Feb 15, 2024 - World

Modified mosquitoes may save millions more lives in Latin America

A young boy holds up a tube with mosquitos in it. A person with a lanyard stands behind him.

A child holds a sample of bioengineered Aedes aegypti mosquitoes during an information session in a Brazilian classroom. Photo: Courtesy of World Mosquito Program

A program that uses genetically engineered mosquitoes in Brazil, Colombia and Mexico to reduce the prevalence of diseases that can be fatal may soon serve millions more people.

Why it matters: Outbreaks of dengue, chikungunya, zika and yellow fever —diseases carried by the Aedes aegypti mosquito —have long hit the Americas and other tropical regions hard.

  • Climate change has worsened the spread of these diseases, experts say, as rising temperatures favor the life cycle of the mosquitoes and their proliferation in more areas — including, increasingly, the U.S.
  • These diseases also tend to affect impoverished regions where a lack of health care options mean mosquito bites can become deadly.
  • Diseases such as dengue "feed on poverty and inequity, and they fuel it also," World Health Organization chief Tedros Adhanom Ghebreyesus said last week during an event in Brazil.

What to know: Studies show that over the past few years, work led by the World Mosquito Program in collaboration with local groups and governments has contributed to 70% fewer dengue cases and 56% fewer chikungunya cases in Niterói, Brazil.

  • In another targeted city, Medellín, Colombia, dengue contagion reports dropped by up to 97% from 2022 to 2023.
  • The program, first launched in Latin America in 2014, has been slowly expanding and will grow even more with a new factory that will, by year's end, be able to manufacture up to 100 million bioengineered mosquito eggs a week.
  • That could protect 70 million people in Brazil over a decade, although researchers hope to use the factory to supply other nations, too.

How it works: Mosquito eggs are injected with the bacteria Wolbachia, which has been nicknamed a Trojan horse as it neutralizes the mosquitoes in several ways:

  • The bacteria slows down the replication of the virus mosquitoes carry, sometimes making it inactive so that the mosquito doesn't spread it even if it bites.
  • When male mosquitoes with Wolbachia mate with female mosquitoes without the bacteria, their eggs don't hatch.
  • When female mosquitoes with Wolbachia lay eggs, the larvae hatch already carrying the bacteria, making it far less likely that they'll be able to spread diseases for several generations.

What they're saying: The modified mosquitoes are released only with buy-in from local communities and governments, says Luciano Moreira, lead of the World Mosquito Program in Brazil and a researcher at the Oswaldo Cruz Foundation, a leading public health institution.

  • "Partnerships with the communities and governments is part of what helps the program be successful," Moreira tells Axios Latino.

Yes, but: Using Wolbachia is only one part of the solution.

  • A recent paper published in The Lancet medical journal says bug spray use should remain a priority, especially as mosquitos spread to places where they were once rare, like central-northern Europe.
  • Most mosquitoes are able to breed in people's homes in stagnant water, so campaigns telling people to cover water containers and use nettings also matter.
  • Vaccines, like a new one against chikungunya and recent ones against some dengue strains, will also help make a difference, the Pan-American Health Organization says.
  • But the health agency stresses that rollout to enough people will take time, especially as prices of these vaccines make mass purchasing difficult.

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