Pthiriasis is an infestation of the human pubic region by the parasitic louse known as Pthirus pubis. This infection is commonly known as "crabs"; It primarily spreads via sexual contact with individuals who are infected with the parasite. Hence, it is classified as a sexually-transmitted disease (STD) Pthirus pubis is an ectoparasite (meaning it lives on the outside of its host organism) that requires the blood of its host for survival Infected individuals may present symptoms, such as mild to severe itching in the genital area, where the parasites reside. A healthcare provider may diagnose Pthiriasis upon inspection of the pubic area for lice or eggs of P. pubis