 Hey everybody, Dr. O here. In this video, we're going to cover the three phases of HIV infection. So just real quickly, I'll get them out of the way. Phase one, either going to be asymptomatic or if you have any symptoms, it would be chronic swollen lymph nodes, chronic lymph adenopathy. Phase two is just going to be this persistent decline in health that happens as your immune system gets weaker and weaker. So you're just going to be no specific infections, but it's more likely to get infections, this type of things. We'll talk about what are known as constitutional symptoms in just a little bit near the end here. And then at phase three, we'll talk about how when an HIV infection actually leads to AIDS, acquired immunodeficiency syndrome, and that'll be phase three. So I'll start here at the beginning. So after this primary infection, you'll see what's known as acute HIV syndrome. So the virus is winning right away. You can see the CD4 T cell population plummets while the viral load gets really high. And that's because it takes the serial conversion process, it takes up to three months to get the full antibody response to the virus. And then once that happens, then you'll see the opposite. Now the viral load is going to drop and the CD4 population is going to go back up. First of all, because there's less viruses killing them, but also your body will make and clone more CD4 positive T cells. So that's why you see, so in the beginning, the virus is definitely winning. But then after a few weeks up into three months, when you see this full antibody response from your immune system, now you'll see the CD4 T cell count climbs back up a bit, the viral load drops down quite a bit, but then you see this slow, steady decline in T cell population. So you may not have any problems. If you do, you just kind of have a weaker immune system than you would expect for someone of your age, et cetera. But every day, some of these viruses are picking off more and more of your CD4 positive T cells, your helper T cells. That's why you see this slow, steady decline into the years where the CD4 T cell count is dropping. So again, phase one, there really won't be any symptoms. If there are any, it'll be the chronically swollen lymph nodes, because that's where these CD4 positive T cells are being cloned. So your body's fighting off the virus the best that it can. During phase two, what they call here, this classic latency, you're just seeing for some reason, you've just got a weaker immune system than you should have. And then we're reaching a point where near the end of that, you're going to start to see what are known as constitutional symptoms. That's going to be things that can affect the entire body, fever, night sweats, chills, weight loss, these types of things. And then we get into the territory where you now have AIDS. And it's very, very important to note when this happens. So an HIV infection leads to AIDS when your CD4 positive T cell count drops below 200 that you can see on the chart. So once that number is under 200 or under what's 14% of normal, so the 200 is the most important number there, but it's also, that's another way to look at it. So once you reach a CD4 T cell count of 200 or below, you now have AIDS. And that's where, as you can see on the right-hand side of the chart, the opportunistic diseases are going to show up. So I have a list of some of them I'll show you in just a moment. But these will be diseases that shouldn't impact someone with a normal immune system or at least not the same way. Let's go and look at a few of those and then we'll come back and see the end of this. So just I'm going to just pick out a few of them here like toxoplasma, Gondii. So this is only immunocompromised people should have a problem with this. There are many people that have been infected with this organism, but your immune system walls it off and doesn't cause any problems. But if you're immunocompromised, it can lead to encephalitis, the inflammation swelling in the brain, sadomegalovirus. So most humans have been exposed to it. It usually causes no problems or maybe a mild fever for a few hours. But if you don't have a strong immune system, as you can see here, fever, encephalitis, blindness, even death, those would be good examples. Tuberculosis with mycobacterium tuberculosis. Obviously, many, many people are infected with that that have normal immune systems. But if you have HIV or AIDS, it appears to be worse. And also this is where we think some of the drug-resistant strains of tuberculosis are basically incubating in AIDS patients. So hard to say for sure, but I've seen that from multiple sources. Just a few more here. We talked about pneumosis a little bit in the history of HIV video. Use infections can become a problem. Kaposi sarcoma is one of the ones you hear the most often with AIDS patients. So it's actually a cancer of the skin and the blood vessels. So these are all common examples. Let me just jump back to that first image. So those would be the examples of the opportunistic diseases that are attacking an AIDS patient because they're immunocompromised. They don't have a strong immune system. And then finally, the death. So what kills an AIDS patient is an AIDS. It's the fact that their immune system is gone. So I remember when I was a kid, there was someone named Pedro on one of the real world shows on MTV. And he, at the end of that show, his TESO count was zero. So the virus can completely eradicate your helper T cell population. And they're needed to mount a T cell or cellular immunity response and your B cell, antibody mediated response. So any infectious agent, or organisms that aren't normally pathogens can kill someone without an immune system. So that's what leads to the death there at the end. One last thing I want to cover here would be diagnosis because you're seeing the antibodies and the viral load here on this image. So the first test, the test that most people would do first would be the ELISA test to look for HIV antibodies. But like I mentioned earlier, that can take up to a few months. So let's say you're working in a healthcare environment, get a needle stick injury, like you're going to be tested, but they're also going to want to test you again in a few months. And then a confirmatory test. So the antibody test is a good place to start, but a confirmatory test would be either the Western blot or what's now called the aptema, which is an RNA test, but because HIV is an RNA virus, that's looking for the actual virus. So to me, the first test you would do would be to look for the antibodies with the ELISA, then you would confirm by actually looking for the virus. Okay. All right, so those are the phases of HIV infection as well as some just basics about how to diagnose the disease. I hope this helps. Have a wonderful day. Be blessed.