Disease Outbreak News

Cholera - Malawi

7 November 2022
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Situation at a Glance

Cholera is endemic in Malawi with seasonal outbreaks reported during the wet season. Since 1998, cholera cases have been reported in the country with significant morbidity and mortality in affected populations, especially in the southern region, which is low-lying, flat, and prone to flooding during the rainy season. The current outbreak, which started in March 2022 has affected 27 of 29 districts of Malawi and represents the largest outbreak reported in the country in the past ten years. The outbreak is taking place in the context of tropical storm Ana (January 2022) and Cyclone Gombe (March 2022) which caused floods leading to the displacement of a population with low pre-existing immunity that now lacks access to safe water, sanitation, and hygiene.

Description of the Situation

On 3 March 2022, the Ministry of Public Health of Malawi notified WHO of a cholera outbreak after laboratory confirmation of a cholera case in Machinga district hospital on 2 March 2022.

Between 3 March through 31 October 2022, a cumulative total of 6056 cases including 183 deaths have been reported from 27 of 29 districts in Malawi (overall case fatality rate (CFR) 3.0%) with active transmission ongoing in 23 districts as of 31 October. Five districts account for 79% of the reported cases and 68% of the deaths: Nkhata Bay (1128 cases and 31 deaths), Nkhotakota (811 cases and 40 deaths), Rumphi (783 cases and 13 deaths), Karonga (683 cases and 14 deaths), and Blantyre (650 with 26 deaths).

The outbreak originated in the Southern region of Malawi with cases reported in Nsanje and Machinga districts. Currently, the most affected districts in Malawi are in the Northern part of the country. The most affected age groups are 21-30 years, and males are disproportionately affected. 

Figure 1. Number of suspected and confirmed cholera cases (n=6056) and deaths (n=183) in Malawi by month, 1 January to 31 October 2022.

Source: Malawi Ministry of Health and Population

Figure 2. Geographical distribution of confirmed and suspected cholera cases (n=6056) in Malawi, 1 January to 31 October 2022

Source: Malawi Ministry of Health and Population

Figure 3. Distribution of confirmed and suspected cholera cases (n=6056) by age group and gender in Malawi, 1 January to 31 October 2022

Source: Malawi Ministry of Health and Population

Epidemiology

Cholera is an acute enteric infection caused by ingesting the bacteria Vibrio cholerae present in contaminated water or food. It is mainly linked to inadequate sanitation and insufficient access to safe drinking water. It is an extremely virulent disease that can cause severe acute watery diarrhoea resulting in high morbidity and mortality, and can spread rapidly, depending on the frequency of exposure, the exposed population and the setting. Cholera affects both children and adults and can be fatal within hours if untreated.

The incubation period is between12 hours and five days after ingestion of contaminated food or water. Most people infected with V. cholerae do not develop any symptoms, although the bacteria are present in their faeces for 1-10 days after infection and are shed back into the environment, potentially infecting other people. The majority of people who develop symptoms have mild or moderate symptoms, while a minority develop acute watery diarrhoea and vomiting with severe dehydration. Cholera is an easily treatable disease. Most people can be treated successfully through prompt administration of oral rehydration solution (ORS).

The consequences of a humanitarian crisis – such as disruption of water and sanitation systems, or the displacement of populations towards inadequate and overcrowded camps – can increase the risk of cholera transmission, should the bacteria be present or introduced.

A multi-sectoral approach including a combination of surveillance, water, sanitation and hygiene (WaSH), social mobilization, treatment, and oral cholera vaccines is essential to control cholera outbreaks and to reduce deaths.

Public Health Response

Emergency response activities are being conducted by the Ministry of Health, WHO and other partners since the declaration of the outbreak in March 2022.

Coordination and response:

  • A costed national cholera response plan has been drafted to manage the outbreak. WHO and other partners are supporting the implementation of various activities aligned with the plan.
  • National and district-level emergency operation centres (EOCs) have been operationalized to coordinate the response in collaboration with other health sectors and partners.

