Module 6 Lice Flashcards Preview

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Flashcards in Module 6 Lice Deck (20)
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1
Q

two groups of lice

A
  1. chewing lice (birds, marsupials, placental mammals)

2. sucking lice (oblate hematophagous; placental mammals)

2
Q

lice anatomy

A
small, highly modified
no wings or eyes
dorsoventrally flattened
numerous setae
strong tarsal/tibial claw
3
Q

lice development

A

hemimetabolous (egg - X3 nymph - adult)
eggs called nits
females can produce 10 eggs / day

4
Q

phoresy

A

transportation over short distance by hitching a ride on a non-host organism

5
Q

chewing lice taxonomy

A

order Phthiraptera

suborder Mallophaga

6
Q

chewing lice characteristics

A

most diverse
obligates of birds, marsupials, placental mammals
most feed fur, hair, or skin (not blood)
not medically important

7
Q

Trichodectes canis

A

Dog Biting Louse

  • chewing lice
  • tapeworm uses louse as host, louse eats its eggs, humans accidentally eat the infected louse
8
Q

sucking lice taxonomy

A

order Phthiraptera

suborder Anoplura

9
Q

sucking lice characteristics

A

blood feeders
stylets consist of labium, hypo pharynx, and 2 maxillae
capable of transmitting diseases

10
Q

human body louse

A

Pedicules humanus humanus

  • infest clothing and lays eggs here (exception!)
  • not common in developed nations
  • most important medically (only species to transmit pathogens)
  • overcrowding/unsanitary conditions
11
Q

human head lice

A

Pediculus humanus capitus

  • infects head/scalp
  • eggs cemented to hair
  • very common especially among children
  • person to person contact
  • no major health concerns
12
Q

plica polonica

A

matting of hair and human head lice parts
can develop secondary fungal infections
mainly in peasants

13
Q

human crab / pubic lice

A

Phthirus pubis

  • large claws for gripping thick pubic hair
  • transfer thru intimate contact
  • very short lifespan off of host
  • cause intense itching/purple lesions
  • not know to transmit disease
14
Q

pediculosis

A

infestation of 1 of 3 species
skin becomes tough/pigmented
weariness/irritability caused by repeated injection of saliva

15
Q

epidemic typhus

A
  • caused by infection of Rickettsia prowazekii
  • louse-borne fever
  • Rickettsia invade gut of louse then burst cells and kill louse
  • infection occurs when feces of infected louse is rubbed into abrasions
  • bacteria can live up to 60 days in feces so lice usually not found on human when he/she gets sick
16
Q

louse-borne relapsing fever

A
  • caused by borrelia recurrentis
  • parasite invades body of louse and kills it (but doesn’t reach feces)
  • infection occurs when the louse is rubbed into abrasions
17
Q

trench fever

A
  • caused by Bartonella quintana
  • parasite multiplies in lice gut but doesn’t kill it
  • parasite is voided in feces
  • infection occurs when feces is rubbed into abrasions
18
Q

body louse control

A

limit contact with infested people
wash bedding/clothing in hot water
insecticides

19
Q

head lice control

A

shampoos, lotions (but only kills adults)
repeated treatments needed
use fine toothed comb

20
Q

public lice control

A

change bed linens
shampoo
shaving of hair
awareness of sexual partner