Scabies is a transmissible ectoparasite skin infection characterized by superficial burrows, intense pruritus (itching) and secondary infection.
Caused by the mite Sarcoptes scabiei, variety hominis, it produces intense, itchy skin rashes when the impregnated female tunnels into the stratum corneum of the skin and deposits eggs in the burrow.
The larvae, which hatch in 3-10 days, move about on the skin, molt into a "nymphal" stage, and then mature into adult mites.
The adult mites live 3-4 weeks in the host's skin.
The motion of the mite in and on the skin produces an intense itch which may resemble an allergic reaction in appearance.
The presence of the eggs often produces a massive allergic response which, in turn, produces more itching.
Scabies is transmitted readily, often throughout an entire household, by prolonged skin-to-skin contact with an infected person (e.g. bed partners).