Can an Infection Trigger an Autoimmune Response?
Infections can sometimes disrupt normal immune regulation
Autoantibodies and immune activation do not always mean autoimmune disease
Persistent symptoms after infection may have more than one explanation
Can an infection trigger an autoimmune response? In some circumstances, yes. Viral, bacterial, and other infections can activate immune pathways that contribute to autoimmunity, particularly in people who are biologically susceptible.
But there is an important distinction: an infection triggering an autoimmune response is not necessarily the same as an infection causing a defined autoimmune disease.
The immune system normally has mechanisms that allow it to recognize invading organisms while avoiding attacks against the body’s own tissues. During some infections, however, intense inflammation, tissue injury, cross-reactive immune responses, or other changes can disturb this balance.
Researchers have described several ways this might happen, including molecular mimicry, bystander activation, and epitope spreading. These mechanisms help explain why infection and autoimmunity can sometimes be linked, but they do not prove that every symptom occurring after an infection is autoimmune.
What happens to the immune system during an infection?
When a virus, bacterium, or other pathogen enters the body, the immune system must recognize the threat and mount a response against it.
This involves both the innate and adaptive immune systems. Immune cells release inflammatory signals, antibodies may be produced, and specialized T cells and B cells become activated against specific targets.
Most of the time, these responses help control the infection and then diminish as the threat resolves.
But infection can create an unusually inflammatory environment. Tissue may be damaged, previously hidden cellular components may become exposed, and large numbers of immune cells may become activated. Under certain circumstances, this may contribute to loss of normal immune tolerance and the development of immune responses directed against the body’s own tissues.1,2
How can an infection trigger autoimmunity?
There is no single mechanism explaining infection-associated autoimmunity. Several mechanisms have been proposed, and more than one may operate at the same time.
Molecular mimicry
One of the best-known explanations is molecular mimicry.
A portion of a virus or bacterium may resemble a molecule naturally present in human tissue. An immune response originally directed against the pathogen may therefore cross-react with a similar-looking target in the body.
In other words, an immune response that began appropriately against an infection may inadvertently recognize a self-antigen as well.1,2
Bystander activation
Infection also produces inflammation around infected or damaged tissues.
This inflammatory environment can activate antigen-presenting cells and produce cytokines and other immune signals. Under some circumstances, previously inactive self-reactive immune cells may become activated even though they were not the original target of the response.
This process is known as bystander activation.1,2
Epitope spreading
Another proposed mechanism is epitope spreading.
An infection may initially provoke an immune response against a limited set of targets. As inflammation and tissue damage continue, additional proteins or portions of proteins can become exposed to the immune system.
The immune response may then expand from its original target to additional targets, including self-antigens.1,2
Some infection-autoimmune relationships are stronger than others
The evidence linking infection and autoimmunity varies considerably depending on the infection and disease being studied.
One well-recognized example is Guillain-Barré syndrome, a neurologic disorder in which the immune system damages peripheral nerves. The Centers for Disease Control and Prevention identifies Campylobacter infection as one of the most common causes associated with Guillain-Barré syndrome in the United States.3
Another important example is Epstein-Barr virus (EBV) and multiple sclerosis. A large longitudinal study involving more than 10 million young adults found that the risk of multiple sclerosis increased substantially following EBV infection, strengthening evidence that EBV plays an important role in the development of multiple sclerosis.4
These examples are important because they demonstrate that infection-triggered immune disease is biologically plausible and, in certain settings, strongly supported by evidence.
They do not mean that every infection carries the same risk or that every chronic symptom following infection represents autoimmunity.
An autoimmune response is not necessarily an autoimmune disease
This distinction is particularly important.
A person may develop autoantibodies or other evidence of altered immune activity without meeting diagnostic criteria for lupus, rheumatoid arthritis, multiple sclerosis, autoimmune thyroid disease, or another defined autoimmune disorder.
Autoantibodies themselves also require clinical interpretation. MedlinePlus notes that viral or bacterial infections, particularly chronic infections, can be associated with autoantibody production.5
Finding an autoantibody therefore does not automatically answer three much harder questions:
Is the antibody causing disease?
Does it explain the patient’s symptoms?
Does the patient have a recognized autoimmune disorder?
The answer may be yes in some patients and no in others.
Why symptoms after an infection are difficult to interpret
Suppose someone develops fatigue, dizziness, brain fog, neuropathic symptoms, joint pain, palpitations, exercise intolerance, or other problems after an infection.
The timing is clinically relevant, but timing alone does not establish the mechanism.
