What? Yes. But it’s Apple and it’s not supposed to… But yet it is true! You may recall the dust up a few weeks back when the Flashback trojan was reported to have infected 600,000 Macintosh computers, according to the improbably named Russian security company Dr. Web. That was just the beginning, says a new report by security firm Sophos, which says in a new report that 1 in 5 Macs are carrying some kind of Windows infection. A Windows bug can’t cause harm to a Mac but an infected Mac can be a carrier, and spread the ick to PCs that it comes into contact with. Sophos also says that 1 in 36 Macs has Mac OS X malware.

Graham Cluley of Sophos goes ahead and makes a comparison to a venereal disease:

Just like malware on your computer, Chlamydia commonly shows no obvious symptoms. But left undetected Chlamydia can caused serious problems, such as infertility.

Some countries are so worried about the prevalence of Chlamydia that they have created national screening initatives and advise that people under 25 who are sexually active should be tested for the infection annually.

The good news is that Chlamydia is easy to treat.

And, if it isn’t too tacky to make a parallel, so is malware on Macs.