And then finishing up with
hepatitis A virus.
This virus is resistant to acid,
which makes sense
because it is typically a fecal-
surviving passage through the gastric
mucosa and the acid load,
and then entering itself and causing
Transmission, fecal-oral, but so, too,
aerosols can deliver this virus.
The picture you see is a transmission
electron microscopic graph --
micrographic image, sorry,
of hepatitis A, again, clustered and looking
very beautiful in clustered format.
So, here is the pathogenesis
for hepatitis A virus.
The primary replication occurs,
again, in the point of entry, so
through the stomach to
Then the patients develop
viremia after that first
lytic phase, and the viruses then
attack the hepatocytes.
At the initial point of contact,
binding, and insertion of the
virus into the hepatocytes,
there's minimal damage
Even as the viruses are passaging
creating new additional virions,
which are excreted into
the bile, through the common
bile duct and into the stool
for up to 10 days, there is
still a limited response
with the exception of a systemic immune
or inflammatory response,
which gives you the initial symptoms.
But as yet, there's not a specific
attack on the hepatocytes.
That comes later after the prodromal
and preicteric symptoms.
Prodromal symptoms as immune
reaction is starting to develop in
exposure to those virions,
is low-grade fever, malaise, anorexia;
your common typical viral syndrome.
The preicteric symptoms, so this is as
the immune system is starting to rev up
and starting to recognize that indeed,
we have some damaged hepatocytes to address.
This starts to get much more
gastrointestinal in its approach.
So, nausea, vomiting,
the abdominal pain is crampy
Many patients describe it as lower
down instead of over the liver,
which is somewhat interesting, but
pain can be referred anywhere.
Patients also have fevers which increase
in nature and they start to have rigors,
generally feeling, again, like a miserable
patient with the flu.
However, the flu is not followed,
in most cases,
And when the patient then progresses
to the icteric disease,
this is when they're now starting to get
evidence of a transient, thankfully,
but acute liver failure.
Inflammatory reaction targeting those
infected analytic hepatocytes,
which is causing decrease passage of bile,
and a backup of bilirubin into the body.
So these patients have jaundice.
Their urine is excreting very
dark evidence of bilirubin.
When one checks their liver
numbers, their liver tests,
the transaminases, the AST, ALT,
all of these are elevated.
That all goes with hepatitis A virus.
both clinical, but also, a serologic
immunoglobulin M antibody to
the hepatitis A virus.
Because we actually now
have vaccine product
which can create an IgG
protection and that is
It has a very good efficacy, but yet,
like nothing else, is not 100%.
So, serologic detection of immunoglobulin
would suggest acute infection
with hepatitis A,
and there are very few things
to cause a false positive
Well, actually treatment is prevention
as best as we can because
hepatitis A is sewage or fecal-associated,
so having proper treatment of the water
supply through the municipal water supply.
Chlorine is effective in this.
Certainly, good hygienic practices.
Again, washing hands, wherever
and whenever you go anyplace.
Avoidance of contaminated food and water.
Well, kind of hard to do if you don't
know that they are contaminated,
and because hepatitis A is a fecal-oral
transfer, one could have
exposure to a friend,
a food server, a healthcare worker,
who is actively viremic and expressing
hepatitis A contagious virions
into their stool,
and then could be exposed
through their hands.
So, for yourself, washing hands is important.
Especially for travelers
and those living in parts of the world
that are endemic for hepatitis
A or exposure to that,
there is a very successful vaccine,
as I just mentioned,
which is highly recommended.
In fact, in the States, it's part of a routine,
recommended, or even required
vaccine schedule for pre-
school aged children
because hepatitis A is now becoming
quite so common.
Mostly for those who are immunocompromised
and unable to respond to the virus on
their own is to give immunization with
hepatitis A-specific immunoglobulin,
or even polyclonal immunoglobulin.
However, most of the rest of us are able
to make an appropriate immune response,
and we just need enough time to
get past the active infection,
and to recover fully, 100%.
So, this is a longer session is
discussing some of the most
mportant viruses in terms of, especially
pediatrics, with exposure to the
enteroviruses as a whole.
Probably key to remember here is that
the disease associated with each of
these viruses has so much to do
with the tropism, the target of the virus
in terms of where it causes its disease.
Viruses all cause disease in 1 way;
by lysing their host cell
and precipitating an immune reaction.
And when that immune reaction
targets a disease cell in the liver,
or the brain, or the kidneys, or the
throat, or the hands and the feet,
all causes different manifestations.
Remember those and you'll be good.