HOW COME? Why we get warts

Why do we sometimes find warts on our hands or feet? asks a reader.

Got warts? Studies show that at least 75 percent of us will sprout at least one during our lifetime. Warts are annoyingly common because they are caused by equally common viruses, part of the group called "papilloma." Inside each warty skin hut, millions of soccer-ball-shaped papilloma particles hang out, a veritable viral par-tay.

Dozens of different papilloma viruses cause warts. And it's easy to get infected: The virus simply slips in through any small crack in the skin. So a shaving nick is like a formal invitation to virus particles, which may move in for a few months (or a few years). If you (or your immune system) is under stress, your chances of hosting papilloma partyers rise.

Piling in through an open door in the skin, viral particles issue new instructions to skin cells, causing them to multiply abnormally. The result: On a once-smooth patch of skin, a raised, scaly bump appears.

Warts can range from pinhead to pea size, often have a cauliflowerlike surface, and come in at least 10 different varieties. The most familiar are common warts, which crop up on hands and other body parts; flat warts, which are found everywhere from hands to face to legs, and plantar warts, which usually grow on the soles of the feet.

Plantar warts can be painful to walk on, and are often covered with small black specks. But the specks aren't particles of dirt. Instead, they're tiny clotted blood vessels near the wart's surface.

Papilloma viruses spread easily from one person to the next, especially in warm, moist conditions like those found in showers. If you can ignore a wart, it will usually disappear on its own in a matter of months.

If not, doctors advise making sure what you're treating at home is actually a wart. If in doubt, see your family doctor or dermatologist. For a simple wart, you can try drugstore wart removers. These contain salicylic acid, which gradually peel off the upper layers of skin. Gradually, over several applications, the virus-laden bump shrinks.

Studies show that the most effective medical remedy is freezing the wart with liquid nitrogen. Freezing often takes more than one try, and can cause pain.

And then there's duct tape. According to a 2002 study, duct tape may be even more effective than liquid nitrogen. Doctors had patients cover warts with a piece of gray duct tape, leaving it on for six days. Patients then sanded it with an emery board or pumice stone.