Parasitic Infections Flashcards
Pediculosis
Lice!
- Belong to order Anoplura (sucking lice)
o Sucking mouthparts penetrate skin & feed on blood
- 1-3 mm flat creatures with 3 pairs of legs. Females lay 300 nits during a lifetime
o Nits are opalescent, found on hair shafts, and hatch in about 1 week
what are the 3 forms taht are parasitic to humans?
body, head, and pubic
Body louse
Pediculosis humanus corporis
Head louse
pediculosus humanus capitus
pubic
phthirus pubis
how are they transmitted?
P2P
Lice CF
pruruitus is variable in severity, excoriations may become secondarily infxn
o Classic: small erythematous papules (papular urticaria)
Axillae, neck, shoulders
Hemorrhagic puncta and linear excoriations also common (former represent intradermal hemorrhage at site of bite)
nits may be seen on hair shaft
maculae caerulaea
bluish-brown or gray macules at site of bite, may be heme breakdown product
first line tx of lice
prevention is key Permethrin pyrethrins malathion *** Need to reapply in 7-10 days to kill any newly hatched lice
vasaline can be used to suffocate lice
alternative tx of lice
lindane or ivermectin
scabies
- Sarcoptes scabiei – an 8-legged mite
- can live as long as 48 hours on clothing bedding and furniture
scabies CF
- Itching, scabs, burrows – intensely pruritic rash that is usually worse at night
o Excoriations and crusting - Infants get nodular eruption, including head
scabies pathogenesis
hypersensitivity (immediate and delayed. normal incubation period is 21 days for first infestation
scabies dx
- Lesions tunnels (0.5-1 cm); excoriated papules & pustules
- Sites of predilection finger webs, flexor aspects of wrist, elbows, axillae, penis, external genitalia, feet & ankles
o Most commonly distributed on the hands, genitalia, and axillary areas - Clinical diagnosis… look for burrows. Place mineral oil over burrows and scrape off with a #15 blade, then examine under microscope and look for mites
what are most secondary infections caused by in scabies?
GAS
scabie tx
1 %5 permethrin
alternate scabies tx
1% lidocane
ARD: neurotoxicity, avoid in those <2 o, extensive dermatitis, and preg/lactating
how does scabe tx work?
apply to skin and leave on overnight (8 hours) was off in am. repeatt in 7 days
clinical pearls for scabies
humans can be infested by mites of dogs, (self-limiting, no tx) wash bedding, clohtes in hot water
spider bite
brown recluse (Laxaxceles reclusa)
black widow
progression of a spider bite
pain 3 hrs after bite, systemic sx begin 4-6 hours, the acute necrotic injury to skin (lasts 10-15 days)
what can black widows cause?
neurologic overstimuation (muscle aches, spasms, rigidity)
brown recluse rxn
red, white and blue
1) infarct of skin caused by rapid blood coagulation w/in vessles
2) leion is sinking macule, pale grey in color, slightly eroded in cener, halo of tender inflammation and hemorrhage
* can often extend into muscle
tx of spider bites
mostly mananged wtih local care and analgesics
antivenom is rarely indicated
tx of black widow bites?
diazepam and calcium gluconate
