The witch doctor spirit of Aku Aku protects from all manner of sliding seals and turtles with spikes but can't combat the threat of mosquito-borne disease.
Perhaps if Mr. and Mrs. Bandicoot weren't so distrustful of vaccines none of this would have happened, but it's too late for “what ifs.” The real mystery is why the magical mask of Aku Aku wasn't enough to prevent this situation. Thwarting dangers of the jungle is supposed to be his specialty – his one and only job, actually. Now Crash is confined to bed and dealing with these symptoms. Those wumpa fruits have done wonders for the scurvy, but they're no match for the body aches and diarrhea.
Cortex is gonna be straight furious when he finds out his nemesis was taken down by some common mosquitoes rather than any of his traps or minions. After all that money spent on deadly versions of the Scrubbing Bubbles mascot to line the sewers with, Crash is going to die from exploding blood cells and renal failure. Such an iconic character for Playstation and we're just going to ignore his suffering because Naughty Dog is busy with The Last of Us Part II.
Actually, that's fair; that game is gonna be dope as hell.