Hope in the hotspots – how local research is turning the tide against cholera

“Children should be able to play in the rain after school without risking a life-threatening disease,” says Professor Sam Kariuki, Director of the Drugs for Neglected Diseases initiative (DNDi) Eastern Africa and Senior Scientist at the Kenya Medical Research Institute (KEMRI). 

In informal settlements, lack of sanitation and hygiene infrastructure means there are water pools on the ground and open drainage overflows – creating the perfect breeding ground for cholera.  

To stop this we have to understand how the disease spreads. Working with affected communities in informal settlements near Nairobi, Kenya, Kariuki and his team are exploring what makes cholera outbreaks more likely. 

By tracking the communities' activities and the number of cholera cases being reported at the health clinic where they carry out their research, the team found hotspots of infection. When children leave school, they play in contaminated surface water. Adults eat street food washed in contaminated water and stored in open markets. And just like that, they are infected by the water-borne bacteria.  

Despite the disease being both treatable and preventable, cholera deaths doubled from 2023 to 2024, with cases rising by 5%. With 60 countries reporting cases in 2024, cholera continues to be a major global health crisis. 

“Action is needed, and needed now,” Kariuki says. “The communities where cholera is most prevalent are those of poverty, those torn apart by conflict or extreme weather, those where even the municipal water sources are contaminated with the bacteria.” 

What makes cholera so deadly is its speed. Within days or even hours of infection, people can become so dehydrated that their bodies begin to shut down if left untreated.  

The most effective way to prevent cholera is through clean water, sanitation and hygiene – often the first piece of the puzzle to fall during conflict or extreme weather events. This means some of the simplest solutions, such as improving sanitation infrastructure, can prevent cholera spread. 

For example, when Kariuki and his team shared the finding that one source of infection was the leaky drains contaminating water, local councils and public health officials were able to construct concrete-sided drains to prevent leakage.  

The team also found that, while communities were collecting clean water from the communal supply, it was becoming contaminated when stored in large open containers at home. So they designed a straightforward solution – a simple household storage container made from a jerry can with a tap at the bottom which prevented the bacteria from getting into the water. 

Similarly, providing street food vendors with clean storage containers for their ingredients and information on hygienic food storage and preparation has helped reduce infections in adults. 

While infrastructure and tools can solve the environmental causes of cholera spread, one of the most effective ways to change behaviours is education. 

Kariuki’s team found that two of the most effective ways to share health information were through school children and religious leaders.  

“We saw that when children are told to wash their hands or clean storage containers, they go home and tell their parents about it. The parents then come into our cholera clinic asking about this advice, and our healthcare workers can talk to them about how these actions can help prevent disease spread in their communities,” explains Kariuki. 

Similarly, religious leaders can educate their congregation on the benefits of hygiene practices and oral cholera vaccines. Receiving the message through a trusted source like the church meant they were more likely to accept the vaccine during a reactive vaccination campaign.  

Understanding where a cholera outbreak came from is essential to preventing further transmission. If you know where the sources of infection are, you can vaccinate people in that area, particularly the most vulnerable, to protect them from the disease and reduce the scale of the outbreak. 

This mapping is even more important when vaccines are limited, as with the oral cholera vaccine where there is a global shortage. Using the supply in the best way can be the difference between a few infections and a severe, deadly outbreak.  

This is why over the years, Kariuki and his team have mapped areas with high incidence of cholera, known as hotspots. These hotspots include places where drains leak or surface water pools.  

So, when an outbreak began in Kenya in May 2022, the Ministry of Health deployed nearly two million oral vaccine doses to these hotspots and neighbouring communities to protect those at highest risk of infection.  

Vaccination during outbreaks can provide protection for up to five years, potentially protecting against future outbreaks too. 

The reactive vaccination campaign in 2022 and 2023, combined with interventions to improve water, sanitation and hygiene, have helped to curb cholera cases in Nairobi. Kariuki’s team are now only seeing sporadic cases of cholera at the health clinic.  

But the vaccine doesn’t offer full protection for all age groups, and the protection wanes. Whether we’re talking about vaccines or improved infrastructure, there is no single solution. We must take a holistic view if we want to tackle cholera on a global scale. By carrying out research in affected communities, understanding how diseases spread as part of day-to-day life, and who is most at risk, we can create long-term, context-specific solutions – preventing infection and deaths from a preventable disease. 

“In the short-term, the most effective intervention to prevent cholera outbreaks and protect the most vulnerable people is vaccines,” explains Kariuki “But to address the root causes of outbreaks and prevent them in the long-term, improving water sanitation and hygiene infrastructure and practices is vital.”