I'm a flea, tick, and mosquito magnet. Any flea, tick, and mosquito within a 1-mile radius of me has a good chance of finding and feeding on me. So when I noticed my indoor-only cat was more reclusive than usual, I didn't suspect parasites. I thought she might be hibernating for the winter.
Turns out she had fleas. Hundred of them. And somehow they were all staying on her.
I gave her two baths, and the rinse water ran red.
She was extremely anemic, so I took her to an animal hospital for a transfusion.
Now she is fine, but I have to keep treating the trailer to break the flea cycle.