MSF has been responding to dengue outbreaks in Honduras since 1998. These are growing increasingly severe, with emergency thresholds reaching alarming levels and more than 10,000 dengue cases reported each year.  Honduras, 2023. © Martín Cálix © Martín Cálix

Fighting dengue with mosquitoes:  buzzing innovation to protect people from deadly disease

To combat a rapidly growing public health crisis in Honduras, Doctors Without Borders/Médecins Sans Frontières (MSF) is working closely with local communities and health authorities to prevent dengue and other viruses transmitted by mosquitoes.

MSF, the Honduran Ministry of Health, the World Mosquito Program, and the National Autonomous University of Honduras are partnering with local communities to implement innovative public health strategies to reduce illness from arboviruses such as dengue, zika and chikungunya.

Dengue is a public health crisis in Honduras and the wider region of the Americas. 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.

Mosquitoes have four stages in their life cycle: egg, larvae, pupa, and adult. Here you can see hundreds of larvae that in the next few days will become adults to be released. Honduras, 2023. © Laura Aceituno/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.  

In Honduras, outbreaks are growing increasingly severe with more than 10,000 dengue cases reported each year. “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 The use of outdated vector control techniques has also led to mosquitoes becoming resistant to current prevention methods and pesticide products.

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.

“When the mosquitoes carry Wolbachia, the bacteria compete with viruses like dengue, making it harder for viruses to reproduce inside the mosquitoes. 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,” says Claire Dorion, MSF technical adviser.

MSF together with the Ministry of Health began the first releases of the mosquitoes with Wolbachia in one of the intervention areas in Tegucigalpa. Honduras, 2023. © Laura Aceituno/MSF

The World Mosquito Program’s Wolbachia method is safe for humans and the environment and has been successfully deployed in more than 1 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 neighbourhoods 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.

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 release of the adult mosquitoes with Wolbachia consists of the MSF team going by motorcycle to different points in the intervention area for six months. Honduras, 2023. © Laura Aceituno/MSF

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