E2- Ectoparasitic and Arthropod

Question 1

What is burrowing mite that is the most serious?

Answer 1

Sarcoptes scabiei

Question 2

What ectoparasite causes scabies, crusted scabies, mange, and seven year itch?

Answer 2

Sarcoptes scabiei

Question 3

What is the biology of a famale Sarcoptes scabiei?

Answer 3

1. Fertilized on the skin surface
2. Burrows into the epidermis
3. Completes life cycle in 5 weeks and dies in the burrow

Question 4

What is the biology of a male Sarcoptes scabiei?

Answer 4

1. Remains on the skin surface or produces a shallow burrow

Question 5

What is the life cycle of a Sarcoptes scabiei?

Answer 5

Eggs are laid under the skin
Larva emerges from the egg after 4 days
Adult mite develops 2 weeks after hatching

Question 6

What is the main clinical manifestation of Scabies?

Answer 6

Pruritus (worse at night)

Question 7

What causes the majority of clinical issues in a Sarcoptes scabiei infection?

Answer 7

Burrowing

Question 8

What form of scabies has an incubation period of ~1 month, is observed readily in HIV patients, and has lesions that are teeming with mites?

Answer 8

Crusted (Norwegian) Scabies

Question 9

What is similar to Crusted (Norwegian) Scabies, but lesions may be blood-filled?

Answer 9

Pediatric scabies

Question 10

How is scabies usually transmitted?

Answer 10

Direct person contact (crowded living conditions)
In adults, likely and STI
May be zoonotic

Question 11

How is scabies identified?

Answer 11

Apply mineral oil, scrape lesion and visualize microscopically

Question 12

What is the causative agent of pubic lice “Crabs?”

Answer 12

Phthirus pubis

Question 13

How are pubic lice transmitted?

Answer 13

Sexual contact or contaminated bedding

Question 14

What is a causative agent of typhus?

Answer 14

Pediculus humanus

Question 15

How long is the egg-to-egg cycle for Pediculus humanus?

Answer 15

3 weeks

Question 16

How do Pediculus humanus mainly cause irritation?

Answer 16

Bite irritation (blood sucking parasites)

Question 17

What can years of infestation of Pediculus humanus cause?

Answer 17

Vegabond’s disease (darkened, thickened skin)

Question 18

What is the causative agent of human fleas?

Answer 18

Pulex irritans

Question 19

What parasite is laterally compressed and has short spikes on the legs that allow attachment to the host?

Answer 19

Pulex irritans

Question 20

What do Pulex irritans absolutely need to survive?

Answer 20

Blood

Question 21

How do Pulex irritans initiate an allergic response?

Answer 21

During a blood meal, they inject salvia which is known to possess at least 15 substances which initiate allergic responses

Question 22

What is the main clinical manifestation of human fleas?

Answer 22

Rash that appears in groups of 3-4 in a linear pattern

Usually in the lower extremities

Question 23

Are flea bite rashes or scabies contagious?

Answer 23

Scabies

Question 24

Can fleas or scabies mites jump?

Answer 24

Fleas are capable of jumping long distances

Scabies mites cannot jump/fly (crawl slowly)

Question 25

What is the causative agent of Rocky-Mountain Spotted Fever?

Answer 25

Rickettsia rickettsii

Question 26

Is Rickettsia rickettsii gram positive/negative?

Answer 26

Gram negative

Question 27

What is a common arthropod vector of Rocky-Mountain Spotted Fever? What time of yr is this disease most common?

Answer 27

Brown dog tick | Summer (june-july)

Question 28

The first sxs of Rocky-Mountain Spotted Fever begin 2-14 days after a bite and are what?

Answer 28

Non-specific Fever HA N/V

Question 29

What are the 2 types of rash associated with Rocky-Mountain Spotted Fever?

Answer 29

1. Small, flat pink non itchy spots (macules) | 2. Red to purple spotted petechial rash

Question 30

The most successful tx for Rocky Mountain Spotted Fever is initiated within when?

Answer 30

5 days

Question 31

Why are diagnostic test for Rocky Mountain Spotted Fever not good?

Answer 31

Detectable antibody titers are not visible for 7-10 days post infection

Question 32

What is the gold standard test for dx Rock Mountain Spotted Fever?

Answer 32

Indirect immunofluorescence with R. rickettsii antigen | 2 samples 2-4 weeks apart

Question 33

What is causative agent of African sleeping sickness?

Answer 33

Trypanosoma brucei

Question 34

What is the causative agent of Chagas disease?

Answer 34

Trypanosoma cruzi

Question 35

In the US, what is considered a Neglected Parasitic Infections (NPI) by the CDC?

Answer 35

Chagas disease

Question 36

What is vector for Chagas disease?

Answer 36

Triatomine bugs

Question 37

How is chaga transmitted?

Answer 37

Feces of the Triatomine bug Blood transfusion Organ transplants Congenital

Question 38

Trypomastogotes enter cells near inoculation site and differentiate into what?

Answer 38

Amastigotes

Question 39

Amastigotes replicate by binary fission in cells, differentiate into what?

Answer 39

Trypomastigotes

Question 40

What are the two life stages of T. Cruzi?

Answer 40

Trypomastigotes | Amastigotes

Question 41

What is Romanas sign? And what diseases is it associated with?

Answer 41

Chagas disease | Swelling of the eyelid near parasite entry site or where the organism was rubbed into the eye

Question 42

Pseudocysts in amastigotes in cell (Chagas’ disease) can cause what?

Answer 42

Preferential infection of muscle and nerves | Degeneration and necrosis

Question 43

What are some clinical manifestations of the chronic phase of Chagas’ disease?

Answer 43

``` Chronic inflammation Cardiomyopathy Heart failure Cardiac arrest Enlarged esophagus Enlarged colon ```

Question 44

How is Chagas disease dx?

Answer 44

``` Observe parasite under microscope Blood smear (acute phase) -Trypomastigotes Biopsy (chronic cases) -Amastigotes ```

Question 45

What is another name for Chagas disease?

Answer 45

American trypanosomiasis

Question 46

What is the treatment of scabies?

Answer 46

5% permethrin cream or Ivermectin (does not kill eggs)

Question 47

What is the treatment for phthirus pubis?

Answer 47

Permethrin

Question 48

What is the treatment for P. Humanus?

Answer 48

Permethrin

Question 49

What is the treatment for pulex irritans?

Answer 49

- Stop itching - 1% hydrocortisone - Antihistamines

Question 50

What kind of rash in RMSF is worse?

Answer 50

The red/purple spotted petechial rash, this is a sign of late infection and severe disease.