Rising seas tuned the shorelines into swampy wetlands host to all forms of wildlife. The marshy conditions created ideal breeding grounds for mosquitoes which began carrying a nasty germ that killed thousands. The genesis of this new pathogen was oft-debated, some believing it to be an evolved form of malaria while others claimed it was an altogether new menace that had escaped from the melting ice caps.
Regardless of its origin, the mosquito plague claimed many lives in the decades following G-Day. Although the measures taken by Thayer Corporation to fight the epidemic were met with general success, the mosquito plague decimated the population on two occasions. The most severe was after the 2022 arctic event which rapidly pushed the shorelines (and mosquitoes) further inland. The second major flare-up was in the early 2030s. Just as malaria frequently appears in cycles, this outbreak was believed to be a concomitant of the first.