Comment »Posted on Tuesday 26 May 2009 at 6:42 pm by Jessica Bland
In Biology, Health & Medicine

“Nice jeans.” She pauses and gives the semi nude male on the bus stop poster a proper look. Then she spots the slogan at his feet: “MAYbe you’ve got Chlamydia.” She quickly stop looking and hurries on, hoping all those people waiting for the bus don’t think she has Chlamydia.  

Those behind the MAYbe screening programme this month in West London should be congratulated on a very effective ad campaign. Prompted by high rates of the infection in the capital, the MAYbe campaign hopes to increase awareness and encourage more Londoners to get tested for Chlamydia.

It might seem like Chlamydia is just a public health issue; we know how it works, how to treat it and now we just need to stop it spreading. But this week a group of UK scientists published research showing how these bacteria can still surprise us.

In Sweden in 2006, a new variant of Chlamydia appeared: one that was invisible to the tests used at the time. The new study reveals why this happens.

A single bacterium grew without part of the DNA code normally found in the plasmid – floating DNA, not part of the bacteria’s chromosomes. This bit of code was exactly what Swedish labs used to test whether an infection is Chlamydia or not.

“It turns out that this piece of the DNA is not essential to the Chlamydia. Therefore, an accidental deletion of the DNA won’t kill the bacterium, but it will stop it being identified,” explained Helena Seth-Smith, co-author of the study and researcher at the Wellcome Sanger Institute in Cambridge.

She said that they had never seen this kind of mutation before. Most cell mutations occur because of interaction between bacteria. But Chlamydia grows inside human cells. And so, bacteria have little chance to interact with one and other. 

The new type of mutation is a warning for tests on other bacterial infections. If the bacterium of another disease undergoes a similar test, “it’s possible that another chance deletion could make that bacterium invisible.” 

The researchers also identified what they think are the essential parts of the Chlamydia DNA. These make more reliable targets for diagnostic tests because if they mutate the bacterium is unlikely to survive anyway. Seth-Smith is hopeful that future tests will be better designed as a result.

This new research shows just how much we can still learn about diseases we thought we already understood. And it shows how useful these lessons can be for keeping the diseases under control.

Of course, public awareness drives are necessary. And maybe screening campaigns will help London lose its label as the UK’s ‘Chlamydia capital’. But the lesson from this study is that Chlamydia is not just a public health issue. Posters featuring designer jeans still need to be backed up by detailed genetic research.

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