A Virus 95% of Us Carry May Trigger Lupus—Here's What Scientists Just Discovered

A groundbreaking Stanford University study published in November 2025 found that Epstein-Barr virus (EBV)—a pathogen carried by 94% of adults—may be the trigger behind lupus development in virtually all cases. The discovery could reshape how doctors understand and treat lupus and potentially other autoimmune conditions like multiple sclerosis, rheumatoid arthritis, and Crohn's disease.

What Is Epstein-Barr Virus and Why Does It Matter?

Epstein-Barr virus is so common that most people catch it during childhood, adolescence, or young adulthood—often without even realizing it. The virus is transmitted through saliva and is the leading cause of infectious mononucleosis, or mono. Once you're infected, the virus stays in your body for life, lying dormant in immune cells called B cells, even if you never show symptoms.

The virus belongs to the same family as chickenpox and herpes, meaning it embeds its genetic material into infected cells and hides from your immune system. Over time, it can reactivate and trigger cells to produce viral copies that spread to other cells and people.

How Does EBV Connect to Lupus Development?

The Stanford research reveals a striking connection: EBV infects B cells, which are specialized immune cells responsible for producing antibodies and alerting other immune cells to threats. About 20% of B cells are auto-reactive, meaning they naturally target antigens in your own tissues. Normally, these cells stay dormant and cause no problems. But when activated, they begin attacking your body's own tissues, triggering the inflammatory cascade that leads to lupus.

"This is the single most impactful finding to emerge from my lab in my entire career. We think it applies to 100% of lupus cases," said William Robinson, MD, PhD, professor of immunology and rheumatology at Stanford.

Lupus is a condition where the immune system attacks the nuclei of cells, damaging the skin, joints, kidneys, heart, and nerves. Across the United States, several hundred thousand to up to a million Americans have lupus, with approximately 5 million people worldwide affected. Nine out of ten lupus patients are women.

Why Don't All EBV-Infected People Develop Lupus?

Here's the puzzle that researchers are now investigating: if 95% of us carry latent EBV in our B cells, why do only some people develop autoimmune disease? Robinson and his team theorize that certain EBV strains may be more likely to transform infected B cells into "driver" cells that broadly activate large numbers of antinuclear B cells—the cells that attack your own tissues.

This discovery opens a new frontier in understanding autoimmunity. Previous studies have already linked EBV to other conditions including Hashimoto's thyroiditis and multiple sclerosis, suggesting the virus may play a broader role in autoimmune disease development.

What's Next for Treatment and Prevention?

Researchers are currently developing an EBV vaccine, with clinical trials underway. However, there's an important caveat: the vaccine would need to be administered soon after birth, before EBV exposure occurs. Once someone is already infected with the virus, the vaccine cannot help them.

For people already living with EBV and autoimmune conditions, current medical treatments can slow disease progression, though no cure exists yet. The new understanding of EBV's role in lupus may eventually lead to targeted therapies that address the viral trigger rather than just managing symptoms.

The implications of this research extend beyond lupus alone. If EBV proves to be a common trigger across multiple autoimmune conditions, it could fundamentally change how doctors approach diagnosis and treatment for millions of people worldwide. For now, the focus remains on understanding why some EBV strains trigger autoimmunity while others remain harmless—a question that could unlock new prevention and treatment strategies in the coming years.