After a 24- to 48 hour incubation period, symptoms begin with the sudden onset of painless, watery diarrhea that may quickly become voluminous and is often followed by vomiting. The patient may experience abdominal cramps. Fever is typically absent [2] [6]. Most infections are mild to moderate and may not be clinically distinguishable from other causes of gastroenteritis. An estimated 5% of infected patients will develop cholera gravis, severe watery diarrhea, vomiting, and dehydration [4] [5].
The symptoms of cholera include [5]:

• Diarrhea: Stool volume during severe cholera is much more than that in any other infectious diarrhea. The characteristic cholera stool is an opaque white liquid that is not malodorous.

• Vomiting: though a common symptom, may not always be present.

• Dehydration: If untreated, the diarrhea and vomiting lead to isotonic dehydration, which can lead to acute renal failure, vascular collapse, shock, and death Dehydration can develop rapidly, within hours after the onset of symptoms.

• Hypoglycemia: After dehydration, hypoglycemia is the most common lethal complication of cholera.

• Acidemia: results when respiratory compensation is unable to sustain a normal blood pH. Cholera causes bicarbonate loss in stools, accumulation of lactate, and hyperphosphatemia.
• Hypokalemia: results from potassium loss in the stool. Hypokalemia develops only after the acidosis is corrected.

Definitive diagnosis is not a prerequisite for the treatment of patients with cholera. Diagnosis is generally made from history, clinical observation, and physical exam.

Laboratory studies that confirm the diagnosis and guide treatment are:

• Stool examination and culture: These tests may be worthwhile in areas where Vibrio cholerae is uncommon. Direct microscopic examination of stool (including dark-field examination), Gram stain, culture, and serotype/biotype are done.

• Hematologic studies: Blood work is needed primarily to identify the extent and character of dehydration . Serum electrolytes, serum bicarbonate, and renal function tests should be included.

The priority in management of any watery diarrhea is replacing the lost fluid and electrolytes and providing an antimicrobial agent when indicated. The World Health Organization (WHO) guidelines for the management of cholera are practical, easily understood, and readily applied. These guidelines can be used for the treatment of any patient with diarrhea and dehydration. Diagnosis of cholera is not required to initiate hydration therapy [4].
Rehydration is the first priority in the treatment of cholera. Rehydration is accomplished in 2 phases: rehydration and maintenance.

• Rehydration: The goal of the rehydration phase is to restore normal hydration status, which should take no more than 4 hours. An intravenous infusion rate in severely dehydrated patients of 50-100 mL/kg/hr. Lactated Ringer solution is preferred over isotonic sodium chloride solution because saline does not correct metabolic acidosis [5].

• Maintenance: The goal of the maintenance phase is to maintain normal hydration status by replacing ongoing losses. The oral route is preferred, and the use of oral rehydration solution (ORS) at a rate of 500-1000 mL/hr. is recommended [5].

A risk of over hydration exists with intravenous fluids. It usually first manifests as puffiness around the eyes. Continued excessive administration of intravenous fluids can lead to pulmonary edema and has been observed even in children with normal cardiovascular reserve. Thus, it is important to monitor patients who are receiving intravenous rehydration hourly. Serum-specific gravity is an additional measure of the adequacy of rehydration [5].

Antibiotic treatment is indicated for severely dehydrated patients who are older than 2 years. Begin antibiotic therapy after the patient has been rehydrated (usually in 4-6 h) and vomiting has stopped. Single-dose therapy with tetracycline, doxycycline, furazolidone, or ciprofloxacin has been shown effective in reducing the duration and volume of diarrhea. Because single dose doxycycline has been shown to be as effective as multiple doses of tetracycline, this has become the preferred regimen [5]. No other drugs should be used in the treatment of cholera.

Diet: Resume feeding with a normal diet when vomiting has stopped. Continue breastfeeding infants and young children. There is no reason to withhold food from cholera patients.

Before the development of effective regimens for replacing fluids and electrolyte losses, the mortality in severe cholera was more than 50% [5]. Mortality is higher in pregnant women and young children. Mortality rates are lowest where intravenous therapy is available. Average case fatality rates for Europe and the Americas continue to be about 1% [2] [3]. In Africa a marked decline in case fatality rates has occurred since 1970. However, Africa continues to have the highest reported case fatality rates (approximately 4% in 1999) compared with the rest of the world [4].

