What Is Cholera What Causes Cholera
November 17, 2017
Worldwide, cholera affects 3-5 million people and causes 100,000-130,000 deaths a year as of 2010. Due to severe dehydration, fatality rates are high when untreated, especially among children and infants. Death can occur in otherwise healthy adults within hours. Those who recover usually have long-term immunity against re-infection.
The cholera epidemic in parts of Africa has been ongoing for more than 30 years, due to inadequate sanitation and water treatment systems.
Cholera was one of the earliest infections to be studied by epidemiological methods. Individuals' susceptibility to cholera is affected by their blood type, with those with type O blood being the most susceptible.
According to Medilexicon's medical dictionary:
Cholera is an acute epidemic infectious disease caused by the bacterium Vibrio cholerae. A soluble toxin elaborated in the intestinal tract by the bacterium activates the adenylate cylase of the mucosa, causing active secretion of an isotonic fluid resulting in profuse watery diarrhea, extreme loss of fluid and electrolytes, and dehydration and collapse, but no gross morphologic change in the intestinal mucosa.
Cholera was discovered in 1883 to be due to infection with Vibrio cholerae, a comma-shaped bacteria. The discovery was made by the great German bacteriologist Robert Koch (1843-1910). As head of a commission investigating the disease, Koch went to Egypt where an epidemic was taking place and there he found some sort of bacterium in the intestines of those dead of cholera but could neither isolate the organism nor infect animals with it.
Later in 1883 Koch went to India, where he wrote that he succeeded in isolating "a little bent bacilli, like a comma." He discovered that the bacteria thrived in damp dirty linen and moist earth and in the stools of patients with the disease.
Vibrio cholerae bacteria naturally live as rod-shaped bacteria existing primarily in plankton populations in shallow, brackish water. Attaching themselves to microscopic crustaceans called copepods that exist as part of the planktonic ecosystem, they move naturally through several environments. Colonies of the bacteria can exist on the surface of the copepods, flourishing during times when temperature, low salinity and high nutrient levels cause algal blooms in the estuary, explaining why cholera has traditionally been associated with monsoon conditions.
The bacteria also, however, exist as colonies of biofilms coating the surface of various natural features of the estuary, covering the water surface but also plants, stones, shells and similar items. They can take non-active form and survive in the silt of the estuary.
Finally the bacteria has been found resident in the egg masses of native midges, which serve as a reservoir for cholera bacteria. In all of these instances the bacteria is a natural inhabitant, not associated with damage to the ecology or the organisms with which it comes in contact.
When Vibrio cholerae enters the human ecology it can quickly cause severe epidemics. Toxic strains of cholera bacteria produce poison that trigger violent diarrhea in humans. As durable and adaptable a bacteria as Vibrio cholerae is able to survive in spite of the non-ideal conditions that usually apply to human water sources.
Bacteria multiply, particularly in situations where water is filled with nutrients that encourage the same growth that nutrient-enriched estuaries promote. Each newly infected human adds waste and bacteria to the environment, bringing about rapid spread of the disease until such time as a change in environment ends the expansion of the bacterial population. Weather changes, population loss and improved sanitation can all end an outbreak. What are the symptoms of Cholera? A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.
Most infections are not severe, with 75% of infected people not showing any symptoms.
Within 6 hours to 5 days of exposure, symptoms of cholera range from being mild or asymptomatic to severe disease, characterized by huge volumes of explosive watery diarrhea (sometimes called "rice water stools" because of the similarity of appearance to water that has been used to wash rice), vomiting, and leg cramps. Due to rapid loss of fluids up to 20 liters daily, severe dehydration and shock can occur in these individuals.
Signs of dehydration include loss of skin plasticity, sunken eyes, fast heart beat, low blood pressure, and rapid weight loss. Shock occurs as a result of collapse of the circulatory system. What are the causes of Cholera? Cholera is a diarrheal illness caused by the bacteria Vibrio cholerae. This species is not endemic to humans, and its presence in the human digestive system is not part of the natural life cycle of the bacteria. Normally found in an estuary ecology, the Vibrio cholerae bacteria life cycle naturally shifts between various reservoir species such as small snails and crustaceans, free-floating planktonic forms and static forms resident in the silt and muck of the estuary.
Vibrio cholera bacteria enter the human ecosystem through a variety of routes. The most common entry is through contaminated food or water. When humans eat seafood--in particular shellfish native to estuary environments such as oysters or crabs--and fail to cook them completely or even eat them raw, they can ingest the large amounts of bacteria necessary to cause a case of cholera.
Poorly cleaned vegetables irrigated by contaminated water sources are another common source. In situations where sanitation is severely challenged, such as in refugee camps or communities with highly limited water resources, a single affected victim can contaminate all water for an entire population. Diagnosing Cholera One should consider the cholera diagnosis in all cases of severe watery diarrhea and vomiting especially with rapid dehydration and recent travel or consumption of shellfish. 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.
"Cholera cots", cots with openings to allow fecal output into a bucket, are used to measure volumes of stool loss and fluid replacement needs.
Suspect cholera if you notice symptoms after consuming undercooked food or untreated water, especially in less industrialized nations. What are the treatment options for Cholera? Because death from cholera is a consequence of dehydration, the disease is treated using oral rehydration therapy (ORT), which consists of large volumes of water mixed with a blend of sugar and salts.
Prepackaged mixtures are commercially available, but wide distribution in developing countries is limited by cost. Therefore, homemade ORT recipes using common household ingredients and materials have been developed. Severe cases of cholera require intravenous fluid replacement.
Antibiotics can shorten illness, but ORT is still necessary even when antibiotics are used. Do not use anti-diarrheal medicines, since they prevent flushing of the bacteria out of the body.
In many areas of the world, antibiotic resistance is increasing. In Bangladesh, for example, most cases are resistant to tetracycline, trimethoprim-sulfamethoxazole, and erythromycin. Preventing Cholera Eat only fruit you have peeled and avoid salads, raw fish and uncooked vegetables. Suspect cholera if you experience symptoms after consuming these foods in high risk countries.
Learn about cholera if you plan to visit a country experiencing an epidemic. Seek medical attention immediately if you experience cholera symptoms such as leg cramps, vomiting and diarrhea while in a community infected with the disease.
When you are in a different place, do not just drink water from any source. As much as possible, carry with you a tumbler or a water container. Make sure that the water you drink is properly boiled to be safe.
Check out the place first before you eat anything. Cholera is a food-borne disease. The bacteria contaminate water and spread via intake. Poorly cooked foods with water contaminated with bacterium will most likely cause cholera.
Avoid eating raw shellfish because this is known to be contaminated with the cholera. Shellfish that thrive on coastal areas are often contaminated. According to the Center for Disease Control, the source of contamination in US cases of cholera is contaminated seafood.
This also applies to vegetables and fruits. When you are in a foreign place and unsure of the sanitation, avoid eating salads and as much as possible, peel the fruits by yourself.
Street foods should be avoided because they are known to cause not only cholera but other diseases as well. The exposure to dust and other contaminants make it unsafe to eat street foods.
Sy Kraft (B.A.)