infestations Flashcards
how do scabies infect
after mating on the skin’s surface, the female mite burrows into the epidermis at the junction of the stratum corneum and stratum granulosum (any deeper and it loses O2 supply by diffusion)
eggs are laid at the end of burrow
larvae emerge from eggs in 3-5 days
how are scabies spread
prolonged closed contact, possible venereal
*inanimate objects probably dont spread scabies
why is first exposure asymptomatic for 1-2 months
Th1 delayed hypersensitivty reaction
what is disability usually produyced by
secondary complications such as excoriation, secondary bacterial infection, post strep glomerulo, acarophobia
egg size is
1/3 of baby
how do scabies transmit
in lymph (not blood)
classic lesion in scabies
scabietic burrow in adults (not usually seen in kids)- curved ridges or thread-like excoriated lesions, resultin in crusted papules
common lesion locations
genital areas flexor wrists elbows finger and toe webs buttocks breasts waistline
what parts of targeted in kids but spared in adults
head (scalp, face), palms, soles
main characteristic of lesions
intensely pruritic, esp at night
secondary infection leads to
impetiginization
ecthyma
cellulitis
nodular scabies
persistent red-brown pruritic nodules in genital or intertriginous skin
scabies in infants
head, neck, hands, feet
vesicles nad pustules infreq
crusted, norwegian scabies
secondary to immuno def–>infestation with tons of mites–>hyperkeratotic crusted eczematous or papulo-squamous dermatitis in face, palms, soles, and nails
scabies in the clean
pnly 1-2 mites
lab findings
look at mite sin mineral oil!–scrape fresh papule
ink test: link swap over area and burrows show up as dark lines
rare: bx to show above infilitration
tx of scabies
lindane lotion over entire body for 8-12 hrs
crotamiton creams for kids and pregnant (antipruritic)
unlike reg scabies, you CAN get norwegian scabies from
inanimiate objects
lice are also bad because
vectors of human disease
pathophys of lic
occipital scalp (but cna infest beard and pubic hair)–>leave hair to get blood meal from skin–>release an irritating toxin
human response to louse
HSR, so usually increases with second exposure
nits
small, oval whitish- to translucent egg cases cemented into hair shaft on scalp
remain viable for 3 weeks while lice cant live >2-3 days without blood meal
physical findings lice
pruritis
lice and nits
erythematous populat bites on peripheral scalp (neck)–oozing and crust formation
tx lice
lindane lotion/shampoo malathion lotion pyrethin shampoo, fine toothed comb bactrim