Cholera is an ancient disease, dating as far back as Hippocrates in Greece in the 5th century. The discovery of the cholera organism is credited to German bacteriologist, Robert Koch, who identified Vibrio cholerae in 1883 [5]. The seventh pandemic of cholera, and the first in the 20th century, began in 1961; by 1991 it had affected 5 continents. The pandemic continues today [5].

Cholera has been rare in industrialized nations-test for the past century, however, the disease is still common in areas with crowded living conditions and poor sanitation [5]. Epidemics occur after war, civil unrest, or natural disasters, when water and food supplies become contaminated with Vibro cholerae [2].

Cholera has 2 main reservoirs; humans and water. Transmission occurs almost exclusively via contaminated water or food [2]. Transmission via direct person-to-person contact is rare. Household contacts are the exception to this and occurrence through this means is approximately 10-30%. [3]. Asymptomatic carriers may have a role in transfer of disease in areas where the disease is not endemic. Although carriage usually is short-lived, a few individuals may excrete the organisms for a prolonged period [5]. Vibrio cholerae is rarely isolated from animals, and animals do not play a role in transmission of disease [2].

Malnutrition increases susceptibility to cholera. The incidence of cholera appears to be twice as high in people with type O blood. The reason for this increase is not known [5] [6]. An attack of the classic biotype of Vibrio cholerae usually results in the generation of antibodies that protect against recurrent infection by either biotype [7].

In the United States and other developed countries, because of advanced water and sanitation systems, cholera is not a major threat. Individuals living in the United States most often acquire cholera through travel to cholera-endemic areas or through consumption of undercooked seafood from the Gulf Coast or foreign waters. The incidence in the United States continues to be low, 0.50 cases per 100,000 population, with highest number documented in the age group older than 50 years of age [2]. The frequency of cholera among international travelers returning to the United States has averaged 1 case per 500,000 population [1] [2]. Between January 1, 1995, and December 31, 2000, 61 cases of cholera were reported in the United States. Thirty-seven were travel-associated cases; the other 24 cases were acquired in the United States [1] [3].

According to the WHO, the number of cases worldwide surged again in 2005. The actual global burden is estimated to be 3-5 million cases and 100,000-130,000 deaths per year [2] [3]. The cholera burden has grown strikingly during the past 4 years, and has spread to countries previously spared by this disease [6].

In non-endemic areas, the incidence of infection is similar in all age groups, although adults are less likely to become symptomatic than children. The exception is breastfed children, who are protected against severe disease because of less exposure and antibodies to cholera they obtain in breast milk [2] [6].

Although more than 200 serogroups of Vibrio cholerae have been identified, Vibrio cholerae O1 and Vibrio cholerae O139 have been the principal ones associated with epidemic cholera. The current wave of endemic cholera is attributable to a new atypical El Tor strains. This new strain has caused the increase in incidence and deaths during the last 4 years [5] [6].

Vibrio cholera cause clinical disease by producing an enterotoxin that promotes the secretion of fluid and electrolytes into the lumen of the small intestine. Unless the lost fluid and electrolytes are replaced adequately, the infected person may develop shock from profound dehydration and acidosis from loss of bicarbonate. Because the organism is not acid-resistant, it depends on its large inoculum size to withstand gastric acidity. The use of antacids, histamine receptor blockers, and proton pump inhibitors increases the risk of cholera infection and predisposes patients to more severe disease as a result of reduced gastric acidity [5].

Widespread use of cholera vaccines began in the 1960s Most of the vaccines were composed of whole Vibrio cholerae cells, usually a mixture of serotypes, which were killed. The licensed, killed whole cell vaccines are injected and usually given in one or two doses. Injected (parenteral) whole cell vaccines have gone out of favor on the grounds that efficacy is thought to be low and short-lived. Even when injected cholera vaccines were in widespread use in the early 1970s, it was never determined whether an individual's protection was likely to interrupt transmission to others in the community [3] [4].

Recent cholera epidemics have shown that there is still a need for an effective vaccine against this major disease. Oral vaccines have been under development since the 1980s. Their strength is that they stimulate local intestinal immunity. Both killed and live oral vaccines are now licensed and the injected vaccine is no longer used [3].

