When did encephalitis begin?

The history of encephalitis dates back to ancient times. There are descriptions of encephalitis-like illnesses in the writings of Hippocrates (460-377 BC) and Galen (129-216 AD). However, it was not until the 19th century that encephalitis was recognised as a distinct clinical entity. The first major outbreak of encephalitis occurred in the United States in 1918, during the Spanish flu pandemic. This outbreak was caused by the influenza virus, and resulted in the deaths of over 500,000 people. In the years that followed, other outbreaks of encephalitis were reported around the world, and it became clear that encephalitis could be caused by a variety of different viruses, bacteria, and other infectious agents.