ORS & WASH Away Cholera
On September 22, 2023, the World Health Organisation (WHO) released Comprehensive Cholera Statistics for 2022 which provided information on the scope and severity of the ongoing cholera rise. While Cholera data are still lacking, the number of cases reported to WHO in 2022 was more than twice as high as that in 2021. The report emphasised that there were not only more outbreaks, but that the outbreaks were also larger. More than 10,000 suspected and confirmed cases have been recorded from each of the seven countries, including Afghanistan.
The WHO in its earlier ‘Cholera – Global situation’ report on February 11, 2023 noted that researchers have estimated that each year there are 1.3 to 4 million cases of cholera, and 21,000 to 143,000 deaths worldwide due to cholera. In
WHO Southeast Asia Region, both India and Nepal, which reported outbreaks in 2022, remain under monitoring. There is limited surveillance (often sentinel-based) and low reporting. There is continued risk of export to other regions.
Similarly in the WHO Western Pacific Region, in the Philippines, recurrent cholera outbreaks were reported in 2022 with a cumulative number of recorded cases three times higher than in 2021. While countries of the region have overall good control capacity, there is inadequate monitoring of drinking water quality.
The WHO Southeast Asia Region, which includes Bangladesh and India, has the largest populations at risk for cholera. While reported cases decreased by 72 per cent from 2015 to 2016, reported deaths from cholera in Asia increased sixfold.
Many countries in the WHO Southeast Asia Region face challenges with known risk factors for cholera outbreaks including poverty, lack of development, and high population density. Additionally, the region is susceptible to extreme environmental factors, such as frequent and widespread flooding, that can contaminate water sources and dislocate populations.
Lack of development and cross-border population movements also contribute to outbreaks. The latter, along with increased global travel following COVID-19, further increased the risk of international spread.
In Southeast Asia and elsewhere, cholera is under-reported and leads to an underestimation of the global burden of this disease. The WHO estimates that officially reported cases of cholera represent only 5–10 per cent of the actual number occurring annually worldwide because of inadequate laboratory and epidemiological surveillance systems and economic, social and political disincentives to case reporting. Cases of cholera officially reported to WHO in Southeast Asia do not include an estimated 500,000–700,000 cases labelled as acute watery diarrhoea.
Out of the multifaceted approaches used to control cholera, and to reduce deaths, use of oral cholera vaccines is one of the approaches used in conjunction with improving global access to water, sanitation and hygiene (WASH), a critical step in reducing cholera in areas known to be high risk.
Currently there are three WHO pre-qualified oral cholera vaccines (OCV): Dukoral, Shanchol, and Euvichol-Plus. All three vaccines require two doses for full protection. Shanchol and EuvicholPlus are the vaccines currently available for mass vaccination campaigns through the Global OCV Stockpile. The stockpile is supported by Gavi, the Vaccine Alliance. More than 100 million doses of OCV have been used in mass vaccination campaigns. The campaigns have been implemented in areas experiencing an outbreak, in areas at heightened vulnerability during humanitarian crises, and among populations living in highly endemic areas, known as “hotspots”.
The increased demand for cholera materials has been a challenge for disease control efforts globally. Since October 2022, the International Coordinating Group (ICG)—the body which manages emergency supplies of vaccines—has suspended the standard two-dose vaccination regimen in cholera outbreak response campaigns, using instead a single-dose approach.
As cholera is an easily treatable disease, it can also be treated successfully through prompt administration of oral rehydration solution (ORS). Oral rehydration should be made available in communities, in addition to larger treatment centres that can provide intravenous fluids and 24 hour care. With early and proper treatment, the case fatality rate can be maintained at below 1 per cent.