The Current9:17Releasing millions of modified mosquitos to fight dengue fever
It may sound like the premise for a horror movie, or a biblical plague, but the World Mosquito Program plans to release five billion mosquitos into Brazil. And the hope is they will help save lives.
The billions of bugs will be released with a bacteria called Wolbachia, all in an effort to slow the transmission of dengue fever in the country.
“[Once] you see the reductions in disease transmission, it doesn’t seem like a horror movie any more,” Scott O’Neill, director of the World Mosquito Program, told The Current host Matt Galloway.
A mosquito factory is being built for the project. It will open in 2024 and produce five billion mosquitoes each year to be released across Brazil, according to the scientific journal Nature.
The World Health Organization says there were 2.8 million cases of dengue reported in the Americas in 2022. Of those countries, Brazil reported the second most incidence, with 1,104.5 cases per 100,000 people.
Dengue fever is a viral infection, most often transmitted to humans through infected mosquitoes. A mild case can cause a high fever and flu-like symptoms. More severe cases can cause bleeding, a sudden drop in blood pressure and death.
“The situation of dengue in Brazil is becoming worse and worse every year,” said Luciano Moreira, a scientist at the Oswaldo Cruz Foundation, a public health research institution in Rio de Janeiro.
“More than 1,000 people died [in 2022] of dengue because of the spread of mosquitoes around. It’s going everywhere.”
How it works
The mosquitos with Wolbachia actually prevent the bugs from being able to transmit viruses such as dengue, as well as chikungunya, Zika virus, and yellow fever, according to O’Neill.
He was able to accomplish the tedious task of injecting tiny mosquito eggs with the bacteria.
“We actually grow these mosquitoes that contain the bacteria, Wolbachia, and then release them into communities where the bacteria Wolbachia spreads into the wild mosquito population,” said O’Neill, a micro-biologist at Monash University in Melbourne, Australia.
“Then we see dengue cases drop dramatically.”
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His organization has carried out a similar project in Australia, where he says local dengue transmission has been eliminated. A trial in Indonesia has produced similar results.
“In that trial we measured a reduction in confirmed dengue by about 77 per cent and a reduction in hospitalisations due to dengue by 86 per cent,” said O’Neill.
“It’s a big effect we’re seeing.”
‘People are desperate’
Brazil will be the World Mosquito Program’s most ambitious project yet. The goal is to release five billion mosquitos every year, nation wide, which is a level of production the organization hasn’t done before.
He says they usually can produce about 10 million mosquitoes a week. But to produce five billion in a year, it will take 100 million mosquitos a week.
“You need more automation, you need more precise conditions to grow at that magnitude. And so, yeah, this will be a fully automated facility that will be built in Brazil,” said O’Neill.
But the roll out will also be a challenge. They have two methods of deployment. They either put eggs into a small bucket of water and then let the mosquitoes grow themselves. Or, they can release tubes of adult mosquitos, letting out 150 bugs for every 100 metres across a city grid.
But he says most people won’t notice a difference.
“Often when we release the mosquitoes, the numbers we release, people most often don’t notice a change from the regular biting activity that they experience every day,” said O’Neill.
The group will have to release mosquitos in poor communities, and places that aren’t necessarily safe because they are controlled by gangs. But overall, O’Neill is confident it will make a difference in the country.
“This approach looks like it’s having a very large impact,” said O’Neill.
“It’s a challenging prospect for people to understand. But when people live in transmission areas and are fearful of the disease and the impacts it can have on families, people are desperate and hungry for new approaches.”
