Encephalitis Lethargica: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Encephalitis Lethargica?
A neurologist (a doctor who treats brain and nerve conditions) usually leads care for encephalitis lethargica, a rare brain illness. An infectious disease doctor (a doctor who treats infections) may also help. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is encephalitis lethargica?
Encephalitis lethargica (EL) is a rare disease in which the brain becomes swollen and inflamed. It causes extreme tiredness, called lethargy. It is also known as von Economo disease.
A worldwide epidemic of EL took place from around 1916 to 1930. At that time it was called "sleeping sickness." More than one million cases were reported. Epidemics have not come back since. Occasional cases with similar symptoms are still reported.
Symptoms
EL is marked by high fever, headache, and double vision. People also have a slow physical and mental response and extreme tiredness. Some people go into a coma. Other symptoms can include:
- Abnormal eye movements
- Weakness in the upper body
- Muscle pain
- Tremors, which are shaking movements
- A stiff neck
- Changes in behavior, including psychosis (losing touch with what is real)
In some cases, people developed Parkinson's disease after they recovered, sometimes as long as a year after the illness. Parkinson's disease affects movement. How the disease progresses varies from person to person.
Causes and who gets it
The cause of EL is not known. Researchers suspect it may come from a virus. EL is rare. It is listed as starting in adulthood.
Encephalitis in general is brain inflammation. It can come from an infection that invades the brain. It can also happen when the immune system attacks healthy brain cells by mistake. Anyone at any age can get encephalitis. A weakened immune system raises the risk.
How doctors diagnose it
For encephalitis in general, a doctor does a physical exam and asks about your medical history. The doctor may then order tests to look for infection or inflammation.
Brain scans such as CT and MRI can show signs of brain inflammation. They also help doctors rule out other disorders that can cause similar symptoms, such as a stroke or a brain tumor. An EEG can find unusual brain waves. Blood and spinal fluid tests can also help. Spinal fluid is the liquid around the brain and spinal cord.
Treatment
Treatment depends on the person's symptoms. Levodopa and other drugs used to treat Parkinson's disease may be used for EL. They may ease some symptoms.
For encephalitis in general, a person may need rehabilitation once the illness is under control. This can include physical, speech, and occupational (daily-skills) therapy if brain function is badly affected.
When to see a doctor
Anyone who may have encephalitis should contact a doctor or go to the hospital right away. The illness can start suddenly and progress fast.
Call 911 or go to the emergency room if you have trouble breathing, chest pain, fainting or loss of consciousness, a seizure, or a sudden change in mental state such as confusion.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can review symptoms, coordinate visits with a neurologist, and keep track of follow-up care over time. Sudden or severe symptoms still need emergency care.
Common questions
What causes encephalitis lethargica?
The cause is not known. Researchers suspect it may come from a virus. No clear cause has been proven.
Could another epidemic of encephalitis lethargica happen?
No one can say for sure, but no epidemic has been reported since the one that ended around 1930. Occasional cases with similar symptoms are still reported.
Does encephalitis lethargica lead to Parkinson's disease?
It can in some cases. Some people developed Parkinson's disease after they recovered, sometimes as long as a year after the illness.
Can drugs for Parkinson's disease help?
Yes, they may help. Levodopa and other drugs for Parkinson's disease may ease some symptoms of EL. Doctors choose them based on the person's symptoms.
Sources
- NIH Genetic and Rare Diseases Information Center - Encephalitis lethargica
- National Institute of Neurological Disorders and Stroke - Encephalitis
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
