|
|
Sarcoptes scabei undergoes four stages in its life
cycle; egg, larva, nymph and adult. Females deposit eggs at 2
to 3 day intervals as they burrow through the skin .
-
Eggs are oval and 0.1 to 0.15 mm in length
-
and incubation time is 3 to 8 days. After the
eggs hatch, the larvae migrate to the skin surface and burrow
into the intact stratum corneum to construct almost invisible,
short burrows called molting pouches. The larval stage, which
emerges from the eggs, has only 3 pairs of legs,
- and this form lasts 2 to 3 days. After larvae molt, the resulting
nymphs have 4 pairs of legs .
- This form molts into slightly larger nymphs before molting into
adults. Larvae and nymphs may often be found in molting pouches
or in hair follicles and look similar to adults, only smaller.
Adults are round, sac-like eyeless mites. Females are 0.3 to 0.4
mm long and 0.25 to 0.35 mm wide, and males are slightly more
than half that size. Mating occurs after the nomadic male penetrates
the molting pouch of the adult female .
- Impregnated females extend their molting pouches into the characteristic
serpentine burrows, laying eggs in the process. The impregnated
females burrow into the skin and spend the remaining 2 months
of their lives in tunnels under the surface of the skin. Males
are rarely seen. They make a temporary gallery in the skin before
mating.
Transmission occurs by the transfer of ovigerous females during
personal contact. Mode of transmission is primarily person to
person contact, but transmission may also occur via fomites (e.g.,
bedding or clothing). Mites are found predominantly between the
fingers and on the wrists. The mites hold onto the skin using
suckers attached to the two most anterior pairs of legs.
|
|
|
|
Head Lice , Body
Lice,
Pubic Lice, Scabies
or
Bed Bugs |
|
|
|
