BROOKLYN, United States —Â “My brother’s friend had dengue fever,” Sengsouly Phaiboun, a young Lao woman, told the World Mosquito Project. “He went to the hospital. After that, he died.”
In 2024, Laos experienced 20,000 recorded cases of dengue. Dengue is a mosquito-borne disease that induces a high fever, joint pain, skin rashes, vomiting and muscle aches. While usually treatable, it can be deadly. Laos saw 11 dengue-related deaths in 2024.
Two years earlier in 2022, the World Mosquito Project collaborated with Save the Children Laos to begin the Driving Down Dengue in Laos project, known as DDDiL, or Welcome Wolbachia. The project had seen success in Brazil, Peru and Colombia. In Laos, it received support and funding from the Australian Government, the Laos Department of Communicable Disease Control, the Laos Ministry of Health and the Laotian government.
Having increased productivity in recent years, the Laos DDDiL project reached more than 1.5 million people in 2025 across and beyond Vientiane. The initiative recently expanded into four new provinces in 2026. Community members reported a 99% acceptance rating in 2023, demonstrating Welcome Wolbachia’s success in reducing the prevalence of dengue in Laos.
Laotian Poverty
Laos is considered one of the poorest countries in Asia, with an annual income of only $2,000. Its impoverishment is characterized by poorly maintained infrastructure and a reliance on river-based travel. Humid waters are a common breeding ground for mosquito populations.
Within the country, the overall poverty rate sits at 15%, with most of that percentage in rural areas. Urban poverty is 8.9%. While poverty levels in Laos have dropped steadily since the 1990s, access to basic services like health care has mostly remained stagnant.
Additionally, poverty remains concentrated among people with little education, meaning those who are least equipped to prevent the spread of dengue have the least access to health care. These impoverished areas thus become hotspots due to a lack of intentional caretaking.
Laos DDDiL project volunteers work to target these hotspots—not with the intention of helping the poor specifically, but because they tend to be where infectious mosquitoes are most abundant.
Mosquito-Borne Diseases in Poor Populations
A 2025 study from Kampala International University Uganda maps the distribution of mosquito-borne illnesses, specifically malaria, across socioeconomic status.
It shows that poorer populations, especially those in developing nations, tend to live in homes that are not well-ventilated and have open eaves or faulty drainage systems. This contributes to an environment that fosters more mosquitoes, increasing the risk of mosquito-borne diseases.
A 2021 study of Puerto Rico in the Journal of Urban Ecology investigated levels of mosquito-borne illnesses in wealthier neighborhoods versus low-income ones. Researchers found that areas with more well-educated residents and higher income had a more sparse diversity of mosquitoes.
Conversely, a neighborhood of lower socioeconomic status was home to greater diversity in mosquito species due to higher human population density and more abandoned buildings. Residents there were also less likely to have health insurance.
The Borgen Project spoke with Sathaphon Phoumarinno, head of policy, campaigns and communication at Save the Children Laos. Phoumarinno holds an active leadership role in the Laos DDDiL project.
Phoumarinno confirmed that while dengue fever affects everyone regardless of economic status, “A lack of awareness about dengue prevention, or not taking protective measures against mosquito bites, can increase the risk of infection. People who do not regularly use preventive measures, such as eliminating mosquito breeding sites around their homes or protecting themselves from mosquito bites, may be more vulnerable to dengue.”
DDDiL’s Strategy
Save the Children and the World Mosquito Project have worked to create a solution that is not just an emergency response to dengue fever, but a sustainable, community-driven answer.
Laos’s DDDiL project works by breeding mosquitoes containing the Wolbachia bacteria, which makes them immune to dengue and other viruses. It begins to work after just one release.
By setting these immune mosquitoes free into community-determined hotspots, safe mosquitoes mate with infected ones and produce offspring containing the Wolbachia gene. This reduces the prevalence of dengue over time without negatively impacting the ecosystem.
Additionally, the sustainable architecture of this initiative eases financial burdens on local communities. Phoumarinno told The Borgen Project, “By reducing the impact of dengue, the project has the potential to decrease health care-related expenses and productivity losses associated with illness. Healthier communities are better able to attend school, work and contribute to local economic development.”
Phoumarinno noted that in addition to some staff, volunteers mostly consist of local community members determined to help those around them. The organizations compensate volunteers for transportation costs and offer training to educate themselves and others on virus prevention.
This year, the Laos DDDiL project has moved beyond Vientiane into four new provinces: Oudomxay, Luang Prabang, Savannakhet and Champasak. The expansion aims to serve 1.2 million more people.
This marks the first time the Laos DDDiL project has moved out of the north, which, despite housing only 29.6% of Laos’s population, comprises 41% of the low-income demographic.
Results, Hope and Gratitude
Between 2025 and mid-2026, only 1,500 cases of dengue were reported nationwide, whereas in 2024 Laos recorded 20,000. That is a 92.5% decrease over roughly two years.
“For community members, I believe DDDiL means hope for a future with fewer dengue cases, healthier and happier communities,” Phoumarinno said.
He added, “We are grateful for the support and participation of the local authorities [and]community members who have engaged with the project. Their involvement demonstrates the importance of community-led action in addressing public health challenges and contributes to the project’s ongoing implementation across Laos.”
– Aren Lau
Aren is based in Brooklyn, NY, USA and focuses on Technology and Global Health for The Borgen Project.
Photo: Ian Taylor