In the late 1800s Dmitri Ivanovsky used a filter that could retain bacteria in which he poured the sap from an infected tobacco plant.  After filtering the sap, it still had the ability to infect other healthy plants.  Martinus Beijerinck called the infectious substance a virus -- the Latin word meaning “slimy liquid” or “poison.”

Virology had begun, although neither of those two founding scientists probably had any idea how big their discovery would become.  We now know of 219 virus species that are able to infect humans.  Yellow fever was the first to be discovered in 1901, and 3-4 new species are discovered annually.  More than two-thirds can also infect other mammals, and sometimes birds.

Viruses make up over two-thirds of all new human pathogens.  This is highly significant over representation given that most human pathogen species are bacteria, fungi, or helminths (a parasitic worm).  The nature of the viruses remained unknown until the invention the electron microscope in the 1930s.  Many diseases both old and new were discovered to be caused by viruses.

Smallpox and measles are among the oldest viruses to infect humans.  The viral strain that drove the 2014-2016 Ebola outbreak in West Africa killed 90 percent of the people it infected, making it the most lethal member of the Ebola family.  In the modern world, HIV may be the deadliest virus, killing an estimated 32 million people since being discovered in the early 1980s. 

I have the distinct feeling that our world is never going to be quite the same after COVID-19.  I noticed large sheets of plexi-glass are going up everywhere, to separate cashiers from patrons.  The problem with human nature is that once things gradually go back to normal, we are so quick to forget.  Maybe this being worldwide, will leave a lasting impression that leads to government spending the money it will take so that we are never blindsided like this again. 

God bless you all, RHM.