Fighting dengue with mosquitoes

Buzzing innovation to protect people from deadly disease

A gloved lab technician is holding a covered jar full of mosquitos, obscuring their face.

Honduras 2023 © Martín Cálix/MSF

Tegucigalpa, Honduras—To prevent dengue and other viruses transmitted by mosquitoes, Doctors Without Borders/Médecins Sans Frontières (MSF) and local health partners in Honduras are conducting a trial in which mosquitoes carrying the natural Wolbachia bacteria will be released, with the aim of reducing the mosquitoes’ ability to transmit arboviruses such as dengue, zika and chikunguya.

When mosquitoes carry Wolbachia, the bacteria compete with viruses like dengue, making it harder for viruses to reproduce inside the mosquitoes,” says Claire Dorion, MSF technical adviser. “This means that mosquitoes are much less likely to spread viruses from person to person, reducing dengue fever in an area where Wolbachia is established in the local mosquito population.

The trial is one component of a partnership between MSF, the Honduran Ministry of Health, the World Mosquito Program, and the National Autonomous University of Honduras and local communities to implement innovative public health strategies to reduce illness from arboviruses.

Two men stand outside looking at a stack of jars.
The Minister of Health, José Matheu, visited the MSF insectary to learn first-hand about the process of breeding the Wolbachia mosquitoes.
Honduras 2023 © Martín Cálix/MSF

Dengue is a viral infection transmitted through the bite of infected mosquitoes. It is mostly found in urban areas in tropical climates. Symptoms include fever, headache, body aches and nausea. People suffering from severe dengue need care in a hospital and it can be fatal.  

Dengue, in particular, is a public health crisis in Honduras and the Americas. In Honduras, outbreaks are growing increasingly severe with more than 10,000 dengue cases reported each year.

It is also an important global health threat and is rapidly spreading with reported incidence increasing 30-fold over the past 50 years. Today, more than half the world’s population is at risk, and it is expected that another billion people will be exposed to dengue fever in coming decades due to climate change.

“Emergency thresholds are reaching alarming levels and current prevention methods fall short of protecting people from dengue,” says Edgard Boquin, MSF project coordinator in Honduras. No specific treatments are currently available, and no vaccines have yet been produced that provide sufficient protection against infection. The use of outdated vector control techniques has also led to mosquitoes becoming resistant to current prevention methods and pesticide products.

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A man and boy look at a jar of mosquitoes to release as part of an MSF project to prevent dengue in Honduras

With the aim of finding better and more sustainable solutions, MSF and its Honduran partners decided to trial prevention methods that have not been used in Honduras before, but that have proven effective in other countries with high levels of dengue. This includes releasing Aedes aegypti mosquitoes carrying the natural Wolbachia bacteria, which reduces mosquitoes’ ability to transmit arboviruses.

The World Mosquito Program’s Wolbachia method is safe for humans and the environment and has been successfully deployed in more than 12 countries, reaching some 10 million people. Evidence shows that virus transmission is significantly reduced in areas where Wolbachia is maintained at a high level.

MSF has been working closely with local communities to design, prepare and implement all activities, which will be carried out in 50 neighborhoods in El Manchén health district, where some of the highest rates of mosquito-borne diseases are present in Tegucigalpa. MSF teams consulted with more than 10,000 community members in the area before starting activities. Ninety-seven per cent of people consulted support the plans, and many are actively involved in carrying out the mosquito release.

A man is standing in an outdoor tropical setting, smiling, pointing to an open wooden shed full of jars with mosquitos.
Walter Bryan, a volunteer from the community, put the bottles of mosquitos with Wolbachia in a place without direct sun and out of the reach of children or pets.
Honduras © Martín Cálix/MSF

Mosquitoes carrying Wolbachia will be released on a weekly basis for a period of six months. During a three-year period, tests will be carried out on the mosquito population to determine the percentage of Wolbachia mosquitoes.   

In 2024, additional vector-control activities will be carried out in two other areas of the capital to reduce transmission inside people’s homes. 

“The first objective is to reduce death and illness caused by dengue and other arboviruses,” says Boquin. “In the long term, we hope these new methods can become sustainable solutions to prevent people suffering from these illnesses. We have witnessed first-hand the challenges of implementing public policies and good vector-control practices to reduce dengue transmission in Honduras. It is time for a change.”

MSF first worked in Honduras in 1974 and has been responding to dengue in the country since 1998, providing patient care and working to prevent disease transmission in Tegucigalpa.