Infection-Related Chronic Illnesses: Building Off Experience With Long COVID

Experience with long COVID has shone a spotlight on persistent Lyme disease and other often debilitating chronic illnesses that follow known or suspected infections – and on the urgent need for a common and well-funded research agenda, education of physicians, growth of multidisciplinary clinics, and financially supported clinical care.

"We critically need to understand the epidemiology and pathogenesis of chronic symptoms, and identify more effective ways to manage, treat, and potentially cure these illnesses," Lyle Petersen, MD, MPH, director of the division of vector-borne diseases at the Centers for Disease Control and Prevention, said at the start of a 2-day National Academies of Science, Engineering, and Medicine (NASEM) workshop, "Toward a Common Research Agenda in Infection-Associated Chronic Illnesses."

Thinking about infection-associated chronic illnesses as an entity – one predicated on commonalities in chronic symptoms and in leading hypotheses for causes – represents a paradigm shift that researchers and patient advocates said can avoid research redundancies and is essential to address what the NASEM calls an overlooked, growing public health problem.

An estimated 2 million people in the United States are living with what’s called posttreatment Lyme disease (PTLD) – a subset of patients with persistent or chronic Lyme disease – and an estimated 1.7-3.3 million people in the United States have diagnoses of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). More than 700,000 people are living with multiple sclerosis. And as of January 2023, 11% of people in the United States reported having long COVID symptoms; the incidence of long COVID is currently estimated at 10%-30% of nonhospitalized cases of COVID-19.

These illnesses "have come under one umbrella," said Avindra Nath, MD, clinical director of the National Institute of Neurologic Disorders and Stroke (NINDS), Bethesda, Md.

Dr Avindra Nath

To date, common ground in the literature has grown largely around long COVID and ME/CFS, the latter of which is often associated with a prior, often unidentified infection.

Symptoms of both have been "rigorously" studied and shown to have overlaps, and the illnesses appear to share underlying biologic abnormalities in metabolism and the gut microbiome, as well as viral reactivation and abnormalities in the immune system, central and autonomic nervous systems, and the cardiovascular and pulmonary systems, said Anthony L. Komaroff, MD, professor of medicine at Harvard Medical School and a senior physician at Brigham & Women’s Hospital, both in Boston. (An estimated half of patients with long COVID meet the diagnostic criteria for ME/CFS.)

Although less thoroughly researched, similar symptoms are experienced by a subset of people following a variety of viral, bacterial, and protozoal infections, Dr. Komaroff said. To be determined, he said, is whether the pathophysiology believed to be shared by long COVID and ME/CFS is also shared with other postinfectious syndromes following acute illness with Ebola, West Nile, dengue, mycoplasma pneumonia, enteroviruses, and other pathogens, he said.

Persistent infection, viral reactivation

RNA viral infections can lead to persistent inflammation and dysregulated immunity, with or without viral persistence over time, Timothy J. Henrich, MD, MMSc, associate professor of medicine at the University of California, San Francisco, said in a keynote address.

Dr Timothy J. Henrich

Research on Ebola survivors has documented long-lasting inflammation and severe immune dysfunction 2 years after infection, for instance. And it’s well known that HIV-1 leads to aberrant immune responses, inflammation, and organ damage despite antiretroviral therapy, said Dr. Henrich, who leads a laboratory/research group that studies approaches to HIV-1 cure and PET-based imaging approaches to characterize viral reservoirs and immune sequelae.

Viral persistence, which can be difficult to measure, has also been documented in Ebola survivors. And in patients living with HIV-1, HIV-1 RNA and protein expression have been shown to persist, again despite antiretroviral therapy. The UCSF Long-Term Immunological Impact of Novel Coronavirus (LIINC) study, for which Dr. Henrich is the principal investigator, found spike RNA in colorectal tissue more than 22 months post COVID, and other research documented viral protein in gut tissue for up to 6 months, he said.

"I think we’re appreciating now, in at least the scientific and treatment community, that there’s a potential for ‘acute’ infections to exhibit some degree of persistence leading to clinical morbidity," said Dr. Henrich, one of several speakers to describe reports of pathogen persistence. Regarding long COVID, its "etiology is likely heterogeneous," he said, but persistence of SARS-CoV-2 "may lay behind" other described mechanisms, from clotting/microvascular dysfunction to inflammation and tissue damage to immune dysregulation.

Reactivation of existing latent viral infections in the setting of new acute microbial illness may also play an etiologic role in chronic illnesses, Dr. Henrich said. Epstein-Barr virus (EBV) reactivation has been shown in some studies, including their UCSF COVID-19 cohort, to be associated with long COVID.

