New Caledonia's successful implementation of the World Mosquito Program's Wolbachia method has eliminated dengue epidemics across the territory since 2019. We explore how strategic partnerships between government, scientific institutions and local communities created a sustainable solution that has protected residents while delivering significant economic benefits to this South Pacific archipelago.

Naporapoe Kawonion Rose vividly recalls the day she came down with dengue symptoms in her village in New Caledonia. 

“I felt very tired and had no strength,” she says. “I had strong headaches and pain everywhere.”

After receiving treatment at a local hospital and recovering, Rose was determined to prevent future dengue infections in her community.

“I started keeping an eye out for mosquito larvae and checked flower pots for standing water. I always told people to cut the grass and look for mosquitoes,” says Rose. “There are many children here, and I am getting old, so I want to fight against dengue because I’m scared.”

Rose’s village is one of the many communities in the diverse French overseas territory which has benefited from the World Mosquito Program’s (WMP) Wolbachia method over the past seven years.

Reducing mosquito-borne diseases in New Caledonia

Launched in March 2018, the project which announced its completion in recent weeks, saw WMP form a partnership with the Government of New Caledonia, the City of Nouméa and the Institute Pasteur in New Caledonia (IPNC) to protect communities from mosquito-borne diseases.The impact on communities like Rose’s has been resounding following releases of Wolbachia mosquitoes in the capital Nouméa, as well as the towns of Mont-Dore, Dumbéa and Païta. More than 24 million have been released with 86 per cent of mosquitoes carrying Wolbachia, and no dengue epidemic since 2019.

“This programme is a great success,” says Nadège Rossi, WMP’s programme coordinator in New Caledonia. “It highlights all the possibilities that this territory offers in terms of innovative technology.”

While some less urbanised and more dispersed areas, including Saint-Louis, show slightly lower rates of Wolbachia establishment, Rossi is very positive about the wider success and lack of epidemics in recent years.

“The average rate of 87 per cent of mosquitoes carrying Wolbachia in Greater Noumea is sufficient, in any case, to break the chains of dengue transmission,” she says. “Especially since this percentage will of course continue to evolve and move towards 100 per cent.

"In the current context, we are almost certain that we will no longer have dengue epidemics in New Caledonia. However, despite everything, we remain vigilant. There are areas that are not covered by this method and therefore we could have smaller outbreaks.”

The programme has also seen a very high public acceptance rate throughout the communities where releases took place. Around 94 per cent of residents in Nouméa, 92 per cent in Dumbéa and Mont-Dore, and 94 per cent in Païta, were all in acceptance of using the method.

No better example of this is in New Caledonia, where the Government of New Caledonia, the City of Nouméa and the Institute Pasteur in New Caledonia (IPNC) were all initial consortium partners when the project launched in the capital, and are still heavily involved right to the end.

Other major partners in New Caledonia have included a diverse ensemble from EEC ENGIE, an energy provider in Nouméa, OPT, New Caledonia’s postal and telecommunication service, to French sportswear company, Decathlon, and environmental and public health association Ensemble pour la Planète (EPLP). The project has also been financially supported by the South province of New Caledonia and the French government.

“Beyond the financial contributions, the partnerships brought many skills to safely and successfully release mosquitoes in New Caledonia,” says Rossi. “Institut Pasteur de Nouvelle-Calédonie brought scientific expertise and skills for rearing and analysing mosquitoes as well as scientific materials.”

“The government of New Caledonia brought expertise in field entomology and epidemiology. Thanks to the data of the health department, we had historical information of dengue outbreaks in New Caledonia. We also had supporters from environmental associations, as well as public and private companies, which all played a role in helping promote the programme.

“I’ve had the chance to work with the same collaborators for years, so it is a real team success story and we are all proud to help protect New Caledonia from dengue outbreaks.”

