Wednesday’s study is small and needs verification. But specialists called it a promising start at clearing some of the confusion surrounding two illnesses with similar symptoms and no good means of diagnosis.

“It’s a very important first step,” said Dr. Suzanne Vernon of the Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS) Association of America.

Lyme disease usually is cured with antibiotics, but some patients report pain, fatigue and memory or other neurologic problems that linger for months or years after treatment ends. This post-treatment Lyme disease shares symptoms that characterize chronic fatigue syndrome.

The new study analyzed spinal fluid from 25 of those chronic Lyme patients, 43 people diagnosed with chronic fatigue syndrome and 11 healthy people. Using a special high-powered technology, researchers detected more than 2,500 proteins in each group.

More important, they found clear sets of proteins – hundreds each – unique to each disease, said Dr. Steven Schutzer of the University of Medicine and Dentistry of New Jersey, who led the work.

The next step is to study more people to see if certain protein abnormalities might serve as a signature, a way to better diagnose patients, Schutzer said. He also plans to see if they could be found in blood, which would be easier to test than spinal fluid.

Much more work is needed, cautioned Dr. Joseph Breen, a Lyme specialist at the National Institutes of Health, which helped fund the work. But this pool of new clues also might eventually help scientists figure out the underlying biology of these diseases and how they harm, he added.