International Events

​Outbreak overview:

• In 2023, the cholera outbreak continued for the seventh time, with 535,321 cases reported to WHO, compared to 472,697 cases in 2022. Cholera cases were reported in 45 countries and territories, an increase of 44 cases in 2022, and 35 cases in 2021. The geographical pattern of the outbreak has further evolved, with a 32% decrease in the number of cases reported in the Middle East and Asia, and a 125% increase in cases in Africa.
• In 2023, very large outbreaks, with more than 10,000 suspected/confirmed cases in each country, were reported by 9 countries across 3 continents (Afghanistan, Bangladesh, Democratic Republic of Congo, Ethiopia, Haiti, Malawi, Mozambique, Somalia, and Zimbabwe), an increase of 2 from 2022, and more than double the number of very large outbreaks reported annually between 2019 and 2021. Of the 9 countries, 4 (Ethiopia, Haiti, Mozambique, and Zimbabwe) did not report very large outbreaks in 2022. While the number of cholera cases reported in Bangladesh increased in 2023 compared to 2022, this increase can be attributed to the country’s efforts to strengthen cholera surveillance and reporting, rather than to a new outbreak.

A disease at Glance
Cholera is an acute diarrheal disease caused by infection of the intestines with the bacterium Vibrio cholerae. People can become ill when they ingest food or water contaminated with cholera bacteria. The infection is often mild or asymptomatic, but it can sometimes be severe and life-threatening.
There are many serogroups of Vibrio cholerae, but only the toxin-producing strains of serogroups O 1 and O 139 have caused large epidemics.

Disease Transmission

• Cholera bacteria are usually found in water or food contaminated with feces from a person infected with cholera bacteria. Cholera is more likely to occur and spread in places with inadequate water treatment, poor sanitation, and poor hygiene.
• Cholera bacteria can also live in brackish rivers and coastal waters. Raw shellfish is also a possible source of infection.
• Direct transmission from person to person is unlikely, so casual contact with an infected person is not a risk factor for infection.

Treatment

1. Rehydration therapy, which is the primary treatment for cholera patients, to immediately restore lost fluids and salts.
2. Antibiotic therapy reduces fluid loss and duration of illness and is used in severe cholera cases.
3. Zinc therapy helps reduce cholera symptoms in children.

Vaccine

1. Vaxchora, a single-dose oral vaccine approved by the US Food and Drug Administration for use in people ages 2-64 who are traveling to an area with active cholera transmission, is not currently available.
2. Dukoral, ShanChol, and Euvichol-Plus, a two- or three-dose oral vaccine for people 2 years and older.

Geographical Distribution of Cases
Africa:

• 21 countries reported 225,857 cholera cases and 3,167 deaths (case fatality rate = 1.4%) in 2023, including 494 imported cases. This represents a 125% increase in the number of reported cases and a 62% increase in reported deaths compared to 2022. 28 countries also reported no cases.
• In 2023, six countries reported very large outbreaks, including five countries that reported cholera outbreaks in 2022. Three of these countries (Ethiopia, Mozambique, and Somalia), located in eastern and southern Africa, were identified as being at highest risk of the impacts of the 2023 El Niño.
• Cameroon and Nigeria, which reported very large outbreaks in 2022, reported fewer cases in 2023.
• The continent’s case fatality rate of 1.4% is alarming. Of the 17 countries that reported more than 50 cases, 10 had a case fatality rate of more than 1%, including 7 countries that reported a case fatality rate of more than 2%. Discrepancies in reporting, such as the inclusion or exclusion of deaths among community members, contribute to these discrepancies. However, the percentages represent 3,167 lives lost to cholera in Africa in 2023.
• In 2023, the Democratic Republic of the Congo reported 52,654 cases, representing 23% of the total reported cases on the continent. This figure represents a nearly three-fold increase from 2022 (18,961), and the highest number reported since 2017 (56,190). This increase is largely due to the conflict in the eastern part of the country, where cholera is raging, which has led to repeated mass displacement of people to areas with inadequate access to safe water and sanitation, as well as limited humanitarian access due to insecurity. The increase in cases in Southern Africa, which began in 2022, continued into 2023, with the outbreak expanding in Malawi (32,530), while Mozambique (39,101), South Africa (1,478), Zambia (4,531), and Zimbabwe (14,148) recorded the highest numbers of cases in children under 5 years of age. It is worth noting that, with some important exceptions, cases occurred in stable areas not affected by conflict. Long-term investment in climate-resilient water, sanitation and hygiene systems could significantly reduce the risk of recurrence in these areas.
• Many countries in Africa have reported a high proportion of community deaths among cholera deaths. While the number of deaths is a concern, it is encouraging that community deaths are being reported. Real-time monitoring of facility-based mortality rates and community-based mortality during outbreaks would improve identification of critical areas and enable more effective targeting of responses.

