infestations Flashcards
Pediculous humanus capitis aka ?
head lice
- Highly contagious disease that often occurs in schools and day-care centers
- It can cause outbreaks anywhere that people live in close quarters, including nursing homes, dorms, prisons.
- There is usually intense pruritus of the scalp
dx?
pediculosis capitis
describe a louse
- 1-3 mm long, flattened brownish-gray, with 3 pairs of legs and claws
- lifespan 14-18 days
- nits are 1 mm in diameter and opalescent
Pediculosis Capitis is MC in who and during when?
- MC in females
- White school aged children/mothers
- Warmer months
may be mistaken for pediculosis capitis; however, these scales are greasy, yellow, irregular in shape, and are easily removable, unlike the scales of pediculosis capitis, which adhere to the hair shaft
ddx?
seb derm
similar pruritus and lymphadenopathy but is associated with alopecia. Nits are not found on close examination of the hair
ddx?
Tinea capitis
living off plant detritus may be found in the scalp of a child who plays in wooded areas but are morphologically distinct from Pediculosis humanis capitis
ddx?
Psocid lice
3 ddx for Pediculosis Capitis that cause pruritic scalp but are morphologically distinctive skin disorders
- Psoriasis
- lichen planopilaris
- folliculitis
transmission and lifespan of pediculosis capitis
- Transmission is by close contact
- Direct head-to-head contact and fomites (eg, on clothes, brushes, linens, combs, hats, etc) - Lice live approximately 30 days on the host and <1 day off the host only a few hours.
- Eggs (nits) hatch within 7-10 days
- Maculae ceruleae or purpuric stains on the skin of the occipital scalp and nape of neck
- Occipital lymph nodes may swell as a result of secondary infection
- Microscopy will reveal an oblong structure attached to the hair at an acute angle with a lobular breathing apparatus at its superior end
dx?
Pediculosis Capitis
diagnostic pearls of Pediculosis Capitis
- Pyodermas in scalp along with occipital and cervical LAD suggest possible pediculosis infestation
- Nits are oval, tenacious hair concretions
- nits are not easily removed from the hair
- Hair casts, seen in other scalp disorders, move freely on the shaft Nits fluoresce and are readily detected with a Wood’s lamp
Infection with bacteria causing pus under the skin
term?
Pyodermas
best tests for pediculosis capitis
- Demonstration of lice or nits on hair visually or under microscope
- Wood’s lamp demonstrates fluorescent nits
There is evidence of increasing resistance of lice to treatment with ____
permethrin
what may be used as an adjuvant to topical therapy fir pediculosis capitis
Manual nit removal with a fine comb
Standard Precautions for pediculosis capitis
Isolate patient, wear gloves and a gown, limit patient transport, and avoid sharing patient-care equipment
Pediculosis capitis Rx should be reserved for patients with ?
proven infestations that do not respond to proper application of OTC pediculicides
for pediculosis capitis, do not treat a child unless ?
live lice or eggs (not just empty nit cases) are present
OTC options for pediculosis capitis
- Permethrin 1% (Nix): Apply to dry hair, and rinse after 10 minutes Repeat in 1-2 weeks
- Pyrethrins with piperonyl butoxide (RID, Pronto): Apply to dry hair, and rinse after 10 minutes Repeat in 1-2 weeks.
other 5 tx options for pediculosis capitis
Spinosad - adults and children older than 4 years
Malathion 0.5% lotion (Ovide)
Permethrin 5% (Elimite) (off-label use)
Ivermectin-formulated lotion (Sklice Lotion)
Oral ivermectin (off-label) - Not indicated in children < 5 yrs or wt < 15 kg.
Combing of the hair is not necessary, as this agent is ovicidal = first-line lice treatment by the American Academy of Pediatrics
which medication?
Spinosad
tx for pediculosis capitis on eyelid?
petrolatum BID to eyelid margins x 8 days
pediculosis corporis is Rarely found on the skin, as they live in and lay eggs on ?
clothing
- Extremely pruritic, especially at night when the lice move from the clothing to the body to feed
- The bites leave behind macules and papules concentrated in the intertriginous regions
Pediculosis Corporis
Pediculosis Corporis affects which pt demographics?
