Nietzsche: There are no facts, only Interpretations.
Frankly I never cared to comprehend the undisputed policies handed down from above. They are after all “manna” from the scientific heaven. Everything arriving from the “House of the gods” must be relevant and filled with indisputable truths. But now I am set to question the very complexion of that argument; its color and texture, its declaration and gravitas.
Incubation Periods of various illnesses are based on potential event of exposure and the duration that exposure will eventually lead to an illness in a living being (humans in this case). There are several diseases with varying incubation periods. For instance Influenza virus can have a short Incubation of less than 24 hours and wham it is in the body like a wrecking ball. Hepatitis B on the other hand has a range goes from a few days all the way to six months. A few of the virally mediated illness with their prodrome onset are listed below…
Which leads me to the Ebola thingy, its suggested Incubation is 2-21 days and there are fires all over the landscape with fire-hoses positioned on either side to win the fight. The quarantine group assails everything that moves and wants them secluded for at least 21 days after all that is the right tail of that incubation period duration. The argument is sound given the declaration of the potential for infection between a carrier/exposure and the time it takes for the virus to burrow into the various organs of the body and initiate the calamity. The longest incubation period being the Human Immunodeficiency Virus (HIV) is something to reckon with and consider along the spectrum of these illnesses based on the model and behavior of each virus.
But what if it wasn't true? What if the virus incubation period was longer? Huh? Can that be true? Ok here are a few “not so feel-good thoughts.” One, for instance to declare a country Ebola Free it has to have a mandatory period of 42 days of no new infection. Now why would that be? The simple answer would be we want to be “doubly” sure before that declaration. “That’s good, really thoughtful and good,” one would be inclined to say. But then there are the nagging data that come flurrying across the digital landscape, which confound the rational argument from the gods that the virus has expressed itself as illness in humans all the way up to 56 days. “56 days?” you scream in your mind. “What the heck?” It is all a lie? It is all a lie! Is the differing drumbeat of politics emanates from the proponents and the dissidents. Meanwhile the curvilinear sweep of the viral profile as it enters the human habitat is finding a happy medium of coexistence.
We now add another twist to this monstrous discussion that none of us find entirely palatable. What are the potential reasons for the long range of this incubation period? Watson would say, “Elementary, my dear.” The virus, as it enters the body via the mucus membranes and “bodily fluids” or as some have conjectured even through the skin surface, it meets with some issues.
Those issues include; A) the “viral load.” By viral load, science means the amount of virus that enters another human’s body via “exposure.” So a low viral load will mean that the virus has to multiply within the body for a longer period of time to get to the Gladwell’s “Tipping Point” to create illness. A larger load on the other hand has only to multiply a few times to create the same illness. B) The human recipient’s Immune system. There is an immunological pressure imposed upon the virus as it tries to multiply and expose itself to the human body’s immune defenses. A strong immune defense and a weak viral load may make the virus impotent in causing the illness. These individuals would be considered “immune” to the virus. On the other hand a large viral load and a weak immune system would render the body defenseless and exposed to “a thousand natural shocks that the flesh is heir to.” C) The selection pressures impressed upon the virus through the immune systems of humans will force it to mutate and acquire some RNA changes that will help both the deaths of the hosts (humans) and allow for its own survival through a mechanism of co-existence. These mutational forces are well known in the field of virology. Hepatitis B and C viruses have their DNA mutated and now exist in multiple forms and exert damage to humans differently. Some create the acute prodrome and then “are heard from, no more.” Others coexist surreptitiously and raise their ire when the immune system weakens, while others still cause chronic disease in the liver; from cirrhosis to cancer. Similarly the Ebola virus has mutated across its RNA landscape over the four or so outbreaks it has unleashed on the humans and even to some extent from one geographical location to another. This recent onset is the one that got away due to the promiscuity of travel and weaker epidemiological controls at the index (source) site (methinks).
So getting back to the 21 days, there is the very probing and provocative graph that I presented in the beginning. The purpose is to show the linkage between costs and the imposed incubation period. The idea of the hard-and-fast rule of science has been softened and made pliable by the eagerness of cost-effective strategies. We cannot quarantine for more than 21 days since the cost to do such is exorbitant both for the Health Agencies and the financial well-being of the individuals. Exploring the concept that the virus is not infective unless symptoms arise has never been tested to my knowledge and based on the ancillary data from the quoted study I have placed in the reference box there is cause for contemplation. As costs are the over-riding features in all aspects of medical endeavor, this one might as well be too.
The Ebola virus is not considered a “shedding virus” in the incubation period. However the biology of its replication rate seems to suggest other possibilities, yet not completely resolved. If it is not then a series of actions taken by the health agencies appear draconian in visible light.
So the questions remain: 1. Are the incubation period days arbitrary and capricious? 2. Are they based on hard science or soft peddling of the cost structure? 3. Will selection pressures due to immunotherapy ultimately evolve the virus into a more/less comfortable coexistence with its human hosts? 4. Will it change the mode of spread? 5. Will it, like other hardy viruses exist on sufaces longer than we want to think? Ah questions, questions!
This is merely a thought experiment for those interested in a “Borg”-type-mind-meld to extract reality from fiction.
So ponder away…
1b. T.J. Piercy, S.J. Smither, J.A. Steward, L. Eastaugh and M.S. Lever. The survival of filoviruses in liquids, on solid substrates and in a dynamic aerosol. Journal of Applied Microbiology 2010 ⁄ 0516