The Scabies mite burrows and lays eggs under the outer layer of skin (epidermis). The faeces deposited in the burrow cause an allergic reaction, leading to a rash around the site of the burrow. Each burrow contains a fecund female which lays eggs; after three or four days the baby mites (larvae) hatch and move to the surface of the skin where they mature into adults.
Scabies thrive in warm places, such as skin folds, between the fingers, under the fingernails or around the buttocks. They can also be found under jewellery such as rings and wrist watches. The incubation period for scabies is up to eight weeks i.e. the length of time it can take for the symptoms of scabies to appear after initial infection. A simple skin scrape and examination under low power microscopy will reveal the adult and eggs.
Crusted scabies (Norwegian scabies) is a rare form of the disease which affects people with impaired immune systems or the elderly, disabled or debilitated. It is a hyper-infestation, with thousands or millions of mites present in scales of exfoliated skin; people with crusted scabies may not show the usual signs and symptoms such as rash or itching. Individuals with crusted scabies are more contagious and can spread the infestation easily both, by direct skin to skin contact or by contamination of items such as their clothing, bedding and furniture.