- all countries and climates, may infest any age group
- no racial or sex predilection
- associated with poor hygiene, poverty, homelessness
- Multiple erythematous papules that correspond to the insect bites
- Found anywhere on the body but are most concentrated in areas covered by clothing: groin, axillae, trunk, and buttocks
- Maculae cerulea
- There may be excoriations and/or impetiginization
- Exam the clothes; may reveal nits, feces, blood stains, or the insects themselves
dx?
pediculosis corporis
blue-gray macules that are pathognomonic for a lice infestation, may be present
maculae cerulea
individuals that are infested for years may develop thickened and darkened skin after a long period of bites and scratching or rubbing
what is this called
“vagabond skin” (parasitic melanoderma)
best tests for pediculosis corporis
- Close examination of the patient’s clothing for lice, nits, and feces
- The finding of a live louse or a viable nit will confirm the diagnosis
- Wood’s lamp may be helpful fluoresce yellow-green
- They are frequently most concentrated at clothing seams.
- shake the clothing out over white paper and examine the debris that falls off = pieces of tape can be used to pick up the insects for examination
If clinical suspicion warrants, test for one of the three arthropod-borne diseases transmitted by P. humanus corporis:
- Typhus (Rickettsia prowazekii)
- Relapsing fever (Borrelia recurrentis)
- Trench fever (Bartonella quintana)
- The mainstay of treatment is eradicating the infestation.
standard precautions for pediculosis corporis
Isolate patient, wear gloves and a gown, limit patient transport, and avoid sharing patient-care equipment
how to treat clothing and fomites in pediculosis corporis
- All clothing and bed linens should be washed with hot water and dried using high heat
- Discard or avoid using heavily infested items for 2 weeks (seal in plastic bags)
- Iron the seams of furniture with a hot iron
- For heavy infestation 5% permethrin cream or lotion head-to-toe for 8-14 hours
- Highly contagious, sexually transmitted parasitic infestation with the pubic or crab louse, Phthirus pubis
- MC spread from person to person by close physical contact, but it may occasionally be spread via fomites such as clothing or linens
- Household pets do not play a role in transmission
dx?
Pediculosis Pubis
- MC in sexually active individuals
- lives on terminal hair, typically in the pubic and perianal regions, although infestations may also be noted in the eyelashes (pediculosis palpebrarum), eyebrows, and other facial hair, as well as chest and axillary hair
- Scalp infestation may also be seen in tightly curled hair
- The lice are not adapted for crawling
dx?
Pediculosis Pubis
a fibrous substance consisting of polysaccharides and forming a major constituent in the exoskeleton of arthropods.
Chitin
in pediculosis pubis, The ___ are cemented to hair shafts with ____ and are difficult to remove
eggs (nits)
chitin
Pediculosis Pubis is extremely pruritis
it is thought to be secondary to ?
a reaction to the saliva and/or the anticoagulant injected into the skin by the louse during feeding
on dermoscopy you see legs grasping the hair shaft and insertion of mouth parts into the skin
dx?
Pediculosis Pubis
- Nits = brown and full in shape, indicating the presence of a nymph, or they are translucent and more flat in shape when empty
- They may be mistaken for crusts or hair casts when attached near the ostia of hair follicles
other clinical signs of pediculosis pubis
- Erythematous macules or papules present at feeding sites
- Wheals can be appreciated as an acute reaction
- Small pinpoint bleeding on intimate clothing
- +/- Inguinal lymph node swelling
- +/- Maculae ceruleae, or blue-gray macules seen at feeding sites on patients with long-standing infestation
best tests for pediculosis pubis
Finding the louse or nit is diagnostic
CDC recommendations for pediculosis pubis
- sexual partners within the prior month should be notified of possible infestation and should be treated
- Avoid sexual contact until they and their partners have been treated and reevaluated to rule out persistent disease
- Advise patients that condoms do not prevent transmission of infestation
30% of patients with pediculosis pubis infestation also may have concomitant infection with another ?
