An affected host harbors approximately 11 adult female mites during a typical infestation with eggs hatching in 3-4 days. This reaction is responsible for the intense pruritus that is the hallmark of the disease. Individuals who are already sensitized from a prior infestation can develop symptoms within hours. A distinctive, highly contagious form of scabies, known as Norwegian scabies, has a predilection for immunocompromised, aged, physically debilitated and mentally impaired patients. Extensive, widespread crusted lesions appear with thick hyperkeratotic scales over the elbows, knees, palms and soles.
Extensive proliferation occurs in immunocompromised patients.
These individuals can be infested with thousands of mites at a time. Scabies is unlikely to cause long-term morbidity or mortality in an otherwise healthy individual. Prior to the introduction of antibiotics, secondarily infected scabies could cause death or serious disability from septicemia, glomerulonephritis or acute rheumatic fever. No population appears immune to scabietic infestation. Children under the age of 15 years have the highest prevalence of scabies.