Jes Grew?

When I first started reading Mumbo Jumbo, I was really confused about Jes Grew. So some people get this...illness(?) which makes them want to dance and be happy? Really? Is this supposed to be something to really worry about or was it created as something to not be taken seriously? Oh, so this could threaten the Western civilization? Well how? What does people dancing around and being happy have anything to do with civilization? It made no sense to me. I thought at first that Jes Grew was supposed to be something like immigration. Immigrants would bring over their culture, which would spread, just like Jes Grew, and there would be people worrying about how the culture of Western Civilization would be threatened by the new culture of various immigrants. Jes Grew seems harmless, just like immigration, but it's over-hyped by the media and older generation who don't like change. However, as the book progresses, it's revealed that Jes Grew is a movement and it completely shot down any thoughts I would've had about what Jes Grew is. Aw screw it, there's always next time, and deep conclusions are for tools and English teachers anyway.