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Support for this article was provided by the Pulitzer Center.<\/p>\n
Last month, a parade of vehicles wound its way through three cities in Brazil, releasing clouds of mosquitoes into the air. The insects all carry a secret weapon \u2014 a bacterium called Wolbachia that lowers the odds that the mosquitoes can transmit the dreaded dengue virus to humans.<\/p>\n
This is the world\u2019s largest \u2018mosquito factory\u2019: its goal is to stop dengue<\/p>\n<\/p>\n
These infected mosquitoes are the latest weapon in Brazil\u2019s fight against dengue, which infects millions of people in the country each year and can be fatal. A biofactory that opened in the town of Curitiba in July can produce 100 million mosquito eggs per week \u2014 making it the largest such facility in the world. The company that runs it, Wolbito do Brasil, aims to protect about 14 million Brazilians per year through its Wolbachia-infected mosquitoes.<\/p>\n
That will come as welcome news for the Brazilian health officials battling the rapidly growing threat of dengue. In 2024, the country experienced its worst outbreak yet: with 6.6 million probable cases and more than 6,300 related deaths. This year\u2019s outbreak, although less severe, is also one of the highest on record, with 1.6 million probable cases so far (see \u2018Dangerous outbreaks\u2019). And the problem is spreading. Argentina, Colombia and Peru also experienced record-breaking outbreaks in 2024 and have seen a sustained increase in cases in recent years. Across Latin America and the Caribbean, deaths from dengue last year totalled more than 8,400 and the global figure reached more than 12,000 \u2014 the highest ever recorded for this disease.<\/p>\n
SOURCE: Brazilian Ministry of Health<\/span><\/p>\n As outbreaks grow larger and the crisis becomes more urgent, the Wolbachia method isn\u2019t Brazil\u2019s only bet. A locally produced dengue vaccine is now awaiting approval by the country\u2019s drug-regulatory agency, and its health ministry expects to start administering tens of millions of doses by next year.<\/p>\n These twin advances offer some hope to other countries \u2014 in the region and beyond. Driven by forces such as climate change, mosquito adaptation, globalized trade and movements of people, dengue is becoming a crisis worldwide, with an estimated 3.9 billion people at risk of infection. As Brazil rolls out its armies of infected mosquitoes and a vaccine in the coming year, the rest of the world will be watching closely.<\/p>\n Currently, there is one main dengue vaccine in use around the world: Qdenga, licensed by the Japanese pharmaceutical company Takeda. The vaccine has been approved in many countries, including Brazil, which was the first nation to include it in its public-health system.<\/p>\n However, Qdenga\u2019s roll-out in Brazil is limited. The country bought nine million doses of the two-dose vaccine this year: enough to vaccinate 4.5 million of its population of more than 210 million. So far, Qdenga has been administered to children between the ages of 10 and 14, one of the groups most likely to end up in hospital after contracting dengue, together with older people. Its safety and efficacy have not yet been tested in adults aged over 60.<\/p>\n The main reasons for such a limited roll-out in Brazil are availability and cost. Even though Brazil secured Qdenga from Takeda at one of the cheapest prices in the world \u2014around US$19 per dose \u2014 the cost is still high compared with other vaccines. And even in the most optimistic scenario, the maximum number of doses Takeda could provide by 2028 is 50 million \u2014 enough to vaccinate 25 million people. What\u2019s more, for people who have not had dengue before, clinical trials did not show Qdenga to be effective against all four variants \u2014 or serotypes \u2014 of the dengue virus.<\/p>\n When will dengue strike? Outbreaks sync with heat and rain<\/p>\n<\/p>\n Brazil is trying to address all of those limitations with its one-dose vaccine candidate, developed at the Butantan Institute, a public biomedical research centre in S\u00e3o Paulo. \u201cHaving local production capacity gives us independence on decisions \u2014 how many doses we need, and at what speed to vaccinate,\u201d says Esper Kall\u00e1s, Butantan\u2019s director. \u201cYou can practise prices that are more suitable and absorbable by a public-health system such as Brazil\u2019s.\u201d<\/p>\n Butantan is also optimistic that its vaccine will be effective against all four forms of dengue. Severe disease usually occurs when a person is infected by a different serotype to their first infection. That means that a successful vaccine needs to generate antibodies for all four serotypes without triggering severe reactions, which makes it a difficult vaccine to develop. \u201cIt was indeed a challenge, as each serotype behaves differently,\u201d says Neuza Frazatti Gallina, manager of the viral vaccine development laboratory at Butantan.<\/p>\n The vaccine\u2019s development began at the US National Institutes of Health in the late 1990s, where scientists transformed dengue viruses they had isolated from patients into weakened vaccine strains that could trigger the production of protective antibodies without causing disease. In 2009, Butantan extended that research by working to solve the challenges of combining the four strains into a vaccine.<\/p>\n Eggs of mosquitoes infected with Wolbachia bacteria. After hatching, the mosquitoes will be released to prevent the spread of dengue.