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Innovation: Fighting dengue with mosquitos in Honduras

31 Oct 24 | 14 Nov 24

Innovation: Fighting dengue with mosquitos in Honduras

Teresa Arteaga, with Lorena Rodriguez, MSF health promotion supervisor, participate in the release of Wolbachia-carrying mosquitoes in the community of Canaan. Caption
Teresa Arteaga, with Lorena Rodriguez, MSF health promotion supervisor, participate in the release of Wolbachia-carrying mosquitoes in the community of Canaan.

Promising results from deadly disease study has researchers and patients buzzing.

The sky over El Manchén is as blue as ever. This suburb of Honduras’ capital city Tegucigalpa is still bustling, with people jostling to get to work and cars honking in the heavy traffic. To the naked eye, this densely populated area seems much like it did a year ago. 

But one Médecins Sans Frontières / Doctors Without Borders (MSF) team has been working hard to make a microscopic change that could save lives.

A recent test found that eight out of 10 mosquitos caught in El Manchén carry Wolbachia, a harmless bacteria that’s found in over 50 percent of insects. One year ago, almost none of the local mosquitos carried the bacteria. 

This matters, because Wolbachia dramatically reduces the likelihood that mosquitos will transmit diseases like dengue fever, a potentially deadly disease which affects an estimated 100 to 400 million people worldwide each year. El Manchén has seen some of the highest rates of dengue in the city.

The team at the MSF Arbovirus Prevention Project released over eight million mosquitos deliberately infected with the bacteria in El Manchén last year. Their hope was that the mosquitos would thrive, reproducing and passing Wolbachia down through the generations, radically reducing the rate of dengue in the area.

READ THE FIRST CHAPTER OF THE PROJECT

At MSF's out-patient department in Batil refugee camp Gandhi Pant, a nurse, escorts a patient with a possible appendicitis to a waiting ambulance. 

Batil is one of three camps in South Sudan’s Upper Nile State sheltering at least 113,000 refugees who have crossed the border from Blue Nile state to escape fighting between the Sudanese Armed Forces and the SPLM-North armed group. Refugees arrive at the camp with harrowing stories of being bombed out of their homes, or having their villages burned. The camps into which they have poured are on a vast floodplain, leaving many tents flooded and refugees vulnerable to disease. Mortality rates in Batil camp are at emergency levels, malnutrition rates are more than five times above emergency thresholds, and diarrhea and malarial cases are rising.

Help us prepare for the next emergency

Each releaser carried 20 jars containing the Wolbachia-carrying mosquitoes. Daily releases were carried out for six months. In total, more than eight million mosquitoes were released. Caption
Each releaser carried 20 jars containing the Wolbachia-carrying mosquitoes. Daily releases were carried out for six months. In total, more than eight million mosquitoes were released.
Teresa Arteaga is a neighbor of colonia Canaán. Here she curiously observes the Wolbachia-carrying mosquitoes that will be released in her community. Caption
Teresa Arteaga is a neighbor of colonia Canaán. Here she curiously observes the Wolbachia-carrying mosquitoes that will be released in her community.

However, there was a lot that could go wrong. 

“As we continued to release mosquitos, this meant there were more and more of them in the area, which caused distress to the local communities,” said Edgard Boquín, coordinator of the project. 

“At the same time, another dengue epidemic broke out in the capital. This made it more difficult to approach people about dengue, but by engaging them directly in the activities, we were able to do everything as planned.

“We’ve been working in partnership with local communities, Honduran health authorities, the National Autonomous University of Honduras (UNAH) and the World Mosquito Program (WMP). It’s been a real team effort! 

“This is the first time that MSF and the WMP have worked together on arbovirus prevention like dengue. Our strength in community involvement and the WMP's technical expertise complemented each other to make this a reality.”

The team used motorcycles as part of its strategy to release Wolbachia-carrying mosquitoes in El Manchén. Caption
The team used motorcycles as part of its strategy to release Wolbachia-carrying mosquitoes in El Manchén.
Each releaser carried 20 jars containing the Wolbachia-carrying mosquitoes. Daily releases were carried out for six months. In total, more than 8 million mosquitoes were released. Caption
Each releaser carried 20 jars containing the Wolbachia-carrying mosquitoes. Daily releases were carried out for six months. In total, more than 8 million mosquitoes were released.

So has it worked?

El Manchén previously had among the highest rates of dengue fever in Tegucigalpa. However, in the past year there have been fewer cases than in previous years, and lower rates compared to other areas of the city. 

“It’s still too early to claim victory,” Boquín says cautiously. 

“We tested 294 mosquitos in September, and we were really pleased that 85.7 percent were carriers of Wolbachia. However, these are preliminary results. In the first quarter of 2025, definitive tests will be carried out that will tell us to what extent this strategy has served to reduce the impact of dengue in El Manchén”.

Cindy Dueñas, MSF lab technician, works on the process of combining enzymes for PCR reading to determine if Wolbachia is present in Aedes aegypti mosquitoes. Caption
Cindy Dueñas, MSF lab technician, works on the process of combining enzymes for PCR reading to determine if Wolbachia is present in Aedes aegypti mosquitoes.

Although he’s careful about showing too much excitement too soon, Boquín is hopeful. “This is undoubtedly promising,” he says, with a smile of satisfaction. 

“If we continue this path, the Wolbachia method will be a positive tool to reduce dengue in the country. 

“For a long time we have seen how people have suffered from dengue but now we hear positive stories from the community that something is changing after the Wolbachia release; this gives hope to those who has experienced dengue or has seen someone close to them get sick.”

MSF in Honduras

We first worked in Honduras in 1974. Today, we provide healthcare to migrants and marginalised groups, including survivors of sexual violence, sex workers and members of the LGBTQIA community.