaerobe, which means that it can survive in oxygenated or non-oxygenated environments, but prefers oxygenated environments. Typically, Vibrio cholerae is found in contaminated brackish water, as well as contaminated saltwater. These environments contain oxygen, and transmit organisms well, making it an ideal environment for Vibrio cholerae. Once infected with Vibrio cholerae, the bacteria acts fast; with visible symptoms showing as in as soon as a few hours, to two to three days. (CDC)
Epidemiology
Vibrio cholerae is a serious threat to those nations and areas in the world that do not have access to clean, filtered water, and a reliable healthcare system. Countries such as Haiti, most recently, have fallen prey to cholera after suffering a massive natural disaster that damaged the water systems. (New England Journal of Medicine)
Cholera became an epidemic in Haiti and its’ surrounding countries, following the 2010 natural disaster, resulting in hundreds of thousands of people falling ill to cholera, and at least ten thousand people dead due to this disease. This epidemic was able to occur so rapidly and wipe out so many people due to how it’s transmitted. Vibrio cholerae is transmittable through water and infected stool, and since the water in Haiti was contaminated by the natural disaster in 2010, in addition to the water filtration systems being destroyed, the disease ran rampant among the country. (New England Journal of Medicine)
The rate of mortality for Vibrio cholerae ranges from 1%, if treated quickly and properly, to 50%-60% if left untreated. Therefore, those without access to clean water and healthcare are particularly at risk, because if the infection is not treated quickly and properly, then those individuals are more likely to die from cholera. (WHO)
Pathology
In order to diagnose cholera, the bacterium must be separated from the stool of the individual suspected of infection. In order to make the culture more sensitive, the stool can be soaked in alkaline peptone water, allowing for the bacteria to be identified more easily. Typically, selective media is used for culturing, to encourage the growth of Vibrio cholerae if it is present in the stool sample. From there, Vibrio cholerae can be tested using the gram-stain, which it tests negative for, to further confirm the correct identification of the bacteria. (The Lancet)
In addition, darkfield microscopy can be used on a fresh sample of stool suspected of infection. To do this, the fresh sample of stool is treated with antibiotics that drive Vibrio cholerae away from the antibiotics. A sign of the presence of Vibrio cholerae is that, under the x400 magnification of a microscope, Vibrio cholerae is observed darting away from the antibiotics. Since Vibrio cholerae has a very distinct comma-shape to it, it is easy to identify the bacteria. This technique, however, is not the best suited to identifying the organism, boasting positive for Vibrio cholerae on about half of the culture-positive samples. (The Lancet)
The stool of individuals suspected of infection can be tested for Vibrio cholerae because the disease affects the lower digestive tract of the individual, where stool forms. Cholera can also quickly be identified by the stool; since a major symptom is rapidly onsetting (within a few hours to a few days) excessive, watery, diarrhea, if that symptom is present in an area that cholera has been confirmed in, it is safe to assume the individual exhibiting that symptom likely has cholera. (The Lancet)
Prophylaxis
Cholera can be contained by quickly repairing sanitation systems in the affected area, so as to restore clean, filtered water and properly dispose of human waste containing Vibrio cholerae. Since cholera is spread through infected stool and contaminated water, having functioning sanitation systems is essential to containing the spread of the disease. Cholera can also be contained by evacuating individuals out of high-risk areas, like an area after a natural disaster. (The Lancet)
For years, standard sanitation tactics have been used to combat cholera. They have worked well in areas not prone to cholera outbreaks; however, for those areas at risk, standard sanitation techniques have not worked as well as expected, due to lack of access to sanitation.(The Lancet)
As a result, vaccines are being proposed as a new preventative treatment for cholera in at-risk areas. Since standard sanitation tactics, such as handwashing, rehydration, water sanitation techniques, and safe food preparation, have had little to no effect on the spread of cholera in underdeveloped areas of the world, something different must be done to combat this deadly disease. This has suggested to many epidemiologists that a vaccination might be the next reasonable step in further preventing this disease. (The Lancet)
Response and Treatment
For those infected with cholera, there are several treatments available. For mild cholera, patients are typically rehydrated using an oral suspension of glucose, sodium and water. This solution promotes prompt rehydration of the patient, and offsets the dehydration that cholera causes. For those with moderate cholera, hydration tactics are also used; except they are typically given in both oral and intravenous methods. (The Lancet)
For individuals with severe cholera, they must be treated immediately. Within three to four hours, individuals must be given enough solution to eliminate the fluid deficit, then started on a regime of antibiotics, like tetracycline, to decrease stool output and volume. These antibiotics help stabilize the patient’s internal environment, allowing for proper and continued rehydration to occur to combat cholera. (CDC)
Conclusion
In conclusion, cholera is not a bacterial disease that should be taken lightly. Vibrio cholerae is a hardy pathogen, and spreads very easily under certain conditions. Areas, and individuals, without proper sanitation techniques are particularly at risk for suffering from cholera, as it spreads through brackish water and infected stool. While there are treatments for this disease, one must act fast in order to successfully combat cholera and reduce the mortality rate.
Works Cited
"Cholera in Zambia." Bulletin of the World Health Organization, Feb. 2018, p. 80. Health & Wellness Resource Center, http://link.galegroup.com/apps/doc/A532251229/HWRC?u=j061914&sid=HWRC&xid=c9877bc0. Accessed 28 Mar. 2018.
Arnold, Paul. “History of Cholera – Who Discovered Cholera?” Bright Hub, 27 Sept. 2009, www.brighthub.com/science/genetics/articles/50412.aspx.
“The Origin of the Haitian Cholera Outbreak Strain | NEJM.” New England Journal of Medicine, www.nejm.org/doi/full/10.1056/nejmoa1012928.
Morris, J. G., and D. Acheson. “Cholera and Other Types of Vibriosis: A Story of Human Pandemics and Oysters on the Half Shell.” Clinical Infectious Diseases, vol. 37, no. 2, 2003, pp. 272–280., doi:10.1086/375600.
“Cholera – Vibrio Cholerae Infection.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 9 Nov. 2016, www.cdc.gov/cholera/general/index.html.
“Number of Reported Deaths Due to Cholera.” World Health Organization, World Health Organization, 18 Sept. 2017, www.who.int/gho/epidemic_diseases/cholera/deaths/en/.
“How Does Cholera Affect the Body? | Bacterial Infections.” Sharecare, www.sharecare.com/health/bacterial-infections/how-cholera-affect-the-body.
Ahmed, Azam. “Cholera Deepens Haiti's Misery After Hurricane.” The New York Times, The New York Times, 14 Oct. 2016, www.nytimes.com/2016/10/15/world/americas/cholera-haiti-hurricane-matthew.html.