Lecture 5: Infestations Flashcards
(47 cards)
1
Q
Where is pediculosis capitis MC and how does it present?
A
- Lice
- MC in schools, day-cares, SNFs, dorms, prisons
- Intense pruiritis of the scalp
- MC in white school aged girls/mothers
Warmer months
2
Q
What does a louse look like?
A
- 1-3 mm long, flattened brownish-gray, 3 pairs of legs and claws
- lifespan 14-18d
- Nits are 1 mm and opalescent (eggs)
Humanus are in clothing, capitus on hair shafts
3
Q
How to differentiate seborrheic dermatitis, tinea capitis, psocid lice, and psoriasis from pediculosis capitis?
A
- Seborrheic is yellow, greasy, and easy to remove
- Tinea capitis is more closely associated with alopecia
- Psocid lice are MC in plant debris/wooded areas
- Psoriasis is morphologically distinct
4
Q
What do lice and nits do to the scalp?
A
- Mauculae cerulae or purpuritic stains may suggest infestation
- Occipital lymph node involvement
- Microscopy shows an oblong structure attached to hair an an acute angle with a breathing appartus at its superior end
5
Q
Diagnostic pearls for pediculosis capitis
A
- Pyoderma + occipital/cervical LAN suggest infestation
- Nits are oval and tenacious; they stay stuck
- Nits fluoresce under Wood’s lamp
6
Q
Best tests for pediculosis capitis
A
- Microscope
- Wood’s lamp of nits
7
Q
Management of pediculosis capitis
A
- Permethrin has increasing resistance
- Manual combing via fine comb
8
Q
Should you treat a kid with empty nit cases?
A
No
Only live lice or eggs
9
Q
OTC tx for pediculosis capitis
A
- Permethrin (Nix): dry hair then rinse after 10m. Repeat in 1-2 weeks
- Pyrethrins + piperonyl butoxide(RID, Pronto): same as above
10
Q
Rx tx for pediculosis capitis
A
- Spinosad/Natroba: children > 4y First line tx
- Malathion lotion
- Permethrin 5% (off-label)
- Ivermectin lotion: 6 months or older & not preggo
- Oral ivermectin (off-label), don’t use under 5y.
11
Q
Tx for eyelid involvement of pediculosis capitis
A
Petrolatum BID for x8d
12
Q
Organism for pediculosis corporis
A
Pediculus humanus corporis
Lives in clothing
13
Q
Presentation of pediculosis corporis
A
- Pruiritis
- Bites of macules and papules in intertriginous areas
- Maculae cerulea: blue gray macules are pathognomic for lice infestation
- 2-4 mm wingless, blood sucking arthropods.
14
Q
What is vagabond disease?
A
Body louse infection that goes on for years, developing parasitic melanoderma = darkened/thickened skin
15
Q
What is characteristic of bed bug bites?
A
Linear bite distribution
Bfast, lunch, dinner distribution
16
Q
Best test for pediculosis corporis
A
- Physical examination
- Finding a live louse/viable nit = confirmation of dx
- Wood’s lamp will show yellow-green
- Check clothing seams
- Shake clothing and use tape to pick up debris
17
Q
What are the 3 diseases transmitted by P. humanus corporis?
A
- Typhus (Rickettsia prowazekii)
- Relapsing fever (Borrelia recurrentis)
- Trench fever (Bartonella quintana)
Mainstay is just eradicating infestation
18
Q
Tx for pediculosis corporis
A
- Clothing on hot water and high heat
- Iron furniture
- Heavy infestation: 5% permethrin cream or lotion for 8-14 hrs
19
Q
Overview of pediculosis pubis
A
- STD, aka crabs
- Can be spread also by fomites
- Not pet related
- Extremely pruiritic
- Condoms do not stop transmission
20
Q
Why is pediculosis pubis hard to remove?
A
- Chitin formation to cement themselves.
- However, can’t live without a host for more than 24h.
21
Q
Clinical signs of pediculosis pubis
A
- Erythematous macules or papules present at feeding sites
- Wheals
- Small pinpoint bleeding on intimate clothing
22
Q
Management pearls for pediculosis pubis
A
- Notify sexual partners in most recent month
- Concomitant STDs is common
- Sexual contact or fomite can be transmission
- Wash in hot water or store away for 2 weeks in air-sealed bags
- Secondarily infected lesions needs abx
23
Q
Preferred tx by CDC for pediculosis pubis
A
- Permethrin 1% (> 2 month olds)
- Mousse with pyrethrins
- After tx, can remove nits with fine comb
24
Q
How does permethrin work?
