Plantar warts are caused by an infection with HPV in the outer layer of skin on the soles of your feet. They develop when the virus enters your body through tiny cuts, breaks or other weak spots on the bottoms of your feet.
Each person’s immune system responds differently to HPV. Not everyone who comes in contact with it develops warts.
The virus isn’t easily transmitted by direct contact from one person to another. But it thrives in warm, moist environments. Consequently, you may contract the virus by walking barefoot around swimming pools or locker rooms. If the virus spreads from the first site of infection, more warts may appear.