 Surveillance:

  • National rapid response teams (RRT) have been deployed to the affected districts.
  • Surge staff have been deployed and additional staff have been hired to strengthen surveillance and case management in affected districts.
  • Active case search for suspected cholera cases is ongoing in communities in all affected districts. 

Health System Strengthening:

  • Cholera kits and other supplies including oral rehydration salt, IV Fluids, antibiotics, rapid diagnostic test kits, personal protective equipment, tents, and cholera beds have been provided by WHO in affected districts.
  • Supplies for case management and laboratory confirmation of cholera are being distributed to health facilities and the district laboratories although additional supplies are needed.
  • Case management has been strengthened through the establishment of treatment structures and the provision of equipment.
  • Treatment structures have been established in affected districts and private facilities have been engaged to facilitate prompt referrals.
  • Cross-border meetings are held with health officials in Mozambique and Zambia.

Reactive Vaccination Campaigns:

  • As a part of the outbreak response, reactive vaccination campaigns of Oral Cholera Vaccination (OCV) were implemented in eight districts (Balaka, Blantyre, Chikwawa, Nsanje, Mangochi, Mulanje, Machinga, Phalombe) between 23 to 27 May 2022, targeting individuals aged one year and older. Cumulative coverage of 69% was achieved but in Blantyre district the coverage was 42%.
  • In Neno district, two campaigns were implemented in August 2022 with 84% and 72% coverage achieved in each round respectively.
  • The country applied to the International Coordinating Group (ICG) on Vaccine Provision for OCV vaccines and has been awarded 2.9 million doses for use in areas with ongoing outbreaks. Preparations towards a reactive campaign have been initiated.

WHO Risk Assessment

Cholera is endemic in Malawi with seasonal outbreaks occurring during the wet season. The first major outbreak occurred in 1998 and was widespread in the southern region, with 25 000 cases reported. The country reported its largest outbreak occurring from October 2001 to April 2002, which affected 26 of the 29 districts, with 33 546 cases and 968 deaths (CFR 3%). A more recent outbreak occurred in 2019 – 2020 with a total of 26 cases and one death.

Since the beginning of 2022, 27 districts have reported cholera cases. The outbreak was largely confined to the south of the country, including the areas affected by the cyclones until after July 2022, when the outbreak spread to the North of the country resulting in a surge in cases. This upsurge in the number of cases is being reported during the country’s dry season when normally there is low or no transmission of cholera in Malawi. The upcoming rainy season in November poses the threat of further disease spread nationwide.

There is a continued risk for further increases in the number of cases and international spread. Confirmed cases had been reported across the border in Mozambique during the initial period of the current outbreak. In late September, a cholera outbreak was declared in Lago district in Mozambique which borders Malawi (through Lake Malawi). Currently, the most affected districts in Malawi are in the Northern part of the country some of which are on the border with Tanzania and Zambia. There is significant cross-border movement in the region with bordering countries and beyond. Given the history of cross-border spread of cholera during this outbreak, WHO considers the risk of further spread of the disease very high at national and regional level.

WHO Advice

WHO recommends improving access to proper and timely case management of cholera cases, improving access to safe drinking water and sanitation infrastructure, as well as improving infection, prevention, and control in healthcare facilities. These measures along with the promotion of preventive hygiene practices and food safety in affected communities are the most effective means of controlling cholera. Targeted public health communication messages are a key element for a successful campaign.

OCV should be used in conjunction with improvements in water and sanitation to control cholera outbreaks and for prevention in targeted areas known to be at high risk for cholera.

WHO recommends Member States to strengthen and maintain surveillance for cholera, especially at the community level, for the early detection of suspected cases and to provide adequate treatment and prevent its spread. Early and adequate treatment limits the CFR of hospitalized patients to less than 1%.

WHO does not recommend any travel or trade restrictions on Malawi based on the currently available information. However, as the outbreak is taking place in border areas where there is a significant cross-border movement, WHO encourages Malawi and its neighbouring countries to ensure cooperation and regular information sharing so that any spread across the border is quickly contained.

Further Information

Citable reference: World Health Organization (7 November 2022). Disease Outbreak News; Cholera – Malawi. Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON419