PEDICULOSIS

“Interior with a Mother delousing her child’s hair” or “A Mothers Duty”, oil on canvas, Pieter de Hooch, c1658-1660. ,

More often than fathers, it is mothers who figure in Dutch Paintings and prints as the protectors of the pure household. Indeed Cats and the manual writers insisted that this was a mother’s vocation. It was they who patrolled that dangerous frontier between the dirt of the street and the cleanliness of the home, who set maids scrubbing or who plunged themselves into the daily ritual of banishing compromising grime from the premises. But their grooming extended to the members of the family who were most likely (in either their innocence or their incorrigible fecklessness, depending on which kind of Dutch moralist you were), to bring dirt along with them: the children.

Some of the most affecting family scenes in Dutch are of children submitting to their mother’s inspection of their heads for nits and lice. Gerard ter Borch painted two: one as much an image of domestic virtue as a lace worker or a distaff spinner, the second in the much more unusual setting of an impoverished knife grinder’s yard. This is all the more extraordinary for being anything but the idealized image of the kempt bourgeois household. It is, in fact, one of the few authentic pictures of the kinds of hovels in which many of the poorest artisans and semiskilled labourers lived in Dutch towns. Yet, for all the dereliction and squalor, it is also mistakably an image of domestic virtue. It is virtue offered within the same canvas, at work, and at home, the knife grinding itself invoking the universal image of hard unremitting toil, and in the foreground the mother at the threshold of the dwelling, occupied with the “moedertaak”, her labour of love. “Purgo et Ornat” (“It Cleans and it Beautifies”, runs the legend with Visscher’s comb, the latter being conditional on the former. In de Hooch’s scene in the Rijksmuseum, none of the misery so truthfully set out in ter Borch’s picture threatens the scene of unblemished domestic tranquility. Under the kind of safe housekeeping depicted here, the home was indeed Christian arcadia: the bed spotless, unrumpled and without stain or suspicion, the copper bed warming pan polished to a state of brilliance, the tiles modest and pure. And, for once, the scene included an exemplary puss who would no more soil the pristine purity of the floor than it would turn into a devil’s companion.

Simon Schama, “The Embarrassment of Riches”, Knopf 1987.

The great Dutch masters de Hooch and ter Borch were known for their depiction of domestic scenes during the Dutch “golden age”. Cleanliness was next to godliness, from the most humble hovel to the most upper class home. The Dutch trait of domestic cleanliness during the Seventeenth century is personified in the mother of the Dutch household. Unfortunately however small children would tend to disrupt this domestic bliss. A favourite leitmotif of the Dutch masters was the image of the mother lovingly grooming her children.

Head lice were a common problem in the Seventeenth century, and they remain so today, especially among small children. Traditionally these creatures (that is the lice, not the children…although perhaps that is a debatable point) were associated with poor hygiene, as implicated by ter Borch’s “The Stone Grinder’s Family”, however even good hygiene was no guarantee against infestation, as depicted by the upper class bourgeois setting seen in de Hooch’s, “The Mother’s Task”.

PEDICULOSIS

Introduction

Pediculosis is infestation with head lice.

These are crawling insects about the size of a sesame seed.

They live on the scalp but lay eggs (nits) on the hair.

The head louse is a specific human pathogen and has been associated with humans for at least 10,000 years.

It is acquired by direct head-to-head contact.

Infestation is common in school-age children, endemic in Australia, affects all socioeconomic groups and is essentially harmless.

It does not indicate poor hygiene as is commonly believed.

Epidemiology

● Head lice occur worldwide.

● In 2002 the prevalence of head lice among primary school children in Victoria was found to be 13%.

● Females were more than twice as likely to have head lice as males.

● The prevalence of head lice in primary school aged children in other parts of Australia is reported to be up to 60%.

Infectious agent

● Pediculus humanus var. capitus

● Head lice are small, wingless, blood sucking insects.

● Their color varies from whitish-brown to reddish-brown.

● Head lice do not have wings or jumping legs so they cannot fly or jump from head to head. They can only crawl.

For the life cycle of the head louse, see appendix 1 below.

Left: Pediculus humanus var. capitus, via a light microscope (from CDC), actual size 2-4 mm. Right: Egg (nit) of human head louse attatched to a human hair, (Micrographia website)

Scanning electron microscope image of Pediculus humanus var. capitus

Incubation period

The life cycle consists of three stages:

● Egg

● Nymph

● Adult.

The eggs are known as nits and hatch in six to seven days.

There are three nymphal forms that each last one to eight days.

The female lays the first egg one or two days after mating and can lay approximately three to eight eggs per day for the next 16 days.

After a life span of 32–35 days the louse dies.

Reservoir

● Humans are the only reservoir.

● The lice of other animals are not transmissible to humans.

Mode of transmission

● Pediculosis is transmitted through direct head to head contact with a person with head lice.

● Nymphal and adult lice survive, dependent on the humidity of the environment, and according to research undertaken in Queensland, usually die within 24 hours of being stranded away from the head.

● There is no significant risk of transmission from the environment.

