Cholera

Overview

Cholera is an acute bacterial enteric disease caused by Vibrio cholerae O1 and O139 strains. Many other serogroups of V. cholerae, with or without the cholera toxin gene (including the non-toxigenic strains of O1 and O139 serogroups), can cause cholera-like illness. The usual causative agent in Singapore is Vibrio cholerae serogroup O1 which includes two biotypes, Classical and El Tor.

Pathogen(s)

Vibrio cholerae O1 and O139

Transmission

Cholera infections are acquired by consuming food or water that is contaminated with cholera bacteria. Person-to-person transmission can occur via the faecal-oral route, especially within households.

Incubation period: Typically, 2 to 3 days; range is few hours to 5 days.

Infectious period: Throughout the duration of the illness and for a few days after clinical recovery. There is no chronic carrier state, however shedding occasionally may persist for several months.

Clinical features

Cholera infection is often mild or without symptoms but can be severe. Severe cases are characterised by an acute onset of copious watery painless diarrhoea, classically described as “rice-water stool”, and accompanied with vomiting and fever. Untreated severe cases can result in rapid dehydration, electrolyte disturbances, acute renal failure, shock, and death.

Risk factors

People living in places with:

• Unsafe drinking water

• Poor sanitation

• Inadequate hygiene

Diagnosis

For cholera, isolation, and identification of Vibrio cholerae serogroup O1 or O139 by culture of a stool specimen remains the gold standard for laboratory diagnosis of cholera.

Treatment and management

Aggressive rehydration remains the mainstay treatment for cholera. In mild cases, oral rehydration salt solution can be used. In moderate to severe cases, intravenous fluids are required, and electrolyte abnormalities should be corrected.

Antibiotics can shorten the duration of excretion of the V. cholerae bacteria as well as decrease the severity of the diarrhoea.

Precaution, prevention, and control

Provision of safe food and water, proper processing and handling of food items, adequate cooking, and good personal hygiene are key prevention and control measures. Standard and contact precautions apply in healthcare settings.

Contracting cholera may be prevented with good prevention and control measures, such as:

• Drinking and using water from reliable sources

• Washing hands frequently

• Cooking food thoroughly

• Avoiding raw food consumption

Oral cholera vaccines are available. Most travellers to resource-limited settings are at low risk of cholera. Select travellers who are at higher risk may benefit from pre-travel cholera vaccination.

Notification

Who should notify:

• Laboratories

When to notify:

• On laboratory confirmation

How to notify:

• Please refer to the Infectious Disease Notification for more information.

Notification timeline:

• As soon as possible. No later than 24 hours from the time of laboratory confirmation.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of confirmed acute cholera cases in Singapore.