Module 6 Lice Flashcards Preview

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Flashcards in Module 6 Lice Deck (20):
1

two groups of lice

1. chewing lice (birds, marsupials, placental mammals)
2. sucking lice (oblate hematophagous; placental mammals)

2

lice anatomy

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

3

lice development

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

4

phoresy

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

5

chewing lice taxonomy

order Phthiraptera
suborder Mallophaga

6

chewing lice characteristics

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

7

Trichodectes canis

Dog Biting Louse
-chewing lice
-tapeworm uses louse as host, louse eats its eggs, humans accidentally eat the infected louse

8

sucking lice taxonomy

order Phthiraptera
suborder Anoplura

9

sucking lice characteristics

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

10

human body louse

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

human head lice

Pediculus humanus capitus
-infects head/scalp
-eggs cemented to hair
-very common especially among children
-person to person contact
-no major health concerns

12

plica polonica

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

13

human crab / pubic lice

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

pediculosis

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

15

epidemic typhus

-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

louse-borne relapsing fever

-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

trench fever

-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

body louse control

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

19

head lice control

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

20

public lice control

change bed linens
shampoo
shaving of hair
awareness of sexual partner