February 15, 2009
What is scabies?
Scabies is a parasitic skin infestation caused by a tiny mite. This mite causes a skin rash that can imitate other rashes such as drug reactions or hives.
Typically, the scabies rash is very itchy and appears as a linear track on the skin, as if the mite left footsteps as it crawled. The scientific name for scabies is Sarcoptes scabiei variety hominis. Adult females are around 0·4 mm long and 0·3 mm wide and males are smaller.
It spreads by person-to-person contact. These mites cannot fly or jump. On the surface of skin they can crawl as fast as 2·5 cm per min. On average an infested person carries about 10-15 adult mites on their body surface.
These mites penetrate the skin within 30 minutes of contact or hatching. During penetration of the skin, scabies secrete enzymes that dissolve the skin, which is then ingested by the mite as nutrient. The rash results in unbearable itching or puritis.
Female mites lay up to three eggs per day in skin burrows within the stratum granulosum layer of the skin. A single female produces as many as 40 eggs. Larvae hatch at 2-4 days and also dig burrows. In total, mature adults develop within 10-14 days.
The scabies mite also infests livestock and wild populations of dogs, cats, ungulates, boars, wombats, koalas, great apes, and bovids. Some studies estimate that from 50% and 95% of pig herds worldwide are infested with S scabiei.
Animal scabies can be transmitted to human beings, which can also result in pruritic papules (e.g., pig handler’s itch, cavalryman’s itch).
Related Posts
Filed under Scabies by skinmd
Leave a Comment