PATHOGENS AND HUMANS

Chapter One

Infectious Disease and Epidemics

It is said that infectious disease, caused by pathogens whether a virus, bacteria, protozoan, fungi or worms, has been the single most important factor in shaping human history. The most evident is its ability to cause epidemics or worldwide pandemics.

The three most deadly infectious epidemics were the Plague of Justinian in the 6th Century, 30 to 50 million lives lost in Asia, North Africa, Arabia and Europe; the Bubonic Plague or Black Death, in 14th Century Europe, again 50 million dead; and the pandemic of “Spanish” Flu of 1918-1919 with up to 50 million people dead, and half the world, another 50 million, sick from it.

Although differing strains, the first two plagues were caused by the bacteria Yersinia pestis, harbored by fleas on rats. Scientists believe that the first strain in the Byzantine Empire (the Plague of Justinian originated in Egypt and spread first to Constantinople before moving into Asia and Europe) was an evolutionary dead end. But currently viable strains of Yersinia pestis could elicit a new epidemic, or, due to air travel, a worldwide pandemic. The good news is that improved hygiene since 14th Century and antibiotics make this less of a probability.

There are many other examples of pathogens affecting us. In the Southwest US in 1993 a virus from the feces of mice spread through the Navajo nation causing sudden respiratory failure in healthy people. The shaman said this wasn’t new, that it happened during heavy rains and the pine nut harvest was plentiful. And then there’s Enterovirus D-68 and other gastric oriented viruses. This first exploded among vaccinated children in the summer of 2014.

What’s important to understand is that there have been 400 emerging, or new, infectious diseases since the beginning of World War 2, and that 60% of these are zoonotic, meaning they come from animals. This crossover isn’t new. For instance measles originated from the domestication of livestock a long long time ago. More recently we know the source for the Ebola virus is bats, HIV from monkeys and influenza from birds and pigs.

Sticking to influenza, the first swine flu, triangulated from a pig and bird to join a human gene, was the so-called “Spanish” Flu.” Unlike Ebola and other viral infections it is right at home in North America and Europe and doesn’t need an airplane to make an appearance. So unlike the overland trade routes in the 14th century that spread Black Death, a plague harboured by rats, or smallpox by ships centuries later this virus, responsible for the annual outbreak of “flu” lives among us. This is not a bacteria—with a known structure an antibiotic can kill—but an RNA virus that continually changes its structure, easily eluding any attempt at a match for a vaccines. Its RNA nucleic core cannot be stopped. The reality is this virus is a highly mutating pathogen; a virus that—especially when pigs and birds are involved—is exceedingly difficult to pin down and eradicate.

And that’s the danger we face.

A Little History

A few centuries ago, when no one had a clue what a virus or other pathogen was, what it could do or what it looked like the term spontaneous generation arose. This common belief held that life could arise from non-life or inorganic material. For example, people assumed that maggots simply appeared on rotting meat.

This idea was trashed in 1668 when the Italian physician Francesco Redi proved these maggots did not just spontaneously appear. They came, in fact, from flies that had laid tiny eggs on the rotting meat. The maggots were simply the intermediary or larval stage in the cycle of a fly.

This discovery occurred about the same time as the Dutch lens-maker Antonie van Leewenhoek (1632-1723) first visualization of microbes (a general term that covers all microscopic organisms, healthy or unhealthy) through a primitive microscope. He didn’t know exactly what he was looking at but as turned out it was a bacterium, not the much, much smaller entity of a virus.

But the game was on, if slowly, to discover the cause of people falling ill. Many theories crept in and it was well over a century later that Louis Pasteur (1822-95) in Paris and Robert Koch (1843-1910) in Berlin established germs as the cause of infectious diseases.

Pasteur too had dispelled the concept of “spontaneous generation,” by demonstrating the existence of airborne microscopic “germs” while Koch isolated the first bacterium, Bacillus anthracis.

Over time, and to make a longer story shorter there remained a group of infectious diseases that could not be isolated to a causative organism. These microbes were called “filterable agents” in light of the fact they were getting through the material the scientists used to trap bacteria and other pathogens. They decided these “filterable agents” must be extremely small but considered them, simply, tiny bacteria.

Then, in 1898, Martinus Beijerinck, a microbiology teacher at an agricultural school in Holland coined the word “virus.”

Building on Adolf Mayer’s work in Holland and later Dmitry Ivanovsky in Russia, Beijerinck repeated filter experiments (on plants, how it was normally done) and showed that the “filterable agent” they hoped to isolate grew in dividing cells and manifested its strength each time it infected a plant. He deemed the agent a living microbe and gave it the name “virus” from the Latin word for poison venom or slimy fluid.

But even by the early 1900s the nature of a virus remained a mystery, other than that it was infectious and needed living cells as a host to propagate.

In 1918, the virus that caused the so-called Spanish Flu that killed millions was still invisible.

It wasn’t until the 1930s when German engineer Max Knoll and physicist Ernst Ruska invented the electron microscope that viruses could finally be visualized. (By accelerating electrons, and relying on the reality of a corresponding wave of any given particle, these scientists, standing on the backs of many, defeated the limitation of what could be seen by visible light.)

Between 1935-1940 the American biochemist Wendell Stanley, working with the tobacco mosaic virus, proved that viruses contain protein. Then two English biochemists discovered viruses contain nucleic acids.

In 1953 through the work of James Watson and Francis Crick the genetic spiral of DNA and RNA was uncovered as the brains of any cellular operation, including viruses.

By 1964 molecular biologist Howard Temin proposed that some viruses use RNA, some DNA as their genetic information. Takes two years before this idea is acknowledged and accepted.

Approximately twenty years later the proteins of viruses were identified, leading to vaccines, including the yearly one for Influenza, and then, more recently, to anti-viral drugs.

It’s no wonder scientists were excited to finally put a face on a virus that had caused such suffering and death, and is one reason I believe that technological advances were given a pass. To feel helpless and be unable to offer anything concrete for so long made scientists search for ways to destroy the pathogens, ie unhealthy microbes, that seemed intent on killing humans.
No one could have foreseen antibiotic or anti-viral resistance or that these tiny things have a use in evolution and that we need to understand their role in a broader ecosystem.

Unfortunately through all these fabulous discoveries Big Pharma couldn’t let go of the profit margin. The pharmaceutical industry’s need to profit on human suffering has set society up with blinders to an overall, more holistic scheme of keeping us well. This clearly has added to the distrust of what we can do to co-exist, or stay well, or have a shorter recovery time when a virus infiltrates our bodies.

Continuing… in two weeks…