What Is Chronic Lyme Disease? The Debilitating Disease Is Poorly Understood

As autumn arrives and you start plotting Halloween havoc and picnics among the falling leaves, there's another marker of this time of year that might spoil the fall fun: Lyme disease. While most people think of summer as the peak of Lyme season, it's actually been discovered that the risk of Lyme actually reaches its high point about six weeks after the hottest point in summer, well into fall. Lyme is caused by the bite of an infected tick, but there happen to be two diagnostic categories: acute Lyme and chronic Lyme. And knowing the difference between the two, and how to recognize their symptoms, could help mitigate the effects of this poorly understood disease.

The fall Lyme season is of great concern to countries around the world because of the potential long-term health effects of Lyme. France has launched a smartphone app designed to map the spread of Lyme throughout the countryside over the next few moths, while parks around the UK publish specialist guidelines on how to detect and avoid ticks on walks. The Center for Disease Control & Prevention says that between 20 and 30,000 Lyme disease diagnoses per year in the U.S. are average, making it the sixth most common disease in the country, but diagnoses are particularly heavy in areas around New England and on the East Coast in general. You can be hyper-vigilant about tick checks and getting treated for acute Lyme, but you could still experience Lyme symptoms even years after being treated — and studies can't yet explain why.

What Makes Lyme Disease Chronic

Here's how Lyme disease normally works. You're bitten by a nymphal tick, the immature tick that tends to carry the disease in the summer and autumn months, that's infected with the spiral-shaped bacteria B. burgdorferi. You likely don't notice it at the time, but after 1-2 weeks, a distinctive bull's-eye rash, known as an erythema migrans, will form around the bite, accompanied by other symptoms like joint pain and fever. If you're quick, you'll recognize what this is and get a proper diagnosis (though Lyme is often misdiagnosed as other problems, including chronic fatigue syndrome; other times it won't even show up in diagnostic tests at all), and be treated by antibiotics. Most cases of Lyme treated like this will only need a single course of strong antibiotics to clear them up.

Chronic Lyme disease, also known as post-Lyme disease syndrome, occurs when symptoms of Lyme — which include joint and muscle pain, chronic fatigue, fever, lightheadedness, and a host of others — persist despite antibiotic treatment, in some cases for years afterwards. And the condition is very poorly understood. Adriana Marques, MD, wrote in the journal Infectious Disease Clinics of North America in 2008 that there are big problems both with misdiagnosis and what actually causes chronic Lyme:

"Studies have shown that most patients diagnosed with 'chronic Lyme disease' either have no objective evidence of previous or current infection with B. burgdorferi or are patients that should be classified as having post-Lyme disease syndrome, which is defined as continuing or relapsing non-specific symptoms (such as fatigue, musculoskeletal pain, and cognitive complaints) in a patient previously treated for Lyme disease."

Chronic Lyme (or, to give it its proper name, post-Lyme disease syndrome or PLDS) isn't the same as untreated Lyme, which can be very dangerous: if Lyme disease is left without antibiotics, it can affect joints, the nervous system, heart health, muscles and the brain. It's known that patients who get treatment for acute Lyme later are more at risk of developing PLDS, but those who get treatment promptly are still at risk. Up to 10-20 percent of all people with Lyme will develop PLDS. And, unfortunately, the medical community isn't sure why.

What Can You Do If You Have PLDS?

Treatment for PLDS is still a big scientific question mark. There's a theory that people with PLDS still have infections, and that B. burgdorferi is still running havoc in their system. That thinking has proven controversial, though. The CDC itself says that "most medical experts believe that the lingering symptoms are the result of residual damage to tissues and the immune system that occurred during the infection", and doesn't recommend keeping people with PLDS on antibiotics forever. A 2015 study pointed out that there's no current FDA recommendation for treatment for people with PLDS, and that we're still in the dark about precisely why it happens, partially because it shows up so differently in different people. It's also commonly misdiagnosed as other problems, just like Lyme disease itself.

In 2016, a massive European study that looked at long-term antibiotic therapy for PLDS, the Persistent Lyme Empiric Antibiotic Study Europe (PLEASE), showed that antibiotic treatment for chronic Lyme isn't terribly effective. A three-month course of antibiotic therapy "yielded no additional benefit over placebo with respect to serial mental and physical health-related quality-of-life measures," wrote the scientists who headed up the study. While that bodes poorly for cures, it does give more credence to the theory that the 10-20 percent of acute Lyme sufferers who do get PLDS are suffering not from infections, but from some kind of individual recurrent internal damage.

There might be another way to figure out why chronic Lyme affects us this way. Scientists are increasingly looking at the genetics of the Lyme bacteria itself to see if it might reveal answers about how different people metabolize infection, and whether Lyme bacteria with different genes might cause more post-treatment problems. It's currently an area of emerging research, so people with PLDS will just have to wait for the time being.

If you think you may have acute Lyme or PLDS (which can happen even without an obvious Lyme-style bull's-eye rash), get checked out as soon as possible; even though there isn't a cure currently on the horizon, certain treatment regimes can help manage symptoms, and many people with the illness do eventually recover. And if you're going out on a fall picnic, remember to cover yourself, and always check for ticks afterwards.