Do you know what the most dangerous creature in the world is? The one that has been responsible for more human deaths and illnesses than any other?
The mosquito. And it's not even close.
They've brought us such pleasant surprises as malaria, yellow fever, the Zika virus, Dengue Fever, Sleeping Sickness, Chagas Disease, West Nile virus, and a bunch of other diseases you've probably never heard of. The number of illnesses and deaths ascribed to these various diseases is nothing short of staggering.
And now scientists have genetically altered the mosquito in the hopes that they would help lower the mosquito population. You see, these new ":Franken-mosquitoes" were supposed to die quickly. Didn't happen, and even worse, these genetic changes just might make them harder to kill. Which means that the lowly, annoying mosquito could be an even more powerful disease transmitter. File this under unintended consequences.
Bugged Out: https://www.thesun.co.uk/tech/9947305/deadly-super-mosquitoes-accidentally-created/
WHO Executive Summary on Insect-borne Diseases: https://www.who.int/whr/1996/media_centre/executive_summary1/en/index9.html