The complex of symptoms and disorders called Gulf War veterans’ illnesses has been a major medical puzzle for years. One hypothesis is that the complex is caused by an underlying systemic infection with Mycoplasma species, specifically M. fermentans, and that long-term treatment with doxycycline might work.
The U.S. Departments of Veterans Affairs and Defense conducted a randomized, placebo-controlled study of 491 veterans, all of whom had detectable Mycoplasma DNA in their blood. After 12 months of treatment and six months of follow-up, the veterans were, for the most part, no better off. In fact, long-term drug doxycycline therapy not only did not help but might have even harmed them.
Doxycycline might have had a limited effect because there was no underlying infection, or the veterans’ illnesses might have been a consequence of previous infections, the researchers say. Some of the patients who improved at three months might have had another infection that doxycycline did help, or the drug might have had an anti-inflammatory effect.
Adherence to treatment declined after six months, dropping to roughly two thirds of both groups at 12 months. The researchers could not say whether better adherence would have led to more improvement.