Cholera is caused by Vibrio cholerae, the most feared epidemic diarrheal disease because of its severity. Dehydration and death can occur within hours of infection if not properly managed. Robert Koch discovered V cholerae in 1883 during an outbreak in Egypt. By definition cholera is an acute diarrheal disease that can, in a matter of hours, result in profound, rapidly progressive dehydration and death. Even though Cholera is treatable, in 2009, the World Health Organization states that reported cholera cases have remained relatively constant since 1995, varying from 100,000 to 300,000 cases per year, with Africa accounting for more than 94% of the total. There is no reason that cholera and other deadly water-related illnesses should exist anywhere in the world today. Lack of decent water, lack of decent sanitation, and the existence of extreme poverty are related problems that plague the Third World. Roughly 1.1 billion people in developing countries have inadequate access to water. 2.6 billion lack basic sanitation. Almost 2 in 3 people lacking access to clean water survive on less than $2 a day. And, 1 in 3 are living on less than $1 a day. More than 660 million people without sanitation live on less than $2 a day, and more than 385 million on less than $1 a day. The natural habitat of V. cholerae is coastal salt water and brackish estuaries, where the organism lives in close relation to plankton. Humans become infected incidentally but, once infected, can act as vehicles for spread. Ingestion of water contaminated by human feces is the most common means of acquisition of V. cholerae. Consumption of contaminated food can also contribute to spread. There is no known animal reservoir.
Mortality/Morbidity
If untreated, the disease rapidly results in dehydration and can result in death in more than 50% of infected individuals. The mortality rate is increased in pregnant women and children.
Presentation
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 accompanying abdominal cramps. Fever is typically absent. The diarrhea has a "rice water" appearance and a fishy odor.
Diagnosis
The clinical suspicion of cholera can be confirmed by the identification of V. cholerae in stool. Laboratory isolation of the organism requires the use of a selective medium. Monoclonal antibody-based diagnostic kits and methods based on the polymerase chain reaction and on DNA probes have been developed for detection of V. cholerae O1 and O139.
Treatment
Cholera is simple to treat; only the rapid and adequate replacement of fluids, electrolytes, and base is required. The mortality rate for appropriately treated disease is usually <1%. Fluid replacement may be given orally, but oral rehydration is not always feasible in the presence of significant vomiting. For the sake of simplicity, the WHO advises routine use of a single solution of oral rehydration salts (ORS) for diarrheal disease rather than encouraging attempts to choose among multiple formulations according to etiology. If available, rice-based ORS is considered superior to standard ORS in the treatment of cholera.
If prepackaged ORS is unavailable, a simple homemade alternative can be prepared by combining 5 g common salt (about 1 level teaspoon) with either 50 g precooked rice cereal or 40 g sucrose in 1 L of drinking water. In that case, potassium must be supplied separately (e.g., in orange juice or coconut water). In adults drugs used are tetracycline/ doxycycline/ciprofloxacin. In children erythromycin/azithromycin /furazolidone/ trimethoprim-sulfamethoxazole can be used.
Prevention
Provision of safe water and facilities for sanitary disposal of feces, improved nutrition, and attention to food preparation and storage in the household can significantly reduce the incidence of cholera and other gastroenteritis illnesses. So drinking boiled water, through hand washing, proper washing of fruits and other eatables before eating, isolating and treating the affected cases, eating properly and well cooked food, apart from proper disposal of waste and excreta holds the key to control the out break.
Traditional killed cholera vaccine given intramuscularly provides limited efficacy due, at least in part, to its failure to induce a local immune response at the intestinal mucosal surface and not useful in non-immune patients. Two types of new oral cholera vaccines have been developed with protection rates of ~58% and 85% for Whole cell and BS. Protective efficacy rates for both vaccines declined to ~50% by 3 years after vaccine administration.
Conclusion
Cholera outbreak is characterized by the high number of cholera cases in those under 5 years of age. The expected contamination of water, aggregation of cases in areas far removed from main water projects, and the very low history of eating out of the home could lead to a conclusion that the outbreak could be most probably transmitted through the water. Cholera is a preventable disease and can be controlled. What can be learned from an outbreak is that intensive efforts are needed in our state to establish safe drinking-water and proper sanitation for all people; have laboratory and therapeutic needs available on the spot; and ensure year-round surveillance activities for early detection of cholera cases.
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