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By Carlos Olimpo Restrepo S., Journalist at UdeA Communications Office

In 1980, Scott O’Neill set out to find a way to control Aedes aegypti mosquitoes. Today, thanks to his work, infecting these mosquitoes with Wolbachia bacteria, dengue, Zika, and chikungunya has significantly declined across 14 countries and territories. The Australian scientist recently visited Medellín to showcase the project’s results in the Aburrá Valley, where the World Mosquito Program (WMP) and UdeA’s Program for the Study and Control of Tropical Diseases (Pecet) led the initiative.

Scott O’Neill is optimistic that his practice will reach more regions in Colombia and other countries, helping to relieve strain on public health systems. Photo: UdeA Communications Office / Alejandra Uribe F.

The Aedes aegypti mosquito ranks as the second deadliest animal globally, responsible for countless human deaths each year due to diseases like dengue, Zika, and chikungunya. To tackle this problem, Scott O’Neill turned to nature, finding an effective tool to control mosquito populations. Recent data from Medellín, Bello, and Itagüí reveal a significant drop in dengue cases despite Latin America’s current dengue epidemic.

The Australian scientist harnessed the Wolbachia bacterium’s ability to disrupt mosquito and insect reproduction while posing no harm to other living beings to create a global strategy for eradicating these disease vectors. This led to the World Mosquito Program (WMP), which now operates projects in 14 countries and territories across the Americas, Asia, and Oceania.

The pilot project in Colombia started in the Paris neighborhood of Bello in 2014. Over the next ten years, it expanded to the entire Aburrá municipality, as well as Medellín and Itagüí, thanks to the collaboration between the World Mosquito Program (WMP) and the Program for the Study and Control of Tropical Diseases (Pecet) at UdeA.

You may find this interesting: the “Wolbachia” strategy successfully stopped dengue fever in Bello, Itagüí, and Medellín.

In Alma Mater, we spoke with the researcher about the progress made in Colombia and globally. We discussed the future of the fight against mosquitoes—pests that affect not only tropical countries but also cause harm in Europe and North America.

Can you walk us through the process when you and your research team discovered that Wolbachia bacteria could be used for biological control of mosquitoes, stopping them from transmitting dengue and other viruses?

The research was conducted over 15 years in my laboratory, most recently at Monash University in Australia. It involved the dedicated work of many students and postdocs throughout the period.

After this discovery, you set out to eliminate dengue fever and established the World Mosquito Program. What was that journey like?

We started designing and conducting the first open-field trials in northern Australia, near Cairns. We then conducted studies in Indonesia and Vietnam, including a large randomized controlled trial in Yogyakarta, Indonesia. After the success of these early trials, we sought to test the practice in different locations and epidemiological contexts to assess its global applicability. So far, we’ve tested the practice in 14 countries, reaching 11.4 million people through the World Mosquito Program. The results have been remarkable in all regions where we’ve aimed to reduce dengue, and now Brazil and Indonesia are working to implement the practice nationwide. It’s been a challenging journey—developing a new practice to control the disease and expanding its reach to those in need. Despite the difficulties, it’s been rewarding to see the positive impact our work is having across the globe.

What led the WMP to partner with the Program for the Study and Control of Tropical Diseases (Pecet) at the Universidad de Antioquia to expand Wolbachia in Medellín and the Aburrá Valley? What valuable lessons have you gained from this collaboration?

We were looking for partnerships where we could test the practice and confirm its effectiveness. When I met Professor Ivan Velez and saw the capabilities of Pecet and his team, it was clear that a collaborative partnership would be the best approach. Given the widespread dengue issue in Colombia, we recognized it as the ideal location for this work. The project has demonstrated that the practice can be scaled and implemented in millions of people cost-effectively, with outstanding results. Medellín, once one of the worst areas for dengue in the country, has seen significant improvement, mirroring the success we’ve observed in other countries. The impact of this practice will continue to grow and become even more evident in the coming years.

How long can the impact of releasing Wolbachia-infected mosquitoes last in areas like Medellín and the Aburrá Valley?

We began releasing Wolbachia mosquitoes nearly 14 years ago, and we have observed no decrease in the practice’s effectiveness in protecting communities in Australia. Given this track record, we are confident that the practice will provide long-term protection to communities in the Aburrá Valley for years to come.

How does the WMP ensure the long-term sustainability of the Wolbachia practice in cities like Medellín? What actions does the WMP take to maintain the population of Wolbachia-infected mosquitoes?

The strength of this practice lies in its natural sustainability. Once Wolbachia establishes in the mosquito population, it persists without reapplication, offering continuous protection to communities. Unlike vaccination or insecticide programs that require repeated use, this practice is cost-effective and, in many cases, reduces government spending on dengue treatments.

Considering dengue is a public health crisis in the Americas, how would you assess the program’s impact on public health, both globally and in Medellín specifically?

The public health impact has been truly remarkable. This intervention controls not only dengue but also Zika, chikungunya, and potentially other mosquito-borne diseases that may arise in the future. Moreover, it is sustainable and could save governments significant costs. We can confidently say that this practice is a game changer for public health, both in Latin America and worldwide.

Aedes aegypti larvae infected with Wolbachia, released as adult mosquitoes. Photo: UdeA Communications Office / Alejandra Uribe F.

How do you see the future of global dengue control, and what role do you think the expanded use of Wolbachia will play in preventing vector-borne diseases?

I believe this practice will have a profound global impact on preventing mosquito-borne diseases. We’re just beginning to see its adoption, and as more cities and countries implement the technology, its effect will become even more noticeable.

What research does the WMP conduct to assess the long-term impact of Wolbachia on mosquito populations and its effectiveness against diseases like Zika and chikungunya?

We are running projects in several countries, including a crucial program in Brazil, where we’ve seen measurable reductions in Zika and chikungunya. In other countries, we are tracking the practice’s long-term effectiveness. The results show that it remains effective over time.

What challenges have you faced in leading a dengue and disease control project across 14 countries, and what strategies have you used to ensure its sustainability and expansion?

One of the biggest challenges is introducing a new approach that isn’t widely known. It takes political courage to support change, even when it improves existing practices. With global evidence supporting the approach, I’m eager to see its benefits reach more people quickly and hope for faster adoption. As we expand, we focus on building strong local partnerships, like the one with Pecet, and work with the best partners who have the local expertise to implement the technology successfully.

How do you educate populations, particularly in Latin America, about preventive measures for mosquito-borne diseases, and what efforts have you made to build trust in the Wolbachia mosquito infection program?

Community engagement is essential to our work wherever we operate. We dedicate significant time and resources to ensuring communities are well-informed and trust the programs we implement.

What lessons can students, researchers, and health authorities learn about the value of supporting basic research that might initially seem irrelevant but can lead to significant public health advancements?

Fundamental research can result in unexpected discoveries that offer substantial benefits to society. The evidence is clear and well-supported.

What message would you share with governments and research institutions about the importance of funding basic science projects that could impact global public health?

Governments should prioritize funding basic research and ensure that the projects they support are of the highest quality. This approach maximizes the potential for meaningful discoveries that can drive significant advances in public health.