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Last Updated: Friday, 12 January 2007, 07:24 GMT
Scientists decode sex bug genes
Trichomonas vaginalis parasites (green) adhering to vaginal epithelial cells (pink). Image: Antonio Pereira-Neves and Marlene Benchimol.
Trichomonas causes millions of infections each year
Scientists have unravelled the genetic code of an organism that causes millions of sexually transmitted infections every year.

Trichomonas vaginalis is a parasite that can cause a painful infection, trichomoniasis.

Experts from the US and UK have now mapped the genome of the creature, and say it offers clues to better treatments in both men and women.

Their work has been published in the journal Science.

Trichomonas has flourished because approximately half the people who have it never show the trademark symptoms or irritation and discharge, and pass it on to others without knowing.

It is particularly adept at binding to the inside of the vagina and causing damage to cells in its surface.

The work to plot its genetic structure was completed by the Institute for Genomic Research in Maryland, with assistance from experts at Newcastle University, who spent two years on the project.

Targets for medicine

Dr Robert Hirt, a member of the Newcastle team, said that the breakthrough had already thrown up large numbers of genetic areas which might prove useful to doctors looking for potential targets for drugs.

He said: "While many cases of Trichomonas can be dealt with easily, there is between a 2% and 5% resistance to the current drugs, so we need to find alternatives.

"We hope that the information we've produced will help to do that." He said that, unexpectedly, the tiny parasite has an enormous genome, with the likelihood of having more genes than humans.

We have new ways of studying the biology of an organism that continues to be ignored as a public health issue despite the high number of trichomoniasis cases in the world
Jane Carlton
Trichomonas Genome Project
"We think that at some point it increased the size of its genome, perhaps to become physically bigger, as this may have offered an evolutionary advantage when trying to colonise the vagina."

Trichomonas Genome Project director Jane Carlton said: "Now that we have the T. vaginalis genome sequence and analysed its many unique features, we have new ways of studying the biology of an organism that continues to be ignored as a public health issue despite the high number of trichomoniasis cases in the world."

Painful signs

It is estimated that approximately 170 million people each year are affected by the parasite.

Toni Belfield from sexual health charity FPA said that Trichomonas was common in the UK, and almost always passed on through unprotected sex.

She said: "New understanding about sexually transmitted infections like Trichomonas vaginalis is important because it helps develop research which consequently improves treatments.

"Problematically, about half of people who have it don't show any symptoms. This means they can pass it on without knowing.

"Some symptoms can show up as discharge and/or pain when having sex or urinating.

"With all STIs its useful knowing what's normal for your body, so you know when to seek advice if something isn't right."

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