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Microbiology > E2- Ectoparasitic and Arthropod > Flashcards

E2- Ectoparasitic and Arthropod Flashcards

1
Q

What is burrowing mite that is the most serious?

A

Sarcoptes scabiei

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2
Q

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

A

Sarcoptes scabiei

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3
Q

What is the biology of a famale Sarcoptes scabiei?

A
  1. Fertilized on the skin surface
  2. Burrows into the epidermis
  3. Completes life cycle in 5 weeks and dies in the burrow
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4
Q

What is the biology of a male Sarcoptes scabiei?

A
  1. Remains on the skin surface or produces a shallow burrow
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5
Q

What is the life cycle of a Sarcoptes scabiei?

A

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

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6
Q

What is the main clinical manifestation of Scabies?

A

Pruritus (worse at night)

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7
Q

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

A

Burrowing

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8
Q

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?

A

Crusted (Norwegian) Scabies

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9
Q

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

A

Pediatric scabies

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10
Q

How is scabies usually transmitted?

A

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

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11
Q

How is scabies identified?

A

Apply mineral oil, scrape lesion and visualize microscopically

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12
Q

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

A

Phthirus pubis

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13
Q

How are pubic lice transmitted?

A

Sexual contact or contaminated bedding

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14
Q

What is a causative agent of typhus?

A

Pediculus humanus

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15
Q

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

A

3 weeks

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16
Q

How do Pediculus humanus mainly cause irritation?

A

Bite irritation (blood sucking parasites)

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17
Q

What can years of infestation of Pediculus humanus cause?

A

Vegabond’s disease (darkened, thickened skin)

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18
Q

What is the causative agent of human fleas?

A

Pulex irritans

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19
Q

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

A

Pulex irritans

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20
Q

What do Pulex irritans absolutely need to survive?

A

Blood

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21
Q

How do Pulex irritans initiate an allergic response?

A

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

22
Q

What is the main clinical manifestation of human fleas?

A

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

Usually in the lower extremities

23
Q

Are flea bite rashes or scabies contagious?

24
Q

Can fleas or scabies mites jump?

A

Fleas are capable of jumping long distances

Scabies mites cannot jump/fly (crawl slowly)

25
Q

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

A

Rickettsia rickettsii

26
Q

Is Rickettsia rickettsii gram positive/negative?

A

Gram negative

27
Q

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

A

Brown dog tick

Summer (june-july)

28
Q

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

A

Non-specific
Fever
HA
N/V

29
Q

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

A
  1. Small, flat pink non itchy spots (macules)

2. Red to purple spotted petechial rash

30
Q

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

31
Q

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

A

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

32
Q

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

A

Indirect immunofluorescence with R. rickettsii antigen

2 samples 2-4 weeks apart

33
Q

What is causative agent of African sleeping sickness?

A

Trypanosoma brucei

34
Q

What is the causative agent of Chagas disease?

A

Trypanosoma cruzi

35
Q

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

A

Chagas disease

36
Q

What is vector for Chagas disease?

A

Triatomine bugs

37
Q

How is chaga transmitted?

A

Feces of the Triatomine bug
Blood transfusion
Organ transplants
Congenital

38
Q

Trypomastogotes enter cells near inoculation site and differentiate into what?

A

Amastigotes

39
Q

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

A

Trypomastigotes

40
Q

What are the two life stages of T. Cruzi?

A

Trypomastigotes

Amastigotes

41
Q

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

A

Chagas disease

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

42
Q

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

A

Preferential infection of muscle and nerves

Degeneration and necrosis

43
Q

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

A 
Chronic inflammation 
Cardiomyopathy 
Heart failure
Cardiac arrest 
Enlarged esophagus 
Enlarged colon
44
Q

How is Chagas disease dx?

A 
Observe parasite under microscope 
Blood smear (acute phase)
-Trypomastigotes 
Biopsy (chronic cases)
-Amastigotes
45
Q

What is another name for Chagas disease?

A

American trypanosomiasis

46
Q

What is the treatment of scabies?

A

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

47
Q

What is the treatment for phthirus pubis?

A

Permethrin

48
Q

What is the treatment for P. Humanus?

A

Permethrin

49
Q

What is the treatment for pulex irritans?

A
  • Stop itching
  • 1% hydrocortisone
  • Antihistamines
50
Q

What kind of rash in RMSF is worse?

A

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

Microbiology (23 decks)

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