This is a great jam submission. The game is well polished, and has a clear gameplay loop that is a humorous take on the theme. It took me a bit to recognize what I was supposed to do, I got distracted by the population counters and tried to target the highest city with whatever natural disaster I could find near them. I think because I was immediately pressured with the task of getting rid of the parasite I didn't connect that the light bulb is what I needed to target.
The only things I can even think to critique is I would have liked to have had some visual indication of the disasters being ready to be used. I was just flying around scribbling my mouse on the disasters near cities hoping to find one that was recharged. I also didn't really have time to pay attention to what the upgrades did. Not sure if there's anything that can be done about that, perhaps having a level up button that opens a popup to pause the game and let you pick what you wanted. But I'm just nitpicking at this point, these are minor complaints that didn't really harm my experience.
Excellent job.