Scabies infestations spread most often through prolonged skin contact, making household members and sexual partners highly vulnerable, according to the Centers for Disease Control and Prevention. However, mites may also spread indirectly when individuals share infested items such as linens or clothing.
Household members are also vulnerable to scabies when sleeping on infested bedding or sharing a bed with an infested person, the Mayo Clinic explains. Outside the home, scabies infestations are most likely to occur in facilities such as nursing homes and daycares. Since the condition is contagious and spreads rapidly, treatment is likely necessary for any exposed parties.
The Sarcoptes scabiei mite causes scabies infestations by burrowing under the skin and laying eggs, the CDC notes. These microscopic mites remain under the upper layer of skin, causing intense itchiness and pimple-like rashes that commonly form on the elbows, buttocks, armpits, nipples and waist. Other typical sites include the penis, the wrists and the webbing between fingers, and some individuals develop patches of scales or blistering. In rare cases, thin, raised lines may be visible where mites tunneled into skin folds.
People with immune deficiencies are susceptible to a heightened form of the infestation known as crusted scabies, according to the Mayo Clinic. Both forms of scabies increase the risk of developing bacterial infections, such as impetigo, when individuals frequently scratch the irritated skin.