After six years of deployment and surveillance in the four municipalities of the Noumean agglomeration, the World Mosquito Program (WMP) has officially concluded. The program, which involved the release of 24 million mosquitoes infected with Wolbachia bacteria, has successfully prevented any dengue epidemics since 2019. The results were presented on Tuesday, highlighting the program’s effectiveness and the potential for similar initiatives in other regions.

At the start of 2019, New Caledonia was grappling with hundreds of dengue cases per month. This alarming trend was effectively curbed by the WMP, which was deployed across the municipalities of Grand Noumea from 2019. The program’s success has been a testament to the power of biological innovation in combating mosquito-borne diseases.

The key figure of this operation is the widespread presence of Wolbachia bacteria in mosquitoes. After six years, an overwhelming majority of mosquitoes in the Grand Noumea area are carrying the Wolbachia bacteria. This bacteria prevents the transmission of the dengue virus, as well as zika, chikungunya, and yellow fever, and is transmitted from one generation of mosquitoes to another.

In total, 86% of the mosquitoes observed are carrying Wolbachia, according to WMP. To achieve this level, nearly 24 million mosquitoes were released in Noumea in 2019, followed by releases in Mont-Dore (2022), Dumbéa (2022), and Païta (2024). However, there are disparities between municipalities and neighborhoods. For instance, in areas like the gates of iron in Nouméa, the heart of the city of Dumbéa, the petroglyphs in Païta, or at the Pont-des-Français in Mont-Dore, all observed mosquitoes carried the bacteria. Many districts far exceed 90%, such as the three valley (92%) in Païta, Robinson or Boularis (93%) in Mont-Dore, Koutio (95%) in Dumbéa, or the Valée des Colaton (98%) and from the Normandy-Tina sector (93%) in Noumea.

A single district presents a low carrier mosquito level: Saint-Louis in Mont-Dore (38%). A small sector in homes and very wooded. Certain less urbanized and more dispersed areas, such as the Saint-Louis tribe and squats, still display a low rate of mosquitoes carrying Wolbachia, explains WMP. This is due to a higher initial density of mosquitoes and a less concentrated human population, conditions less conducive to the rapid installation of mosquitoes carrying Wolbachia.

As a result of this strong presence of Wolbachia mosquitoes, the dengue virus is hardly circulating in New Caledonia. No epidemic focus has been observed since 2019, even in the municipalities of Bubousse, which are not affected by WMP. According to the NGO, the protection of the Grand Noumea, a usual place of infection, allows the rest of the country to be so protected. Since January 1, 2025, there has been no case of dengue, said Sébastien Mabon, deputy director of DASS. In 2024, nine cases were identified. On these cases, three were local dengues and six concerned travelers who had caught him in another country before arriving in the territory.

Nevertheless, the health authorities specify that it is necessary to remain vigilant. The Wolbachia bacteria does not prevent the bites and has not completely eradicated diseases such as dengue or zika. Although the Wolbachia bacteria has been effective in reducing the spread of dengue, it is crucial to maintain surveillance and control measures to ensure long-term success, said Nadège Rossi, project manager for World Mosquito Program.

The end of dengue epidemics also has an advantage for public finances. According to WMP, the average cost of an epidemic period can reach 1.6 billion francs. The program, it will have cost 800 million francs to institutions and communities. Half in subsidies, the other in kind (equipment, staff, vehicle …).

Implications for the United States

The success of the Wolbachia program in New Caledonia offers valuable insights for mosquito control efforts in the United States. Mosquito-borne diseases like dengue, zika, and West Nile virus pose significant health risks in various parts of the country, particularly in warmer regions like Florida, Texas, and California. The use of Wolbachia-infected mosquitoes could be a game-changer in these areas, providing a sustainable and effective method to control disease transmission.

Potential Challenges and Counterarguments

While the Wolbachia program has shown promising results, there are potential challenges and counterarguments to consider. One concern is the cost of implementing such a program on a large scale. The initial investment required for mosquito breeding, release, and surveillance could be substantial. Additionally, public acceptance and community engagement are crucial for the success of any mosquito control initiative. Some communities may be hesitant to embrace the release of genetically modified mosquitoes into their environment.

Future Directions and Research

As the Wolbachia program concludes in New Caledonia, researchers and public health officials are looking to the future. Future research should focus on optimizing the release strategies, improving surveillance methods, and assessing the long-term impact of Wolbachia on mosquito populations and disease transmission. Additionally, collaboration between international organizations and local health authorities can help scale up successful programs and share best practices.

Conclusion

The World Mosquito Program’s success in New Caledonia serves as a beacon of hope for mosquito control efforts worldwide. By leveraging biological innovations like Wolbachia, communities can effectively combat mosquito-borne diseases and protect public health. As we continue to face the challenges of infectious diseases, it is essential to invest in research, community engagement, and sustainable control measures to ensure a healthier future for all.