Pediculus humanus
(body and head lice)
Adults:
http://www.k-state.edu/parasitology/625tutorials/Arthropods05.html
From: http://www.historyhouse.com/in_history/lousy/
During the Russian revolution, there was an
outbreak of typhus (transmitted by lice) so severe that Lenin remarked, "Either
socialism will defeat the louse, or the louse will defeat socialism."
To
get an idea of how powerful a force disease is, and to remind the historian
that it should not be overlooked, allow us to quote Hans Zinssner's account of
a famous plague of ancient times -- the Plague of Justinian. It started in the
year 540, perhaps prompted by a series of earthquakes and floods which created
refugee conditions across much of Eastern Christendom.
From Hans Zinsser’s Rats, Lice and History
(copyright 1941)
|
|
Four months the plague remained in
Also From
Hans Zinsser’s Rats, Lice and History (copyright 1941)
...among the Aztecs before the advent of Cortez, is the tale cited
from Torquemada. 'During the abode of Montezuma among the Spaniards, in the
palace of his father, Alonzo de Ojeda one day espied... a number of small bags,
tied up. He imagined at first that they were filled with gold dust, but on
opening one of them what was his astonishment to find it quite full of Lice!'
Cortez... then asked... for an explanation. He was told that the Mexicans had
such a sense of duty to pay tribute to their ruler that the poorest, if
they possessed nothing else to offer, daily cleaned their bodies and saved
the lice. And when they had enough to fill a bag, they laid it at the feet
of their king.
MacArthur's story of Thomas a Becket's funeral illustrates [this]:
-- The archbishop was murdered in Canterbury Cathedral on the evening of the
twenty-ninth of December. The body lay in the Cathedral all night, and
was prepared for burial on the following day... He had on a large brown mantle;
under it, a white surplice; below that, a lamb's-wool coat; then another woolen
coat; and a third woolen coat below this; under this, there was the black,
cowled robe of the Benedictine Order; under this, a shirt; and next to the body
a curious hair-cloth, covered with linen. As the body grew cold, the vermin
that were living in this multiple covering started to crawl out, and, as
MacArthur quotes the chronicler: 'The vermin boiled over like water in a
simmering cauldron, and the onlookers burst into alternate weeping and
laughter.'
Robert
Burns’ Ode to a Louse, appearing at http://forums.eslcafe.com/student/viewtopic.php?p=738
Robert Burns
(1759-1796)
TO A LOUSE, ON SEEING ONE ON A LADY’S BONNET AT CHURCH
Ha! whare ye gaun, ye crowlan ferlie!
Your impudence protects you sairly;
I canna say but ye strunt rarely,
Owre gauze and lace;
Tho', faith! I fear ye dine but sparely
On sic a place.
Ye ugly, creepan, blastit wonner,
Detested, shunn'd by saunt an' sinner,
How daur ye set your fit upon her,
Sae fine a Lady!
Gae somewhere else and seek your dinner
On some poor body.
Swith! in some beggar's haffet squattle;
There ye may creep, and sprawl, and sprattle,
Wi' ither kindred, jumping cattle,
In shoals and nations;
Whare horn nor bane ne'er daur unsettle
Your thick plantations.
Now haud you there, ye're out o' sight,
Below the fatt'rels, snug and tight,
Na, faith ye yet! ye'll no be right,
Till ye've got on it,
The verra tapmost, towrin height
O' Miss's bonnet.
My sooth! right bauld ye set your nose out,
As plump an' grey as onie grozet:
O for some rank, mercurial rozet,
Or fell, red smeddum,
I'd gie you sic a hearty dose o't,
Wad dress your droddum!
I wad na been surpriz'd to spy
You on an auld wife's flainen toy;
Or aiblins some bit duddie boy,
On's wylecoat;
But Miss's fine Lunardi, fye!
How daur ye do't?
O Jenny, dinna toss your head,
An' set your beauties a' abread!
Ye little ken what cursed speed
The blastie's makin!
Thae winks and finger-ends, I dread,
Are notice takin!
O wad some Pow'r the giftie gie us
To see oursels as others see us!
It wad frae monie a blunder free us,
An' foolish notion:
What airs in dress an' gait wad lea'e us,
And ev'n Devotion!
Here
is THE quote from Hans Zinsser's Rats, Lice and History (copyright 1941):
"Weizl
(an Austrian anthropologist) informs us that, when
sojourning
for a short time among the natives of Northern
him.
