Lice, Scabies, Bed Bugs, Resistance to Pest Control Flashcards Preview

Parasitology > Lice, Scabies, Bed Bugs, Resistance to Pest Control > Flashcards

Flashcards in Lice, Scabies, Bed Bugs, Resistance to Pest Control Deck (88)
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1

Lice - features

Wingless
Ectoparasites
Bite often

2

Types of lice and infestations

Head louse - Pediculus humanus capitis
Pediculosis capitis - head infestation

Body louse - Pediculus humanus humanus
Body infestation - Pediculus corporis

Pubic/crab louse - Phthirus pubis
Pediculosis pubis - infestation of pubic hair
Pediculosis ciliaris - infestation of eyelashes
Pediculosis - Lice infection

3

Epidemiological factors - head lice

Kids mostly affected
Females affected > males
European descent affected > african descent

4

Epidemiological factors - body lice

Poverty
Poor hygeine
Crowding

5

Epidemiological factors - pubic lice

Sexually active
Young adults

6

Life history - lice

Three growth stages:
Egg - nits, laid singly attached to hair/clothing (cementing substance to attach)
Larva - nymph, feeds on host
Adult

7

Head Lice transmission

Direct contact - person to person
Indirect contact - clothing, bedding, brushes

8

Head lice features

Pointed in front
5 jointed antennae
Claws present
Bi lobed at end - female
Pointed end - male

9

Pruritis

An unpleasant sensation that provokes the desire to scratch.

10

Sensitization

Immune system produces protein, called an antibody, in response to any substance it considers abnormal

11

Excoriation

urge to pick at one's skin

12

Signs+symptoms of crab louse

-Intensely pruritic - due to Allergic reaction to lice saliva
-Sensitization occurs in about 4-6wks
-This causes morbilliform rash (circular rose-red lesions)
Excoriations
Hyperpigmentation

13

Complications - lice

Excessive scratching can break skin barrier leading to bacterial infection -Dermatitis - Scratching and secondary infection

Lice can transmit bacteria causing infections:
- Vectors:
-Epidemic typhus - Rickettsia prowazeki
-Relapsing fever - borrelia
-Trench fever - Rickettsia quintana

14

Diagnosis - lice

Visualise nymphs/adults
If nits are >6.5mm from scalp then not active infestation

15

Control - lice

Permethrin 1% (Nix/Kwellada shampoo)
Removal via fine combing with diluted vinegar solution
Clean clothing in hot water with detergent
Regular infestations
Oral ivermectin

16

Ricksettsiae

Gram -ve coccobacilli
Two groups:
Spotted fever group
Rickettsia rickettsii - RMSF - tick bites

Typhus group
Rickettsia prowazeki - Epidemic typhus - lice feces
Rickettsia typhi - Murine typhus (endemic typhus) - rat fleas

17

Rickettsia is weak gram -ve to giesma stain used (T/F)

True

18

Why is rickettsia intracellular

-intracellular b/c can't make NAD+ and CoA so requires cells
Attach to endothelial cells and invade.

19

Scabies etiology

Skin conidition caused by mites - Sarcoptes scabei

20

Scabies risk factors

Crowding
Skin to skin
---direct and prolonged
Fomites (furniture, chairs, beds) - happens in one type of scabies --survive 1-1.5 days

21

Pathogenesis - scabies

Female mite secrets proteolytic enzymes - allows entry into epidermis
Eggs laid
Larvae hatch

22

Types of scabies

Classic
Pruritic

23

Classic scabies pathogenesis

Classic
Eruption of small erythematous paules
-appearance of "knots on a rope"

24

Pruritic scabies pathogenesis

Pruritic
--severe at night
--3-6 wks after colonization due to delayed sensitivity
--1-3 days if reinfestation occurs
--Response could be caused due to allergens in mites fecal pellets

25

Classic scabies papules locations

Webs of fingers
Axillae
Areola
Genitalia

26

Crusted scabies has less mites present than classic scabies (T/F)

False, more mites present in crusted scabies

27

Transmission via fomites is not common in crusted scabies (T/F)

False

28

Crusted scabies/Norwegian scabies is found where on the body?

Hands, feet, scalp

29

Diagnosis - Scabies

Microscope - eggs/mites
Often clinical diagnosis
-Pruritis
-Crusting, scaling fissuring

30

Treatment - Scabies

Topical permethrin
Ivermectin