<\/span>Credit: Xinhua\/Shutterstock<\/span><\/p>\n After testing 30 formulations, Butantan arrived at one that proved highly effective in preventing infections, according to the preliminary results of a phase III trial involving more than 16,000 volunteers in Brazil. The study reported that two years after vaccinations, the formulation was 89% effective in preventing infections in people who had previously been infected with dengue, and 74% effective in those with no previous exposure1.<\/p>\n \u201cIt was a well-designed trial,\u201d says Annelies Wilder-Smith, who is team lead for vaccine development at the World Health Organization (WHO). But she says one limitation of the trial is that it was conducted in a single country, and therefore runs a risk that all four serotypes were not circulating at the time.<\/p>\n In fact, serotypes 3 and 4 were not prevalent during the data-collection period of the clinical trial, although they are now circulating in Brazil. Butantan researchers suggest that the vaccine will be effective against serotypes 3 and 4, pointing to data from a phase II trial2 in 300 adults that showed participants produced neutralizing antibodies to each of the serotypes. That study evaluated safety and immunological response in the short term, rather than looking at the vaccine\u2019s long-term efficacy in preventing infections. The full results of the Brazilian phase III trial \u2014 which will provide data on long-term effectiveness \u2014 are not yet public and are undergoing peer review.<\/p>\n The vaccine is already moving through the country\u2019s regulatory process. And although there\u2019s still no certainty about when Anvisa, Brazil\u2019s regulatory agency, will approve the vaccine, the government is counting on it. In February, President Luiz In\u00e1cio Lula da Silva announced that, starting in 2026, the Ministry of Health would be buying 60 million doses annually.<\/p>\n To meet that demand, Butantan is now producing the vaccine at its S\u00e3o Paulo facility. On its lush campus, an entire building is dedicated to churning out doses.<\/p>\n Regarding the vaccine\u2019s approval, \u201cWe are very confident,\u201d says Kall\u00e1s. \u201cWe also anticipate that there is a very prominent need to have this product in the arms of people. So we hit the road running and started producing vaccines late last year.\u201d<\/p>\n Although Butantan\u2019s production efforts will focus initially on meeting Brazil\u2019s need for millions of doses, Kall\u00e1s expects that the vaccine could reach other countries. Butantan has been discussing with its development partner \u2014 the pharmaceutical giant Merck \u2014 and the Pan American Health Organization (PAHO) how to make the vaccine accessible to other countries. The logical first step, he says, would be to roll it out through PAHO to Latin America and the Caribbean, and then to other regions.<\/p>\n In the meantime, Merck is developing a potential vaccine for Asia with an almost identical formulation, which builds on the knowledge that Butantan has developed. In a statement, the drug firm said that Butantan is \u201csharing clinical data and other learnings\u201d. In June, Merck started enrolling participants for its own phase III trial. \u201cAll the data, experiences and insights they have collected with the Butantan vaccine will be helpful,\u201d says Wilder-Smith.<\/p>\n While Butantan awaits news about the vaccine\u2019s approval, the Wolbachia method to control dengue is gaining momentum. The World Mosquito Program (WMP) \u2014 a non-profit group of companies owned by Monash University in Melbourne, Australia, where the strategy was developed \u2014 has operations in 14 countries, including Vietnam, Indonesia, Mexico and Colombia, but Brazil leads the way in terms of the scale of its expansion.<\/p>\n The method\u2019s arrival in the Americas is tied to Brazilian researcher Luciano Moreira, now the chief executive of Wolbito do Brazil. Wolbachia is naturally present in around 50% of insects, but not in the mosquito species Aedes aegypti, which is the main transmitter of dengue and many other viruses.<\/p>\n","protected":false},"excerpt":{"rendered":" Support for this article was provided by the Pulitzer Center. Last month, a parade of vehicles wound its way through three cities in Brazil, releasing clouds of mosquitoes into the air. The insects all carry a secret weapon \u2014 a bacterium called Wolbachia that lowers the odds that the mosquitoes can transmit the dreaded dengue<\/p>\n","protected":false},"author":1,"featured_media":21769,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[58],"tags":[103,727,151,9195,3908,13351,2133,6384],"class_list":{"0":"post-21768","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-beat","9":"tag-billions","10":"tag-deadly","11":"tag-dengue","12":"tag-hacked","13":"tag-mosquitoes","14":"tag-vaccine","15":"tag-virus"},"_links":{"self":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/21768","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=21768"}],"version-history":[{"count":0,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/posts\/21768\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=\/wp\/v2\/media\/21769"}],"wp:attachment":[{"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21768"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21768"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/naijaglobalnews.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21768"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}The local approach<\/h2>\n
Infecting mosquitoes<\/h2>\n