Crab lice are small parasitic insects that infest the pubic hair of humans. This condition is also known as pubic lice infestation. Common synonyms for crab lice are pubic lice, phthirus pubis, and crabs. Pubic lice are different from head lice and body lice. They are usually spread through sexual contact but can also be transferred from contaminated clothing or bedding. Symptoms of pubic lice infestation include itching, inflammation, and visible lice or eggs in the pubic area. Treatment involves the use of topical or oral medications, as well as thorough cleaning of bedding and clothing to prevent re-infestation.