26. Arthropods (lice, part 1) Flashcards
where can lice be found?
on people’s heads, and human bodies, including the pubic areas
how do human lice survive?
by feeding on human blood
what do both males and females (immature and adult) require to complete their development?
blood meals
which is the only louse known to spread disease?
body louse
how are lice infections spread most commonly?
by close person to person contact
do cats, dogs and other pets play a role in transmission of human lice?
no
how do lice move?
by crawling
can lice fly or jump?
no
do lice have wings?
no
what do lice have on their legs? what are they for?
claws that grip and hold onto their shafts
how many legs do lice have?
6 legs
how many segments do the antennae have?
5 segments
what is the shape of their abdomens?
longer than they are wide
are the lice found in different parts of the body the same?
no, they are different from each other
what are the three types of lice found on humans?
- Pediculus humanus capitis (head louse)
- Pediculus humanus corporis (body louse, clothes louse)
- Pthirus pubis (“crab” louse, pubic louse)
what is the head louse?
Pediculus humanus capitis
what is the body louse, clothes louse?
Pediculus humanus corporis
what is the “crab” louse or pubic louse?
Pthirus pubis
among who, is head lice most common?
among preschool and elementary school-aged children and their household members and caretakers
are head lice known to transmit disease?
no
what is a common malignancy associated with head lice?
secondary bacterial infections of the skin resulting from scratching (any lice infestation)
is getting head lice related to cleanliness?
no
what is the most common way to get head lice?
head to head contact with an already-infected person
what is head lice’s means of camouflage?
they can change their color to match the hair of the infected person
how are lice treated?
with lice-killing shampoos and rinses (insecticides), and nit combs should be used to comb nits and lice from the hair shaft
what are nits?
lice eggs, laid by the adult female at the base of the hair shaft nearest the scalp
how long to nits take to hatch?
1 week
what does the nit hatch into?
nymphs
what does the lice nymph resemble?
they look like adult head louse, but is the size of a pinhead
after how many molts are nymphs mature?
3 molts
how many days after hatching are lice nymphs are eventually adults?
about 7 days
how many legs do adult lice have? how many claws?
6 legs, each having a claw
what color is adult lice?
tan to greyish white
who is larger in lice, females or males?
females are usually larger than males
how many nits do female lice lay per day?
up to 8
how long can lice live on a person’s body?
up to 30 days
where do body lice live that is different from other lice?
body lice prefer to live in the seams and linings of unwashed clothing, blanket and sheets and only move to the skin to feed
how long without blood meals can body lice go before they die?
1 to 2 days
where are the nits of body lice found?
Although body lice usually deposit their nits on unwashed clothing fibers, the nits are sometimes found on body hair as well
are body lice known to spread disease?
yes
what can body lice spread in terms of diseases?
epidemic typhus
trench fever
louse-borne relapsing fever
is louse-borne epidemic typhus wide spread?
no
do outbreaks of louse-borne epidemic typhus still occur? if yes, when?
yes, in times of war, civil unrest, natural or man-made disasters, and in prisons where people live together in unsanitary conditions
where does Louse-borne typhus still exist?
in places where climate, chronic poverty, and social customs or war and social upheaval prevent regular changes and laundering of clothing
how us body lice infestation diagnosed?
by finding eggs and crawling lice in the seems of clothing or feeding on skin
how is a body louse infestation treated?
by improving the personal hygiene of the infected person, including assuring a regular (at least weekly) change of clean clothes
how do you treat the environment of an infected person?
Clothing, bedding, and towels used by the infested person should be laundered using hot water (at least 55°C) and machine dried using the hot cycle
where can pubic lice be found?
- usually attached to pubic hair
- can also be found in the eyebrows, eyelashes, beard, moustache, chest, armpits, etc
- any course hair
what is the common name for pubic lice?
crabs
why do pubic lice prefer the pubic regions?
they are adapted to grasp hairs that are rather widely spaced from each other
how is pthiriasis usually spread?
through sexual contact
what would kill pubic lice?
lice-killing lotion
what do you do after killing the pubic lice?
you have to comb them out with a fine toothed comb because most nits will still be attached to the hair
