Influenza: Ancient Disease in Modern Times

Many folks will get a runny nose or mild sore throat and declare that they have “the flu”. Influenza does indeed cause the symptoms of upper airways viral infection – runny nose, sore throat, coughing. However, it also doubles down with fever, headache and fatigue. If you have ever had real influenza, you will never label a mere cold as such again! Influenza can turn quite serious, causing pneumonia and/or exacerbating pre-existing medical conditions such as asthma or heart issues.  

The disease has been with us a long time. Ancient chroniclers were sadly remiss about including robust immunology data, but the first possible epidemic was in 6000BC China, with the Greek historians describing flu-like illnesses in the 5th Century BC. Epidemics of what was probably influenza occurred across Europe in 1173AD and 1387AD. An epidemic resembling influenza killed most of the population of the Antilles in 1493.  

The first influenza pandemic was recorded in 1510, starting in East Asia and spreading to Africa and Europe. The disease occurred seasonally thereafter, with pandemics every few years. The disease began to be reliably recorded after 1700, as pandemics occurred every 20 to 50 years. The first “bird flu” to hit humans was recognized in 1878.  

The deadliest influenza pandemic was the “Spanish Flu” in 1918-1920, which started in the US and was spread by soldiers travelling to and returning from WW1. It hit in 3 waves and was estimated to have infected as many as half the population of the world. Deaths were in the tens of millions! Since then there was: “Asian Flu” in 1957, killing a million; “Hong Kong Flu”, killing 2 million; and “Swine Flu”, causing hundreds of thousands of deaths. Avian Flu H7N9 emerged in China in 2013 and variants of this have been causing trouble since. Future flu pandemics are considered inevitable.  

There is a wide range in the severity of symptoms. The delay from exposure to presentation is one to four days. People are infective from one day before symptoms till five to seven days after. Children and the immunocompromised may continue to transmit the virus for several weeks. Spread is usually via respiratory droplets, which have a range of about 2m, though it can also occur via the longer ranged aerosol method. The virus can survive for hours on non-porous surfaces. The recommended methods of infection control are respiratory etiquette, hand hygiene, and mask-wearing – although evidence for the effectiveness of the latter is not yet proven with influenza (it is proven with Covid!).