Eh. Worms are easy to treat. I would absolutely argue that the health benefits of hunting and eating raw foods, particularly for an obligate carnivore, far outweigh the concern over parasites. Millions of cats kill and eat rodents the world over. If you’re concerned, ask your vet about routine deworming every 3-4 months, or just keep an eye out for signs of tapeworms or roundworms.
The only thing that would concern me about that (and it’s not much of a concern) would be toxoplasmosis. Cats get toxoplasmosis from mice and other raw meats. Just don’t change your cats litter when your pregnent (unless you are male, in that case always change the cat litter when there is someone pregnant around.) A large portion of the population already tests positive for toxoplasmosis, and if you’ve been a cat person all you life, you probably already test positive as well.
On the other hand, my wife has been a cat person all her life and she tested negative for toxoplasmosis despite the fact that her grandmother caught it while pregnant with her mother. Needless to say, changing the cat litter is my job for the next few months.
Most cats are natural mousers, but they’re not always so dedicated to getting every last mouse. That’s more a terrier’s style. As for the group of ten tails, many cats do that. We can guess that it’s for the human’s approval, but you never know with cats. 
As a Vet Tech and as a shelter worker who’s shelter houses approximately 250-300 cats at any given time, I can personally attest to mice not caring about the presence of cats as long as there’s food for them to get to! We had an infestation of mice about 5 years ago, that required visits from the Orkin man for several months to eliminate. Believe me, it was quite the controversy and debate for a humane organization to resort to the means we needed to eliminate the mice. However, this is a city, and unfortunately, the mice were indeed damaging our building’s foundation, damaging supplies, and threatened other problems such as health issues for the people who work there and the cats who live there. Once we moved the main food storage (giant bags of kibble) out of the basement and into an industrial outdoor storage shed, the mice finally disappeared.
Some of the cats did catch mice and were none the worse for the wear. However, our shelter has strict deworming protocols, and all the cats also get doses of an anti-parasitic called Revolution that is applied topically once a month. Fleas are the carriers of tapeworm. Cat eats flea-infested mouse, cat gets tapeworm. Keep the flea’s life cycle from completing by using topical flea medication.
Everyone who has responded is right, especially if you’re in the country, mice are probably not harmful (as long as anti-parasitic precautions are taken) and in terms of raw-food for kitties, it’s ideal since they are carnivores. I know a lot of people who feed raw food to their cats and dogs, and those are some of the healthiest animals I’ve seen.
And as for toxoplasmosis, it’s a bad, bad, thing for fetuses. However, I know two women who work at the shelter - one who’s been there for 12 years - who both got tested and had negative titers. Completely negative titers, not +1 which would indicate past exposure, but totally negative.
I had to share. I’m shutting up now…
On an almost completely unrelated note, my family has a German shepherd who considers herself something of a mousing dog, providing for the pack by catching mice in the (fairly smallish) back yard and leaving them on the back porch for us. We try to get angry, but she is a master of being cute and looking proud of her accomplishment.
We’ve had a cat in the house for nigh on ten year now and of late there have been no mouse, rabbit or bird remains around the garden. I’m not sure if our current cat is just a bad mouser or if the continual presence and some sort of tribal mouse memory of the excellent mousers we’ve had in the past have scared them all away.
I always assumed it was along the lines of waking up next to a severed horses head.