From Tanzania to South Sudan, and Nepal to Yemen, cholera – and the threat of a cholera outbreak – is a major public health concern for governments and the international health community. Use of Oral Cholera Vaccines (OCV) is proving to be an efficient tool to effectively control cholera outbreaks. New outbreaks are ongoing in South Sudan and Tanzania fanned by insecurity and displacement. Intensive control efforts are ongoing, and vaccination programmes have been rolled out to target communities at risk. In conflict-wracked Yemen and earthquake-ravaged Nepal, WHO has been working with national authorities and partners on the ground to prepare for any outbreak of cholera, as well as acute water diarrhoea.
What is cholera?
Cholera is an acute intestinal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. It has a short incubation period, from less than one day to five days, and produces an enterotoxin that causes a copious, watery diarrhoea; vomiting also occurs in most patients. Cholera can quickly lead to severe dehydration and death without prompt treatment.
Effectively controlling cholera
WHO and its partners are responding to outbreaks to effectively control the deadly water-borne disease through improved water and sanitation practices, use of oral cholera vaccines, better surveillance, and greater awareness among communities as to how to control it. The WHO-led Global Task Force on Cholera Control (1) aims to end cholera deaths by strengthening international collaboration and increasing coordination among partners in 3 of the main situations where cholera circulates:
- in endemic conditions, where the disease is entrenched in communities, such as regions of the Democratic Republic of the Congo;
- in sudden outbreaks, where an instant vaccination response is deemed most effective, such as in Guinea and Malawi; and
- as a consequence of a humanitarian crisis, such as the late 2013 outbreak in South Sudan, or current outbreak in Tanzania when thousands of people displaced by fighting in neighbouring Burundi were successfully vaccinated against the disease.
Effectively controlling a disease means reducing new cases in defined locations to zero through targeted efforts. In the case of cholera, these include the use of oral cholera vaccine, improving water and sanitation practices, engaging the community in implementation of control measures, and sustaining control efforts to prevent its re-emergence.
Using the cholera vaccine to stop outbreaks
A global stockpile, funded by the Bill and Melinda Gates Foundation, the ELMA Vaccines and Immunization Foundation, the EU Humanitarian Aid and Civil Protection department (ECHO), the Margaret A Cargill Foundation and the USAID Office of Foreign Disaster Assistance, initially made 2 million doses of the vaccine available. In 2015, with funding from the GAVI Alliance, the number of doses available for use in both endemic hotspots and emergency situations is expected to rise to around 3 million.
The oral cholera vaccine is an important tool in fighting cholera. Its use must be both supported by local authorities and used hand-in-hand with focused, sustainable water and sanitation actions in targeted communities.
Since the establishment of the stockpile in 2013, close to 2 million doses of OCV were distributed. As this equals the number of vaccines used in 15 years before 2013, it is clear that, by increasing the supply of OCV, the stockpile mechanism was successful in developing the demand for cholera vaccines which is one of its main objectives.
There are several examples where the vaccine has stopped cholera outbreaks in their tracks, such as in South Sudan in 2014 when, before the occurrence of the outbreak, thousands of displaced people who had found shelter in makeshift camps at UN sites were given the vaccine. This action almost certainly averted increased illness and death amongst the vulnerable camp inhabitants who had been at high-risk of the disease.