Encephalitis lethargica is an inflammation of the brain caused by two trypanosomes (microscopic protozoan parasites).

If treated early, a person with encephalitis lethargica can be cured. If not treated early, the prognosis is much less favorable due to resulting brain damage. Encephalitis lethargica is fatal if untreated.

The illness, which can be fatal, is transmitted from one infected person to another by the tsetse fly. While it can occur globally, encephalitis lethargica is especially prevalent in Africa.

The people in the movie have encephalitis lethargica.

Arthur J. Hall has written:

'The Lumleian lectures, abridged, on encephalitis lethargica (epidemic encephalitis)' -- subject(s): Epidemic encephalitis