[mist2123]

Originally Posted by Davidj

Spoiler for Spoiler about syndrome:

They sealed the swamp because that's where it lives. The thing about every infectious agent that you have to ask yourself is, "What's the vector?". There's no human to human transmission because the syndrome isn't spreading beyond Hinamazawa. The primary infection reservoir could be an animal native to the area but they never showed any enounters between Keiichi and local animal life. The source of the contagion is probably the swamp water itself. As water from the swamp seeps into the local groundwater, it carries with it a microorganism that contaminates the water supply for the town. The microorganism has very particular tastes in environment though so the degree to which it can spread is limited. Destroy its environment and you wipe out all but the colony living inside Rena which will die when she does. Ooishi and the other visitors to the area were never infected because they didn't drink the water.

impossible why didnt the other citizens got weird? why just them??