Does trying to live healthy make sense considering an imminent bird flu outbreak?

[Astreja]

Could it be that vegetarians tend to care about hygiene more and thus have been infected with fewer types of germs in their lifetime?

Two things:

• If you've spent any time at all cooking meals from scratch, you should be aware that meat preparation requires more stringent adherence to hygiene protocols.  In particular, whenever I've just worked with raw chicken I immediately wash down the cutting board, knife, kitchen shears or whatever tools I've been using (very hot soapy water) and never use unwashed tools for other ingredients.
  
• It's impossible to quantify the number and variety of germs any individual has been infected with - for every one pathogen that makes someone ill, they could have been exposed to a thousand more that never manifested in symptoms.  As a general rule, though, someone who hasn't encountered many types of germs has a relatively untrained immune system and is more vulnerable to unfamiliar organisms.