There was an episode of Monsters Inside Me in which a woman’s cat had scratched her on the chest and transmitted a worm that was on the claw to her.
I think it was a round worm of some sort, but it was incapable of penetrating deeper, so it actually grew under her skin on her chest over about a month or so.
She said after a couple weeks it took on a distinctly serpentine shape and eventually started moving under her skin where she could clearly see that it was alive. It was a good size too about 10 inches long or so if I recall correctly.
She had it removed with no further complication, but GEEZ!
Yuk. I was scratched on the chest also. I had swollen lymph nodes in my neck and right armpit. In my case, it was good old gram-negative bacteria; Tetracycline did the trick, but I’ve never completely recovered the stamina I lost.