Genetically Modified Mosquitoes Released in Brazil to Combat Soaring Dengue Fever Cases
In a desperate attempt to combat the alarming rise in dengue fever cases, scientists in Brazil have turned to an unconventional solution – genetically modified mosquitoes. Dengue fever, a viral infection spread by mosquitoes, has seen a staggering increase of 226% in reported cases in the first two months of this year compared to the same period in 2023. With more than 1 million cases already reported, various cities in Brazil have declared a state of emergency. Rio de Janeiro, for instance, recorded over 42,000 cases since the beginning of the year, prompting the city to declare a public health emergency.
Dengue fever is endemic in Brazil, meaning it is constantly circulating. Between 2003 and 2019, the country reported over 11 million cases, with peak transmission occurring during the annual rainy season from October to May. Unusually large outbreaks tend to occur every three to four years. The symptoms of dengue fever include fever, headache, and nausea, which usually clear within a week. However, in severe cases, the disease can lead to hospitalization and even death.
With no specific treatment available for dengue fever, health authorities in Brazil are exploring alternative approaches to control its spread. In addition to rolling out a vaccine, they are now testing the use of genetically modified mosquitoes. Biotech company Oxitec is at the forefront of this effort, breeding male Aedes aegypti mosquitoes – the species responsible for transmitting the dengue virus – that are genetically modified to carry a gene that kills their female offspring before they reach adulthood.
Female Aedes aegypti mosquitoes are the ones that spread dengue fever through their bites. By releasing these modified male mosquitoes into affected regions, the number of pests capable of transmitting the virus to humans can be significantly reduced. Oxitec’s modified mosquitoes complete their life cycle inside specially designed boxes, mimicking their natural habitat. The eggs are placed in the boxes and hatch when water is added, as Aedes aegypti mosquitoes typically lay their eggs in stagnant water.
Natalia Ferreira, Oxitec’s general manager in Brazil, explained that the adult insects emerge from the boxes after about ten days to carry out their work. According to Ferreira, this approach can reduce the population of Aedes aegypti mosquitoes by up to 90% in regions where the genetically modified mosquitoes are released. As a result, the spread of dengue fever can be curbed significantly.
Oxitec has been releasing these modified mosquitoes in several cities across Brazil, including Suzano in the state of São Paulo, which declared a state of emergency due to dengue fever in February. This is not the first time Oxitec’s genetically modified mosquitoes have been used. In 2021, they were released in the United States to reduce the population of disease-causing mosquitoes in the Florida Keys.
Another approach being explored by scientists involves intentionally infecting mosquitoes with a type of bacteria called Wolbachia. This bacteria reduces the mosquitoes’ ability to spread dengue fever. However, concerns have been raised about genetically modified mosquitoes producing viable offspring that could survive and pass on their genes to native insects, with unknown consequences. So far, there is no evidence to suggest that this poses any harm to humans.
The fight against dengue fever in Brazil is intensifying as health authorities employ innovative strategies to control its spread. While the release of genetically modified mosquitoes may raise some concerns, it offers hope in combating this deadly disease. As the battle against dengue fever continues, researchers and scientists are determined to find effective solutions to protect the population from this ongoing threat.
