Micro: Greenberg 2 Flashcards
chilopoda: millipedes and centipedes
centipedes have poison claws in first segment, millipedes don’t
tropic, usually in leaf litter
bites occupational/accidental, rarely fatal
pentastomids
bloodsucking endoparasites, not insects or worms, occasionally infect humans
2 body parts: cephalothorax and abdomen
most asymptomatic
Halzoun syndrome - coughing, sneezing, nasopharyngeal discomfort
human follicle mite
demodex
entire life cycle in follicle or gland
rare in childhood, increases at puberty
chigger mites and house mites
family trombiculidae
larva feed on blood then drop off
no infestation, hypersensitivity rxn
tx: antihistamines, topical corticosteroids
scabies
skin dz caused by itch mite
*sarcoptes scabiei
sac-like body w 4 legs near mouth and 4 behind
What is the scabies life cycle?
female mites burrow and lay eggs at end, 2-3 eggs/day
larva in 3-4 days, 17 days to adult
mites predominately b/w fingers and on wrists
What is the clinical presentation of scabies?
ITCHING! - b/w fingers, wrists, beltline, armpit, groin = at burrows, hypersensitivity rxn to mite and eggs
What is Norwegian (crusted) scabies?
usually in immunocompromised (HIV, HTLV-1)
severe scaling, can be inches thick
tremendous numbers of mites
What is the treatment for scabies and lice?
permethrin (prolongs activation of Na channels), hexachlorocyclohexane (neurotoxin at GABA gated Cl)
ivermectin (paralysis, GABA gated Cl) for norwegian
wash clothes in hot water, bathe frequently, treat contacts
*may need to repeat
What are lice?
insects, 6 legs
separate head, thorax, segmented abdomen, antennae
What is the life cycle of lice?
eggs laid on follicle or clothing (egg case = nit)
becomes nymph in one week
mature into adults
200-300 eggs in lifetime of female
head louse and crab louse complete life cycle on human body
body louse lays eggs on fibers of clothing - nymphs feed on humans periodically
What is the epidemiology of lice?
correlation w poor hygiene, crowded environments
transmission person to person, inc sexual
fomites on clothing
*lice can survive for 2 weeks in the environment
What are the features of hexachlorocyclohexane?
topical lotion - absorbs through skin
more in neonates, young children, older adults - contraindicated, also during pregnancy/breastfeeding
causes tics, seizures, permanent damage
What are the features of Ivermectin?
little neurotoxicity, doesn’t cross BBB
two doses cures more than one dose
What is malathion?
insecticide
Ach esterase inhibitor - causes tonic paralysis in lice
smells bad, oily, toxic