Persistent symptoms after an infection may have several potential explanations. Depending on the illness and the individual patient, clinicians may consider tissue injury from the original infection, persistent inflammation, autonomic dysfunction, immune dysregulation, a post-infectious process, a newly triggered autoimmune disease, medication effects, another medical condition, or—in infections where it remains clinically relevant—persistent or recurrent infection.
This is one reason symptoms that involve several different diagnostic categories can be challenging to interpret. The same symptoms may occur through different biological mechanisms, and more than one mechanism can sometimes be present.
What about Lyme disease and autoimmunity?
Lyme disease provides an especially interesting example of the complicated relationship between infection, inflammation, and autoimmunity.
Lyme disease is caused by infection with Borrelia burgdorferi. The infection can involve the skin, joints, nervous system, heart, and other tissues, producing a wide range of Lyme disease symptoms.
Researchers have investigated immune-mediated mechanisms in Lyme disease for decades. One of the best-described examples is persistent synovitis in a subset of patients with Lyme arthritis after antibiotic treatment.
A review of Lyme arthritis described excessive pro-inflammatory immune responses, autoimmune and cytotoxic processes, vascular damage, and other immunologic abnormalities in post-infectious Lyme arthritis. The authors proposed that this form of arthritis may provide a useful model for understanding how an infectious agent can trigger and shape a subsequent inflammatory or autoimmune response.6
A 2024 review similarly described a small percentage of patients with Lyme arthritis who develop a dysregulated pro-inflammatory response associated with persistent post-infectious synovitis and autoimmune features.7
However, this specific model of post-infectious Lyme arthritis should not automatically be generalized to every patient with persistent symptoms following Lyme disease.
Autoimmunity is not the only proposed explanation for persistent Lyme symptoms
Patients may continue to experience fatigue, pain, cognitive problems, dizziness, neurologic symptoms, autonomic problems, or other complaints after treatment for Lyme disease.
Several mechanisms have been proposed for persistent symptoms, including immune dysregulation, inflammation, autonomic dysfunction, tissue injury, retained microbial components, coinfections, unrelated medical conditions, and persistent infection in some patients.
For example, research has identified Borrelia burgdorferi peptidoglycan in the context of persistent inflammatory responses, raising the possibility that microbial material can continue stimulating immune pathways even when the mechanism is not classic autoimmunity.
This distinction matters because immune activation, inflammation, autoimmunity, and persistent infection are different biological concepts. They can overlap, but one should not automatically be substituted for another.
Likewise, there is no routinely available clinical test that can establish in every patient whether Borrelia burgdorferi has been completely cleared from the body. Therefore, attributing persistent symptoms to an autoimmune or post-infectious mechanism should not be treated, by itself, as proof that persistent infection has been excluded.
Patients trying to understand ongoing symptoms may benefit from considering the broader range of proposed mechanisms discussed in persistent symptoms after Lyme treatment.
Could infection trigger autonomic or neurologic symptoms through immune mechanisms?
This is an active area of research.
Autonomic dysfunction can produce dizziness, changes in heart rate, exercise intolerance, gastrointestinal symptoms, abnormal sweating, temperature intolerance, fatigue, and cognitive difficulties.
Researchers studying post-infectious illnesses have investigated whether autoantibodies and other immune abnormalities might contribute to autonomic or neurologic dysfunction in subsets of patients.
However, finding an association between autoantibodies and symptoms does not establish that those antibodies are pathogenic. Some may represent markers of immune activation rather than the direct cause of illness.
This is why autonomic dysfunction should be evaluated clinically rather than assumed to be autoimmune simply because it developed after an infection.
How do doctors determine whether symptoms are autoimmune?
There is usually no single test that answers this question.
Evaluation depends on the clinical pattern. Physicians may consider the patient’s history, timing of symptoms, physical examination, family history, inflammatory markers, blood counts, organ-specific testing, autoantibodies, imaging, neurologic testing, and other studies depending on the suspected disorder.
The interpretation of autoimmune testing is particularly important because abnormal antibodies do not always indicate disease.
A laboratory result becomes much more meaningful when it matches a recognizable clinical syndrome.
Conversely, a negative autoimmune test does not necessarily explain persistent symptoms. It may simply mean that the specific autoimmune conditions evaluated by those tests were not demonstrated.
Why the distinction matters for treatment
Determining the likely mechanism behind persistent symptoms matters because different mechanisms may require very different approaches.
