Ceará abandona fumacê por novas tecnologias contra dengue

Anyone who lived through Ceará's dengue epidemics in the early 2000s remembers the fog. The fumacê trucks rolled through city streets trailing clouds of insecticide, and people watched them pass with a sense of relief—here was protection, visible and chemical and official. For decades, that image meant safety. Now the trucks are gone from most neighborhoods, and the reason is both biological and bureaucratic: the very tool that once seemed like salvation had become counterproductive.

Antonío Silva Lima Neto, the state's executive secretary for health surveillance and an epidemiologist known as Tanta, explains the shift plainly. Spraying insecticide indiscriminately—the technical term is Ultra Low Volume, or UBV—trains mosquitoes to resist it. The more you spray without an active outbreak, the more you breed a population of insects that can survive the poison. The fumacê, in other words, created the very problem it was meant to solve. "What did the fumacê produce? Greater resistance in the insect," Tanta says. "You only use it when there's an active outbreak with confirmed transmission. Why? Because it only works on adult mosquitoes."

Today, Ceará's health department deploys the technology sparingly, only during periods of significant transmission of dengue or chikungunya. In the first months of 2026, dengue transmission in the state has remained low—a continuation of the previous year's pattern. Tanta attributes this to herd immunity, the accumulated protection that comes when most of a population has either been vaccinated or infected. Nearly four decades of dengue circulation in Ceará has exposed people to the virus's four distinct serotypes. The two most common strains circulating now, serotypes 1 and 2, have already swept through the state in previous years, leaving much of the population with immunity. Fewer susceptible people means fewer epidemics. "Herd immunity is when most people have already had the disease and it doesn't become an epidemic," Tanta explains. "Why didn't we have one? Because we have a crowd of people who are essentially vaccinated."

But the state remains vigilant. In 2025, Ceará detected serotype 3 in the municipalities of Limoeiro do Norte, Tabuleiro do Norte, and Barbalha—a strain that has not circulated sustainably in the region for decades. The population's immunity to this particular virus is uncertain, making it a potential threat. Even in 2026, with overall transmission low, some smaller municipalities have reported localized outbreaks. Reriutaba, in the Sertão de Sobral region, required fumacê spraying because the town lacks easy access to laboratory testing and needed rapid intervention to prevent the outbreak from spreading.

The shift away from fumacê reflects a deeper understanding of how the mosquito actually lives. The insecticide kills adults but leaves larvae untouched, making it incomplete as a strategy. Prolonged exposure to the pesticide also carries risks for humans—respiratory problems—and collateral damage to other insects essential to ecosystems, like bees and butterflies. Tanta emphasizes that fumacê must always be paired with the daily work of field agents who eliminate breeding sites. One new tool doing this work is the Larval Dissemination Station, or EDL, recently deployed in Fortaleza. The device uses the mosquito's own behavior against it. Unlike traditional egg-monitoring traps, the EDL has a screen impregnated with larvicide. When a female mosquito lands to lay eggs, her legs pick up microscopic particles of poison. As she flies to other breeding sites—gutters, elevated tanks, places field agents cannot easily reach—she carries and deposits the larvicide. When those eggs try to hatch, they fail to develop, breaking the reproduction cycle.

Another technology on the horizon is the Wolbachia mosquito, sometimes called the "good mosquito." These are Aedes Aegypti infected with a bacterium that prevents dengue, Zika, and chikungunya viruses from developing inside them. Released into the wild, they mate with wild mosquitoes and pass the bacterium to their offspring. All descendants are born already carrying the protection. The technology has been deployed in at least 15 countries with dramatic results: dengue cases fell more than 90 percent in Australia and Colombia. In Brazil, a pilot program in Niterói, Rio de Janeiro, reduced dengue cases by roughly 69 percent, chikungunya by 60 percent, and Zika by 37 percent. Ceará expects to receive these mosquitoes in 2027, and the Oswaldo Cruz Foundation is building a biofactory in Eusébio, in Fortaleza's metropolitan region, designed to supply modified mosquitoes to roughly 1,794 municipalities across the Northeast.

Vaccination remains central to the strategy. The dengue vaccine was incorporated into Brazil's public health system in 2024, offered free in a two-dose regimen, though uptake in Ceará has been modest. A new single-dose vaccine developed by the Butantan Institute may change that. It was tested in mass vaccination in Maranguape, targeting people aged 15 to 59, and the Health Ministry plans to roll it out gradually across the country, beginning with people 59 and older and working down to age 15. The combination of new technologies, vaccination, and sustained surveillance represents a fundamentally different approach to dengue than the fumacê era—less visible, more targeted, and built on the understanding that you cannot spray your way out of a problem you've been spraying at for forty years.