Tracing Mosquito Evolution: Uncovering the Genetics of Disease Spread

Mosquito bites aren’t just itchy and annoying, they can also spread dangerous diseases like dengue fever, malaria, yellow fever, and Zika virus. These illnesses can be hard to diagnose and treat, and some, like dengue fever, have no vaccine. Every year, roughly 4 billion people are at risk of getting Dengue and its associated symptoms of dangerous fever, headaches, and rashes. Dengue was mostly confined to tropical areas; however, it’s growing into a global problem as cases rise in previously cooler regions. Recent work to better understand the genetic make-up of the mosquitoes that transmit Dengue has  potential insights for our ability to stop dengue fever at the source.

With this in mind, scientists studied 1206 different mosquitoes from 73 locations around the world. Using a technique called whole genome sequencing, they have read the DNA, or genetic instructions for each of these mosquitoes. Using this genetic information, they were able to distinguish two different subspecies of mosquitoes, one of which is found in North and South America, the other found in Africa. Interestingly, the study shows that these species split from their common ancestor around 320 years ago, coinciding with the trans-Atlantic slave trade. They found that different subspecies of mosquitoes have adapted to different viruses and food sources, and that breeding between these two species has led to a higher frequency of mosquitoes with a mutation that makes them resistant to chemicals used to kill them, called insecticides.

This study provides evidence of how different mosquito populations have evolved around the world, and how the interaction between these two populations have led to mutations that make them harder for humans to control. This has important effects for public health efforts that seek to manage the spread of insecticide resistance and for scientists to develop new tools to decrease the spread of Dengue fever and other mosquito-borne diseases. It’s clear that mosquitoes have some impressive tricks up their sleeves, and tackling mosquito-borne diseases will require equal ingenuity from scientists.

This study was led by Jacob Crawford Ph.D., a senior scientist at Verily Life Sciences in San Francisco, California.

Managing Correspondent: Sophia Renauld

Press Article: Genomic clues into the spread of deadly mosquitoes, Science.org

Original Research Article: 1206 genomes reveal origin and movement of Aedes aegypti driving increased dengue risk, Science

Image Credit: Mosquito Photo by Erik Karits on Unsplash