New prawn project targets snails threatening health and harvests in Kenya

Mwea’s rice fields are not only feeding households but also sustaining communities that have lived with two silent dangers.

One is schistosomiasis, or bilharzia, a parasitic disease that affects more than 200 million people worldwide and remains a serious health problem in Kenya, especially for children.

The other is an invasive species, the golden apple snail, which has been eating away at rice crops since it appeared in Mwea about five years ago.

A team of scientists from Israel’s Ben Gurion University and the Ministry of Agriculture, together with the Kenya Medical Research Institute (KEMRI), has begun pilot testing a novel solution.

They are introducing freshwater prawns to rice paddies in Mwea to act as natural predators of the snails.

The prawns could help break the cycle of bilharzia transmission while at the same time saving rice fields from destruction.

Dr Geoffrey Maina, a principal laboratory analyst at KEMRI, explained that schistosomiasis remains one of Kenya’s most neglected tropical diseases.

“Traditionally, we have relied on mass drug administration using praziquantel, but it is a vicious cycle. Children are treated, then go back to infested waters and catch the infection again,” he said.

He added that reliance on donor-funded drugs is becoming less sustainable, especially after COVID-19 disrupted supply chains.

The snails pose another danger. Apart from carrying parasites that transmit bilharzia, the invasive apple snail is also linked to rat lungworm, a nematode that can cause meningitis in humans.

“We are engaging clinicians in rice-growing areas to be on the lookout for eosinophilic meningitis. It is an emerging condition that could become a serious health concern,” Dr Maina said.

The damage to rice production is already visible. As Kenya’s third most important staple food, rice is under threat, with invasive snails cutting yields.

Surveys in Mwea have recorded infestations of up to 200 snails per square metre at peak season, leading to crop losses of around 16 per cent.

Bernard Maina, a rice farmer in Mwea, described the struggle. “Whenever you plant the rice, the snails invade at the seedling stage. You can end up with nothing. We have tried spraying with chemicals like Duduz and Ranger, but they do nothing when the fields are wet,” he said.

Farmers also spend hours handpicking snails instead of tending to other work.

The heavy use of agrochemicals is adding to the burden. According to KEMRI scientists, the residues not only contaminate water and soil but may also contribute to rising cases of cancer in the region.

The Israeli–Kenyan project aims to change this trajectory. Professor Amir Sagi, a leading aquaculture scientist at Ben Gurion University, explained how prawns offer a safe biological control.

“The prawns are voracious predators of freshwater snails. They can eat dozens of juvenile snails within minutes. By targeting the snails, they interrupt the life cycle of bilharzia and protect rice plants at their most vulnerable stage,” he said.

To prevent prawns themselves from becoming invasive, the team has developed monosex populations.

“They cannot reproduce in these waters. Their life cycle ends after about eight months, so they are self-limiting and safe for the environment,” Professor Sagi added.

Dr Amit Savaya from Israel’s Ministry of Agriculture said this is the first time the method is being tested in rice fields.

“We hope to begin with small plots as proof of concept. If it works, we can expand to other rice growing regions in Kenya and beyond. It is a win-win: protecting human health and food security, while also offering prawns as a future protein source,” he said.

The Embassy of Israel views the project as part of its wider commitment to development cooperation.

Stellah Wakesho from the embassy said, “We are proud to bring this partnership to life. It showcases the spirit of Mashav, which is about sharing Israeli knowledge, technology and innovation with the world through local partnerships for sustainable development.”

Scaling up is already being discussed. Beyond Kenya, the embassy is engaging partners in Uganda, Tanzania, Malawi and Seychelles, where rice pests and bilharzia remain pressing challenges.

The work is still at an early stage, but the promise is significant. If the pilot succeeds, it could reduce bilharzia cases, lessen the need for harmful chemicals, and restore rice yields for farmers in Mwea.

Farmers in Mwea say their hope rests on the project showing results. “If these prawns can clear the snails better than chemicals, it will help us and our children. We are waiting to see what happens,” Bernard said.