Clinical Presentation

There are 3 clinical forms of scabies: 1) Papulovesicular lesions, 2) Persistent nodules, 3) Norwegian (crusted) scabies

Classic Scabies: Distribution of Characteristic Lesions

 

Naive individuals may be asymptomatic for up to 4-6 weeks, while those who have The distinctive scabies lesions are roughly symmetrical and their locations are highly predictable. The hands are often the first body part to demonstrate cutaneous lesions, especially in the webbing and the sides of the fingers. Hand eczema may follow. Lesions are also found on the skin folds under the wrist, elbow, knee, penis, breasts, shoulder blades, and abdomen. (Orkin 14)
Above: Distribution of lesions, classic scabies Above: frequency of lesions/body part
Burrows: Classic Lesions
Scabies causes more than 4 types of lesions, of which the burrow best characterizes the disease. Burrows can be linear, curved, or S-shaped, and are generally 1-2mm wide, less than 15mm long, pink-white, and slightly raised. They are often V-shaped at one end (the burrow opening in the stratum corneum) and have a small black dot at the other end, which is where the mite resides. Burrows are most common on the fingers, wrist, penis, and feet. (Scabies, CDC)

Above: Scabies burrow

Below: Lesions on the penis

Inflammation & Rash

Above: Classic burrow

Below: Eczematized elbows, papules on abdomen

Scabies is intensely pruritic, principally at night. Excessive scratching renders the body vulnerable to secondary bacterial infection and corresponding secondary lesions. Inflammatory pruritic papules are found at most sites of infection. The popular scabies rash is oftentimes seen in areas of the body that actually lack adult female mites (buttocks, scapular region, abdomen), suggesting that the rash may be a result of both sensitization from previous infection and a reaction to immature mite stages.
Nodular Scabies
Persistent nodular scabies is found in 7% of infested individuals. This clinical variety is most likely to be manifest in children and young adults . Red-brown pruritic nodules develop primarily on the lower trunk, scrotum, and thighs. Mites are rarely found, implying that this variety represents a delayed hypersensitivity reaction to the scabies mite. (Weedon 624) Left: Lesions of nodular scabies. A burrow runs across the top. This individual is developing an intentse immune reaction to the mite's presence.
Nodular scabies occurs relatively frequently in the United States, in a ration of 1 case (nodular scabies) to 15 cases (classic scabies). Patients with nodular scabies are often diagnosed by the significant plasma IgE elevation associated with the category. Moreover, histopathology reveals that nodular lesions often extend into subcutaneous fat, unlike the lesions of classic (Weedon 624)
Norwegian (Crusted) Scabies
Norwegian scabies is highly contagious due to the large number of parasites living on the host, possibly close to 1 million mites. This variety is differentiated by vesicles and the formation of thick crusts over the skin. Although there are exponentially more mites present than in classic scabies, Norwegian scabies itches much less and often not at all. The face and ears are often involved in infection, which often results in massive orthokeratosis. Signs of Norwegian scabies are found on the face and ears.
Very thick crusts cover the skin between fingers. (Cox 569)