Dirty water and endless wars: why cholera outbreaks are on the rise again

The number of cases globally has surged since 2021, as war and the climate crisis pile pressure on vaccine supplies

Cholera, the scourge of the Victorian era, is staging a comeback fuelled by conflict and climate breakdown. In 2024, there were 804,721 cholera cases and 5,805 deaths, according to the World Health Organization, a near 50% increase from the 535,321 cases and 4,007 deaths in 2023. Numbers have been surging since 2021 and scientists say official figures are probably very conservative. They estimate between 1.3m and 4m cases, and a range of 21,000 to 143,000 deaths from cholera globally each year.

Already in 2025, six countries – Myanmar, the Democratic Republic of the Congo, Sudan, South Sudan, Angola and Ghana – have requested doses from the global stockpile of cholera vaccines to help contain outbreaks.

The stockpile is supposed to hold 5m doses, but a flood of requests, and reliance on a single supplier of cholera vaccines, left it totally depleted at some points in 2024. The high demand for emergency supplies has meant no preventive vaccine drives in high-risk countries since 2022.

Inside a cholera ward

The scene at a cholera treatment unit (CTU) in Gurei, on the outskirts of the South Sudanese capital, Juba, is typical. At the doorway of a large tent, staff wearing full protective gear spray the feet of anyone willing to enter. Inside, everything is white and the smell of chlorine is in the air. The unit can accommodate 10 cholera patients on two rows of beds made of plastic material with a hole pierced in the middle, to enable the sick to relieve themselves into buckets placed underneath.

People get cholera after exposure to a bacteria, usually by drinking contaminated water. Sufferers develop acute, watery diarrhoea. The first line of treatment is rehydration salts, dissolved in water for patients to drink. Some severe cases will need IV fluids, and antibiotics can be given to curtail the illness and limit symptoms.

The Gurei CTU was set up by Médecins Sans Frontières (MSF) last November and needed to double its capacity in mid-January. Guta Epulo, the nurse activities manager overseeing the unit, says 217 people have been treated successfully, with no deaths: “But deaths have been reported in the community.”

People fleeing the war in Sudan into South Sudan brought cholera into overcrowded camps, where poor sanitation and lack of access to clean water led to the disease spreading rapidly. As people from South Sudan returned home across the country, cholera moved with them, and seven out of 10 states have been affected.

Saber Juma, 33, from Jebel Timan, developed cholera symptoms the day after his wife, Hawati Ajong, 27, had recovered and been discharged from the CTU.

“In the morning, he was about to go to work. He took tea, and then he went to the bathroom three times,” she says. “Then he started vomiting and couldn’t move.”

After two days of care, he is being discharged and will return to work picking through rubbish, which is “the only way I can get money”, he says. Many people in Jebel Timan believe the nearby dump is the source of the cholera outbreak, although Ajong highlighted the lack of clean water.

“We are drinking the water from a well dug in the ground. I think the problem is coming from this water,” she says.

Albino Diari Wornyang, 39, a pastor in Jebel Timani, lost his stepbrother to cholera on 13 January. “It started at 3am, and he died at 3pm,” he says.

Vaccination seems to be bringing the outbreak under control in South Sudan, he says, but he is still worried. There is only one privately owned borehole serving several thousand people, and filling a 20-litre jerry can costs 1,500 SSP (about 25p). Alternatively, people can fetch water from a dug well, for 500 SSP, but it’s not entirely fenced and animals may come and drink there if no one is there to chase them away. The only free option is the unsafe water from the stream.

Vaccine shortages

Africa Centres for Disease Control and Prevention (Africa CDC) highlighted cholera as a significant killer on the continent during a January 2025 briefing. Chief of staff, Prof Ngashi Ngongo, says outbreaks frequently resulted in high death rates because of “the weak health system with the quality of care and the lack of the key supplies that are needed to provide quality care”.

He says the drivers are increased flooding related to the climate crisis, combined with poor water and sanitation conditions.

Ngongo also says a lack of cholera vaccines in Africa is a key challenge, adding that Africa CDC wants to accelerate plans to manufacture them on the continent.

Allyson Russell, an epidemiologist and a senior programme manager in the high impact outbreaks team at Gavi, the vaccine alliance responsible for the global stockpile, says supply is “in a better place now than we were a few years ago”.

A rise in cases since 2022 has “put a lot of strain on health systems, health workers, vaccine, supply, everything”, she says, adding: “We started off the year with the stockpile full.”

It can also now be fully replenished in three or four weeks, she says, down from two months last year.

EuBiologics in South Korea is the only company supplying the stockpile. It is now making a simplified version of its cholera vaccine, approved by the WHO in 2024, and has increased manufacturing capacity. “The combination of those two things has really increased the production. Last year, we delivered 40m doses for 40 million people, which is the highest number ever. This year, we’re aiming to have about 70 million,” Russell says.

Russell stresses the importance of clean water and sanitation as the first line of defence, but adds: “It’s very hard to control cholera when you’re in the middle of a war, when there’s conflict, people are moving … That’s where vaccines can be most helpful.”

Sami Ahmed, 35, is one of hundreds of cholera survivors in Sawakin, in eastern Sudan, where he fled from his home in Omdurman, the twin city of Khartoum. Some relatives, also displaced by conflict, lost their children in the rainy season cholera outbreak last August.

“Almost in every household somebody had cholera in Sawakin … for the first time in my life I had it, I lost 40kg of my weight,” he says.

An influx of people displaced by the civil war, coupled with limited toilets, has meant people in Sawakin being forced to defecate in the open.

A bad smell pervades the city and in September Ahmed says armies of flies attacked it and Port Sudan, the de facto capital since the outbreak of war. “It was unbearable and I have never experienced such a thing in my life,” he says.

Rapid testing and preventative campaigns

New rapid tests for cholera, which provide answers in about 15 minutes, are being introduced by Gavi to 14 low and middle income countries, and experts say they should give a clearer picture of where to focus control efforts.

Gavi has also launched a plan to create a stable cholera vaccine supply, including preventive vaccination campaigns in vulnerable regions that should create confirmed and predictable demand.

“It doesn’t make it very attractive for manufacturers if we don’t know [for] next year [or] especially in five years: how many vaccines do we need? What kind of manufacturing facility should be set up to support that?” Russell says. She adds that three high-priority countries – Bangladesh, DRC and Mozambique – have been approved for roll out when supplies allow.

Prof Jan Holmgren of the University of Gothenburg led the team that developed the first WHO approved oral cholera vaccine, Dukoral, in the 1990s. In recent years he has repeatedly said that a shortage of vaccine is “the most acute threat” to WHO’s aim of ending cholera by 2030.

Amid shortages in October 2022, the International Coordinating Group (ICG), which manages the oral cholera vaccine emergency stockpile, announced that it could be used as a single dose vaccine, rather than two doses about two weeks apart.

For Holmgren, the decision was “a step of despair”. While there is evidence that, in people who may have been previously exposed to cholera, a single dose can work as a form of booster jab, “younger children would absolutely need two doses in order to be protected”, he says. Early trials in Bangladesh have shown that a single dose given to under-fives has no protective effect.

Holmgren adds: “And if you also take this approach to populations which have not seen cholera frequently in the past, then one can assume that they will behave as young children in Bangladesh and not be protected by a single dose vaccine. So it’s obviously a risky approach.”

Russell says the evidence so far is that the approach is proving effective at reducing spread of the disease in emergency settings, because it created herd immunity.

Preventive vaccination campaigns will remain at two doses, however. “We know that this gives a longer protection, and that’s really the goal, especially in these endemic areas.”

This story originally appeared on The Guardian.