Cholera - Malawi

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 cases

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. 

Epidemiology of Cholera

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.