L24: Ectoparasitic Infections+RMSF

Question 1

most serious of the mites

Answer 1

sarcoptes scabiei

Question 2

Scarcoptes scabiei aka

Answer 2

Scabies
Mange
Crusted scabies
Seven year itch

Question 3

Small mite with short legs

Answer 3

sarcoptes scabiei

Question 4

Where is the female scabies mite fertilized?

Answer 4

Skin surface

Question 5

Female scabies mite life cycle

Answer 5

once fertilized, burrows into epidermis

lives 5 weeks, die in burrow where it has laid eggs

Question 6

Male scabies mite life cycle

Answer 6

shorter life span, remains on skin surface/produces shallow burrow

Question 7

Scabies eggs

Answer 7

laid under skin
4 days incubation: larva emerges
2 weeks after hatching: adult mite

Question 8

main clinical manifestation of scabies

Answer 8

pruritis

worse at night

Question 9

first time someone is infected with s scabiei

Answer 9

sensitization and allergic response takes weeks to develop

Question 10

s scabiei reinfections

Answer 10

already sensitized so pruritis can develop within 24 hours

Question 11

Crusted/Norwegian scabies

Answer 11

HIV patients
incubation 1 month
crusted lesions teeming with mites. v v itchy

Question 12

How is scabies transmitted?

Answer 12

person to person
can be an STI
zoonotic
crowded living conditions

Question 13

How to identify scabies

Answer 13

mineral oil + scrape lesions + microscope

look for mite, mite parts, eggs, fecal pellets

Question 14

Pubic lice/crabs aka

Answer 14

Phthirus pubis

Question 15

Decribe phthirus pubis

Answer 15

Bigger mites with longer legs and “clamps”

Question 16

How do pubic lice lay their eggs?

Answer 16

nits cemented to hair

Question 17

Identify a pubic lice infection

Answer 17

visualize a louse or nit

Question 18

Head louse

Answer 18

Peiculus capitis

Question 19

Body louse

Answer 19

P humanus corporus

Question 20

what do head/body lice carry?

Answer 20

epidemic typhus

Question 21

Egg-to-egg cycle of a louse

Answer 21

Nit cemented to hair or clothing fibers

cycle takes 3 weeks

Question 22

Vagabond’s disease

Answer 22

years of lice infestation causes darkened, thickened skin

Question 23

Human flea aka

Answer 23

Pulex irritans

Question 24

Pulex irritans description

Answer 24

1-4 mm in length

short spikes on legs for attachment

Question 25

Pulex irritans are considered

Answer 25

parasites, absolutely need blood to survive

Question 26

what causes an allergic reaction/*rash* from a flea?

Answer 26

during a blood meal, they inject saliva | has at least 15 substances that initiate allergic responses

Question 27

Scabies vs fleas: rash

Answer 27

Scabies: tunnel or burrow beneath skin Fleas: linear pattern, groups of 3/4 bites

Question 28

Scabies vs fleas: where do they live?

Answer 28

Scabies: on human skin, lay eggs beneath it Fleas: do not live on humans, prefer pets

Question 29

Scabies vs fleas: spread

Answer 29

Scabies: skin-to-skin, sexual, family members Fleas: not contagious

Question 30

Scabies vs fleas: mobility

Answer 30

Scabies: crawl very slowly Fleas: jump long distances

Question 31

Ticks that'll give you rocky mountain spotted fever (3)

Answer 31

American dog tick Rocky mountain wood tick **Brown dog tick** AZ

Question 32

Causative agent of Rocky mountain spotted fever

Answer 32

Rickettsia Rickettsii

Question 33

Rickettsia morphology

Answer 33

G- *Obligate intracellular* Non motile Pleomorphic (cocci, rods, threadlike)

Question 34

Brown dog tick seasonality

Answer 34

April-October | peak in June and july

Question 35

When do Rocky Mountain Spotted Fever symptoms first appear?

Answer 35

2-14 days after tick bite

Question 36

How does Rocky Mountain Spotted Fever present once symptomatic?

Answer 36

Sudden onset of fever and headache | non-specific: N/V, abdominal pain, anorexia, conjunctivitis

Question 37

Rickettsia life cycle

Answer 37

invade endothelial cells that line blood vessels causes rashes fatal

Question 38

2 types of Rocky Mountain Spotted Fever rashes

Answer 38

1. Small, flat pink non itchy macules 2. Red to purple spotted petechial rash - pinpoint hemorrhages (60%) - 6 days post infection - sign of late disease and severe infection

Question 39

Diagnosis and treatment of Rocky Mountain Spotted Fever

Answer 39

Not easy, tests aren't great, Abs take 7-10 days postinfection DON'T delay treatment

Question 40

Gold standard for detection of Rocky Mountain Spotted Fever

Answer 40

Indirect Immunofluorescense of Rickettsia antigen | 2 samples 2-4 weeks apart