Back in the old days on my grand parents' farm there was a large old wood house. They had lived in the house years before, but after building a new home they used the old house for storing tools, tobacco sticks, and occasionally bundles of tobacco.
Somehow, the front two rooms (that were used for tools) got infested with fleas. I think maybe one of the old hounds had a litter of puppies in one of the rooms. Before you knew it the fleas were so bad that you couldn't walk into those two rooms without getting literally covered with fleas.
I don't know if they ever cured the problem. It got to the point that I wouldn't even go near the old house. It finally burned down. If it hadn't been cured before, I'm sure the blaze fixed it.