therefore, thorough review of systems and appropriate laboratory screening should be encouraged
sexually transmitted infection
Steps for containment of peiculosis pubis:
- Machine wash (130° F) and machine dry any clothing, linens, or towels that were worn in the 3 days prior to treatment
- If unable to launder, items can be dry cleaned or stored away in air-tight plastic bags for 2 weeks
- If utilized in affected areas, soak combs and brushes in very hot water x 5 min
- Avoid sharing clothes, linens, and towels
- Thorough cleaning of living quarters - lice are able to live on fomites
tx recommendations for adults in pediculosis pubis
- Many OTC products, although may benefit from thorough exam by a provider
- Treat all affected areas
- if increased hair density - treat adjacent areas
- Shaving the involved area(s) but not essential to resolve the infection
- determined by the patient’s preference - Treat any secondarily infected lesions
Medication regimens (preferred by CDC) for pediculosis pubis
- Permethrin 1% lotion / cream
- Mousse containing pyrethrins
- Wash the infested area and towel dry
- Apply the product generously to affected areas
- Leave product on for the duration indicated on the package label or insert
- Following treatment, nits can be forcibly removed from hair shafts with fingernails or with a fine-toothed comb
indications for Permethrin (Nix, Elimite)
scabies, head lice, body lice, pubic lice
CI of permethrin
< 2 months old, hx of hypersensitivity
MOA permethrin
neurotoxin resulting in respiratory paralysis of parasite
Pregnancy category B
SE of permethrin
transient burning, stinging, pruritus, redness, swelling
MOA of Pyrethrin/piperonyl butoxide (Rid - OTC)
pyrethrin: neurotoxic to parasite
piperonyl butoxide: synergistic to pyrethrin
CI of Pyrethrin/piperonyl butoxide (Rid - OTC)
hx of hypersensitivity to product or ragweed, < 2 y/o
SE of Pyrethrin/piperonyl butoxide
transient burning, stinging, pruritus, redness, swelling
indications for Malathion (Ovide - Rx)
head lice
CI for Malathion (Ovide - Rx)?
SE?
- CI: < 6y, hypersensitivity
- SE: transient stinging, irritation, contact dermatitis/chemical burn
MOA of Malathion (Ovide - Rx)
neurotoxic by inhibiting cholinesterase
Last resort for adults with scabies, head/body/pubic lice
Lindane (Kwell)
MOA of Lindane (Kwell)
neurotoxicity resulting in seizure & death of parasite
BBW & CI of Lindane (Kwell)?
Avoid in who? Where is it banned
-
BBW: neurotoxicity (seizures/death) with prolonged application
- Avoid in infants/children, elderly, wt < 50kg, hx of seizure d/o, open skin lesions, severe liver dz, excessive ETOH use, concomitant use of meds that lower seizure threshold - Lindane is banned in California
what medication do you NOT REPEAT- may use other pediculicide in 1 wk if needed?
Lindane (Kwell)
SE of lindane
transient skin irritation, CNS toxicity (dizziness, ataxia, seizure, paresthesias), alopecia, hematuria, aplastic anemia, hepatitis, pulmonary edema
preg cat and lactation pt ed for lindane
cat C
express and discard milk for 24 hours post application
an intensely pruritic eruption caused by the mite Sarcoptes scabiei var. hominis
Scabies
how are scabies transmitted
Transmitted most often via direct person-to-person contact and less frequently by fomites
extremely contagious, spreading between individuals who share close contact or living spaces
factors that contribute to the persistence and spread of scabies are ?
overcrowding, delays in diagnosis, and poor public health awareness outbreaks in health care facilities, such as nursing homes, can result in dozens of patients and staff becoming infected
pathogenesis of how scabies happen
Hypersensitivity reaction to the mites burrow into the stratum corneum of the epidermis = highly pruritic eruption 2-6 wks after initial infestation
burrow is a fine, thread-like line with a terminal tiny (smaller than a pinhead) black speck representing the mite itself
dx?
scabies
For scabies, Small erythematous papules, are seen mostly on where
- the flexor wrists
- around the axillae and areolae
- interdigital web spaces and umbilicus
- genital and buttock regions
Scabies classically spares what parts of the body?
the head and neck areas
what dx has an Itch worse at night, esp just after getting into bed, also patient cannot keep from scratching in the exam room
scabies
if you observe lesions/itchiness around the Areola in women and on the penis and scrotum in men, what is this highly suggestive of?
scabies
secondary lesions of scabies are due to ?
scratching and include excoriations, impetiginized lesions with crusts, and prurigo-like nodules
on dermascopy you observe a slightly darker, V-shaped structure leading the burrow, followed by the burrow is “jetliner with its trail;” dark brown / black material in the burrow corresponds to eggs and feces left by the mite
dx?
scabies
does a negative scabies prep r/o scabies?
nope
mites can be infrequent and difficult to isolate in patients with normal immune function
This type of scabies is MC seen in immunocompromised or institutionalized patients.
Crusted Scabies
Severe and highly contagious variation.
tx for crusted scabies
TOC - Topical Permethrin 5% full body application left on 8-14 hours (overnight), repeat in 1 week
AND oral ivermectin 0.2mg/kg/dose on days 1,2,8,9,and 15
best test for scabies
Scabies prep
- Place a small amount of mineral oil on the skin area to be tested, a #15 blade, and a microscope slide take the blade and gently remove the terminal end of the burrow where you see the tiny black speck
- Apply this scraping to a glass slide, cover with a cover slip, and examine under the microscope for the presence of the mite or its ova or fecal pellets, known as scybala
Skin biopsy is not needed but can be helpful when there is clinical uncertainty
special w/u for crusted scabies
add a few drops of 10% KOH solution to the skin scraping to break down the excess keratin. Scales will typically contain many mites
environmental control for scabies
- apply clean clothing after application
- wash/dry on hot cycle all bedding/clothing/curtains/pillows
- vacuum and dust anything that can’t be washed (furniture/carpets/floors)
pt ed for scabies? post-tx options?
