There is concern that the troops from Iraq are bringing home drug-resistant bacteria:

American troops wounded in Iraq and brought back to military hospitals in the United States have unexpectedly high rates of infection with a drug-resistant type of bacteria, doctors are finding.

The bacteria, Acinetobacter baumannii, are not unique to Iraq. They live in soil and water in many parts of the world, and had already been known to cause trouble in hospitals and on battlefields in Vietnam. They can invade wounds, the bloodstream, bones, the lungs and other parts of the body.

Typically, "big-gun" antibiotics such as amikacin or imipenem are needed for treatment. (Grady, "Troops in Iraq Bring Resistant Bacteria Home", NY Times, Aug.4)

Update:
Forbes discusses this story in-depth.