What’s Behind the Resurgence of Cholera?

“Everything has to do with geography.”

Judith Marz, American businesswoman, politician, 22^nd governor of Montana

“There are only two reasons to sit in the back row of an airplane: Either you have diarrhea, or you’re anxious to meet people who do.”

Henry Kissinger, political scientist, former United States Secretary of State

According to the Centers for Disease Control and Prevention (CDC), American adults experience about one episode per year of acute diarrhea—defined as loose or watery stools lasting less than two weeks. Cholera is a bacterial diarrheal disease in which patients can produce 10 to 20 loose, watery stools per day losing up to 1 liter of fluid per hour leading to severe dehydration, shock and death within a matter of hours. It is very rare in the US; only 12 cases were reported to the CDC in 2024. But, cholera is the cause of catastrophic illness and death globally.

The world is now witnessing a major resurgence of cholera.  In this week’s post, I provide a brief overview of cholera and discuss why solving the cholera problem is such a challenge.

What is cholera (a recap)? Cholera is a life-threatening diarrheal disease that sickens an estimated 1-4 million people per year and kills between 21,000 to 143,000. It is caused by the toxin-producing gram-negative bacterium Vibrio cholerae.

V. cholerae can be transmitted by consuming contaminated or undercooked seafood, especially shellfish. The most common vehicle of infection, however, is drinking water contaminated with human feces.

Most people who get infected have either mild symptoms or no symptoms. But about 10% of infected people develop severe watery diarrhea—aka “rice water stools” because they are milky white. A patient can lose as much as 1 liter (about 1 quart) of fluid an hour and that can lead to profound, even fatal dehydration if untreated. The mainstay of treatment for cholera is rehydration with water and electrolytes.

The “cholera cot” or “Watten cot” was an important practical innovation in the management of cholera. Developed by Dr. Robert Watten in the 1960s for fluid balance studies, the “cot” revolutionized the management of severe dehydration, the primary cause of death in cholera patients.

The “Watten cot” is an army cot with a hole cut where the patient’s buttocks would lie that has a plastic sheet that funnels a patient’s diarrheal output into a calibrated bucket underneath the cot.  The design allows severely dehydrated and weak patients to expel fluids without getting up, enabling uninterrupted Oral Rehydration Therapy or intravenous drip treatments. It also allows healthcare workers to track what fluid is being lost and to replace those fluids milliliter-for- milliliter intravenously or with Oral Rehydration Solutions thereby keeping patients alive.

The cot is considered an important advance in clinical medicine and public health contributing to  a drop in the cholera mortality rate from over 50% to less than 1%. It is now the standard of care for cholera and is used throughout the world for millions of people with severe diarrhea.

Geography of cholera. Cholera is a disease that primarily affects the world’s poorest people—those lacking access to safe water, adequate sanitation and hygiene facilities. The World Health Organization (WHO) “estimates that at least 2 billion people lack access to safely managed drinking water, more than 3 billion do not have safely managed sanitation, and more than 350 million defecate in the open each day.” (Ryan, E.T, et al. “Global Cholera-Control Efforts—Progress and Remaining Challenges, “ New England Journal of Medicine, June 6, 2026). The global hotspots of cholera are countries throughout much of Africa, the Eastern Mediterranean Region (Yemen, Sudan, and Afghanistan), and South-East Asia (particularly Myanmar).

Globally, cholera cases have been increasing since 2021. The current resurgence, however, is one of the largest seen in decades. The main drivers  are: (1) lack of safe water and sanitation; (2) armed conflict and population displacement; (3) floods, droughts, and other climate-related events; (4) lack of trained health systems; and (5) shortages of oral cholera vaccine.

The WHO describes the current situation as a “global cholera upsurge.” Some key indicators of the upsurge are:

(1)  More countries are affected—60 countries reported cholera in 2024, up from 45 in 2023 with this upward trend continuing in 2025; and

(2)  Cases remain high—more than 614,000 cases and 7,500 deaths were reported in 2025 with deaths rising substantially.

(Munoz, F. M., “Global cholera cases climbed 20% in April, surging more than 56% in Angola,” World Health Organization, June 12, 2026).

Prevention of cholera. Different oral cholera vaccines (OCVs) are available and they play a crucial role in preventing cholera. The choice of a cholera vaccine depends on your location and whether you are traveling to or a resident of an epidemic region.

In the US, the Food and Drug Administration has approved the single dose OCV Vaxchora for people aged 2-64 traveling to areas where cholera is endemic. The WHO has prequalified Shanchol, Dukoral, and Euvichol for mass immunization campaigns as well as for international travel; all three of these OCVs require two doses for full protection. The global supply of OCVs, however, remains a major roadblock to curtailing cholera.

In 2013, GAVI, the Vaccine Alliance, helped to establish and support a global OCV stockpile. According to the above-cited New England Journal of Medicine article, since then the annual global production capacity of OCV has “increased from 4-to-6 million doses per year in 2013-2016 to more than 65 million in 2025.”

In addition, Euvichol-S, a simpler-to-produce version of OCV, achieved WHO prequalification in April 2024 and has been incorporated into the stockpile supply. (“EuBiologics’ simplified OCV achieves, WHO PQ, International Vaccine Institute, April 15, 2024). It improved productivity by about 40% over the existing Euvichol-plus™ by modifying the formulation and manufacturing method of the original vaccine material. As Dr. Julia Lynch, Director of the International Vaccine Institute said:  “The addition of Euvichol-S to the global heath market will contribute to easing the shortage of OCV supply amid a dire global cholera situation.”

Incorporation of OCVs into global cholera-control strategies has been transformative. “[M]ore than 250 million doses have been shipped to 37 countries, averting an estimated 8 million cholera cases and more than 100,000 deaths.”

In many outbreak settings, vaccination acts as a crucial emergency measure. But the underlying drivers of the disease—unsafe water, poor sanitation, conflict, and humanitarian crises—remain.

The long-term control of cholera depends on global access to safe water and adequate sanitation. A conservative estimate is that at least 2 billion humans will need new access to safe water over the next few decades. And the World Bank estimates that investments of $1.4 trillion would be required to meet WHO Sustainable Development Goals for water and sanitation by 2030.

The challenges to controlling cholera seem insurmountable. But, human ingenuity has solved many seemingly insurmountable problems in the past. It can do so again.