Dear Dr. Fox: I adopted a cat from the Golden Valley Humane Society. He was tested for ear mites, given Revolution, neutered, two teeth were removed and his lacerated left front leg received stitches. They started him on an upper-respiratory antibiotic and I took him home.

Upon bringing him home, I noticed he was itching a lot, so I took him to a vet and he was treated further for ear mites and roundworm. The itching persisted throughout his body and white things came out of his fur.

The vet did not know what the white things were. Subsequently, I took several samples to the diagnostic vet lab at the University of Minnesota, but the tests were inconclusive.

It was suggested that he might have a walking mite of some sort. We gave him a series of three shots of Ivomec two weeks apart, and then a fourth about a month later.

The white things continue to come out. It seems they will use human hosts, as well -- I have some embedded in my skin. They produce a burning or prick sensation. I have some behind my left ear and other smaller skin spots. -- S.P., Minneapolis, Minn.

Dear S.P.: Your cat most likely became infested as a kitten while in contact with decaying organic matter like straw and filthy bedding in a barn or stable.

Minute worms -- saprophytic nematodes called Pelodera (Rhabditis) strongyloides -- thrive in these kinds of moist materials.

Being a skin parasite is not typical. They only occasionally invade the skin of dogs, cows, horses, sheep, guinea pigs and humans. Other species of this parasite, especially in the tropics, can be fatal to humans.

Other alternate skin parasites include hookworm and heartworm. Occasionally, another strongyle worm (Strongyloides cati or tumefaciens that can infest a cat's small intestines) also may live free in a cat's environment, and the larvae invade the cat's skin.

All bedding should be destroyed and clean sheets put down where the cat lives after the cat has been treated with a cat-safe parasiticidal dip or spray. Treatment should be repeated a week later.

Alternatively, a treatment regimen using albendazole or thiabendazole may eliminate these parasites.

If the parasites persist in infesting you, I would urge you to call your state public health authorities -- but put the cat in quarantine at the vet's first, since some public health agents have little respect for animals suspected or known to have a zoonotic (human-transmissible) disease.

Dear Dr. Fox: We have been responsible for feeding four feral cats. We had them spayed and neutered through a local feral-cat program.

One of the male cats (shorthair) has recently started losing fur on the back of his neck, and the fur loss is starting to affect the top of his head. The exposed skin looks clear, intact and without broken or apparent bite areas.

I periodically put brewer's yeast in all the cats' food and brush them, but fleas do not appear to be a big problem. What do you suggest I try for the male cat? -- M.D.C., St. Louis, Mo.