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Thursday, 7 March, 2002, 18:48 GMT
Bacteria 'holds key' to river blindness
River blindness affects millions
Cheap antibiotics could revolutionise treatment for a disease which blinds thousands every year in developing countries.

River blindness is caused by a worm which burrows into the skin before releasing many hundreds of offspring which spread throughout the body.

Over decades, they appear to cause inflammation in the eye which eventually destroys sight.

In some parts of Asia and Africa, where the disease is endemic, as many as 15% of people carry the worms.

Traditionally, drugs have been employed to tackle the worm and its descendants, but research in Liverpool, Hamburg in Germany, and the US could change that.

According to experts, the worms are heavily dependent on a particular type of bacteria, called Wolbachia, which they carry in their guts.

They may need the bugs in order to reproduce successfully.

Mouse tests

And the new evidence, published in the journal Science, suggests that the bacteria also cause the inflammation which causes lasting damage to skin and eyes.

These bacteria appear to be vulnerable to simple and inexpensive antibiotics, giving doctors working in developing countries an effective tool to attack them.

Two researchers from the Bernhard Nocht Institute for Tropical Medicine in Hamburg, infected some mice with the contents of worms treated with antibiotics, and others with extracts from non-treated worms.

Mice exposed to the treated extracts showed significantly less thickening and haze of the eye's cornea, and fewer overall signs of inflammation.

Drug resistance

Dr Mark Taylor, from the Liverpool School of Tropical Medicine, said: "This research has totally changed our understanding of the disease and opens up new options for its treatment.

"Even in a mud hut medical centre, you will find the antibiotics, which are effective at sterilising the worm and clearing the bacteria.

"The hope is that this new approach to treatment will both clear the pathogenic bacteria from existing worms and, through sterilisation, prevent the release of new worms, so preventing the onset of disease and recurring infection."

The worms, Onchocerca volvulus, which are responsible for river blindness, are carried by a black fly, and passed on humans via their bite.

While many strategies to combat river blindness focus on prevention of infection, with frequent washing, infected patients are given the drug ivermectin, which targets the worms directly.

There has been concern that the worms are now developing resistance to this drug.

The BBC's Kevin Boquet
"Until now doctors have tried to attack the worm"
Dr Mark Taylor of Liverpool Tropical Disease School
"The new therapy will be able to kill the adult worms"
See also:

22 Sep 00 | Health
Danger worms tracked from space
07 Jun 00 | Health
River blindness 'breakthrough'
04 Sep 01 | Health
Worm turns for blindness remedy
31 Oct 00 | Health
Tropical disease drugs withdrawn
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