Americas

• In the Americas, 3 countries reported 55,078 cholera cases and 712 deaths (case fatality rate = 1.3%) in 2023.
• Haiti reported 54,767 cases, accounting for more than 99% of cases and deaths in the region. The Dominican Republic reported 310 cases (1 imported), including 1 death. The Turks and Caicos Islands reported 1 imported case and no deaths. In Haiti, after a decline in cases following a cholera outbreak in 2010, including cases reported in 2020 and 2021, a resurgence of cholera was reported in 2022, leading to a very large outbreak in 2023. This outbreak occurred in the context of escalating civil unrest and large-scale movement and displacement of people, resulting in reduced access to safe water and health care services.

Middle East and Asia
In the Middle East and Asia, 16 countries reported 254,368 cholera cases and 128 deaths (CFR = 0.1%) in 2023. Of these, 36 were imported, with Bahrain, Japan, Qatar and Saudi Arabia reporting only imported cases. In addition, 15 countries reported no cases, with Afghanistan reporting 87% of cases and 79% of deaths in the region, all of which were classified as suspected cases. Lebanon and the Syrian Arab Republic experienced a major outbreak in 2022, after decades of no cases. In 2023, the Syrian Arab Republic reported no cases, while Lebanon reported 2,406 cases, a 58% decrease. Yemen, which reported 89% of cholera cases in the region in 2021, did not report in 2022 or 2023. The number of cases reported by Bangladesh increased significantly between 2022 (1,191 cases) and 2023 (23,369 cases). This increase can be attributed to increased surveillance and reporting, rather than a new or worsening outbreak. Enhanced reporting will contribute to the implementation of cholera control programs in Bangladesh. The high numbers of cases reported in the Southeast Asia region highlight the need for continued vigilance, improved surveillance and targeted cholera control efforts.

Europe
Three countries in Europe reported a total of 14 cases in 2023, all imported. Effective water and sanitation systems, combined with active public health surveillance, have prevented local transmission in Europe; however, the presence of imported cases highlights the continued risk of cholera spreading globally from active outbreaks elsewhere.

Oceania
Two countries in Oceania reported a total of 4 cases in 2023, all imported, and a further 15 countries reported no cases. As in Europe, the presence of imported cases in Oceania underscores the risk of international spread due to global travel.

Surveillance

• Cholera surveillance should be part of an integrated disease surveillance system, including collection of information at the local level and sharing it globally.
• Detection of a suspected cholera case is based on clinical suspicion in patients aged 2 years and older with acute watery diarrhoea and severe dehydration, or death from acute watery diarrhoea.
• Rapid diagnostic tests can be a useful tool for detecting cholera outbreaks; however, to confirm the diagnosis, stool samples are sent to the laboratory for confirmation of the presence of serogroup O1 or O139, by culture or PCR.
• Cholera outbreaks are monitored by reporting patients with acute watery diarrhoea and regular testing of these patients. Local capacity to detect (diagnose) and monitor (collect, classify and analyse data) cholera cases is essential for effective surveillance and control planning.
• Countries affected by cholera are encouraged to strengthen national surveillance and preparedness to rapidly detect and respond to cholera outbreaks. Notification of all cholera cases is no longer mandatory under the IHR, but public health events involving cholera should always be assessed against the criteria set out in the IHR (decision-making guidelines in Annex 2 of the IHR) to determine whether formal notification is required.

WHO Response

• WHO encourages countries neighboring cholera-affected areas to strengthen national disease surveillance and preparedness, so that they can rapidly detect and respond to cholera outbreaks if they spread across their borders. Information should be provided to travellers and communities about the potential risks of cholera, its symptoms, precautions to avoid the disease, when and where to report cases, and where to seek treatment if necessary.
• WHO does not recommend routine cholera screening, vaccination or quarantine for travellers from cholera-affected areas, nor does it recommend the administration or proof of prophylactic antibiotics for travellers from or heading to a cholera-affected country.
• WHO and partners are supporting cholera-affected countries in implementing immediate and long-term control measures, including surveillance and outbreak response, water, sanitation and hygiene services, and preventive measures such as oral cholera vaccine, risk communication and community engagement.
• WHO continues to host the Secretariat of the Global Task Force on Cholera Control, a partnership to coordinate global cholera activities and support countries. The Global Task Force on Cholera Control (GTFCC) advocates for long-term cholera control based on multisectoral national cholera control plans. Since the launch of the End Cholera: A Global Roadmap to 2030 strategy in 2017, GTFC partners have collaborated to establish a support system for cholera-affected countries, including the Country Support Platform hosted by the International Federation of Red Cross and Red Crescent Societies, which provides multisectoral technical and operational support and guidance on advocacy, coordination and policy for the development, financing, implementation and monitoring of National Cholera Action Plans (NCPs).

References
WHO