Lyme disease, an infection that leaves you with a rash, a headache, aches and fatigue, and, in serious cases, nervous system or heart problems or arthritis, is caused by a family of bacteria that can be transmitted if you happen to get bit by a deer tick.

Normally, when faced with a diagnosis of Lyme disease, you’re given a round of antibiotics and sent on your way. Some people, however, catch what has been dubbed “chronic Lyme disease,” a disorder that they claim is a recurrent version of the disease—one that fights back the regular antibiotic treatments and causes the affected person to relapse later on. The problem with chronic Lyme disease, however, is that it likely doesn’t actually exist, says a new study reported on by The New York Times. It seems that, rather than having relapses, patients with chronic Lyme disease are just getting infected all over again, says the study.

The conclusion that new symptoms come from new infections is based on genetically fingerprinting the Lyme bacteria in people who have had the illness more than once, and finding that the fingerprints do not match. The result means that different episodes of Lyme in each patient were caused by different strains of the bacteria, and could not have been relapses.

The link between Lyme disease and the bacterium Borrelia burgdorferi was first discovered in 1981, and in the time since, researchers have been working out the specifics of the disease.

The scientists gathered bacteria for people who had multiple bouts of Lyme-disease rashes, culturing the samples and checking their genetic make-up. In every case but one, the rashes were caused by different bacterial strains. In that last hold-out case, however, where the person’s Lyme disease was caused by the same bacterial strain in two separate cases, they also had a third case caused by a second bacterial strain. The odds of all this happening by chance, says the Washington Post, are “one in five million.”

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