What is Cholera?
Cholera is an extremely virulent infection characterised by acute diarrhoea, which if left untreated, can be fatal in a matter of hours; it is acquired through the consumption of food and water contaminated with the bacterium Vibrio cholerae.
What are the symptoms?
The incubation period is between 12 hours and 5 days and, in most cases, someone with cholera does not develop any symptoms and is unaware they have the disease (although they do shed the bacteria in their faeces for 1-10 days, potentially infecting any contacts). For those who do develop symptoms, they will usually be mild or moderate and resemble other ‘gastro’ type illnesses. Only between 5 and 10 percent of cases will deteriorate further, resulting in the passage of large volumes of acute watery diarrhoea, causing severe dehydration that can lead to death if left untreated. Intravenous fluids and antibiotics are needed in severe cases, however up to 80% of cases can be successfully treated with oral rehydration solution (ORS).
Where is it found?
Cholera continues to represent a threat to public health in developing countries. It is endemic in around 50 developing countries worldwide, especially in Africa, South and Southeast Asia and in areas with inadequate access to clean water and sanitation facilities. Typical risk areas include peri-urban slums and camps for internally displaced persons or refugees.
Risk to travellers
The risk of infection is estimated to be 0.2 cases per 100,000 travellers from western countries, however the probability of developing severe disease is substantially less. Sporadic cases associated with travel to or from cholera-affected countries in Asia and Africa continue to occur.
Precautions regarding food and water consumption and personal hygiene are most important, regardless of vaccination.
One cause of travellers’ diarrhoea is from the toxin produced by a type of E.coli bacteria (LT-ETEC). As this toxin is similar to the one produced by cholera bacteria, vaccination against cholera can provide some degree of protection against ETEC diarrhoea (off-label use in Australia). It is recommended for people who have a higher risk of severe or complicated diarrhoeal disease travelling to areas where cholera exists. These include people with:
- Poorly controlled or complicated diabetes
- Inflammatory bowel disease
- HIV or other immunocompromising conditions
- Significant cardiovascular disease
No countries currently mandate cholera vaccination in their entry requirements.
For most travellers, this oral vaccine is recommended for long-term travellers and for those visiting countries experiencing floods.
What is Cholera Vaccination?
Type: Oral vaccine
Cholera vaccination is recommended for children (≥2 years of age) and adult travellers who:
- have a high risk of acquiring diarrhoeal disease, including those with achlorhydria
- are travelling to areas where there is a high likelihood of exposure to cholera
- Humanitarian workers operating in an epidemic or refugee camps.
The cholera vaccine is an oral vaccination that stimulates the immunological defence in the gut. No food or drink should be consumed for 1 hour before and 1 hour after administration.
Children aged 2–6 years are recommended to receive 3 doses of cholera vaccine with an interval of 1–6 weeks between each dose.
Adults and children aged ≥6 years are recommended to receive 2 doses of cholera vaccine with an interval of 1–6 weeks between each dose.
Hypersensitivity to vaccine components.
Administration of oral cholera vaccine should be delayed in the event of acute gastrointestinal or febrile illness.
The cholera vaccine is not routinely recommended for pregnant or breastfeeding women.
Level of protection
- Two doses of oral cholera vaccine (3 doses for 2-5 years) provides 60-70% protection against severe cholera for up to 2 years. Boost with a single oral dose 2-5 years after primary course for cholera protection. If more than 5 years have passed the full primary course of two doses is required.
- Note: Although protection against ETEC diarrhoea is off-label use in Australia, ETEC protection only lasts 3 months. If continuing ETEC protection is required, boosting with a single dose after 3 months is advised.
Possible Side Effects
Abdominal pain, fever
Diarrhoea, nausea and vomiting
Allergic reactions can also occur
Potentially serious side effects including dehydration and shortness of breath are rare
Australian Immunisation Handbook: https://immunisationhandbook.health.gov.au/vaccine-preventable-diseases/cholera