The characteristic symptoms of a scabies infection include intense itching and superficial burrows. The burrow tracks are often linear, to the point that a neat "line" of four or more closely placed and equally developed mosquito-like "bites," is almost diagnostic of the disease.
Itching
In the classic scenario, the itch is made worse by warmth and is usually experienced as being worse at night, possibly because there are fewer distractions. As a symptom it is less common in the elderly.
Rash
The superficial burrows of scabies usually occur in the area of the hands, feet, wrists, elbows, back, buttocks, and external genitals. The burrows are created by excavation of the adult mite in the epidermis.
In most people, the trails of the burrowing mites show as linear or s-shaped tracks in the skin, often accompanied by what appear as rows of small pimple-like mosquito, or insect bites. These signs are often found in crevices of the body, such as on the webs of fingers and toes, around the genital area, and under the breasts of women.
Symptoms typically appear 2–6 weeks after infestation for individuals never before exposed to scabies. For those having been previously exposed, the symptoms can appear within several days after infestation. However, it is not unknown for symptoms to appear after several months or years. Acropustulosis, or blisters and pustules on the palms and soles of the feet, are characteristic symptoms of scabies in infants.
Crusted scabies
The elderly and people with an impaired immune system, such as HIV, cancer or those on immunosuppressive medications, are susceptible to crusted scabies (formerly called "Norwegian scabies"). On those with a weaker immune system, the host becomes a more fertile breeding ground for the mites, which spread over the host's body, except the face. Sufferers of crusted scabies exhibit scaly rashes, slight itching, and thick crusts of skin that contain thousands of mites. Such areas make eradication of mites particularly difficult, as the crusts protect the mites from topical miticides, necessitating prolonged treatment of these areas.