Coronaviridae. The coronaviridae are large, enveloped, and intracellular-membraned helical capsid viruses.
They have a linear, single-stand, positive-sense RNA genome.
So again, as a positive-sense RNA, they can function as -- or their genome can function as a messenger RNA.
Transmission of these viruses is fecal-oral but also sometimes by respiratory droplet
especially for upper respiratory type illnesses.
There are medically important or relevant species which we talk about.
One is the severe acute respiratory syndrome virus, otherwise known as SARS by its initials S-A-R-S virus.
And then the coronaviruses themselves which are a frequent cause of respiratory
and some gastrointestinal disorders.
Unfortunately, we now need to add a third relevant virus,
the SARS-CoV-2 causing the coronavirus infectious disease 19 or a COVID-19 pandemic
initially noted in Wuhan province, China in late 2019.
The transmission electron micrograph in front of you is showing typical appearance of,
in this case, an animal strain of a coronavirus.
And you can see that they have a pedicle arrangement around the outside of the membrane itself.
So the first and most common medical illness associated with the coronavirus is the common cold.
Incubation period, 3 days. So very short, it is very common.
In fact, it is probably as common as an enterovirus or a rhinovirus.
Prognosis, fabulous unless one has a man cold.
But it is a very common and very rapid-resolving upper respiratory tract illness.
Patients have the typical sneezing, rhinovirus, headache, sore throat, malaise.
Sometimes the fevers are high enough to also have shaking, chills, or rigors along with them.
But it's mostly pediatric-aged patients, infants and children who are exposed to this.
And again, it's probably because the infectious particles are very readily available
through respiratory droplet which deposits on horizontal surfaces.
Children explore the world through their hands and their mouths.
So respiratory droplet or fecal-oral transmission,
and you can see why the coronavirus is such a common cause of the common cold.
Gastrointestinal tract infections are far less common especially due to coronaviruses
but when occurring, they also have a very fast incubation period up to 3 days.
Prognosis, superb for this as well.
It's a very mild version of what are sometimes very severe gastrointestinal infections caused by other viruses.
In this case, diarrhea, gastroenteritis causing inflammation of the gut
with a mild or non-specific abdominal pain, rarely some vomiting-associated.
The one associated medical illness which is quite severe
which may be triggered by a gastrointestinal coronavirus would be a neonatal necrotizing enterocolitis.
That is where the lining of the gut becomes inflamed, perhaps initially due to the coronavirus.
But then due to innocent by-standard damage,
sort of secondary attack by the immune system in an uncontrolled setting, the gut lining,
the enteric mucosal cells are destroyed, allowing leakage of blood, puss, et cetera.
That is a very dangerous process which can be triggered among other things by the coronavirus.
And then last but not the least, the SARS virus, the severe acute respiratory syndrome virus.
This, at least, at the time of this recording,
is now a historic event having last occurred in any significant fashion in 2003.
The incubation period for this particular virus was up to 6 days, typically around 4 or 5
and thankfully, worldwide is quite rare except when one was in the middle of an outbreak in Asia
and allowing or waiting for patients to travel to all parts of the rest of the world.
During that outbreak and subsequently only sporadic cases,
there's about a 30% spontaneous resolution rate.
The other 70% go on to progress to severe infection and of those,
10% die typically from respiratory failure.
The clinical manifestation start with a higher fever so above 100 degree Fahrenheit,
approaching 38.5 degree Celsius with associated myalgias: lethargy, cough, and the sore throat.
The patients feel, again, like they have a severe flu-like illness.
However, they go on then due to secondary immunologic reaction to develop primary tact
within the pulmonary parenchyma and this leads to a very severe multilobar diffused pneumonia
with many times, a superimposed bacterial pneumonia to even further worsen the process.
And there is a new type of coronavirus, the SARS-coronavirus-2
which began to cause disease in Wuhan Province, China in late 2019
with an initial limited cluster of cases associated with an open air, live animal market.
However, that initial small number of cases rapidly began to spiral along the same pathway
as did the SARS-CoV-1 coronavirus with first, thousands and then tens of thousands of cases
developing in China followed by an overwhelming spread throughout the rest of the world.
Diseased caused by SARS-CoV-2 is called COVID-19
and was identified as a global pandemic in early March 2020.
This illness is highly infective thus, far more contagious than the original SARS virus
and carries a higher mortality rate especially for high risk populations.
The clinical manifestations are high fever, myalgias, lethargy,
anosmia or a loss of sense of taste and smell, and a severe respiratory illness with cough,
very noticeable shortness of breath, and dehydration.
The incubation period appears to be from 2-14 days and human to human transmission is extensive.
Fatalities have occurred in all age groups and those who are older than 60 years old
or those who have such comorbidities as hypertension, coronary artery disease, obesity, or diabetes
are especially and severely affected. COVID-19 has devastated the world's population and economy,
and attempts to control the pandemic via social distancing
and stay at home restrictions have been partially successful.
Ultimate control needs and effective vaccine, to be accomplished.
So this particular cluster of viruses under the coronavirus heading is most often a cause of common cold.
It's a relatively minor or benign process, although very common,
and the only time one needs to worry about this is if there's an outbreak of SARS virus
or SARS-CoV-2 causing the COVID-19 global pandemic, or if one has a neonate
which has been exposed to a gastrointestinal coronavirus.