The average patient is infected with 10-15 live adult female mites at any given time. Pruritus, the main clinical manifestation, is caused by the phenomenon of hypersensitivity to the debris, eggs and feces, rather than by direct effects of the mite. The primary lesions appear between 3-10 days after exposure to the mite. These lesions include burrows, papules, vesicles and pustules. The rash usually becomes intensely pruritic several days later as the immune system requires time to mount a hypersensitive response.
Nocturnal pruritus is characteristic of scabies infestation.
It is not always a disease of overcrowding. Intense pruritus is the major morbidity associated with scabies. This often leads to excoriation and secondary bacterial infection. There appears to be no racial predisposition to acquiring scabies. Scabies can infect all age groups from infancy to adulthood.