Global progress against dengue with Wolbachia

The success in New Caledonia follows proven evidence, at scale, in other parts of the world. Recent impact from Colombia has seen three and half million people in the Aburrá Valley protected. Medellín, Itagüí and Bellow are now consistently among the lowest ranked cities in the country for dengue incidence. Niterói, WMP’s first fully protected Brazilian city, once one of Rio State’s highest-ranking cities for dengue rates, is now consistently one of the lowest, following Wolbachia establishment.

In Indonesia, following a large three-year randomised controlled trial, the city of Yogyakarta showed a 77 per cent reduction in dengue cases and an 86 per cent reduction in dengue hospitalisations, where Wolbachia mosquitoes were released. The results were published in the New England Journal of Medicine and garnered global media coverage and interest in 2021. In Australia, WMP effectively eliminated dengue as a public health concern with a 98 per cent reduction in transmission rates.

Economic impacts of preventing mosquito-borne diseases

Frequent dengue outbreaks across the world continue to strain health systems, reduce school attendance, and hurt household budgets. And economists estimate the global cost of dengue to be close to $9 billion per year. In New Caledonia, in addition to the lives saved, WMP’s project averted health costs estimated at roughly 67 million euros, while eliminating the use of insecticides on the South Pacific archipelago.

Hospital doctor and city councillor, Tristan Derrick, says: “I have personally seen people die of hemorrhagic dengue fever in intensive care, for whom our care service was powerless. It’s a monumental success (to have avoided any arbovirus epidemics).”

Hope for the future: Expanding Wolbachia beyond New Caledonia

“The method could be an inspiration for the other French overseas territories.….such as the French Antilles, Mayotte and the Réunion, which are really affected by dengue epidemics,” says Julien Pailhère, the Director of the Office of the High Commissioner of France in New Caledonia.

“I really hope (with good results) to develop the project in other French overseas territories and beyond. In the times we live in, skies have no borders.”

For Rossi, it marks the end of a seven-year project, which has seen challenges but also fantastic rewards.

“It is very challenging to implement such a programme, but it is also a rare opportunity to participate in a project which will change the lives of many people,” reflects Rossi.

A Model of Mosquito-Borne Disease Control

Niterói fights dengue with Wolbachia

However, one city in Brazil is dramatically bucking the trend. Home to roughly half a million people, Niterói, just across the Guanabara Bay from neighbouring Rio de Janeiro, has seen its lowest number of dengue cases in more than 20 years between 2020 and 2023.

Health officials credited the successful impact of WMP’s Wolbachia method, which was first deployed in the city to help battle dengue in 2015. Nine years on, it is the first Brazilian city to be fully protected by Wolbachia. Long-term monitoring in Niterói, showed that at least 97% of Aedes aegypti mosquitoes carried Wolbachia up to eight years after release efforts ended.

“The sustained absence of dengue, chikungunya and Zika outbreaks in Niterói during the past four years has provided an increasingly clear signal of the real-world effectiveness of large-scale Wolbachia deployments," says Dr Katie Anders, WMP’s Director Integrated Evidence.

In the ten years prior to the start of the city-wide roll-out of Wolbachia mosquito releases in Niterói in 2017, more than 46,000 dengue cases resident in Niterói were reported to Brazil’s national disease surveillance system (SINAN). Large dengue outbreaks numbering thousands of cases were an almost annual occurrence in the city, and more than 12,000 cases were reported in 2013 alone. By comparison, in the first four years 2020 - 2023 after Wolbachia was rolled out across Niterói, there were a total of 326 dengue cases reported in the city - lower than any previous period on record.

Record year of dengue

While surging dengue transmission in 2024 has seen case numbers creep up also in Niterói, the 1,754 cases recorded so far this year are dramatically lower than historical outbreaks.

"This year has provided the litmus test,” adds Anders. “To see dengue incidence remain low in Niterói while dengue is inflicting a public health emergency on so much of Brazil and the region really highlights the extraordinary impact that Wolbachia is having in preventing illness and deaths and protecting health systems.”

