Minas opens modified mosquito factory to combat dengue; learn about the Wolbachia method

Minas Gerais inaugurated this Monday, 29th, a biofactory of modified mosquitoes, characterized by carrying the bacteria Wolbachia (you Wolbites), which is capable of blocking the transmission of arboviruses from vectors to humans, especially dengue. Production, however, should only begin in 2025.

The resources for the construction of the building in Belo Horizonte came from the agreement to repair the damage caused by the collapse of the mining company’s dam OKin Brumadinho, in January 2019. The tragedy took the lives of 272 people. Therefore, in the first phase of the new project, mosquitoes Aedes aegypti with the bacteria will be released in the city of Brumadinho and in 21 other municipalities in the Paraopeba River Basin.

According to the Ministry of Health, Vale will also pay for the assembly of equipment and the cost of operations for five years. The construction of the building received an investment of approximately R$20 million, and the operation stage foresees another R$57 million, according to the Minas Gerais government.

The idea is that, in the future, the factory will be able to meet the demand for Wolbitos in all municipalities in Minas Gerais. “The factory will certainly reach a capacity of 60 million mosquitoes per month. Over time, we will have much better numbers here in Minas regarding dengue fever”, stated governor Romeu Zema (Novo). The State has already registered more than 1.3 million probable cases and confirmed 324 deaths from the disease this year. “It’s a factory that will revolutionize the future of Minas Gerais in the medium and long term.”

As shown by the Estadão, at the end of last year, in cities where the method has been used, researchers achieved reductions of up to 90% in the incidence of dengue. They have also had positive results for other diseases caused by mosquitoes, such as Zika and chikungunya.

In Brazil, the Australian method has been conducted by the Oswaldo Cruz Foundation (Fiocruz), with funding from the Ministry of Health in partnership with local governments, since 2014. Until last year, the World Mosquito Program (WPM), holder of the patent for the methodology, used, on a temporary basis, the Fiocruz building, in Rio, and in a space provided by the city of Belo Horizonte to produce the Wolbitos.

During the inauguration, the Secretary of Health and Environmental Surveillance at the Ministry of Health, Ethel Maciel, said that “this is the first biofactory other than the one in Rio de Janeiro”, but the department has plans to expand to other states. According to her, there are plans to build similar structures in Paraná and Ceará.

In February, Ethel informed the Estadão that the department had purchased all of Fiocruz’s mosquito production for this year. With the R$30 million invested, the Wolbachia method reached six new cities: Natal (RN), Uberlândia (MG), Presidente Prudente (SP), Londrina (PR), Foz do Iguaçu (PR) and Joinville (SC). Previously, it was present in five others: Rio de Janeiro (RJ), Niterói (RJ), Campo Grande (MS), Belo Horizonte (MG) and Petrolina (PE).

The method

Aedes aegypti is the scientific name of the mosquito that serves as a vector not only for dengue, but also for chikungunya and zika, which are part of a group of diseases defined as arboviruses. The mosquito, known for its white stripes, is considered domestic and has preferably diurnal habits. Only the female bites humans, and she only acquires the virus that causes these diseases when she feeds on the blood of someone infected.

Renowned scientist Scott O’Neill, CEO of WPM, began his studies with Wolbachia years ago. Interest began after an American group discovered that so-called fruit flies (Drosophila melanogaster) survived half the time when they carried this bacteria in their bodies.

Wolbachia is an obligate intracellular bacterium (that is, it does not survive outside the host) and is found in half of the existing insect species, but not in Aedes aegypti. There is no evidence that it is a pathogen (causes disease) in humans or any vertebrate.

The first strain of Wolbachia tested managed to reduce the lifespan of Aedes, but, because of some problems, it was not able to establish itself in a mosquito population. Therefore, they tested another strain, also from the fruit fly. The discovery was surprising: it blocked the virus.

When the bacteria is in its cells, the mosquito has a significantly reduced chance of becoming infected with an arbovirus. And, when this happens, the virus has a reduced replication and dissemination capacity, that is, they become less competent vectors.

To introduce the bacteria to Aedes aegypti, scientists use microscopic needles to first pick it up from the fruit fly. They then insert it into young mosquito eggs. When they crack, a colony of Aedes aegypti is established with Wolbachia, as it is inherited through successive generations.

Over time, Wolbachia manages to gain a foothold within the mosquito population and becomes part of the species’ genes, due to something called cytoplasmic incompatibility. It “manipulates” the mosquito’s reproductive output so that when a Wolbachia-infected male mates with a wild-type female, the eggs are nonviable and will not hatch. Now, if females with the bacteria mate with any male, all of the eggs will carry Wolbachia and hatch.

With urbanization without adequate water and sewage networks, climate change and ineffective control measures, dengue fever is becoming an increasingly latent problem in Brazil and the world. For experts, only combined “disruptive” innovations will be able to change the course of this story – this includes controlling transmission by the vector, offering a vaccine and developing treatments against the disease. This is because they assess that the classic vector control measures, insecticides and elimination of mosquito outbreaks, although important, are not very effective.

The Wolbachia method differentiates itself by being long-lasting, natural (there is no genetic alteration) and presenting a promising cost-benefit ratio. But there are challenges to be faced, such as understanding why mosquitoes with the bacteria have difficulty establishing themselves in certain locations and finding ways to scale production.