A
- Neurotoxin resulting in respiratory paralysis of parasite
- Body: leave cream overnight and then rinse
- Head lice: leave 10 mins, rinse and comb out.
Both are repeated in another week PRN.
25
How does pyrethrin/piperonyl butoxide work and its CI?
* Lotion/shampoo
* Pyrethrin is a neurotoxin
* Piperonyl is a synergist
* Cannot be used in **< 2 y/o or allergy to ragweed**
* Apply to wet areas for 10 mins and rinse.
26
How does malathion work and its CI?
* Head lice lotion that is Rx only
* Neurotoxic: inhibits cholinesterase
* CI: < 6y
* Leave in dry hair for 8-12 hrs
* **It is flammable**
27
Last resort tx for pediculocide therapy
Lindane/Kwell
28
What does Lindane do and CIs?
* MOA: neurotoxicity causing **seizure and death**
* BBW: neurotoxicity, so no children, elderly, light wt ppl
* **Banned in CA**
* Place on before you shower
* **Do not use more than once**
29
What causes scabies and MC mode of transmission?
* Mite: Sarcoptes scabiei var. hominis
* MC: Direct contact
| fomite spread is rare
30
Overview of scabies
* 10-20 mites per infestation
* Extremely pruiritic 2-6 weeks later
* **Persists without tx!**
31
Presentation of scabies
* **Worse at night**
* Diagnostic sign: **fine, thread-like line with tiny black speck at the end.**
* Small, erythematous papules
* **Rarely on head or neck**
32
What location on men and women suggests scabies if itchy/papular?
* Women: areola
* Men: Penis and scrotum
33
Dermoscopy finding for scabies
Jetliner with a trail
| Negative prep != lack of scabies
34
Who is crusted scabies/norwegian scabies MC in?
* Immunocompromised
* Institutionalized
35
What is crusted scabies like?
Thousands to millions of mites
36
Tx of crusted scabies
* Topical Permethrin 5% overnight
* +
* Oral ivermectin x5 dosing
37
Best tests for scabies
* Scabies prep via scraping and microscopy and mineral oil
* **Add on KOH for crusted scabies**
38
Management of scabies
* **First-line**: permethrin 5% or Rid
* Last resort: Lindane (**Avoid in crusted**)
* Oral ivermectin (2nd line, **0.2mg/kg/d**)
39
Supplies for skin scrapings
* 15 scalpel blade
* Microscope slide
* Slide cover
* Mineral oil or KOH
* Microscope
| **KOH is for fungal or crusted**
## Footnote
Mineral oil is applied prior to scraping for scabies.
40
Overview of a black widow
* MC widow spider
* Likes **woodpiles**
* Makes you extremely sick
* **Halo-like lesion around bite**
* **Females have the red hourglass on their abd**
| Lactrodenus genus
41
Overview of recluse spiders
* MC in temperature and tropical regions
* Cause **local necrosis primarily**
* Loxosceles genus
* Can cause DIC
* **Brown recluse spider** has a violin shaped figure
| Main concern is hemolysis i think
42
Funnel-web spider overview
* Hobo spider: tegenaria agrestis
* PNW
* Neurotoxic venom **extremely fatal**
43
Overview of tarantulas
* Theraphosphidae have **relatively harmless bites**
* Generally cause **local skin reactions/allergies**
44
How to find a spider bite
* **2 small puncta fang marks**
* Erythema and edema
* **Necrotic/dusky center in a red inflammatory plaque**
* Brown recluse: vesicles and bullae quickly
* Black widow: Local sweat, piloerection, mild edema
45
Gold standard for diagnosing a spider bite
Spider collection with positive identification
46
What should we check if we suspect brown recluse bite?
* Hemolysis
* Order Serial Hgb and plasma-free haptoglobin if hemolysis suspected.
* Rhabdo, renal, DIC
47
What controversial drug can we give for necrotic lesions due to spider bites within 36 hrs?
Dapsone