"Physicians have been trained to be skeptical about the role [of latent viral infections]," Michael Peluso, MD, an infectious disease physician and assistant professor at UCSF, said during a talk on viral reactivation. This skepticism needs to be "reexamined and overcome," he said.

Herpesviruses have frequently been associated with ME/CFS, he noted. And evidence of a strong association between EBV and multiple sclerosis came recently from a prospective study of 10 million military recruits that found a 32-fold increased risk of MS after EBV infection but no increase after infection with other viruses, Dr. Peluso and Dr. Henrich both noted.

Research needs, treatment trials

Research needs are vast: The need to learn more about the mechanisms of pathogen persistence and immune evasion, for instance, and the need for more biomarker studies, more imaging studies and tissue analyses, more study of microbiome composition and activity, and continued development and application of metagenomic next-generation sequencing.

Workshop participants also spoke of the need to better understand the molecular mimicry that can occur between pathogen-produced proteins and self-antigens, for instance, and the effects of inflammation and infection-related immune changes on neuronal and microglial function in the brain.

"We should perform similar forms of analysis [across] patients with different infection-associated chronic conditions," said Amy Proal, PhD, president of the PolyBio Research Foundation, which funds research on infection-associated chronic infections. And within individual conditions and well-characterized study groups "we should perform many different forms of analysis … so we can define endotypes and get more solid biomarkers so that industry [will have more confidence] to run clinical trials."

In the meantime, patients need fast-moving treatment trials for long COVID, long Lyme, and other infection-associated chronic illnesses, speakers emphasized. "We all agree that treatment trials are overdue," said the NINDS’ Dr. Nath. "We can’t afford to wait for another decade until we understand all the mechanisms, but rather we can do clinical trials based on what we understand now and study the pathophysiology in the context of the clinical trials."

Just as was done with HIV, said Steven G. Deeks, MD, professor of medicine at UCSF, researchers must "practice experimental medicine" and select pathways and mechanisms of interest, interrupt those pathways in a controlled manner, and assess impact. "Much of this can be done by repurposing existing drugs," he said, like antivirals for persistent viral infection, EBV-directed therapies for EBV reactivation, anti-inflammatory drugs for inflammation, B–cell-directed therapies for autoantibodies, and antiplatelet drugs for microvascular disease.

When done correctly, he said, such "probe" studies can deepen mechanistic understandings, lead to biomarkers, and provide proof-of-concept that "will encourage massive investment in developing new therapies" for long COVID and other infection-associated chronic illnesses.

Trials of treatments for long COVID "are starting, so I’m optimistic," said Dr. Deeks, an expert on HIV pathogenesis and treatment and a principal investigator of the Researching COVID to Enhance Recovery (RECOVER) study. Among the trials: A study of intravenous immunoglobulin (IVIG) for neurologic long COVID; a study of an anti-SARS-CoV-2 monoclonal antibody that can deplete tissue/cellular reservoirs of viral particles (replicating or not); and a study evaluating baricitinib (Olumiant), a Janus kinase inhibitor, for neurocognitive impairment and cardiopulmonary symptoms of long COVID.

Alessio Fasano, MD, professor of pediatrics at Harvard Medical School and professor of nutrition at the Harvard T.H. Chan School of Public Health, Boston, described at the workshop how he began investigating the use of larazotide acetate – an inhibitor of the protein zonulin, which increases intestinal permeability – in children with COVID-19 Multisystem Inflammatory Syndrome (MIS-C) after learning that SARS-CoV-2 viral particles persist in the gastrointestinal tract, causing dysbiosis and zonulin upregulation.

In an ongoing phase 2, double-blind, placebo-controlled trial, the agent thus far has expedited the resolution of gastrointestinal symptoms and clearance of spike protein from the circulation, he said. A phase 2 trial of the agent for pediatric patients with long COVID and SARS-CoV-2 antigenemia is underway. "What if we were to stop [chains of events] by stopping the passage of elements from the virus into circulation?’ he said.

In the realm of Lyme disease, a recently launched Clinical Trials Network for Lyme and Other Tick-Borne Diseases has awarded pilot study grants to evaluate treatments aimed at a variety of possible disease mechanisms that, notably, are similar to those of other chronic illnesses: persistence of infection or remnants of infection, immune dysregulation and autoimmune reactions, neural dysfunction, and gut microbiome changes. (Microclots and mitochondrial dysfunction have not been as well studied in Lyme.)

