Krrrreeow, krrrreeow, krrrreeow, three loud guttural calls repeated themselves all night long from the pond just outside our bedroom window. This was not the melodious song and varied repertoire of the Mockingbird who is known to sing long into the night, but rather a more primitive and monotonous rattle. I was thinking wounded Mottled or Muscovy Duck or perhaps even a sick Red-shouldered Hawk. Lying in bed and unable to sleep, I felt the forlorn cry appropriate for our time of global pandemic. Has the virus even infected the birds?
At daybreak I found the culprit. It was actually two healthy Limpkins foraging along the far shore of the pond, under the yellow flowering Tabebuia tree. It was not a sick call, but rather the male’s sorry excuse for a love song, apparently attractive to his mate who was now ready to submit after a full night of begging. Perhaps we can all sleep again tonight.
The Limpkins may be okay, but I couldn’t help but dust off my old virology texts to educate myself about the COVID-19 virus, the tiny pathogen that has invaded our civilization and caused this global calamity.
The existence of viruses was postulated long before they were seen. In the late 19th century fine filters, usually effective in trapping bacteria from diseased tissue, were not fine enough to strain out these minute structures. Optical microscopes, adequate for bacteria, could not resolve the much smaller viruses. Martinus Beijerinck first described a virus, the tobacco mosaic virus, in 1898 but it wasn’t until the invention of the electron microscope in the 1930’s that we could actually see the evil doers.
Scientists were amazed to see these geometric particles that resembled spaceships or underwater mines more than life forms. They have no cell membrane or other standard cellular structures. They are primarily genetic material contained within a protein capsule. Can you even call them living? This question is still debated as they barely meet the criteria of life; they have genetic material, they reproduce, and they evolve. Today viruses are the most numerous life form on the planet, more than all other entities combined.
How do viruses cause disease? A virus outside a cell is a harmless, inert particle. Inside the cell, however, it reeks havoc with the cell’s genetic apparatus and biochemical pathways, eventually causing cell lysis and death. It first needs the cell, however, to help it replicate and spread daughter viruses into other unsuspecting host cells. Some are even more nefarious and become latent intracellular sojourners, waiting to cause their mischief later, perhaps when the host’s defenses are weaker.
Birds, just like all other living things, are not exempt from viral infections. Their most famous recent epidemic was that caused by the avian influenza virus in 2008. This scourge primarily infected flocks of domestic chickens and turkeys–practicing social distancing within a coop is problematic. Thankfully wild birds and humans were only minimally affected.
In the midst of our corona virus pandemic it is interesting to reflect on how far we have progressed in fighting infectious disease. These are all, of course, in addition to our inherent biologic defenses. The effects of over-crowding and poor sanitation were apparent to even the ancient civilizations. Without even understanding the biologic mechanism or specific pathogen, Edward Jenner started vaccinating for the small pox virus in 1796. In the 1860’s Louis Pasteur and others promoted the concept of germ theory, even before the germs themselves were identified. This was followed by improvements in personal hygiene, isolation of infected patients, and sterilization of medical equipment. Sulfa was the first antibiotic used against bacteria in the 1930’s, with antivirals first appearing on the scene more recently in the 1980’s.
At the time of this writing we are in the middle of the 15 day voluntary quarantine, attempting to dampen the rapid spread of the virus which requires coughing and sneezing humans to spread to the next nearby host. Most of us get this, except for those foolish snowflakes on spring break crowding our Florida beaches, sharing the pathogen, and then heading back north to infect their financing parents. Yesterday I noticed that there were hardly any other walkers on our beach as I counted birds and got some sorely needed exercise. I found out why we were alone when escorted off the sand by the polite ranger and sheriff. Thank you snowflakes.
With the beach now off-limits, and after cancelling my birding trip to Costa Rica, I’ve begun an indoor birding adventure. Andy lent me his 2000 piece jigsaw puzzle of all the North American passerines. The pieces have taken over the den, sorted by color, body part, etc. It helps if you know the birds, beak shapes, leg colors, and other field marks. My wife thinks I’m practicing for the nursing home, but this exercise is just another aspect of our fascinating hobby and suits me perfectly during the lockdown.
They say we are in a war against this virus, and I agree. Our most recent wars were fought by only a few, barely affecting the rest of us. This one feels different, perhaps more like the 1940’s when the entire population was mobilized. In those prior wars the medical corps was in the rear, but in the current struggle our nurses and their medical colleagues are the frontline. I’m now retired from their ranks but proud of them and have complete faith that they will win this war. For the rest of us, keep calm, stay separated by six feet, and carry on.