Cholera is an intestinal infection caused by the Vibrio cholera bacteria. The primary symptom of the disease is profound watery diarrhea [1]. Severe cholera can cause dehydration and death within hours of onset. Cholera is transmitted by the fecal-oral route [1] [2]. Cholera can be endemic, epidemic, or pandemic. Despite all the advances in research, treatment and prevention the condition still remains a significant problem worldwide [2].

Cholera was a major cause of death in many countries in the past. Although epidemics are now less common, it remains an important cause of death in developing countries [2] [3]. Up to 40% of patients die if untreated [4].

The priority in management of any watery diarrhea is replacing the lost fluid and electrolytes and providing an antimicrobial agent when indicated.

What is Cholera?
Cholera is an acute infection of the intestine with the bacterium Vibrio cholera, which causes severe diarrhea. It accounts for an estimated 3-5 million cases and over 100,000 deaths each year around the world. The infection is often mild or without symptoms, but in approximately 5% of infected persons will become severely ill. Severe disease is characterized by profuse watery diarrhea, and vomiting leading to dehydration, hypovolemic shock and eventual death. Without treatment, death can occur within hours.

Where is Cholera Found?
The cholera bacterium is found in water or food that has been contaminated by feces from a person infected with cholera. Cholera is found and spread in places with inadequate water treatment, poor sanitation, and inadequate hygiene. Cholera is found endemically in India, sub-Saharan Africa, and most recently in Haiti.

Shellfish eaten raw have been a source of cholera, and a few persons in the U.S. have contracted cholera after eating raw or undercooked shellfish from the Gulf of Mexico.

How Does a Person Get Cholera?
A person can get cholera by drinking water or eating food contaminated with the cholera bacterium. The contamination is usually from the feces of an infected person. The disease is not likely to spread directly from one person to another, therefore, casual contact with an infected person is not a risk for becoming ill.
Travel to a region where cholera is endemic is a major risk to acquiring the disease.

What are the Symptoms of Cholera?
Cholera infection is characterized by profuse watery diarrhea, vomiting, and leg cramps. Symptoms typically appear in 2-3 days, but can occur in a few hours or as long as a week. Rapid loss of body fluids leads to dehydration and shock. Without treatment death can occur within hours.

What Should I Do If I Think I Have Cholera?
If you think you may have cholera, seek medical attention immediately. Dehydration can be rapid so fluid replacement is essential.
To test for cholera, doctors must take a stool sample or a rectal swab and send it to a laboratory to look for the cholera bacterium.

What is the Treatment for Cholera?
Cholera can be successfully treated by immediate replacement of the fluid and electrolytes with oral rehydration solution. This solution is used throughout the world to treat diarrhea. Severe cases may require intravenous fluid replacement. With prompt rehydration most patients recover without injury. Antibiotics shorten the course and severity of the illness, but they are not as important as rehydration.

How Can I Avoid Getting Cholera?
The risk to people visiting areas with epidemic cholera is very low if simple precautions are observed. These include:
Drink only bottled, boiled, or chemically treated water and carbonated beverages. When using bottled drinks, make sure that the seal has not been broken. Avoid tap water, fountain drinks, and ice cubes.
Wash your hands often with soap and clean water. Clean your hands especially before you eat or prepare food and after using the bathroom. If no water and soap are available, use an alcohol-based hand cleaner with at least 60% alcohol.
Use bottled, boiled, or chemically treated water to wash dishes, brush your teeth, wash and prepare food, or make ice.
Eat foods that are packaged or that are freshly cooked and served hot. Do not eat raw and undercooked meats and seafood or unpeeled fruits and vegetables.
Dispose of feces in a sanitary manner to prevent contamination of water and food sources.

Is a Vaccine Available to Prevent Cholera?
Currently, there are two oral cholera vaccines available, Dukoral and ShanChol. The vaccine is a two dose vaccine given several weeks apart. Persons receiving the vaccine may not be protected in that time period. Therefore, vaccination should not replace standard prevention and control measures. The Center for Disease Control (CDC) does not recommend cholera vaccines for most travelers, nor is the vaccine available in the U.S. This is because the available vaccines offer incomplete protection for a relatively short period of time.

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