The connection between chronic Lyme and mold illness

What is Lyme disease?

Lyme disease is a condition spread through the Borrelia burgdorferi bacteria, and rarely Borrelia mayonii.¹ These bacteria are usually spread through a tick bite. Ticks pick up the bacteria by biting infected animals like deer or mice, then pass it to humans. In the Eastern U.S. it’s often a deer tick; in the West, the western blacklegged tick. The longer a tick stays attached, the greater the risk of transmission. Maternal-fetal (congenital) transmission across the placenta has also been reported, though how often it happens and its effect on outcomes remain under study.²

Lyme is a multisystemic disease and can show up in many organs — but it’s very hard to test for and to culture. Its symptoms are far more than the classic bull’s-eye rash. They include gastrointestinal, cardiac/pulmonary, musculoskeletal, neurological, neuropsychiatric, and reproductive symptoms.³ Notably, many overlap with the symptoms of mold.

How mold illness (CIRS) and Lyme are similar

Like mold illness (CIRS), Lyme symptoms are driven by a dysregulated immune system and overproduction of pro-inflammatory cytokines — and both can trigger the same inflammatory pathways. Used appropriately, these immune responses kick in to fight pathogens, then calm to restore balance. In Lyme and CIRS, they go into overdrive. When the bacteria (Lyme) or mycotoxins (CIRS) stay in the body, the person stays inflamed — a dysregulated immune system producing many life-changing symptoms.

How the combination affects a patient

As is often the case in functional medicine, it’s hard to pin a chronic condition on a single culprit — and that’s certainly true for someone battling Lyme or CIRS. When a person has Lyme and is then exposed to mold mycotoxins, their body can weaken significantly. The same happens if a person has CIRS and is then exposed to Lyme. Having one condition makes you more susceptible to the other, creating a cascade of negative effects.

Because mold exposure can burden and dysregulate the immune system, resolving any infection may be harder while it’s ongoing. In our experience, some Lyme patients seem to struggle to fully clear the infection until any mold exposure is also addressed — and once it is, the immune system tends to rebound.

Telling the two apart

In navigating these tricky waters, it helps to know the patterns tend to differ:

Impact on the digestive tract

Together, Lyme and mold can be devastating for the gut. Mold reaches the body’s mucous membranes via the respiratory and digestive tracts, eventually making its way to the lower gut mucosa,⁴ leading to bowel dysfunction and nutrient-absorption issues. Lyme, meanwhile, can destroy the gut’s bacterial community (the microbiome) and the endothelial lining of the bowel. As the gut is damaged by Lyme, mold can expand and release more mycotoxins — causing further harm.

Some clinicians have also observed patients who were treated for Lyme, appeared to recover, and then had symptoms return after exposure to a water-damaged building.⁵ Whatever the mechanism, if mold or Lyme is suspected it’s reasonable to consider testing for both and treating appropriately. These can be overwhelming conditions — but there is real hope, and a clear path once the full picture is on the table.