Current and upcoming studies include evaluations of transcutaneous auricular vagus nerve stimulation for those with persistent Lyme fatigue, transcranial direct current stimulation with cognitive retraining for Lyme brain fog, and tetracycline for PTLD, said Brian Fallon, MD, MPH, professor of clinical psychiatry at Columbia University, New York, who directs the Lyme & Tick-Borne Diseases Research Center and the coordinating center of the new network.

Dr Brian Fallon

Moving forward, he said, it is important to loosen exclusion criteria and include patients with "probable or possible" Lyme and those with suspected infections with other tick-borne pathogens. All told, these patients comprise a large portion of those with chronic symptoms and have been neglected in an already thin research space, Dr. Fallon said, noting that "there haven’t been any clinical trials of posttreatment Lyme disease in ages – in 10-15 years."

(PTLD refers to symptoms lasting for more than 6 months after the completion of standard Infectious Diseases Society of America–recommended antibiotic protocols. It occurs in about 15% of patients, said John Aucott, MD, director of the Johns Hopkins Lyme Disease Research Center, Baltimore, a member of the new clinical trials network.)

Calls for a new NIH center and patient involvement

Patients and patient advocacy organizations have played a vital role in research thus far: They’ve documented post-COVID symptoms that academic researchers said they would not otherwise have known of. Leaders of the Patient-Led Research Collaborative have coauthored published reviews with leading long COVID experts. And patients with tick-borne illnesses have enrolled in the MyLymeData patient registry run by LymeDisease.org, which has documented patient-experienced efficacy of alternative treatments and described antibiotic responders and nonresponders.

At the workshop, they shared findings alongside academic experts, and researchers called for their continued involvement. "Patient engagement at every step of the research process is critical," Dr. Nath said.

"We need to ensure that research is reflective of lived experiences … and [that we’re] accelerating clinical trials of therapeutics that are of priority to the patient community," said Lisa McCorkell, cofounder of the long COVID-focused Patient-Led Research Collaborative.

Ms. McCorkell also called for the creation of an office for infection-associated chronic illnesses in the NIH director’s office. Others voiced their support. "I think it’s a great idea to have an NIH center for infection-associated chronic illnesses," said Dr. Fallon. "I think it would have a profound impact."

The other great need, of course, is funding. "We have ideas, we have drugs that can be repurposed, we have a highly informed and engaged community that will enroll in and be retained in studies, and we have outcomes we can measure," Dr. Deeks said. "What we’re missing is industry engagement and funding. We need massive engagement from the NIH."

Real-world treatment needs

In the meantime, patients are seeking treatment, and "clinicians need to have uncertainty tolerance" and try multiple treatments simultaneously, said David Putrino, PT, PhD, director of rehabilitation innovation for the Mount Sinai Health System and professor of rehabilitation and human performance at the Icahn School of Medicine at Mount Sinai, New York. He oversees a multidisciplinary hybrid clinical care research center that has seen over 1,500 patients with long COVID and is beginning to see patients with other infection-associated chronic illnesses.

Dr David Putrino

It’s a model that should be replicated to help fill the "enormous unmet clinical need" of patients with infection-associated chronic illness, said Peter Rowe, MD, professor of pediatrics at the Johns Hopkins School of Medicine and an expert on ME/CFS. And "as we request [more research funding], we will also need [financial] support for clinical care," he emphasized, to provide equitable access for patients and to attract treating physicians.

Moreover, said Linda Geng, MD, PhD, the culture of stigma needs to change. Right now, patients with long COVID often feel dismissed not only by friends, families, and coworkers, but by clinicians who find it find it hard "to grasp that this is real and a biological condition."

And it’s not just conditions such as long COVID that are stigmatized, but treatments as well, she said. For instance, some clinicians view low-dose naltrexone, a treatment increasingly being used for inflammation, with suspicion because it is used for opioid use disorder and alcohol use disorder – or because the "low-dose" label summons mistrust of homeopathy. "Even with therapies, there are preconceived notions and biases," said Dr. Geng, cofounder and codirector of the Stanford (Calif.) Long COVID program.

"What almost killed me," said Meghan O’Rourke, who has ongoing effects from long-undiagnosed tick-borne illness, "was the invisibility of the illness." Ms. O’Rourke teaches at Yale University and is the author of "The Invisible Kingdom: Reimagining Chronic Illness."

Teaching young physicians about these illnesses would help, she and others said. During a question and answer session, Dr. Putrino shared that the Icahn School of Medicine has recently committed to "create a complex chronic illness medical curriculum" that will impact medical education from the first year of medical school through residencies. Dr. Putrino said his team is also working on materials to help other clinics develop care models similar to those at his Mount Sinai clinic.

The NASEM workshop did not collect or require disclosures of its participants.

This story originally appeared on MDedge.com, part of the Medscape Professional Network.