Cholera, the disease
Cholera is a bacterial infection that causes copious, painless, watery diarrhoea and vomiting. It is spread rapidly through water contaminated with bacterium vibrio cholera carried in the faeces of infected people. Symptoms develop from less than one to five days and the water loss can lead to severe dehydration if an oral rehydration solution (ORS) is not taken promptly. Severe cases may require rehydration with an intravenous drip and can cause death. Mild cases, which are difficult to identify as cholera, contribute to the infection spreading.
Provision of safe water, proper sanitation and the promotion of improved hygiene and food handling practices are the most effective ways of limiting the spread of cholera.
The spread of cholera
Cholera has existed since ancient times and as people have begun to travel more it has spread around the world. It is most common in developing countries that have not been able to invest in safe drinking water and adequate sanitation. Outbreaks are common when people are living in crowded areas on the fringes of cities and where conflict or disaster has resulted in people living in camps.
The ability of vibrio cholera to persist in water is determined by the temperature, pH, salinity and availability of nutrients. It can survive under unfavourable conditions in a viable dormant state.
The reported case fatality rate (CFR) is a measure of the severity of a disease and is defined as the proportion of reported cases that are fatal within a specified time. With proper and timely treatment, the CFR should remain below 1%.
Prevention and treatment
Prevention, using the following five messages, is the most effective way of limiting the spread of cholera:
1) drink and use safe water
2) wash your hands often, using soap and water
3) use latrines or bury faeces and do not defecate in any body of water
4) cook food well, keep it covered, eat it hot, and peel fruits and vegetables
5) clean up safely in the kitchen and in places where the family bathes and washes clothes.
Vaccines are available but they only offer partial and short-term protection. They require two doses and are specific to particular strains of the disease so are not effective during an epidemic.
Cholera in Haiti
On 22 October 2010, ten months after the catastrophic January 2010 earthquake in Haiti that killed over 200,000 people and displaced over one million, the first cholera outbreak in Haiti in at least a century was officially announced. At the beginning of November the overall case fatality rate (CFR) in hospitals was 3.8%. This reflected the lack of experience of the healthcare system in dealing with cholera, patients reaching health facilities too late and lack of immunity to the identified variant strain present in several countries in South-East Asia and Africa. In November 2010 the first cases were detected in the neighbouring country Dominican Republic.
In the following 12 months over 470,000 cases of cholera were reported, with 6,631 attributable deaths. Improved access to clean water and sanitation and hygienic practices have dramatically decreased the number of people affected. As of June 2013 the outbreak was still ongoing, at a total of 661,468 cases, including 8,139 deaths (CFR 1.2%). There are likely to be further outbreaks in the future.
Cholera in Australia
Cases of cholera in Australia (about two to six cases a year) almost always occur in individuals who have been infected in endemic areas overseas.
Cholera in Papua New Guinea
Until recently cholera had never been reported in Papua New Guinea, despite it being close to countries where cholera was present and despite the environmental conditions. In July 2009 cholera was identified in people from two coastal villages near Lae on the north-eastern coast. It spread quickly along the coast. By mid-September cases were reported in villages around Madang and by mid-November cholera was identified in remote areas along the Sepik River.
By mid-2011 there had been more than 15,500 cases of cholera and over 500 deaths (CFR approximately 3.2%). Despite poor access to water, sanitation and health there were none of the usual causes for the outbreak. It is thought that travel throughout the country to attend funerals spread the disease.
In October 2010 a cholera outbreak on the remote island of Daru, Papua New Guinea in the Torres Strait was causing up to 70 people a day to become ill.
The Australian Government responded to ensure that the outbreak was contained and that future outbreaks were prevented. Emergency experts flew to the affected area to assist the Papua New Guinea Government assess the environmental, health, sanitation and water supply interventions.
The team delivered emergency medical supplies including:
- 1,200 doses of oral rehydration salts
- 800 x 10 litre containers of clean water
- 50,000 water purification tablets
- 1,000 information posters on how to prevent cholera
- more than 1,000 litres of intravenous (IV) fluids.
Cases in Papua New Guinea continued to be reported in 2010 and 2011, and cholera was declared to be endemic.
Surveillance and prevention
Cholera remains a global threat while people do not have access to adequate drinking water and sanitation and safe hygiene practices. Australian aid has been providing assistance for the prevention of cholera in Papua New Guinea and Haiti – improving collection and storage of rain water, building functional sanitation systems and providing hygiene education. Australian aid has also provided funding for medical supplies and expert assistance to improve surveillance and training of health providers for rapid response to outbreaks of cholera.
World Health Organization
World Vision, Water-based diseases in Papua New Guinea