- symptoms should improve within 3 day but pruritus can persist for up to 4 weeks after tx
- Post-tx pruritus
- benadryl OTC at night
- severe-persistent - 14 d tapered course of prednisone
indications for skin scraping
scabies, fungal infections
supplies for skin scraping
- 15 scalpel blade
- microscope slide
- slide cover
- mineral oil or KOH
- microscope
technique for scabies evaluation via skin scrap
- apply 1-2 drops of mineral oil to the burrow
- use scalpel perpendicular to skin, scrape multiple burrows (>15)
- smear specimen on slide
- crusted scabies: add 10% KOH to skin scraping to dissolve excess keratin - seal with slide cover
- examine under microscope with low and high power
technique for fungal evaluation
via skin scraping
- use scalpel to remove scale along border of the lesion
- transfer to slide, apply 1-2 drops of 10-20% KOH to slide
- allow to sit for 10-15 min
- examine under microscope with low and high power
potential sources of error in skin scraping
- not obtaining adequate specimen
- KOH: not allowing enough time to dissolve all healthy/keratin cells
- abrasive technique resulting in blood contamination
The severity of a spider bite depends on ?
- the type of spider
- the amount of venom injected
- the site of the bite
- the health and age of the patient
Latrodectus genus neurotoxic venoms, with alpha-latrotoxin as the major component
what type of spider?
Widow Spiders
____, Lactrodectus mactans, is the MC widow spider in the United States and is found in woodpiles
The black widow spider
s/s of widow spider bite
- Painful, HTN, tachycardia, palpitations, diaphoresis, anxiety, SOB, hyperthermia/hypothermia, excessive salivation, N/V, and severe abd pain
- Noticeable fang marks with development of a halo-like lesion around the bite
Loxosceles genus are found worldwide in temperate and tropical regions
Can cause local necrosis and, rarely, severe systemic symptoms
what type of spider?
Recluse Spiders
The bite is often initially painless
Pain, swelling, bullae, and ischemia develop minutes to hours later
Eventually ulcerate and become necrotic and gangrenous
DIC = disseminated intravascular coagulation can occur
what type of spider bite
Recluse Spiders
- Pacific Northwest, the hobo spider (Tegenaria agrestis), MC the aggressive house spider, is often blamed as the cause of necrotic skin lesions
- neurotoxic venom, capable of producing severe pain at the bite site and systemic symptoms that can rarely be fatal within minutes
what type of spider?
Funnel-Web Spiders
Family Theraphosidae have relatively harmless bites
However, they can disperse urticating hairs from their abdomens, resulting in local skin reactions, ocular problems, and allergic rhinitis.
what type of spider
Tarantulas
for a spider bite PE, what are you looking for?
- 2 small puncta, the fang marks of the spider.
- Erythema and edema
- Necrotic or dusky center within a red, inflammatory plaque is characteristic
- More prominent sx: Systemic symptoms muscle pain, cramps, abdominal pain, salivation, lacrimation, sweating, and tremors
- in ____ spider bites, vesicles and bullae can present early
- Between 12-24 hours after envenomation, a large plaque consisting of erythema, ischemia, and necrosis (“red, white, and blue” sign) develops
- Later, these lesions can progress into painful, full-thickness necrotic plaques
Brown recluse
___ bites = local sweating, piloerection, redness, and mild edema
black widow
gold standard for spider bites?
Spider collection with positive identification
clinically dx tho
If systemic involvement due to a brown recluse spider bite is suspected, check for evidence of ___
hemolysis
If systemic involvement is present, what levels should be obtained
serial hemoglobin and plasma-free haptoglobin levels
tx for spider bites
- Collection and identification of spider, if possible.
- Wound irrigation.
- Rest, cold compresses, elevation of the affected extremity.
- Symptomatic tx as indicated
- Tetanus prophylaxis as indicated.
- Conservative local debridement of clearly necrotic tissue.
- Antivenom as indicated.
- For necrotic lesions - dapsone within the first 36 hrs has been advocated by some.
- controversial due to serious rare SE and lack of clear evidence of improvement with therapy.
