Recent surge in cholera outbreaks globally during the COVID-19 pandemic era: a potential threat to the African continent and salient counteracting strategies

Dear Editor:

Cholera is caused by the pathogenic bacterium Vibrio cholerae (V. cholerae) of serogroup O1. Cholera is one of the oldest infectious diseases known to human civilisation that affect annually between one and four million people with 21 000–143 000 deaths worldwide. Cholera exists as an endemic disease in around 47 less developed countries, mainly in Africa, South and South-East Asia1. It is outbreaks are rare in developed countries, however, cholera importation from endemic or epidemic to cholera-free nations by travellers have happened2,3. Primarily associated with poor sanitation and the lack of access to clean potable water, it is caused by ingesting water and/or food contaminated with V. cholerae, resulting in acute intestinal infection. A highly contagious illness that could cause severe acute watery diarrhoea (AWD) with significant morbidity and mortality, its contagiousness is dependent on the frequency of exposure, the population exposed, and other environmental factors. Humanitarian crises like a disrupted sanitation system and the lack of access to clean potable water, or displacing the population to overcrowded and inadequately organised camps as a disaster management measure, could elevate the risk of cholera transmission. One of the effective strategies to achieve global targets for cholera control could be to tailored cholera prevention and control programmes specific to local epidemiological factors, as a comprehensive systematic description over vast geographies is still lacking4.

The incubation period of cholera varies between 12 h to 5 days after consuming the contaminated water or food. V. cholerae bacteria persist in the faeces of an infected individual for 1–10 days after infection and are released into the environment, where they might infect others. More critically, the majority of the infected population does not demonstrate discernible symptoms. Most others exhibit mild or moderate symptoms, while only a small percentage show AWD and severe dehydration. The majority of such patients are successfully treated by timely administering oral rehydration solution (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON398_1).

Repeated cholera outbreaks have been documented in Somalia since 2017. During the past year (2022), 25 drought-affected districts recorded a total of 7796 cholera cases between 1 January 2022 and 10 July 2022, along with 37 related deaths (case fatality ratio: 0.5%). This ongoing endemic began after the flash floods of 2021. The males and females were equally affected, while more than half of the cases (53.5%) were in children under 2 years old, and severe dehydration was recorded in 27% of the patients. Interestingly, none of the affected cases had received the oral cholera vaccine. Oral cholera vaccine campaigns in Somalia were carried out in 2017, 2018 and 2019. With a total of 6205 AWD or suspected cholera cases and 39 deaths (CFR-case fatality ratio: 0.63%), there were more reported cases in the first half of 2022 than there were in all of 2021 in the drought-affected regions of Somalia (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON398_1). The prevailing cholera outbreak is more critical as it occurs in the background of other ongoing outbreaks, high malnutrition rates and a growing drought, all of which put additional pressure on the already overburdened and underperforming healthcare system. At the moment, the escalating vulnerability of Somalia’s humanitarian situation and the country’s inadequacy to respond to the outbreak raise the possibility of negative public health effects (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON398_1).

Not only in Somalia, but cholera outbreaks have also been documented in other countries like Iraq, Syria, Haiti, Lebanon and Malawi (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON415; https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON416; https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON419)5. Recently, cholera cases, geographical distribution, and associated deaths have increased worldwide after years of decline. In 2021, 23 countries reported cholera outbreaks, mainly in the WHO Regions of Africa and the Eastern Mediterranean, and over 29 countries reported cholera cases or outbreaks in 2022; of these, 16 countries particularly reported prolonged outbreaks as of 30 November 2022 (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON426). The average CFR reported in 2021 was 1.9% at the global level and 2.9% in Africa, well above the acceptable level of less than 1% and the highest recorded in over a decade. The present situation of resurgence in cholera points toward its ongoing seventh pandemic which began in 1961 (https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON426).

Cholera treatment largely depends on fluid replacement and antibiotic administration. V. cholerae can freely survive in the environment, within fish, crustaceans and algae6. Thus, it is increasingly difficult for public health experts to predict possible outbreaks. V. cholerae strains from Siberia and the Far East of Russia showed multidrug resistance7. It further complicates cholera management, especially during outbreaks. Oral rehydration therapy is associated with its own complications8. A ligand (metanitrophenyl α-galactoside) based therapy that effectively neutralises the cholera toxin was proposed9. Potential use of the bacterial subunit toxins for therapy has been found effective in controlling cholera in experimental animals, which may call for confirmatory studies for their human efficacy10.

A cholera outbreak could be controlled or minimised by limiting human-to-human transmission using effective quarantine protocols. While such a measure is effective, however, it affects national economic growth due to restricted human movement11. Further, war, conflicts and natural calamities combined with the shortage of vaccine could worsen the situation12. Water sanitation and hygiene were effective in controlling the cholera outbreak in Yemen13. Rehydration therapy reversed the condition, as noted in a recent study of an outbreak in India (Bengaluru), where acute kidney injury in the form of focal glomerulonecrosis/tubular necrosis and proteinuria was prevalent among the patients14.

In light of the ongoing response efforts, strengthening rapid response measures is vital. Setting up a state-of-the-art cholera response strategy could help simplify the coordination of the cholera response. At this stage, identifying and reporting alerts in necessary for carrying out risk mitigation, and deploying more rapid response teams and community healthcare workers at the district level is also necessary. Clinical management of cholera cases by frontline healthcare professionals and kits for cholera prevention need to be enhanced. Creating oral rehydration points in affected areas and establishing a connection between oral rehydration points and Cholera Treatment Centres could help mitigate (https://www.unicef.org/somalia/press-releases/stepping-humanitarian-operations-drought). Escalating drought conditions in the Horn of Africa caused extensive cross-border migration of population between Somalia and neighbouring countries, particularly to Ethiopia, Kenya, Djibouti and Yemen. Issues of limited access to clean water, adequate sanitation and food are also seen in these nations and may contribute to the spread of diarrhoea, particularly among the displaced populations.

Considering the recent surge in cholera cases during 2021–2022, the risk of international spread of the outbreaks looms large, therefore, it is high time for exploring advanced diagnostics, enhancing surveillance, developing efficacious vaccines and drugs, and adopting adequate mitigation measures which would aid in achieving the global mission of controlling cholera outbreaks and incidences. Of note, cholera transmission and retransmission across the borders of different countries across the globe necessitate the strengthening of health systems and enhanced vigilance at the point of entry to prevent its further spread. There is need for promoting vaccination coverage, tackling the current situation of short supplies of cholera vaccines, addressing emerging microbial drug resistance, following appropriate sanitation and hygiene, facilitating safer water supplies, avoiding drinking water contamination with sewage and wastewater, and designing proactive prevention and control measures and advanced preparedness plans to counteract cholera at the global level1,5,15–17. The WHO launched a global strategy in 2017 to end cholera by 2030, and considering the recent rise in cases globally, we need to adopt adequate infection prevention and control strategies and increase awareness to counteract cholera.

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This article does not require any human or animal subjects to acquire such approval.

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No funding received.

Author contribution

R.K.M.: conceptualised, writing – review and editing. L.V.S.K. and L.S.T.: made the initial draft. V.K. and S.M.: updated the manuscript. V.K.: writing – review and editing. All authors have critically reviewed and approved the final draft and are responsible for the content and similarity index of the manuscript.

Conflicts of interest disclosure

No conflicts to declare.

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Data not available/not applicable.