Ectoparasites

Question 1

Ectoparasites live where?

Answer 1

On the skin

Question 2

Distinctive features of ectoparasites

Answer 2

Exoskeleton

Articulated/bent legs

Question 3

Body’s general response to infection

Answer 3

Allergic dermatitis

Bite patterns

Question 4

Allergic dermatitis in ectoparasitic infections

Answer 4

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

Question 5

Bite patterns - ectoparasitic infections

Answer 5

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

Question 6

Ticks - two types

Answer 6

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

Question 7

Tick borne diseases

Answer 7

Lyme disease
Rocky Mountain Spotted fever - Rickettsiae 
Ehrlichia 
Anaplasma 
Babesia

Question 8

Hard tick - stages of growth and num of legs

Answer 8

Larvae - nymph - Adult

8 legs

Question 9

Pathogenic host preference for Ticks

Answer 9

Humans/animals

Question 10

Lice - three types

Answer 10

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

Question 11

Lice borne diseases

Answer 11

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

Question 12

Lice - number of legs and host preference

Answer 12

Six legs

Humans

Question 13

Mites - one type

Answer 13

Sacroptes scabei

Question 14

Mite host preference and num of legs

Answer 14

Anthropophilic

8 legs

Question 15

Anthropophilic

Answer 15

Preferring animal host to humans

Question 16

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

Answer 16

True

Question 17

Diseases spread by mites

human = accidental host

Answer 17

• Rickettsialpox (Rickettsia akari)

- Scrub Typhus (Orienta tsutsugamushi)

Question 18

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

Answer 18

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

Question 19

Fleas - 4 types

Answer 19

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

Question 20

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

Answer 20

True

Question 21

Fleas - number of legs

Answer 21

6 legs

Question 22

Flea borne infections

Answer 22

Rat flea causes the foll:

• -Bubonic plague (caused by Yersinia pestis)
• Tularemia (caused by Francisella tularensis)
• Murine “endemic” typhus (R. typhi)

Question 23

Mosquito - 3 types

Answer 23

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

Question 24

Distinguishable features of Anopheles compared to other mosquitoes

Answer 24

No humped back

Question 25

Mosquito borne infections

Answer 25

Culex
Filariasis and West Nile

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

Anopheles
Malaria

Question 26

Possible diagnosis methods - ectoparasites

Answer 26

• 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

Question 27

Treatment - ectoparasites already left person

Answer 27

If parasites have already left person then we treat symptoms of scratching to prevent skin infection

• Antiinflammatories, antihistamines
• Assess for vector borne epidemics

Question 28

Treatment - ectoparasites residing inside person

Answer 28

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