Period of communicability

● Communicability continues as long as lice or their nymphs remain alive.

Susceptibility & resistance

● Anyone can get lice and given the opportunity head lice will move from head to head without discrimination.

● They are however most frequently associated with children.

Clinical features

1. Symptoms:

● Most cases are totally asymptomatic.

● Head lice are not vectors of infectious disease.

Louse-borne relapsing fever, trench fever and typhus, none of which occur in Australia, are all associated with the body louse Pediculus humanus var. corporis, a different species.

● It presents when eggs are noticed to be attached to the hair or when itching of the scalp and nape of the neck becomes a problem.

● Excoriations and papules may be found around the occiput and nape, and lymphadenopathy with or without secondary bacterial infection may occur.

2. Appearance:

● Head lice are about 2-4 mm in length.

● Head lice eggs (nits) are small (the size of a pinhead) and oval. A live egg will “pop” when squashed between fingernails.

3. Diagnosis of active lice infestation is made by observing a live, moving louse on the scalp.

Investigation

The diagnosis of pediculosis is clinical and no specific investigation is required.

Management

1. Finding head lice:

Lice can crawl and hide. The easiest and most effective way to find them is to follow these steps:

Step 1

● Comb any type of hair conditioner on to dry, brushed (detangled) hair. This stuns the lice and makes it difficult for them to grip the hair or crawl around.

Combs with long, rounded stainless steel teeth positioned very close together have been shown to be the most effective, however, any head lice comb can be used.

Step 2

● Now comb sections of the hair with a fine tooth, head lice comb.

Step 3

● Wipe the conditioner from the comb onto a paper towel or tissue.

Step 4

● Look on the tissue and on the comb for lice and eggs.

Step 5

● Repeat the combing for every part of the head at least 4 or 5 times

If lice or eggs are found, the child's hair should be treated.

2. Wet combing:

● Some cases can be cured by wet combing (applying hair conditioner to wet hair and using a fine nit comb as above), every day for 10 to 14 days until no lice are found. This method has only about a 40% success rate.

● Combing is easier with shorter hair styles, but shaving the head is not necessary.

3. Dry heat:

● Another physical treatment that may be used involves applying heat with a hair dryer to small sections of hair for 1 to 3 minutes, over a period of 30 minutes.

● Although this method is more effective in killing eggs than live lice, it is more effective in achieving cure than wet combing.

3. Topical insecticides

Otherwise topical insecticides can be used.

Lotions include:

● Maldison 0.5% or 1%

● Permethrin 1%

● Pyrethrins 0.165%

See latest Antibiotic Therapeutic Guidelines for full prescribing details.

No treatment kills all of the eggs so treatment must involve two applications seven days apart. All lice treatments should be repeated 7 to 10 days later.

Concentrate on the head - there is no evidence to suggest that you need to clean the house or classroom.

If you are using lotions, apply the product to dry hair.

4. Treating other family members:

● There is no need to treat the whole family, unless they also have head lice.

5. Clothing:

● Only the pillowcase requires specific laundering; either wash it in hot water (at least 60 degrees centigrade) or dry it using a clothes dryer on the hot or warm setting.

6. Prevention:

● There is no product available that prevents head lice.

● Tying back long hair can help prevent the spread of head lice.

● In between treatments use the same wet combing method twice, removing all eggs less than 1.5 cm from the scalp with a head lice comb or by pulling them off with fingernails. These eggs may contain viable larvae. Wet combing should be repeated weekly for several weeks after cure to detect recurrence. The presence of eggs on the hairs more than 1.5 cm from the scalp only indicates previous, not active, infestation. 2

7. Cleaning comb:

● Head lice rarely fall from the head.

● Data from James Cook University show head lice on combs and brushes are easily killed by immersion in hot water at 60°C for one minute.

● There is then no subsequent risk of transmission from the comb or brush to the next client.

8. Treatment failures:

● For strategies in apparent treatment failures, see latest edition of Antibiotic Therapeutic Guidelines.

Resources

Resources for school: www.health.vic.gov.au/headlice

“Purgat et Ornat”, (“It Cleans and it Beautifies”)

Emblem from Roemer Visscher, Sinnepoppen. 17th century print. Houghton Library, Harvard University.

Appendix 1

Life cycle of the head louse:

1. Egg is laid on hair shaft. Egg is called a “nit”.

2. Louse emerges after 6-7 days.

3. First moult 2 days after hatching.

4. Second moult 5 days after hatching.

5. Third moult 10 days after hatching.

6. Emerging from their third moult as adult lice, the female and slightly similar male begin to reproduce.

7. Female lays first egg 1 or 2 days after mating.

8. Female can lay approximately 3 to 8 eggs per day for the next 16 days.

9. Having lived 32 to 35 days the louse then dies.

“The Stone Grinders Family”, oil on canvas, Gerard ter Borch, 1653-55, Gemaldegalerie, Berlin.

References

1. The Blue Book Website

2. Antibiotic Therapeutic Guidelines, 13th ed. 2006.

3. www.health.vic.gov.au/headlice

Dr J. Hayes 1 October 2009.