Lecture 25 Flashcards
what is the lifecycle of a female Sarcoptes Scabiei
- fertilized on skin surface
- burrows into epidermis
- completes life cycle in 5 weeks, dies in burrow
what is the lifecycle of a male Sarcoptes Scabiei
- remains on skin surface or produces a shallow burrow
- shorter life span
Sarcoptes Scabiei eggs are laid where? When does an adult mite develop
- eggs laid under skin
- larva emerges from egg after 4 days
- adult mite develops 2 weeks after hatching
clinical issues caused be Sarcoptes Scabiei is due to
- burrowing
- causes an intensely pruritic eruption, worse at night
Sarcoptes Scabiei causes what 2 conditions
-
crusted (norwegian scabies)
- crusted scaling lesions readily observed in HIV patients
-
pediatric scabies
- lesions may be blood filled
how is Sarcoptes Scabiei transmitted
- direct person contact
- can be zoonotic: does not last long
how is Sarcoptes Scabiei identified
- apply mineral oil, scrape lesion and visualize microscopically
- looking for whole mite or mite parts, eggs or fecal pellets in burrows
What does Phthirus pubis cause
pubic lice - “crabs”
how do Phthirus pubis feed
- nits egs cemented to hair
- adults bite and feed in pubic area
how is Phthirus pubis transmitted
- sexual contact
- contaminated bedding
Pediculosis is caused by what pathogen
Pediculus humanus
- P. humanus capitis: head louse
- P. h. humanus: body louse
Pediculus humanus are blood sucking parasites that can cause what disease as a result of years of infestation
Vagabond’s disease
Pulex irritans is a human flea that absolutely needs what to survive
blood
main manifestation of Pulex irritans is
- a rash
- during blood meal, it injects saliva
do Pulex irritans live on humans
- no, they prefer hairer and warmer environment like pet hair
are flea bite rashes contangious
no
flea bite pattern
- groups of three or four, generally in a linear pattern
- characterized by raised bumps or halo surrounding the actual bite site
- concentrated in lower extremities
scabies commonly infects what patient populations
children and elderly
Lyme disease is caused by what pathogen
- bacterium Borrelia Burgdorferi
- no gram reaction
lyme disease can be classified into what two things based on location in US
- Ixodes scapularis: northeasten, mid-atlantic, north central US
- Ixodes pacificus: pacific coast
ticks attach to what part of the body
can attach to any part of the body
tick must be attacked to host for how long to transmit borrelia burgdorferi
36-48 hrs
tick bite produces what rash
- Erythema migrans
- bulls eye rash
up to 20% of lyme disease patients have symtpoms that last months to years after proper abx tx: Post treatment lyme disease symptoms include
- muscle and joint pain
- cognitive defects
- sleep disturbance
- excessive fatigue
how is B. burgdorferi infection diagnosed
- bullseye rash is key
- 2 step approach
- ELISA
- detect B. burgdorferi
- Western blot (confirmatory)
- detects B. burgdorferi proteins
- ELISA
Rocky mountain spotted fever is caused by
- tick
- american dog tick
- rocky mountain wood tick
- brown dog tick
- caused by Rickettsia rickettsii
Rickettsia rickettsii
- gram status
- special feature
- motile
- shape
- gram negative
- obligate intracellular
- non motile
- pleomorphic
- cocci
- rods
- thread-like
prognosis of rocky mountain spotted fever
fatal if not treated in the first few days of symptoms
if arizona, rocky mountain spotted fever is caused by ? During what season?
- brown dog tick
- summer months
Rickettsia rickettsii invades what cells
- endothelial cells that line blood vessels
first symptoms of rocky mountain spotted fever
- 2-14 days after tick bite
- sudden onset of fever and HA
rocky mountain spotted fever produces what 2 characteristic rashes
- small, flat pink non itchy spots
- wristst, forearms, ankles and spreads to trunk, palms, and soles
-
red to purple spotted petechial rash
- pinpoint hemorrhages
- sign of late infection and severe disease
how is rocky mountain spotted fever diagnosed
- difficult
- clinical signs and symptoms
- gold standard: indirect immunofluorescence with a R. rickettsii antigen (2 samples 2-4 weeks apart)
- do not delay tx waiting for confirmation
