Victoria Gill, a BBC science correspondent, recently wrote an article about how the current Coronavirus pandemic likely will not the last pandemic we experience during our lifetime. As humans encroach on the natural world the potential for a viral “spillover” becomes more and more certain. The pandemic we are experiencing is the proverbial tip of the iceberg.
In the last twenty or so years we have experienced the Hendra virus, SARS, MERS, Ebola (there are eight types), avian flu, and swine flu. All of the viruses mentioned here are what we call “zoonotic”, meaning they have been passed on to humans through animals. Zoonosis occurs more often than not when a living reservoir host, such as a plant or animal, harbors a pathogen which is then passed on to an intermediate host. The intermediate host then passes the pathogen on to humans.
In his book “Spillover: Animal Infections and the Next Human Pandemic” (2012) David Quammen outlines the case of the little known Hendra virus, first appearing in Australia, as a prime example of a zoonosis. First appearing in the Brisbane suburb of Hendra in 1994, the virus found it’s natural reservoir host in fruit bats. These fruit bats then passed the pathogen on to horses which would later show symptoms of fever, swelling, bloody froth and exhaustion. According to the World Heath Organization website “The [original] outbreak involved 21 stabled racehorses and two human cases. As of July 2016, 53 disease incidents involving over 70 horses have been reported. These incidents were all confined to the north-eastern coast of Australia. A total of seven humans have contracted Hendra virus from infected horses, particularly through close contact during care or necropsy of ill or dead horses”