People with celiac disease usually have a certain type of cell surface receptor that helps set off the immune reaction.

FORBES: Gluten-Free Diets: Miracle Or Hype?

Beyond obvious mood spoilers such as poor hygiene and bad breath, we each have a distinct natural scent that appears to guide us toward choosing a partner with compatible DNA. Scientists have found that women prefer the scents of men with a complementary set of genes that code for the immune system.

CNN: The science of kissing

If SARS takes root in Africa, hitting populations where AIDS has already weakened immune systems, it could exact a devastating death toll and set back economic development for decades.

FORBES: Aftershock

The American Academy of Pediatrics is now recommending that children who have potentially been exposed to rabies receive four shots in two weeks. (Children with weakened immune systems should continue to receive the five-shot regimen, the group says.) This recommendation affirms a set of 2010 guidelines for all ages from the Centers for Disease Control and Prevention.

CNN: Four shots enough to ward off rabies