Acinetobacter Baumann has popped up in facilities like Walter Reed Army Medical Center in Washington and the Army's Landstuhl Regional Medical Center in Germany -- infecting an unknown number of soldiers’ and civilians’ bloodstreams, cerebrospinal fluid, bones and lungs -- The Los Angeles Times reported Sunday.

Since 2001, the percentage of admissions caused by the antibiotic-resistant virus has increased from 2 percent to 12 percent, the newspaper said.

Like many other types of bacteria, Acinetobacter Baumann was once easily controlled by antibiotics, but has become increasingly resistant over the last few decades as use of the drugs has become widespread.

After a 2003 outbreak aboard the U.S. hospital ship Comfort in the Persian Gulf, researchers struggled to find the source of the outbreak, the Times reported. In May, a group of researchers narrowed the source of the infection down to field hospitals in Iraq and Kuwait, though some doctors and scientists still have doubts.

The number of cases has begun to subside and doctors have identified the most effective drugs, but now they wonder if it is the bacterium that is sickening soldiers -- or if it is just a marker of vulnerability in the sickest patients.