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Flashcards in Ectoparasites Deck (28)
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1

Ectoparasites live where?

On the skin

2

Distinctive features of ectoparasites

Exoskeleton
Articulated/bent legs

3

Body's general response to infection

Allergic dermatitis
Bite patterns

4

Allergic dermatitis in ectoparasitic infections

When organism bites, the creature gets into the subctuaneous tissue
Saliva is exposed to dendritic cells which survey inside the skin
Result: Red, raised, itchy papules at biting site

5

Bite patterns - ectoparasitic infections

Can identify some ectoparasites by where/how they bite:
Linear pattern/straight parallel lines - flea bites
Scabies burrows into finger webs

6

Ticks - two types

Hard ticks - Ixodes scapularis (causes Lyme disease)
Larvae - nymph - adult
Soft ticks - Ornithodoros turicata

7

Tick borne diseases

Lyme disease
Rocky Mountain Spotted fever - Rickettsiae
Ehrlichia
Anaplasma
Babesia

8

Hard tick - stages of growth and num of legs

Larvae - nymph - Adult
8 legs

9

Pathogenic host preference for Ticks

Humans/animals

10

Lice - three types

Head louse - Pediculus capitis
Body louse - Pediculus humanus
(looks the same but prefers body; lives in clothing)
Pubic "Crab" louse - Pthirius pubis (STD)

11

Lice borne diseases

(Body louse)
Epidemic typhus (Rickettsia prowazekii)
Trench fever (Bartonella quintana)
LBRF - Louse Borne Relapsing Fever caused by bacteria -> (Borrelia recurrentis)

12

Lice - number of legs and host preference

Six legs
Humans

13

Mites - one type

Sacroptes scabei

14

Mite host preference and num of legs

Anthropophilic
8 legs

15

Anthropophilic

Preferring animal host to humans

16

Mites typically dont spread disease to humans but if it bites a human then diseases can occur (T/F)

True

17

Diseases spread by mites
(human = accidental host)

-Rickettsialpox (Rickettsia akari)
-Scrub Typhus (Orienta tsutsugamushi)

18

Mites are easy to spot on a person (T/F)

False, mites are almost microscopic, difficult to see with naked eye

19

Fleas - 4 types

Human flea - Pulex irritans
Rat flea - Xenopsylla cheopis
Cat flea - Ctenocephalides felis
Dog flea - Ctenocephalidies canis

20

Fleas can jump thousand times their body size (T/F)

True

21

Fleas - number of legs

6 legs

22

Flea borne infections

Rat flea causes the foll:
--Bubonic plague (caused by Yersinia pestis)
-Tularemia (caused by Francisella tularensis)
-Murine "endemic" typhus (R. typhi)

23

Mosquito - 3 types

-Culex (brown mosquito)
Aedes (aegypti and albopictus)
Anopheles

24

Distinguishable features of Anopheles compared to other mosquitoes

No humped back

25

Mosquito borne infections

Culex
Filariasis and West Nile

Aedes (aegypti and albopictus)
Yellow fever, Dengue fever, Chikungunya fever

Anopheles
Malaria

26

Possible diagnosis methods - ectoparasites

- Can identify nymph
-Gently scrape skin to find eggs/nymphs
-May see egg shell casing/nit left behind e.g. lice
-Bite patterns e.g. linear

27

Treatment - ectoparasites already left person

If parasites have already left person then we treat symptoms of scratching to prevent skin infection
- Antiinflammatories, antihistamines
- Assess for vector borne epidemics

28

Treatment - ectoparasites residing inside person

If infested:
-Remove tick gradually to get whole head out intact
-Lice/Mites -> topical/oral agents
Topical agents
Pyrehtroids
Organophosphates
Benzyl alcohol
Spinosad
Lindane
Ivermectin
Oral agent
Ivermectin (poison them via the food source i.e. blood)
-> then treat itchy skin symptoms