Crab lice (commonly referred to as public lice) are one of the many sexually transmitted diseases that we must protect ourselves from in this day and age. The only way to get crab lice is through genital contact, because lice can only live for a day or two without the heat and humidity of the human body.
Lice survive by making small bites in the skin and feeding off of your blood (the bites are what make the area itchy). Pubic lice are called “crabs” because they have six legs that pinch around the pubic hair to keep them in place. When viewed through a microscope, they actually look like miniature beach crabs.
Crab lice are different from head and body lice in that they are adapted to live in a different environment. In rare cases they may appear in other coarse hair, such as the eyelashes or armpit, but for the most part they will only be seen in and around pubic hair.
Most people know that they have crabs because of itching and small brown spots that appear on the lower abdomen. An adult louse reproduces by hatching several eggs, which bind to the pubic hair. For this reason, crabs can also be diagnosed by the appearance of small white eggs on the hair, which are called nits. Nits usually take a week and a half to hatch.
There is a small chance of contracting crab lice through use of a shared towel, sheet, or clothing item, but the old idea that you can get them from a toilet seat is absolutely false. It is also impossible get them from animals.
Treatment for pubic lice is pretty straightforward. Shaving your pubic hair will eliminate the nits, but adult lice actually live under your skin, so they will still be alive. To truly treat crab lice you need to find a medicated ointment to put on your skin. See a doctor for a prescription for an appropriate pediculicide, which penetrate the skin to kill parasites.
After treatment, be sure to either wash your clothing and linens in VERY hot water (at least 130 degrees F) or remove them from human contact for two weeks. If you choose the latter, put clothing in a sealed plastic bag.