Infections and Autoimmunity: Why the Relationship Is Complicated
If you have an autoimmune condition, you may have wondered whether an infection played a part in it. Maybe your symptoms began after a particularly rough illness, or a condition that had been stable flared after you got sick. In Episode 171 of A Functional Approach, “To Treat or Not to Treat? Infections and Autoimmunity,” I explore the complicated relationship between infections and autoimmune disease—and why deciding whether to treat an infection takes more than a positive test result.
These are reasonable questions. The relationship between infections and autoimmunity is one of the more fascinating—and frustrating—parts of my work. An infection may contribute to the onset or worsening of an autoimmune condition. Some infections may also change immune activity in ways that appear protective in certain circumstances. And autoimmune disease, or its treatment, can affect how a person handles infections.
So what do we do with all of that? We look at the person in front of us.
How an infection might set off an autoimmune response
Your immune system is supposed to recognize a threat, respond to it, and then settle down. In autoimmune disease, that response becomes misdirected toward the body’s own tissues.
There are several ways an infection might be involved. One is called molecular mimicry: a piece of a microorganism may resemble a piece of human tissue closely enough that an immune response to the infection also reacts with that tissue. Infections can also create inflammation that changes how the immune system behaves.
That doesn’t mean everyone who catches a particular virus will develop an autoimmune disease. Genetics and other factors influence who is susceptible. An infection may be one part of the story, rather than the whole explanation.
Epstein–Barr virus is an example I discuss in the podcast. Researchers have found a strong association between Epstein–Barr infection and multiple sclerosis. That’s an important finding, but it doesn’t mean an Epstein–Barr test can tell us everything about one person’s symptoms—or that treating the virus will necessarily treat their autoimmune disease.
Here’s where it gets interesting
In the episode, I talk about research examining whether some infections can dampen certain autoimmune responses. Parasitic worms, or helminths, are one example. They’ve evolved ways to influence the immune system, and researchers have explored whether understanding those effects could lead to treatments.
I find that science fascinating. It is not a reason to seek out a parasitic infection or leave a diagnosed one untreated. A parasite can cause real harm, including nutritional problems. What happens in a laboratory study, or what researchers observe across populations, doesn’t automatically tell us what will benefit an individual patient.
The same care applies to any test result. Finding evidence of past exposure to a microorganism is different from finding an active infection that is causing symptoms. That distinction matters before anyone decides what to do next.
How I think through it with a patient
I start with the history. When did the symptoms begin? Was there a clear illness beforehand? Are there recurring fevers, swollen lymph nodes, digestive symptoms, or other clues? How is the autoimmune condition behaving? What testing has already been done, and what would a new test actually help us decide?
Basic bloodwork can sometimes offer clues, and more specific testing may make sense when the history points us in a particular direction. But I don’t want to chase a long list of microorganisms simply because a test exists. The useful question is whether a finding fits the patient’s symptoms and changes the plan.
Sometimes an infection needs prompt, established treatment. Sometimes a result calls for a closer look before we can even say whether there is an active infection. And sometimes the most productive place to start is with sleep, nutrition, movement, and the other factors affecting how a person feels and functions.
That’s the conundrum I wanted to explore in this episode. Infections matter in autoimmunity, but there is no single rule that tells us what a positive test means for every person. My job is to help put the pieces together, explain what we know and what we don’t, and make a thoughtful plan with you.
If you have an autoimmune condition and suspect an infection may be part of your story, I’m happy to help you take a closer look.
This post is adapted from an episode of A Functional Approach with Dr. Jim Chialtas.
