A Million Were Struck by This Mysterious Disease Before It Vanished

In the film Awakenings, Robert De Niro’s character laments, “People have forgotten what life is all about” after he revives from a 30-year shutdown state. This film, based on Dr. Oliver Sacks’ true story, explores the lives of individuals impacted by encephalitis lethargica, or “sleepy sickness.”

Far from rare, this disease affected over a million people during and after World War I, then mysteriously vanished for a century. The unanswered question remains: what caused it?

First described by a neurologist in Vienna in 1917, the disease began with flu-like symptoms but quickly diverged. Some patients became unable to sleep, while others were so lethargic they could only be roused briefly for food. About half died in this initial phase, but those who survived faced perplexing challenges. Many returned to work only to later experience stiffness, slowed movements, and fixated eye positions.

Sadly, the condition often progressed, leaving many, like De Niro’s character, frozen and unable to speak or move. Additionally, some patients developed slurred speech and changes in mood, perception, and personality. In a study my colleagues and I conducted, we even identified four patients who exhibited kleptomania as part of their illness.

What might have led to this?

Determining the origin of a disease can be complex. For example, identifying HIV as the cause of AIDS and HPV as the cause of cervical cancer both took time and were not immediately clear, similar to the case with encephalitis lethargica.

Since the disease appeared suddenly and then disappeared, some have proposed a link to an infection, especially considering the Spanish flu was prevalent around that time. However, initial cases of encephalitis lethargica appeared even earlier, and we haven’t detected any influenza virus in the brains of affected individuals, which complicates the connection.

To explore this further, we meticulously reviewed records from over 600 patients diagnosed with encephalitis lethargica.

Reevaluating the Flu Infection Theory in Encephalitis Lethargica Cases

Our research revealed that only 32% of patients experienced flu-like symptoms in the year before their illness, and less than 1% had an affected family member, undermining the flu infection theory.

Next, we considered environmental factors. The year 1917 was notable due to World War I and the massive mobilization of people and resources. While a new chemical could be a factor, we found no link between the illness and exposure to specific substances.

A new theory suggests that an autoimmune process may be involved, where the body’s defense mechanisms mistakenly attack the brain. This occurs in conditions like type 1 diabetes, which results from attacks on pancreatic cells, and Graves’ disease, caused by antibodies targeting thyroid cells.

In the brain, such attacks can be devastating. We now recognize multiple sclerosis as an immune system issue, and autoimmune encephalitis occurs when antibodies attack nerve cells. Our study suggests that nearly half of those diagnosed with encephalitis lethargica might have had autoimmune encephalitis, even though it doesn’t match any recognized types today.

Understanding the Varied Symptoms of Sudden-Onset Disease

But how does this explain a disease that appeared suddenly and caused varied symptoms? Some patients experienced significantly slowed movements and thoughts, while others had hallucinations, bizarre delusions, or a distorted sense of right and wrong.

This leads us back to the infection theory. Certain autoimmune conditions can be triggered by infections that resemble familiar substances, confusing the immune system. Once recognized, the body risks attacking its own defenses.

So, does this understanding matter? Should we investigate a pandemic that claimed its last survivor two decades ago? Unfortunately, encephalitis lethargica wasn’t the first neurological epidemic. If we don’t unravel this mystery, we may not be prepared for the next one.

Read Original Article On: Science Alert

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