Head Lice

Question 1

What are head lice?

Answer 1

parasitic insects that infest the hairs of the human head and feed on blood from the scalp

Question 2

What infective organism is known as head lice?

Answer 2

Pediculus humanus capitis

Question 3

What is the range of severity of headlice?

Answer 3

The severity of infestation varies from a few lice (fewer than 10) to over 100 lice (in up to 5% of people) and more than 1000 in severe cases

Question 4

How many headlice does a typical infestation involve?

Answer 4

30 lice per head

Question 5

What is the life cycle of head lice?

Answer 5

Louse eggs (ova) are laid close to the scalp surface and are strongly attached to the hair with a glue-like substance. They are oval shaped, translucent, may be confused with dandruff

Nymphs are baby lice that hatch from the eggs. They look like the adults but are about the size of a pinhead. They are pearly white in colour and generally take about 7–10 days to mature into adult lice.

Adult head lice are about the length of a sesame seed (up to 3 mm long). They are tan to grey in colour and have six legs ending in hook-like claws to hold onto the hair. The female louse lays anywhere from 50–150 eggs during her 30–40-day lifespan.

Question 6

How long does it take the ova to hatch?

Answer 6

7-10 days

Question 7

What is ‘nits’ referring to?

Answer 7

nits are technically the empty shells of hatched louse eggs that turn white and remain attached to the hair, but further from the scalp surface.

Question 8

What is the route of transmission for headlice?

Answer 8

Transmission of head lice requires head-to-head contact.

Are extremely unlikely to be transmitted by sharing hats, combs, or pillows. However, head lice that are caught in combs and brushes, or remain clinging to stray hairs in them, can be returned to the head unhurt at a subsequent stroke.

Question 9

What is the life span of lice once detached from the human head?

Answer 9

The life span of a louse is very short once it is detached from a human head (1–2 days), as lice are completely dependent on their human host for nutrition and warmth.

Question 10

What is the most common age range for head lice?

Answer 10

4-11 years old

Question 11

Is it more common in boys or girls?

Answer 11

Girls

Question 12

What are some complications of headlice?

Answer 12

1. Pruritic rash
2. Anxiety
3. Rarely excoriation and secondary skin infection caused by scratching

Question 13

How should a head lice infestation be confirned?

Answer 13

By detection combing (Wet or dry)

Question 14

What must be found to confirm active head lice infestation?

Answer 14

A live lice

Question 15

Describe the pathogenesis of headlice:

Answer 15

adult lice inject the scalp with saliva and feed on human blood, causing itching and irritation

Question 16

How many eggs can a female louse lay in one day?

Answer 16

up to 10

Question 17

Give 4 clinical features associated with headlice:

Answer 17

1) itchy scalp
2) feeling of things moving in the hair
3) crusting and scaling (caused by excessive scratching)
4) visible headlice (in some cases)
5) louse bites

Question 18

Describe the appearance of louse bites:

Answer 18

small red papules under the hair line behind the ears

Question 19

What is the first line treatment of headlice?

Answer 19

dimeticone 4% lotion

Question 20

Describe how dimeticone lotion should be applied and used:

Answer 20

apply to hair and leave overnight before washing off and repeat 7 days later to kill any headlice that have hatched since treatment

Question 21

How does dimeticone treat headlice?

Answer 21

it creates a coating on the louse, suffocating it

Question 22

What method can be used to manually remove headlice from hair?

Answer 22

fine tooth combs (4 times over 2 weeks)

Question 23

What medication should be considered if dimeticone treatment continuously fails to treat headlice?

Answer 23

ivermectin (topical/oral)