Scabies is an arthopodic dermatitic infection caused by Sarcoptes scabiei var hominis in humans and is characterized with intense itching as a result of heavy mite infestation on the hosts’ bodies. The similarities between Classical and Norwegian scabies end at the causal organism, whereas the differences between Classical scabies and Norwegian scabies can be stated in terms of the target population, symptoms, pathogeneticity, incubation periods and treatment options. Norwegian scabies cases are reported from HIV and HTLV patients, cognitive impaired, elderly and immunocompromised individuals. The life cycle of the ectoparasite Sarcoptes is the same in the two variants but the incubation period of the two vary largely. In a previously unexposed person, symptoms of classical scabies take 4-6 weeks to appear but in Norwegian scabies they appear much faster, in two weeks maximum (Kolar, 1991).
The number of mites present on the host body in the two cases differ significantly – compared to fewer than 20 mites in case of classical scabies, Norwegian scabies is associated with millions of them in extreme cases. This reason brings about vast symptomatic differences between classical scabies and Norwegian scabies. Whereas in classical scabies, the pruritus is the characterizing symptom, its very less in Norwegian scabies which is otherwise associated with hyperkeratotic plaques all over the hosts’ bodies specially on the scalps (Chosidow, 2000). The difference in severity of the symptoms changes the treatment regime for the two conditions. Whereas
topical ointments report good success in the case of classical scabies, in Norwegian scabies they are useless due to their limited access on thick crusts and hence oral medication is often recommended by medical practitioners. The high number of parasites makes Norwegian scabies extremely contagious in already immunosuppressed people. Thus the magnitude of the infestation is responsible for generating differences between classical scabies and Norwegian scabies and makes the two conditions easily distinguishable from each other even when the infection stems from the same parasite (Bouvresse, 2010).
BOUVRESSE, S., & CHOSIDOW, O. 2010. Scabies in healthcare settings. Curr Opin Infect Dis., 23, 111-8.
CHOSIDOW, O. 2000. Scabies and pediculosis. The Lancet, 355, 818.
KOLAR, K. A., RAPINI, R.P. 1991. Crusted (Norwegian) scabies. Am Fam Physician., 44, 1317-21.
Image adopted from http://explow.com/scabies