On inquiry concerning this disconcerting procedure, he was
embarrassed
by learning that this was the customary manner of
indicating
love, and a notice of serious intentions. A sort of
'My
louse is thy louse' ceremony."
Phylogeny: Order Anoplura
(sucking lice)
Metamorphosis: Incomplete
Geographical
location: Cosmopolitan
Organs
affected; Skin
Symptoms
and clinical signs: Saliva induces
roseate elevated papules. Severe infestation
lead to scarring, induration, ulceration.
Diseases
transmitted: Epidemic typhus,
trench fever, relapsing fever
Treatment/control: Head lice: Shampoo with pyrethrins (0.2%), piperonyl
butoxide and copper oleate. If that
doesn't work, use olive oil or mayonnaise, leave on head overnight. Brush hair thoroughly.
Body
lice: Shampoo containing 0.2% or 0.3%
allethrin synergized with piperonyl butoxide.
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NOTE: To view the article with Web enhancements, go to:
http://www.medscape.com/viewarticle/556115
This activity is supported by funding from WebMD.
Therapy for
Head Lice Should Be Based on Life Cycle, Resistance, and Safety Considerations
News Author: Laurie Barclay, MD
CME Author: Charles Vega, MD
Complete
author affiliations and
disclosures, and other CME information, are available at the end of
this activity.
Release Date: May 7, 2007; Valid
for credit through May 7, 2008
Credits Available
Physicians - maximum of 0.25 AMA PRA Category 1
Credit(s)™ for physicians;
Family Physicians - up to 0.25 AAFP Prescribed credit(s) for physicians
All
other healthcare professionals completing continuing education credit for this
activity will be issued a certificate of participation.
Physicians should only claim credit commensurate with the extent of their
participation in the activity.
May
7, 2007 — Malathion should be used as first-line treatment of head lice
infestation in children, according to a review published in the May issue of Pediatrics.
Therapy for head lice should be based on life cycle, resistance, and safety
considerations.
"Traditional
pharmacological therapies for the human head louse, Pediculus humanus var.
capitis, have focused on 1 or 2 courses of various ovicidal and
pediculicidal topical therapies," write Mark Lebwohl, MD, from the Mount
Sinai School of Medicine in
"Head
lice, within the past 20 years, have developed resistance to nearly all
first-line pharmacotherapy in the
The
timing of head lice maturation most favorable to their survival when exposed to
anti-lice agents is the maximum time as an ovum (12 days) and the shortest
possible time of maturing from newly hatched nymph to egg-laying adult (8.5
days).
Pediculicides
that are not reliably ovicidal, such as the pyrethroids and lindane, mandate 2
to 3 treatment cycles to eradicate lice, whereas ovicidal therapies, such as
malathion, require 1 to 2 treatments.
Treating
with an agent to which genetic resistance has developed is unproductive. In the
The
guidelines state that nit combing can be performed adjunctively, and that no-nit
policies should be rendered obsolete.
Complications
of head lice infestations include poor sleep and excoriation from untreated
infection, which can occasionally become superinfected with
methicillin-resistant Staphylococcus aureus or streptococcus. Social
consequences include stigma, embarrassment, low self-esteem, disgust, and
inability to attend school because of no-nit policies, which result in
absenteeism, lost work for parents, missed education for the child, and
needless anxiety.
The
Based
on review of life-cycle considerations, therapeutic mechanisms of action,
development of resistance, and head lice biology, the guidelines recommend
malathion, in the formulation containing isopropyl alcohol and terpineol, as
the favored first-line agent for head lice. At any given time, a patient
infected with head lice will have lice existing at different points in the life
cycle, and the only therapy that will ensure head lice eradication when used
according to the package insert is malathion.
Malathion,
0.5%, is flammable when the hair is wet, and it is in pregnancy category B.
However, the review states that concerns about flammability may be ill-founded
because there are no known reports of bodily injury resulting from the
isopropyl alcohol catching fire. Nonetheless, appropriate precautions about
avoiding heat sources during use should be followed.
Other
pharmacologic therapies currently approved by the US Food and Drug
Administration for head lice include lindane, 1% (γ-benzene hexachloride),
with adverse events including neurotoxicity, and a Food and Drug Administration
black-box warning that it should not to be used in patients with psoriasis or
atopic dermatitis. It is in pregnancy category C. It noncompetitively inhibits
the γ-amino butyric acid receptor, resulting in neuronal hyperstimulation
that paralyzes the louse. Lindane's efficacy has decreased over the years, it
is not consistently ovicidal, and development of resistance is widespread.
