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Encephalitis lethargica

Encephalitis lethargica is a disease characterized by:

  • High fever
  • Headache
  • Double vision
  • Delayed physical and mental response
  • Lethargy/fatigue

In acute cases, people with the disorder may enter coma. Some also may experience:

  • Abnormal eye movements
  • Upper body weakness
  • Muscular pains
  • Tremors
  • Neck rigidity
  • Behavioral changes including psychosis

The cause of encephalitis lethargica is unknown. An epidemic of encephalitis lethargica occurred from 1917 to 1928, but no recurrence of the epidemic has since been reported. It was possible for Postencephalitic Parkinson's disease to develop after a bout of encephalitis—sometimes as long as a year after the illness.

Treatment for encephalitis lethargica is symptomatic and may include Levodopa and other anti-Parkinson drugs. The course of the disease varies depending upon complications or accompanying disorders.

How can I or my loved one help improve care for people with encephalitis lethargica?

Consider participating in a clinical trial so clinicians and scientists can learn more about encephalitis lethargica and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with encephalitis lethargica at

Where can I find more information about encephalitis lethargica?

Information may be available from the following resource:


Content source: Accessed June 22, 2023.

The information in this document is for general educational purposes only. It is not intended to substitute for personalized professional advice. Although the information was obtained from sources believed to be reliable, MedLink, its representatives, and the providers of the information do not guarantee its accuracy and disclaim responsibility for adverse consequences resulting from its use. For further information, consult a physician and the organization referred to herein.

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