April 10 2020
In the previous blog titled “Serial Passage or Why All Epidemics End”, I addressed natural history of epidemic(s) in immunocompetent population.
What happens if a host (patient) immune system is NOT up to par and what it has to do with fatalities amongst medical personnel?
To remind, our defense mechanisms include:
Behaviors:
staying clean (not just by washing hands), changing clothes frequently, keeping residence and office clean;
Avoiding contacts with family, friends and strangers with symptoms of infections; or known exposure to infected people;
Staying home or away from others while being sick;
Non-specific immune response: the first line of defense, which is agnostic of pathogen and aims to destroy and remove infection before it reaches the next line of defense;
Cell-mediated immune response - the response which does not involve antibodies, also known as T-lymphocyte mediated immunity;
Humoral immune response - antigen-specific antibodies production by B-lymphocytes.
One, or a combination of the above, must fail for a disease process to occur, unless:
(Viral) infection circumvents defenses, such as happened during German offense against France in 1940, when Germans circumvented the Maginot Line and forced France to surrender before any of the major fortresses were captured;
Infection overwhelms defenses altogether, such as happened in 1939 war between Soviet Union and Finland, when the Red Army broke through the Mannerheim Line by sheer force and numbers at the great human cost, losing x10 soldiers than Finnish army.
Hence, an infectious agent, such as virus, must find a weak link(s) - “Achilles heel" in one’s defenses to enter and replicate.
Once infectious agent overcomes defenses of immunocompromised host, the process of replication - production of new viruses starts in host cells and goes unimpeded. This creates a high viral load (“burden”) which may not only make host very sick but can also kill it. In the process, immunocompetent hosts caring for the sick get are exposed to viral shedding - the process of expulsion and release of virus following successful reproduction during a host-cell infection.
Importantly, when not confronted by defenses, despite the process of serial passage virus is not attenuated (not weakened), thus maintaining original or even higher degree of virulence.
This exposes immunocompetent (young) physicians, medical staff and other caregivers to overwhelming number of viruses, having potential to circumvent or overcome their defenses. This is aggravated by factors known to affect resistance, namely stress, sleep deprivation, poor nutrition, pre-existing conditions, etc. - all in confines of hospital rooms and corridors filled with immunocompromised individuals.
This is akin of ingesting a large dose of poison, which in smaller quantities would not be enough to make one sick.
Also, doctors “do not grow on trees”. They are subject to the same behaivioral and medical ailments as a general population. See Doctors do not adequately look after their own physical health or as I say: do not follow their own advice!
The bottom line: a hospital filled with a multitude of very sick immunocompromised patients is not just a battleground, but rather a minefield both for patients and caregivers.