Permethrin,
1%, is in pregnancy category B. Pyrethrins, 0.33%, plus piperonyl butoxide, 4%,
may cause an asthma attack if the patient is allergic to ragweed, and it is in
pregnancy category B.
"The
use of malathion as a first-line treatment also has broader implications for
school head lice policy in the
On
the other hand, the authors of the current review acknowledge that nits
represent the possibility of infestation and that detection of active
infestation is imperfect, mandating a more definitive demonstration of freedom
from lice. The authors suggest that one option would be to require children
with index cases of head lice and their family members to be treated with
malathion. Classmates could be screened for head lice, and those with head lice
could be treated promptly with malathion, preferably simultaneously and at days
0 and 7.
Rescreening
after malathion treatment would not be needed, because the examination is
imperfect and the probability of treatment success is very high. As was the
policy for permethrin treatment in the past, a child could return to school the
day after treatment.
"Were
the concern that a parent is neglectful or would not apply the product
correctly, direct observational therapy could be used in the school," the
authors conclude. "Such a practice would allow for the elimination of
no-nit policies without risk of reinfestation in the school and with all the
attendant pharmacoeconomic benefits: breaking the cycle of spread, decreasing
absenteeism from schools, decreasing missed work by the parent, and eliminating
repeated spends on ineffective modalities."
One
of the authors has disclosed he is vice president and a major shareholder of
Taro Pharmaceutical Industries Ltd, which makes and markets malathion (Ovide)
lotion. The other authors have disclosed no relevant financial relationships.
Pediatrics. 2007;119:965-974.
Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:
- Identify a
recommended treatment of head lice.
- Describe current
recommendations for policies of school attendance when head lice nits are
present.
Clinical Context
Head
lice are a public health concern and can be more than a nuisance. Lice can
negatively affect sleep and promote scalp excoriations, which may become
secondarily infected with bacteria. In addition, many schools prohibit children
with nits from attending class, leading to significant degrees of absenteeism
nationwide.
The
treatment of head lice has changed as more is understood about the parasite and
as patterns of resistance have emerged. The current review focuses on the best
treatment practices for head lice.
Study Highlights
- Lindane inhibits
the γ-amino butyric acid receptor. Treatment of head lice with
lindane is not recommended because of widespread resistance, inconsistent
ovicidal efficacy, and the potential for neurotoxicity. The authors
estimate that 2 to 3 treatments with lindane would be necessary to
adequately treat head lice, and such treatment is not accepted as safe by
the Food and Drug Administration.
- Permethrin and
pyrethrins delay closure of voltage-gated sodium channels, paralyzing the
louse's nervous system. Permethrin is generally very safe, but resistance
to the treatment is significant. Whereas previous cure rates following use
of permethrin exceeded 95%, 2 recent studies found that 2 applications of
permethrin at 0 and 7 days were only 45% to 55% effective in eliminating
lice.
- Malathion
irreversibly inhibits acetylcholinesterase, and louse resistance to
malathion has not been reported in the
- Oral ivermectin
may kill lice that take a blood meal, but the precise dosing of this
treatment is not clear. Oral trimethoprim/sulfamethoxazole has a mixed
record of efficacy in the treatment of head lice.
- Nonpharmacologic
therapies for head lice, including vinegar, mayonnaise, petroleum jelly,
olive oil, butter, isopropyl alcohol, and water submersion, generally have
not been proven to be effective. Nit combing can be expected to have cure
rates as low as 38%.
- Only 18% of
children with nits on screening examination will develop active head lice
infection. The authors of the current review call for a rejection of the
policy that any child with nits should avoid school. Instead, they call
for research into empiric treatment with malathion for children with nits,
and they also suggest that empiric treatment of close contacts of children
with active infection may be an effective strategy.
Pearls for Practice
- The current
review recommends malathion as the best treatment of head lice in
children.
- The current
review recommends that children with head lice nits should not
automatically be removed from school. Instead, empiric treatment with
malathion may be considered.
News Author
Laurie Barclay, MD
is a freelance reviewer and writer for Medscape.
Disclosure:
Laurie Barclay, MD, has disclosed no relevant financial relationships.
CME Author
Charles P. Vega, MD
Associate Professor; Residency Director, Department of Family Medicine,
Disclosure:
Charles Vega, MD, has disclosed an advisor/consultant relationship to Novartis,
Inc.
Medscape Medical News 2007. ©2007 Medscape
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