It is possible to contract Lyme disease more than once. The human immune system does not develop lasting immunity to the bacteria, allowing reinfection from new tick bites, even after prior treatment. With at least 18 known strains, a person can be infected by a different strain. Symptoms of reinfection are often similar to the initial infection.
Why Reinfection is Possible
The human immune system does not develop long-term protective immunity to Borrelia burgdorferi, the bacterium responsible for Lyme disease, even after a treated infection. Research indicates that the bacteria can disrupt the immune system’s ability to form a “memory” of the invading pathogen, which is necessary for lasting protection. This means that even if antibodies are produced during an initial infection, their protective effect may wane over time, leaving an individual susceptible again.
Reinfection most commonly occurs from a new bite by an infected tick, rather than a resurgence of a prior infection. This highlights the ongoing risk in areas where Lyme disease is prevalent. Studies have shown that some individuals experience multiple documented episodes of Lyme disease, often presenting with a new rash at a different body location.
Adding to the possibility of reinfection is the genetic diversity of Borrelia burgdorferi. There are at least 18 known species or genospecies of Lyme-causing Borrelia within the broader Borrelia burgdorferi sensu lato complex. In North America, Borrelia burgdorferi sensu stricto and Borrelia mayonii are the primary causes. Some studies suggest that a person might develop strain-specific immunity lasting several years to the particular strain they were first infected with, but they remain vulnerable to the many other strains.
Recognizing and Addressing Reinfection
Recognizing a potential reinfection with Lyme disease involves being aware of symptoms that often mirror those of an initial infection. These can include a characteristic expanding red rash, known as erythema migrans, appearing at the site of a tick bite. This rash emerges within one to four weeks after a bite. Alongside the rash, flu-like symptoms such as fever, headache, fatigue, and muscle or joint pain are common.
Given the similarities in symptoms, it is important not to dismiss these signs if they reappear, especially after any potential tick exposure. Prompt medical evaluation is recommended if symptoms of Lyme disease resurface. Early diagnosis and treatment with antibiotics are important for preventing the infection from progressing to more severe stages, which could involve complications affecting joints, the nervous system, or the heart.