cholera

(kol′ĕ-ră)

[L. cholera, fr Gr. cholera, intestinal disease, fr. cholē, bile, gall]
An acute infection involving the gastrointestinal tract, marked by profuse, watery diarrhea. Without treatment, the loss of fluids and electrolytes resulting from cholera can cause dehydration and vascular collapse. The incubation period is from a few hours to 4 or 5 days.
choleraic (kol″ĕ-rā′ik), adj.
SYN: SEE: Asiatic cholera

CAUSES
The causative organism, Vibrio cholerae, is a short, curved, motile gram-negative rod. Several serotypes have been identified: 01 (Ogawa, Inaba), and 0139 (Bengal). The bacteria do not invade the bowel wall but produce a potent enterotoxin that causes increased secretion of chloride, bicarbonate, and water into the small intestine, which overwhelms the large intestine's ability to reabsorb.

INCIDENCE
The World Health Organization (WHO) estimates that cholera infects 3 to 5 million people and causes at least 100,000 deaths annually.

SYMPTOMS AND SIGNS
Approximately 80% of patients have a mild case of the disease marked by diarrhea and malaise. Severe attacks are characterized by periodic voluminous rice water stool, vomiting, and muscle cramps. Without treatment, severe dehydration develops, characterized by loss of skin turgor, dizziness, increased heart rate and respiration, decreased urinary output, and, ultimately, circulatory collapse and shock. Hypoglycemia may be a problem in very young children.

DIAGNOSIS
Cholera can be identified by stool cultures, which can also be used to identify antibacterial sensitivities; it can also be rapidly identified with commercially available rapid diagnostic kits. During diarrheal epidemics in which cholera has already been identified, any case of watery diarrhea should be treated as a presumptive case of cholera.

TREATMENT
The use of oral solutions to replace the lost water, sodium, chloride, and bicarbonate has decreased the death rate from cholera by preventing death due to dehydration. A commercial or over-the-counter oral rehydration solution can be used or a solution made by adding 1 level tsp of salt and 1 heaping tsp of sugar to 1 L of water; patients should replace 5% to 7% of body weight, e.g., a 20-kg child should receive 1 to 1.4 L of fluid per day. Hospitalization and intravenous fluid replacement are required if the patient is already dehydrated. Quinolone antibiotics decrease the duration and severity of the disease.

PREVENTION
Natural disasters, such as tsunamis and earthquakes, can disrupt the sanitary distribution of water and produce widespread outbreaks of cholera. One such outbreak occurred in Haiti in 2010, when a large earthquake resulted in over 600,000 cases of the disease. Cholera spreads in epidemics when sewage contaminates drinking water. To avoid infection with cholera, travelers to developing countries should not drink unboiled water, add ice to beverages, or eat raw or partially cooked shellfish, uncooked vegetables or salads, or fruits they have not peeled themselves. They should not assume that bottled water is safe, and they should swim only in chlorinated swimming pools.

TREATMENT
Oral rehydration is a mainstay of treatment. In moderately severe or severe infections, empirical antibiotic therapy that matches the sensitivities of known strains of the bacterium should be given. Zinc supplementation favorably affects the outcome of the illness both by reducing secretory diarrhea and by enhancing antibody responses against Vibrio species.

PROGNOSIS
People infected by cholera who have underlying chronic illnesses (such as malnutrition) are more likely to be harmed or killed by cholera than healthier people. Blood type O seems to confer an increased risk for severe infection as well.

PATIENT CARE
Health care providers working in diarrheal epidemics should follow standard precautions to avoid spreading the disease. Infection control practices may limit the spread of the disease in health care facilities. Laundry services should be upgraded to manage contaminated linens or bedding. Sanitary waste disposal practices should be followed scrupulously. Health care professionals should become familiar with oral rehydration protocols. Efforts to provide hygienic sources of drinking water should be supported in communities affected by epidemic disease.