Anders notes that while cases have increased this year, the caseload is still 90 per cent lower than before the deployment of WMP’s Wolbachia method.

Ana Eppinghaus remembers when WMP first approached the city with its novel method in 2015. “The first contact we had with the project was a little surprising," says the Health Surveillance Coordinator at the Municipal Health Foundation of Niterói. “It’s not often you come across a proposal to release mosquitoes when our entire history of disease prevention was to fight against the mosquitoes. But… we accepted the challenge.”

The project first began in Jurujuba before expanding to another 33 neighbourhoods in 2017. The final 19 neighbourhoods were completed in May 2023, with scientific results from other areas already showing a drop in dengue cases.

“We were used to seeing dengue epidemics in the city every three to five years, with tens of thousands of cases,” adds Eppinghaus. “And today, we see the impact of Wolbachia all over the city, with at most a hundred or so cases. The impact was clear, cases were decreasing.”

Since Wolbachia has been rolled out across the city, Anders says dengue incidence has dropped to an average of 84 cases per 100,000 people per year, compared to an average rate of 913 cases per 100,000 per year in the 10 years pre-Wolbachia.

The 1,736 dengue cases reported in Niterói from January to June 2024 represent a rate of 336 per 100,000 this year. This compares to the national rate of 3,121 and 1,816 in Rio de Janeiro state during the same period.

Anders points out that historically Niterói has ranked among the highest dengue incidence cities in Brazil, so this protective effect of Wolbachia in the city translates into thousands of dengue cases prevented that would otherwise have occurred during this year's unprecedented dengue surge in Brazil.

Replicating Niterói’s success

At the end of last year, the city’s symbolic Museum of Contemporary Art (Mac), hosted an exhibition entitled: Wolbachia pipientis: Niterói em Três Tempos, which told the story of how WMP implemented the Wolbachia method across the city over eight years.

“It gives me much joy and I’m really proud of our city being the first Brazilian municipality to be 100% protected by Wolbachia,” says Juliana Martins, the Education, Sustainability, Sport and Health Coordinator from the City Education Secretariat of Niterói.

“We are really proud to be part of this project and to see how effective it has been — and in such a sustainable way. It’s wonderful to see that science is not meant to stay in a drawer and with WMP, it has benefited those who most need it. It’s fantastic.”

It is hoped the success of Niterói will be replicated across much of the country in the coming years. WMP, alongside Fiocruz and the Ministry of Health, have great ambitions to protect more than 100 million people in Brazil over the next decade.

Alongside previous releases in other cities including Petrolina, Campo Grande and a randomised controlled trial in Belo Horizonte, with results expected in mid-2025, Joinville, Foz do Iguaçu and Londrina are currently in the midst of Wolbachia releases. Uberlândia, Presidente Prudente and Natal, will also commence deployments early next year.

Ethel Maciel, the Ministry of Health’s Secretary for Health and Environment Surveillance, emphasises the importance of these new initiatives to protect more people from mosquito-borne diseases.

“Expanding the number of cities that use the Wolbachia method and building new factories are of great importance if we are to face future epidemics and better protect the Brazilian population,” she says.

“This technology is proof that science needs to be increasingly fostered and valued.”

The factory, which is owned by IBMP/Fiocruz and WMP, is part of the formal partnership between the two organisations to dramatically expand access across the country. It will produce about five billion mosquito eggs annually at a rate of up to 100 million per week in the initial stages.

“In Brazil, we’re in the process of moving past Wolbachia as an experimental measure to its use as a cornerstone of dengue control,” says Luciano Moreira, WMP’s project leader in Brazil. “We’ve partnered with the Brazilian government to build a Wolbachia mosquito production facility that will enable deployment in multiple cities simultaneously — with the goal of protecting millions of people.”

Anders concludes: “In a record year for dengue outbreaks, Niterói has shown that Wolbachia can provide long-term protection for communities against the increasingly frequent surges in dengue we’re seeing globally.”