Modifying Mosquitoes to Stop Transmission of Dengue Fever

1. Modifying Mosquitoes to Stop Transmission of Dengue Fever Dengue is a virus spread via the Aedes aegypti mosquito that infects as many as 100 million people annually in more than 100 tropical countries worldwide. It causes fevers, extreme headaches, and muscle and joint pains. In a few extreme cases, leakage of blood plasma through the walls of small blood vessels into the body cavity occurs, resulting in bleeding. This is known as dengue hemorrhagic fever. For more information, visit: https://speakingthreads.com/republication-policy/ Global Dengue Transmission Risk Map. World Health Organization The number and severity of dengue infections has been escalating since the Second World War, culminating in a 30-fold increase between 1960 and 2010. It is now 20 times more common than the flu. Because of global warming, decreased heavy pesticide use due to environmental concerns, and the Aedes mosquito’s preference for urban environments, the insect – and the virus it carries – are rapidly spreading around the world. There is no treatment for dengue fever. At best, doctors can give their patients supportive care, such as painkillers and liquids to keep them hydrated. Untreated dengue fever has a mortality rate of about 5%; fortunately, with treatment that number drops to zero and each year “only” 20,000 dengue deaths are recorded.

2. As a result of its prevalence all around the world, scientists are looking for new ways to control Aedes mosquitoes – and thus dengue transmission. Helpful host The dengue virus does not harm its mosquito host. When an infected female mosquito bites a person, the virus enters the blood stream with the mosquito’s saliva and anticoagulant. Aedes aegypti are smaller and quieter than the mosquitoes typically found in the US. They thrive in urban environments and are more at home in the city than in the jungle. Controlling and limiting Aedes habitats is extremely difficult since they like to live indoors, residing in places such as dim closets and cupboards. They can lay eggs in a single drop of water. The stealthy bloodsuckers enjoy feeding around human beings’ ankles, biting as many as 20 people a day. Transmission electron micrograph depicts a number of round, dengue virus particles in a tissue specimen. Frederick Murphy Somehow, the simple dengue viruses with RNA genetic material coding for just 10 proteins can change the production of 147 different proteins expressed by Aedes. It makes the mosquito hungrier for human blood, its saliva more hospitable to the viruses, and changes the protein mix in the antennae of the mosquitoes making them more sensitive to odors –thereby increasing the mosquito’s ability to find a victim. Bombarding them with bacteria An Australian group led by Scott O’Neill at Monash University has infected mosquitoes with bacteria that prevent the dengue viruses from taking up residence in the mosquito. It prevents the dengue’s carrier from hosting the virus. The Wolbachia-infected mosquitoes are the result of an idea that O’Neill had 20 years ago. He knew that Wolbachia-infected fruit flies would not transmit any RNA virus. So he hoped Wolbachia-infected Aedes aegypi would act in the same way and not transmit dengue, an RNA virus. The trouble was, even though Wolbachia infections are common in many insects, including non-Aedes mosquitoes, he couldn’t infect sufficient numbers of Aedes with the bacteria. He says he persisted because, “I thought the idea was a good

3. idea, and I don’t think you get too many ideas in your life, actually. At least I don’t. I’m not smart enough.”