Lyme arthritis is an inflammatory condition affecting the joints that can arise as a late-stage complication of Lyme disease. This health issue is caused by the bacterium Borrelia burgdorferi, which is transmitted to humans through the bite of infected ticks. When the bacterial infection is not treated in its early stages, it can spread throughout the body and lead to more significant health problems, including impacts on the joints.
The Development and Symptoms of Lyme Arthritis
Lyme arthritis typically develops weeks to months after the initial tick bite. For some individuals, the early signs of Lyme disease, such as the characteristic rash, may be absent or go unnoticed, making joint problems the first clear indication of the illness. The bacteria, having spread through the bloodstream, can settle in the joint tissues, triggering an inflammatory response from the body’s immune system that leads to the symptoms of arthritis.
The condition is characterized by recurring episodes of joint swelling. These attacks can appear suddenly, last for several weeks or months, and then resolve, only to return later. The knee is the most commonly affected joint, with many cases presenting as swelling in a single knee. Other large joints like the shoulder, ankle, elbow, and wrist can also be involved, often in an asymmetric pattern, meaning it might affect the right knee but not the left.
Unlike some other forms of arthritis that cause severe, constant pain, the discomfort from Lyme arthritis can be less intense and is often described as pressure from the swelling within the joint. The affected joint may also be red and feel warm to the touch. Typically, fewer than five joints are affected during an episode, and this presentation helps distinguish it from other rheumatologic conditions that often involve many joints symmetrically.
The Diagnostic Process
Diagnosing Lyme arthritis involves a combination of clinical evaluation and laboratory testing. A physician will first consider the patient’s history, including whether they live in or have visited an area where Lyme disease is common. The specific pattern of symptoms, particularly the intermittent swelling of a large joint like the knee, is a strong indicator.
The laboratory diagnosis is a two-tiered blood testing approach recommended by the Centers for Disease Control and Prevention (CDC). The first step is an enzyme-linked immunosorbent assay (ELISA) test, which detects antibodies to the Borrelia burgdorferi bacterium. If the ELISA test is positive or its results are uncertain, a more specific test called an IgG Western blot is performed to confirm the findings. Individuals with this condition will almost always have a positive blood test for the antibodies.
In some situations, a doctor may perform a procedure to draw fluid from the swollen joint, a process known as arthrocentesis. This synovial fluid can be analyzed for signs of inflammation and to help rule out other causes of arthritis, such as gout or septic arthritis. A polymerase chain reaction (PCR) test can be used on the joint fluid to detect the genetic material of the bacteria, but this test is not always reliable and is considered an adjunctive test.
Available Treatment Options
The primary treatment for Lyme arthritis is a course of antibiotics aimed at eliminating the underlying bacterial infection. For an initial episode, healthcare providers typically prescribe a 28-day course of oral antibiotics, such as doxycycline or amoxicillin. This initial treatment is successful for the majority of patients, with up to 90% experiencing resolution of their arthritis.
If joint swelling and inflammation persist after the first round of antibiotics, a second course of treatment may be necessary. This might involve another 28-day course of the same oral antibiotic. For patients who do not show improvement after oral treatments, a course of intravenous (IV) antibiotics, such as ceftriaxone, may be administered for two to four weeks.
In a small percentage of individuals, joint inflammation continues for months or even years after antibiotic therapy has been completed. This condition is thought to be driven by ongoing immunologic factors rather than an active infection, so further antibiotic treatment is not beneficial. Instead, management focuses on controlling the inflammation with medications like nonsteroidal anti-inflammatory drugs (NSAIDs) or other antirheumatic drugs, and referral to a rheumatology specialist is often recommended.
Differentiating From Post-Treatment Lyme Disease Syndrome
It is important to distinguish persistent Lyme arthritis from Post-Treatment Lyme Disease Syndrome (PTLDS). While both can occur after antibiotic treatment for Lyme disease, their symptoms and management are different. PTLDS is characterized by generalized symptoms that linger for more than six months after treatment is complete, including widespread muscle and joint pain, severe fatigue, and cognitive difficulties, often described as “brain fog.”
The pain in PTLDS is typically diffuse and not associated with the obvious, localized swelling seen in Lyme arthritis. In contrast, persistent Lyme arthritis involves ongoing, objective inflammation, usually in one or a few joints, that can be seen and felt as swelling. This persistent joint inflammation is a lingering consequence of the original joint infection, even after the bacteria are gone.
The distinction is significant because the treatment approaches differ. While persistent Lyme arthritis may be managed with anti-inflammatory drugs, there is no single proven treatment for PTLDS. Understanding the difference helps ensure patients receive the correct follow-up care for their specific condition.