27 - 178 - SCABIES, OTHER MITES AND PEDICULOSIS Flashcards
Incubation period of Scabies
4 - 6 weeks
What is the parasite in scabies
Sarcoptes scabiei var. homini
The scabies mite is able to live for ____ days away from the host in a sterile test tube, and for ____ days if placed in mineral oil mounts.
3 days
7 days
The female mite, by a combination of chewing and body motions, is able to excavate a sloping burrow of ______mm/day in the stratum corneum to the boundary of the stratum granulosum
0.5 to 5 mm/day
Lifespan of scabies in the skin
30 days
Scabies eggs hatch in how many days
10 - 12 days
In scabies, after the larvae molt, they become nymphs which can only survive_____ days off host.
2 to 5
Pruritus typically appears how many weeks after initial infestation
4 to 6 weeks
Pathognomonic lesion of scabies
Burrow
What can you do to identify a burrow?
Identification of a burrow can be facilitated by rubbing a black felt-tip marker across an affected area. After the excess ink is wiped away with an alcohol pad, the burrow appears darker than the surrounding skin because of ink accumulation in the burrow.
Scrapings for mineral oil examination can be best taken from what sites?
Scrapings are best taken from a burrow, papule, or vesicle that is not excoriated.
A definitive diagnosis is made by microscopic identification of the scabies mites, eggs, or fecal pellets (scybala). This is accomplished by placing a drop of mineral oil over a burrow and then scraping longitudinally with a number 15 scalpel blade along the length of the burrow or a suspicious skin area, being careful not to cause bleeding.
The scrapings are then applied to a glass slide and examined under low power
In scabies, most treated individuals experience relief of symptoms within how many days after treatment
3 days
but patients must be informed that even after adequate scabicidal therapy, the rash and pruritus may persist for up to 4 weeks.
Differential diagnosis of scabies
Give at least 5 treatment options for scabies
Scabies treatment with antipruritic property
Crotamiton 10% cream
Apply for 8 hours on days 1, 2, 3 and 8
What anti scabies treatment is Considered safe in neonates and during pregnancy
Precipitated sulfur 5 - 10%
This medication has received a “black box” warning as well as restrictive labeling changes from the U.S. Food and Drug Administration (FDA) to greatly restrict its usage. Moreover, it is banned in California.
Black box” warning warns against usage in premature infants and individuals with known uncontrolled seizure disorders, as well as cautious usage in infants, children, and the elderly including people who weigh less than 50 kg (110 pounds) and over 65 years old may be at risk of serious neurotoxicity.
Lindane 1% lotion
Pregnant females, breastfeeding mothers, and children younger than age 2 years should limit their 2 applications (1 week apart) to how many hours only when using permethrin.
2 hours
Ivermectin has been approved since 1996 by the FDA for treatment of what 2 diseases
onchocerciasis
Strongyloidiasis
Dose of ivermectin for scabies
200 µg/kg given twice 1 week apart.
Ivermectin is not recommended for use in children who weigh less than how many kg or in pregnant or lactating women.
15 kg (33 lbs)
only mites that routinely live on humans
Demodex folliculorum hominis and Demodex brevis
Mite that resides in the hair follicles
Demodex folliculorum hominis
Demodex that resides in the infundibulum of the sebaceous gland
Demodex brevis
Species of lice for head louse
Pediculus humanus capitis
Lice species of Body/clothing louse
Pediculus humanus humanus
Lice species of pubic or crab louse
Phthirus pubis
After the initial exposure, it may take ____ weeks for the pruritus to occur. Subsequent exposure results in symptoms within ______ days of exposure
2 to 6 weeks
1 to 2 days
Transmission of head lice
Transmission occurs primarily by means of direct head-to-head contact and less commonly by indirect (fomite) transmission through combs, brushes, blowdryers, hair accessories, upholstery, pillows, bedding, helmets, or other headgear
Life span of head lice
30 days
How many days will it take before the eggs of head lice hatch producing larvae referred to as “nymphs” or “instars”
10 days
Lice typically survive less than how many days away from the scalp?
Nits can survive for ______ days away from the scalp.
Less than 2 days - lice
10 days - nits
The average incubation before symptoms occur in head lice infestation
4 - 6 weeks
Differentiate newly laid pediculosis eggs vs hatched nits based on location on the scalp
newly laid eggs are usually identified within a few millimeters of the scalp and lice embryos can be seen on dermoscopy, while hatched nits are usually further from the scalp
Give 5 treatment options for pediculosis capitis aside from permethrin
First choice treatment for pediculosis capitis
Permethrin 1% lotion Topically to damp hair for 10 minutes, rinse then repeat in 7 days
Permethrin 1% lotion is approved for patients older than?
2 months
Which pediculicidal medication has a black box warning because of risk for neurotoxicity
Lindane 1%
body louse’s life span
20 days
Epidemic typhus is caused by
R. prowazekii
Murine typhus is caused by
Rickettsia typhi
Relapsing fever is caused by
Borrelia recurrentis
What is the preferred treatment for pediculosis pubis
Oral ivermectin
adult crab louse can survive for how many hours off the human host
36 hours
skin lesions named ____________ representing hemorrhage, can be seen with pubic lice, with slate gray to bluish, irregular-shaped macules approximately 1 cm in diameter
maculae caerulea
infestation of the eyelashes with crab lice
Pediculosis palpebrarum, or phthiriasis palpebrarum
T/F. Shaving is not curative for pediculosis pubis
TRUE
Shaving is not curative as the louse will seek another hairy area of the body to reside
Nits are usually found on what part of the scalp
Occipital and retroauricular regions
first-line therapy for Phthiriasis palpebrarum
Ivermectin
