Defining a disease under pressure: medicine responds to the 1918-1928 encephalitis lethargica outbreak

Department of Biology, Husson College, Bangor, Maine, USA
brownt AT

In the shadow of the 1918 pandemic flu, a smaller but far more perplexing epidemic raged.  While previous Encephalitis Lethargica (EL) outbreaks probably occurred, the 1918-1928 outbreak was the first to be widely described.  During this epidemic, more than 900 papers were written in an effort to understand a “new” disease.  This literature comprised the thoughts of a full spectrum of medical talent, from greats like Von Economo and Kinner Wilson to small town general practitioners.

I will show that many doubtful cases were labeled EL in the heat of the epidemic and that some cases went unrecognized and were misdiagnosed as influenza. Depending on the location of the lesions, the symptoms of EL resemble those of many other neurological diseases, brain infections, and even trauma. Conversely, the other causes of lesions resemble EL. The polymorphic nature of the symptoms of EL allowed it to serve as a Rorschach onto which the era’s neurologists projected their diagnostic biases.

In the last years of the 1918-1928 epidemic, a new condition emerged that became known as Post-Encephalitic Parkinson’s disease (PEP). PEP is a Parkinson’s-like condition that develops following EL. Since PEP patients are much younger than those who develop Parkinson’s disease from other causes, PEP provides a reliable tool for retrospectively identifying EL patients. The younger the patient the more certain we can be that we have a case of PEP. Consequently, this allows us to distinguish between EL and patients with other diseases.  

My study illuminates the neurological community’s decision-making under pressure and provides a new perspective on the relation between EL and other diseases including the flu.

Symposium.  Encephalitis Lethargica
Thursday, 21 June 2007, 9:30 - 11:15 am

12th Annual Meeting of the International Society for the History of the Neurosciences   (ISHN)
Los Angeles, California, USA, 19-23 June 2007