- So we know that an untreated HIV infection
destroys your immune system and leads to
essentially an immune less state that we call AIDS,
acquired immune deficiency syndrome.
So how do we know when an HIV infection
isn't just HIV anymore?
How do we know it's progressed to AIDS?
Well, in one or both of two ways.
So here's a graph I'll use to explain.
So here's CD4 T cell count on this y-axis.
And here's a little timeline
and we'll say that 10 years is about here.
Because in an untreated HIV infection
it takes about 10 years before your immune system
is completely destroyed and AIDS is developed.
So when your CD4 cell count has dropped
from its normal levels, right,
of about 1,200 or so CD4 cells per cubic millimeter of blood
to less than or equal to
about 200 cells per cubic millimeter of blood,
you've developed AIDS.
That's one of two ways to tell.
The other possible way to know if you've developed AIDS
is if you have any of what are called
the AIDS defining opportunistic infections.
Which are sicknesses that can only take hold in your body
if you have a failing immune system.
So regardless of your CD4 count,
if you have any of these opportunistic infections
and, of course, an HIV infection as well
you will be diagnosed with AIDS.
So let's do some drawing here
to look at what types of AIDS defining illnesses can come on
and when they might come on.
Because it's important to be on the lookout
for signs and symptoms of these conditions.
You know because they can be really dangerous
to your health.
So generally speaking,
people with CD4 counts greater than 500 cells
per cubic millimeter of blood
are not at risk for opportunistic infections.
But if you're hovering right around 500ish,
then sort of the daily ebb and flow in your CD4 counts
means that you might develop some minor infections
like thrush in your mouth.
Or yeast infections in the vagina.
So thrush symptoms to look out for
would be white patches on the gums or on the tongue.
And you might also get some pain in the mouth
or in the throat
and that would cause some trouble swallowing.
And yeast infections symptoms
might include vaginal irritation or itching
and also a thick white discharge.
And I should probably clarify,
so all of these ranges that we're looking at,
these aren't set in stone.
So you could get certain opportunistic infections
at slightly higher T cell counts, or CD4 cell counts,
or slightly lower CD4 T cell counts.
These aren't sort of fixed numbers.
These are just sort of ranges.
Good, so, if your CD4 levels continue to drop
you could develop something called Kaposi's sarcoma
which is a tumor, a set of tumors
caused by human herpesvirus-8.
Which can only really infect a person
with a weakened immune system.
So the classic signs that you should look out for
with Kaposi's sarcoma are these purple patches or nodules,
growths almost, that appear usually in the mouth,
on the gums, or on your skin.
If your CD4 count drops even further
to between 100 and 200 cells per cubic millimeter of blood,
then you might develop
some of the more severe opportunistic infections.
For example, Pneumocystis jiroveci pneumonia.
Also known as Pneumocystis carinii pneumonia or PCP.
So this is a fungal infection of the lungs.
And it causes a really, really, severe chest infection.
And in fact this is most often the cause of death
for someone with AIDS.
Two other common fungal infections that might take hold
are Histoplasmosis and Coccidioidomycosis.
It's a bit of a mouthful, Coccidioidomycosis.
And these two are pretty severe
because they infect many different parts of your body,
not just your lungs.
So, you can look out for a PCP infection
because it presents kind of like a chest infection.
So you'd have shortness of breath, you'd have a cough,
you'd have chest pain.
And, you know, at this point your immune system
would still be able to mount a fever,
so you'd have a fever.
And these two fungal infections
present in a similar way, right, Histo and Coccidioido.
But remember I said that they're systemic diseases
so these can also cause some weight loss
and just general fatigue.
Those are systemic symptoms.
Now if your CD4 levels continue to fall,
to between 50 to a 100 cells per cubic millimeter,
you can start to develop opportunistic infections
that affect your brain
such as Toxoplasmosis and Cryptococcosis.
So Toxoplasmosis is caused by a parasite
and it can cause Encephalitis
which is swelling of the brain.
And because of this swelling of the brain or Encephalitis
a person might develop neurological symptoms
like a headache, or weakness of their muscles, or seizures.
These are all signs of a sick brain.
And Cryptococcosis is yet another fungal infection.
And this one usually starts as an infection in your lungs.
And then it sort of moves up to your brain
and causes Cryptococcal meningitis
which can rapidly be fatal.
So symptoms of Cryptococcal meningitis would be
sort of the classic meningitic symptoms,
things like a headache, and neck stiffness, and a fever.
And while we're in this little bracket here,
two other organisms that can cause serious infections,
right, between this 50 to a 100 bracket
are Cryptosporidiosis and CMV, Cytomegalovirus.
So Cryptosporidiosis causes severe
gastrointestinal symptoms.
So you'd get this chronic, longstanding, watery, diarrhea.
Because your intestines just aren't absorbing
food or water properly.
You would get serious stomach cramps
and you'd have severe weight loss.
And CMV here, actually CMV is present in most adults
but it only really starts to cause trouble
if something's wrong with your immune system.
So in someone with really low CD4 levels,
CMV can cause problems in the digestive system as well.
So the last one I'll talk about
happens if your CD4 cell count
is less than 50 cells per cubic millimeter of blood.
And this one is called Mycobacterium avium complex or MAC.
And this bacteria sort of similar to all the other bacteria,
and viruses, and fungi that I've talked about so far.
They're all present in many different places
soil, water, on trees,
really many places in the environment.
But again, they don't cause any problems in people
with healthy immune systems, we just fight them off.
But MAC in a severely immunocompromised person,
like someone with AIDS,
can cause a really, really serious infection that spreads
through the bloodstream to many other parts of the body.
And that will result in things like high fevers,
night sweats, diarrhea, all sorts of systemic symptoms.
And MAC can be rapidly fatal as well.
Now everything I've talked about,
all of these AIDS defining opportunistic infections,
they can be treated with the right medications.
So with access to treatment
they don't have to be life-threatening.
You just have to get medical help right away.
And then once they're treated
the focus would then be on raising your CD4 cell count
with ARV treatment, like HAART.
So that hopefully your immune system gets stronger
and none of these develop again.