hey everyone this lesson is on scabies
and this lesson or talk about what
scabies is how its transmitted the
pathogenesis of scabies we've also
talked about different types of scabies
and we'll talk about how we can treat
scabies so scabies is a skin condition
due to infestation by mites of the
species Sarcoptes scabiei so here's an
image of that mite so the transmission
of risk factors of scabies includes
crowding so you can imagine if there's a
lot of individuals around any of those
individuals that might have scabies can
pass those scabies along to other
individuals skin-to-skin contact is
probably one of the largest ways how
these mites get transmitted and
generally speaking skin-to-skin contact
has to be direct in it has to be
prolonged so casual skin-to-skin contact
will not usually transmit scabies from
one individual to another so it has to
be direct and prolonged another way
scabies can be transmitted is through
fomites now foam lights are things like
furniture so chairs beds desks anything
that an individual with scabies might
have touched leaving mites behind on
those surfaces and then another
individual comes along and touches that
surface they can have scabies
transmitted through that way this is
generally not the case in certain types
of scabies but there is one type of
scabies I want to talk to you about that
this can be transmitted through fomites
or through indirect contact with
furniture in scabies these mites of
Sarcoptes scabiei can live for about 1
to 1.5 days without a host so they
couldn't live on a surface for a while
but eventually they will die so what is
the pathogenesis of scabies so just to
warn you the next few things I'm gonna
talk about may be distressing for some
individuals so first a female mite is
what generally causes the signs and
symptoms of scabies we'll talk about it
a little later
so what happens is a female mite
secretes proteolytic enzymes these
enzymes that can break down proteins and
enter into the skin it allows them to
enter into the epidermal layer of the
skin the outer surface layer of the skin
and when they enter they burrow in and
lay about 2 to 3 eggs per day for about
4 to 6 weeks until they die once those
eggs get laid
the larvae hatch from those eggs within
3 to 4 days and this is how the cycle of
scabies and these mites continue to
infest and cause these signs and
symptoms so what are the signs and
symptoms of scabies so first I want to
say that there are two types of
scabies there's a classic scabies and
crusted scabies both of these have
different signs and symptoms in
different distribution of infections on
the body so the first one we're gonna
talk about is the classic scabies so
classic scabies looks like this it
involves eruption of small ear 'litham
it is papules and it has an appearance
of what we call knots on a rope so if
you're to take a look at this image here
you can see that there's generally a
line that kind of attaches these three
little papules so there's a very faint
line you may not see it but then you've
got these three little papules that line
up on the line so these are the knots
essentially on a rope this is what we
say the classic
appearance of classic scabies is knots
on a rope and the big characteristic
symptom of classic scabies is pure itis
and it's generally severe pure itis so
they get very very itchy and the pure
itis is often again severe and worse at
night this is again a very common and
characteristic finding worse krytus at
night the pure itis will begin to occur
about three to six weeks after initial
colonization it seems to be due to a
delayed hypersensitivity reaction to the
mites but if an individual had been
infected with mites before they cleared
the infection or any infestation and
then they were reinvested with mites
again they can actually get pure itis
quicker and usually can be within one to
three days after a reinfestation there
is a particular characteristic skin
distribution of classic scabies
generally speaking the skin distribution
involves the webs of the fingers the
axel s of the armpit the areola and the
genitalia are generally where Classic
scabies affects individuals the other
type of scabies is crusted scabies
crusted scabies is also known as
Norwegian scabies it's less common than
classic scabies it occurs in patients
with immunosuppression very key here is
that crusted scabies occurs in
individuals with immunosuppression HIV
patients older patients patients with
cancers like lymphoma or on chemo
therapies are more likely to get crusted
scabies crisis scabies has a higher mic
burden so there's more of these
Sarcoptes mites in crusted scabies as
opposed to the classic scabies and
transmission via fomites
is more common in crusted scabies than
it is in classic scabies so you can
imagine that if there's lots of mites
more mites if
an individual with crustose KB's touches
a foam light they're leaving even more
mites behind so this is why transmission
via phone lines can be more common with
the crusted scabies in hands and feet
along with the scalp are where crushes
scabies affects individuals so how do we
make the diagnosis and how do we treat
scabies the diagnosis of scabies can
occur by microscopy so he can look at it
under a microscope and see mites and/or
eggs that can be a way to diagnose
scabies but often times scabies is
diagnosed clinically so in classic
scabies we can see pure itis that's
worse at night not on a rope appearance
of the skin lesions can be very
characteristic and you can see a
characteristic distribution where head
is spared that is again classic scabies
if it's crusted scabies you can see
crusting scaling and fishery that
affects an older immunosuppressed adult
so once we've made the diagnosis how do
we treat scabies we can use topical
permethrin so topical permethrin can be
used to treat scabies and we can use
ivermectin to treat scabies as well so
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watching and hope to see you next time