Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. Vibri cholerae produces cholera toxin, whose action on the mucosal epithelium is responsible for the characteristic diarrhoea of this disease. The infection is often mild or without symptoms, but sometimes it can be severe. Less than 10% of infected persons develop severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.
Reservoir
A person may get cholera by drinking water or eating food contaminated with the cholera bacterium. In an epidemic, the source of the contamination is usually the feces of an infected person. The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water.
Incubation period
Incubation period: few hours to 5 days; usually two to three days.
Signs and Symptoms
- Asymptomatic illness is most frequent.
- Profuse watery stools
- Vomiting
- Rapid dehydration
- Circulatory collapse
- Death if untreated
Diagnosis
Stool culture and sensitivity.
Visualisation by dark field or phase microscopy of characteristic motility.
Treatment
- Prompt fluid therapy with adequate volumes of electrolyte solution should be undertaken.
- Most cases of diarrhoea can be treated adequately by giving a solution of oral rehydration salts (the WHO/UNICEF standard sachet).
- Patients with severe dehydration require urgent intravenous fluid therapy with Hartmann's solution or WHO solution or other similar fluid.
- Antibiotic treatment (prescribed by medical doctor, to which the strain is sensitive) shorten the duration of diarrhoea and the duration of vibrio excretion:
- Adults: Tetracycline drugs (if strain sensitive)
- Children: Co-trimoxazole (if strain sensitive).
Control and Prevention
- Contacts should be observed for five days from the date of last exposure. This may include, for example, all air travellers on a flight from overseas.
- Effective food hygiene measures in endemic areas include cooking food thoroughly and eating it while still hot; preventing cooked foods from being contaminated by contact with raw foods, including water and ice, contaminated surfaces or flies; and avoiding raw fruits or vegetables unless they are first peeled.
- Washing hands after defecation, and particularly before contact with food or drinking water, is equally important.
- Stool culture of any contacts with symptoms of diarrhoea and stool culture of all household contacts, even if asymptomatic, should be undertaken.
- Cases should also be looked for among those possibly exposed to a common source.
- A recently developed oral vaccine for cholera is now licensed, but Immunization is not recommended.