Patients often ask whether a person can become immune to Lyme disease or whether you can get Lyme disease more than once.
In 2014, a small study found that some people may, in fact, develop strain-specific immunity to Borrelia burgdorferi, the bacteria causing Lyme disease. “Once infected with a particular strain of the disease-causing bacteria, humans appear to develop immunity against that strain that can last six to nine years,” the authors wrote. [1] Ask the Lyme doc.
However, they also pointed out that at least 16 different strains of the Lyme disease bacterium have been shown to infect humans in the United States, so being bitten by a tick carrying a different strain of the disease is entirely possible.
Whether a person can develop immunity to Lyme disease is still unknown. Further studies are needed. There are certainly many instances of people contracting the infection more than once or redeveloping symptoms.
Re-infected through a new tick bite
There may be several reasons for this. A person can become re-infected with a new tick bite. Nadelman and colleagues described 17 patients who were re-infected multiple times with Lyme disease. [1]
Persistent infection
Lyme disease symptoms can resurface in a person who has already been treated for the infection. Findings from both animal and human studies suggest that B. burgdorferi can cause a persistent infection. [2,3] Some doctors, however, dismiss the idea of a persistent infection. [4]
Lyme disease co-infections
Lastly, Lyme disease symptoms may return due to untreated co-infections. As of 2020, scientists have discovered 15 other diseases transmitted by ticks. [5] The list consists of viral, bacterial and parasitic infections and includes:
Editor’s note: This is part of a Ask the Lyme doc series. For the purposes of transparency, I’m an author on the International Lyme and Associated Diseases Society (ILADS) treatment guidelines, and I believe that symptoms can be due to a persistent infection in some patients. [6,7]