News: Head lice forming a resistance movement.

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Ye Old One

News: Head lice forming a resistance movement.

Legg inn av Ye Old One » 17 jun 2006 22:03:57

Head lice forming a resistance movement
new Scientist Wednesday June 14, 05:00 PM
http://uk.news.yahoo.com/14062006/12/he ... ement.html

By Roxanne Khamsi

It is enough to make your head spin - or at least itch. Eighty per
cent of head lice appear resistant to a common treatment that relies
on pyrethroid chemicals, researchers report. They add that the
problem, identified in Wales, could spread.

Parents should try products containing organophosphates or
silicone-based insecticides as a first-line approach to rid their
children's hair of the bugs, according to the new study.

Head lice, also known as nits, cooties or by their scientific name,
Pediculus humanus , have plagued humans for millions of years (see
Staying ahead in the fight against lice ).

The head of a child infected with lice typically hosts between 10 and
100 bugs. And while head lice do not cause any serious medical
problems, they can cause itchiness and swollen lymph nodes in people
who have an immune reaction to them.

The most common weapons against the head louse use chemicals known as
pyrethroids and organophosphates, both of which disrupt the creature's
nerve . Pyrethroids, for example, wreak havoc by attaching to sodium
channels on nerves.

Pyrethroids are also used against mosquitoes, and some populations of
these insects have also developed resistance, explains Janet
Hemingway, at the Liverpool School of Tropical Medicine in the UK.
Resistance develops because individual bugs which have a natural
genetic resistance to a chemical are more likely to survive and breed.

Anecdotal reports of pyrethroid resistance among head lice in Wales
prompted Hemingway and colleagues to investigate. The team screened
nearly 3000 children selected randomly from 31 schools across Wales to
determine which youngsters had head lice. About 8% of the children
were infected with the bugs.

The researchers sent 316 of the head lice obtained from infested
children for genetic analysis and found that 82% tested positive for
pyrethroid-resistance genes. These genes code for a sodium channel
that will not bind to pyrethroid, and so protects the bug's nerves,
explains Hemingway.

She says that louse resistance to pyrethroids has also been documented
in other countries, such as Israel.

Daniel Thomas of the Wales Communicable Disease Surveillance Centre in
Cardiff, also part of the research team, adds that resistance was
greatest in areas that had the most use of pyrethroid treatments for
head lice.

In southern parts of Wales more than 11% of head lice had two copies
of the pyrethroid-resistance gene. But in northern Wales, where
pyrethroid treatments had been discouraged for five years preceding
the study, only 3% of the head lice had two copies.

Journal reference: Archives of Disease in Childhood (DOI:
10.1136/adc.2005.091280)




--
Bob.

Gjest

Re: News: Head lice forming a resistance movement.

Legg inn av Gjest » 17 jun 2006 22:33:29

Ye Old One schrieb:

Head lice forming a resistance movement

Er, Bob, did you mean to post this to SGM?

Ye Old One

Re: Re: News: Head lice forming a resistance movement.

Legg inn av Ye Old One » 17 jun 2006 22:51:29

On 17 Jun 2006 14:33:29 -0700, mjcar@btinternet.com enriched this
group when s/he wrote:

Ye Old One schrieb:

Head lice forming a resistance movement

Er, Bob, did you mean to post this to SGM?

No, and a cancel went within minutes.

Two posts to the wrong group - I blame the heat myself :(

--
Bob.

Merilyn Pedrick

Re: Re: News: Head lice forming a resistance movement.

Legg inn av Merilyn Pedrick » 18 jun 2006 02:06:02

Although I'm sure medieval children would have had head lice. So perhaps
there is some relevance.
Merilyn Pedrick

-------Original Message-------

From: Ye Old One
Date: 06/18/06 07:24:51
To: GEN-MEDIEVAL-L@rootsweb.com
Subject: Re: Re: News: Head lice forming a resistance movement.

On 17 Jun 2006 14:33:29 -0700, mjcar@btinternet.com enriched this
group when s/he wrote:

Ye Old One schrieb:

Head lice forming a resistance movement

Er, Bob, did you mean to post this to SGM?

No, and a cancel went within minutes.

Two posts to the wrong group - I blame the heat myself :(

--
Bob.

Ye Old One

Re: News: Head lice forming a resistance movement.

Legg inn av Ye Old One » 18 jun 2006 10:42:58

On Sun, 18 Jun 2006 00:04:51 +0000 (UTC), pedricks@ozemail.com.au
("Merilyn Pedrick") enriched this group when s/he wrote:

Although I'm sure medieval children would have had head lice. So perhaps
there is some relevance.
Merilyn Pedrick


Indeed, though as I understand it they have become more of a problem
as we have become cleaner :)

--
Bob.

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