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Defining AIDS and AIDS defining illnesses | Infectious diseases | NCLEX-RN | Khan Academy

August 27, 2019

– 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.


  • Reply Fatima Binte Zahir January 21, 2016 at 3:38 pm


  • Reply Fatima Binte Zahir January 21, 2016 at 3:38 pm


  • Reply Benjameen Benjamin June 11, 2016 at 1:16 am

    what about tuberculosis? is it falls under MAC?

  • Reply MissDesi April 8, 2017 at 11:54 pm

    not 10 years in everyone a woman named Jennifer Vaughn has a YouTube channel and had full blown aids after contracting it unknowingly 2 years prior

  • Reply King Kato March 2, 2019 at 4:02 pm

    What if your cd4 count is normal HIV neg but u are expierincin all these things

  • Reply The Sensual World April 29, 2019 at 3:19 pm

    Where´s Tuberculosis stand in this graphic? At what stage of CD4 lowering can we get Tuberculosis?

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