An active infection may require antimicrobial treatment. A defined autoimmune disease may require immunomodulatory treatment. Autonomic dysfunction may require treatment directed at blood-volume regulation, heart-rate control, physical conditioning, medications, or other contributors. Structural neurologic disease, endocrine disorders, nutritional deficiencies, and other conditions require their own approaches.
Assuming that all persistent symptoms are caused by ongoing infection can miss other treatable conditions.
But the reverse is also important: assuming that symptoms following an infection must be autoimmune or post-infectious can prematurely close the diagnostic process.
The goal is not to choose between infection and immunity as though they are always mutually exclusive. It is to determine which mechanisms are best supported in the individual patient.
Frequently Asked Questions
Can a bacterial or viral infection trigger an autoimmune response?
Yes. Both bacterial and viral infections have been associated with autoimmune responses. Proposed mechanisms include molecular mimicry, bystander activation, tissue injury, and epitope spreading. However, developing an autoimmune response does not necessarily mean that a person will develop a defined autoimmune disease.
Does having autoantibodies after an infection mean I have an autoimmune disease?
No. Autoantibodies may occur without a defined autoimmune disease, and infections themselves can sometimes be associated with autoantibody production. The significance of an autoantibody depends on the specific antibody, the clinical symptoms, examination findings, and other testing.
Can autoimmune symptoms begin after an infection is gone?
Yes. Some immune-mediated disorders can develop during or after an infection. In certain conditions, an immune response initiated by infection may continue after the acute illness has resolved. However, persistent symptoms alone do not prove that autoimmunity is responsible.
Can Lyme disease trigger an autoimmune response?
Research supports immune-mediated and autoimmune mechanisms in certain manifestations of Lyme disease, particularly post-infectious Lyme arthritis. These findings should not automatically be generalized to every patient with persistent Lyme symptoms, because immune dysregulation, inflammation, autonomic dysfunction, microbial remnants, persistent infection, coinfections, and other conditions may also need consideration.
How can doctors tell persistent infection from post-infectious autoimmunity?
The distinction can be difficult and depends on the specific infection and clinical presentation. Physicians consider symptom patterns, objective findings, treatment history, laboratory testing, imaging, and other diagnostic information. In Lyme disease, there is no routinely available clinical test that definitively proves eradication of the organism in every patient, so an autoimmune hypothesis alone should not be considered proof that persistent infection has been excluded.
Clinical Takeaway
Infections can sometimes trigger autoimmune responses through mechanisms such as molecular mimicry, bystander activation, and epitope spreading. In certain diseases, the relationship between infection and subsequent immune-mediated disease is well supported.
But an autoimmune response, an autoantibody, and an autoimmune disease are not interchangeable concepts. Likewise, symptoms that continue after an infection should not automatically be attributed to autoimmunity simply because they began after the infection.
Lyme disease illustrates this complexity particularly well. Autoimmune and inflammatory mechanisms have been described in specific manifestations such as post-infectious Lyme arthritis, while persistent symptoms in other patients may have several possible explanations.
This article is for educational purposes and is not a substitute for individualized medical evaluation or treatment.
The important clinical question is not simply whether infection can trigger autoimmunity, but whether an autoimmune mechanism actually explains the symptoms of the individual patient.
Related Articles
These articles explore related questions involving infection, immune responses, persistent symptoms, and multisystem illness.
Can Lyme bacterial fragments persist after infection?
Why can Lyme disease affect multiple body systems?
Lyme disease as a reversible cause of chronic illness
COVID-19 or Lyme disease triggering autoimmune dysfunction?
References
- Fujinami, R. S., von Herrath, M. G., Christen, U., & Whitton, J. L. Molecular mimicry, bystander activation, or viral persistence: infections and autoimmune disease. Clinical Microbiology Reviews. 2006;19(1):80–94.
- Johnson, D., Jiang, W. Infectious diseases, autoantibodies, and autoimmunity. Journal of Autoimmunity. 2023;137:102962.
- Centers for Disease Control and Prevention. Guillain-Barré syndrome. CDC. 2024.
- Bjornevik, K., Cortese, M., Healy, B. C., et al. Longitudinal analysis reveals high prevalence of Epstein-Barr virus associated with multiple sclerosis. Science. 2022;375(6578):296–301.
- MedlinePlus. Autoantibody testing. U.S. National Library of Medicine. 2025.
- Lochhead, R. B., Strle, K., Arvikar, S. L., et al. Lyme arthritis: linking infection, inflammation and autoimmunity. Nature Reviews Rheumatology. 2021;17:449–461.
- Steere, A. C. Lyme arthritis: a 50-year journey. Journal of Infectious Diseases. 2024.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
