What kind of bacterium is Vibrio Cholera?

Vibrio Cholera was first discovered in Italy, by Filippo Pacini in 1854. It was believed that Robert Koch was the first to discover this bacterium nearly thirty years later, in 1884, in Berlin.

Vibrio Cholera is a comma – shaped bacteria. It is a Gram negative bacteria and its characteristic is a single polar flagellum, which helps the bacteria move. They do not form spores, or capsule. Vibrio cholera is aerobic and facultative aerobic microorganism.

There are numerous strains of Vibrio Cholera, some of which are pathogenic and some of which are not. Three serologic types of Vibrio Cholera are known. These serologic types are called Inaba, Ogawa and Hikojima.  The classical O1 biotype or the El-Tor biotype, are the most common known. There are different other strains of Vibrio Cholera from O2 – O138. The O antigen is specific for different types of Vibrio Cholera, while the H flagellar antigen is the same in all species.

When Vibrio Cholera is growing during the logarithmic phase there is little or no change to the cellular envelope. However, when the stationary phase begins, the cholera toxin is produced.

Vibrio Cholera has an anaerobic respiration, which appears to be the energy producing process. Vibrio cholera is catalase and oxidase positive.

The bacterium is transmitted through contaminated water or food and enters the intestine. When Vibrio Cholera enters the intestine, it increases the mucus production causing nausea, vomiting and severe diarrhea. This will result in dehydration and with no treatment it will lead to death. Vibrio Cholera has this effect in the gastrointestinal tract, through imbedding itself in the villi of absorptive intestinal cells. When Vibrio Cholera is imbedded with the gastrointestinal villi, it will release the cholera toxin. The adenylate cyclase enzyme in the intestinal cells, are activated by the cholera enterotoxin. These enzymes are turned into pumps which collect the water and electrolytes from blood and tissues and pump it into the lumen of the intestine. This all leads to dehydration, anuria, acidosis, shock and death in a very short time.

Cholera toxin is an enterotoxin. This toxin is made up of five B-subunits, which form a pore where an A-subunit fits.  The A-subunit is made of two chains A1 and A2. These chains have a polypeptic nature. Cholera toxin stimulates the intestines to secrete fluids and mucous linings.

What kind of infection is Cholera?

Cholera is an infectious disease, caused by Vibrio Cholera. This infection is characterized by severe watery diarrhea (10-20 liters a day, and maybe more), which can lead to dehydration and even death if untreated. It is caused by eating contaminated food or drinking contaminated water. The disease is more common in Africa, south Asia, Middle East and Latin America. Cholera is more common in places with poor hygiene, poor sanitation, crowded places, wars, etc.  Vibrio Cholera is found in municipal water supplies, foods and drinks sold in the streets, undercooked food, fish’s caught in contaminated waters, vegetables grown with water, which contained human or animal waist, etc.

Cholera is the most rapid fatal disease ever known. Signs and symptoms may develop very quickly, and death may occur in a few hours. A healthy person may become hypotensive within an hour of the onset of symptoms and may die within 2-3 hours if no treatment is provided. More commonly, the disease progresses from the first liquid stool to shock in 4-12 hours, with death following in 18 hours to several days.

Cholera signs and symptoms

The incubation period is few hours to as long as five days after infection. Usually these symptoms are mild, but in some cases they are very serious. Signs and symptoms of Cholera include: severe watery diarrhea, nausea, vomiting. These symptoms lead very quickly to dehydration. As the result of dehydration and loss of minerals and electrolytes, weakness, headache, muscle and joint pain, muscle cramps, low blood pressure, tacycardia and in later stages bradycardia, loss of skin elasticity and color, thirst, abdominal pain, etc. will occur. If not treated on time severe dehydration leads to circulatory shock and death. Death can occur in few hours.

The so called rice – water stool consists of diarrhea speckled with flakes of mucus and epithelial cells. These stools also contain enormous numbers of Vibrio Cholera, which spreads the disease very quickly, turning it into a Cholera epidemic, within a few days.

Vibrio Cholera

How is Cholera diagnosed?

Diagnose is serologic, when the collected material (feces) are incubated for 10-18 hours. If there is any suspect for Vibrio Cholera colonies, microscopic examination is performed and Vibrio Cholera is seen.

How is Cholera treated?

Rehydration is the main goal of the treatment for Cholera. Depending on how severe the diarrhea is, treatment will consist of oral or intravenous solutions to replace lost fluids. Antibiotics are not used in the first stage of the treatment, because they will reduce the diarrhea and kill the bacteria. After the hemodynamics stabilization, antibiotics will help avoid the spread of the disease. Most antibiotics have no effect on Vibrio Cholera. Tetracyclines are usually used. They reduce the amount of the fluid lost and may shorten the duration of diarrhea in some cases.

Treatment is very important to be quick and on time. Even though, cholera is a highly preventable and treatable disease, treatment should be started right away. The amount of fluids administrated, should be very good calculated. Without fast and good treatment, death may occur.  Treatment also includes replacement of lost ions, electrolytes, bicarbonates, etc. Glucose is often administrated. This treatment should continue until the diarrhea ceases.

Untreated cholera has a mortality rate 50-60%.

There is a vaccine against Cholera, but its effect is very short, only 2-3 months. The vaccine is produced by dead serotypes Inaba and Ogawa.

How is Cholera prevented?

Cholera prevention can be achieved through good personal hygiene, good water supply, good sanitary infrastructure, avoiding food that is undercooked, etc.

Clear water is the most important preventing method for Cholera. To disinfect the water on your own, it should be boiled for one minute or filter it.  Adding two drops of bleach or one-half of an iodine tablet per liter of water is also recommended for disinfection.