Why are search results in MediaWiki displaying without formatting?

I installed MediaWiki and I noticed that the search results are not being formatted, This means, if I have an article which contains the following text:

'''This is a test'''

This will show up in bold when you are viewing the actual article but when you search for example: test,开发者_C百科 the search results will be displayed without the formatting and will be displayed with the full code, which means that in the search results, this is what is shown:

Article Name
      '''This is a test'''

I obviously want it to look like this:

Article Name
      This is a test

I didn't modify any of the code in MediaWiki yet. How can I achieve this?

Thanks

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As of now MWSearch has been replaced by Cirrus:
http://www.mediawiki.org/wiki/Extension:CirrusSearch

While SphinxSearch is more recommended for smaller sites (compared to Wikipedia):
http://www.mediawiki.org/wiki/Extension:SphinxSearch

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Which version of MediaWiki are you using?

You may need to install the MWSearch extension to get the results without the formatting. http://www.mediawiki.org/wiki/Extension:MWSearch