- [Instructor] Now with immune system, sometimes there's special case. AIDS is one of those cases. AIDS, or Acquired Immune Deficiency Syndrome, is caused when a person is infected with the HIV. HIV is Human Immunodeficiency Virus. The name right there, immunodeficiency. The immune system will not function properly. The HIV is so potent because it targets the helper T cells. Now if you remember, the helper T cells are one of the main cells that will activate your immune response, so if you don't have these helper T cells you really can't activate your immune response efficiently. Now HIV can be transmitted through any body fluid. We're talking blood, semen, breast milk, vaginal secretions. The idea is though, blood probably is one of the more potent ways, but usually semen, vaginal secretions, breast milk, all have high enough concentrations. Here's how HIV works. HIV is a retrovirus, so when it's in your body it will find a cell to bind to. It will then insert the viral DNA. The viral DNA will use your own cell's machinery to make a single-stranded DNA. Well, DNA is our genetic code. That single-stranded DNA becomes a double-stranded DNA just like our DNA. It will head into the nucleus and in the nucleus it will be reproduced, copied, and read just like any other bit of DNA. When the double-stranded DNA from the retrovirus is read it will make viral codes. It will make proteins which can make up the virus itself. That means that this viral RNA that was inserted into a cell uses your cell's machinery to make more of that virus. That just keeps on going and going and going. So now, in AIDS, there's several different phases. Phase one, if you know it's going to take a few weeks to a few years. There is no one set time frame. Everyone progresses at different rates. You'll have these flu-like symptoms, swollen lymph nodes, chill, fever, fatigue, body aches but if the doctor does a test for the flu it will come back negative. At this point, the retrovirus is just getting going. It's invading the cells, creating more retroviruses, and spreading throughout your body. You body's aware there's a problem so it's trying to attack it. It's acting like you have a flu but the problem is a lot of people don't exhibit symptoms. It just occurs in their body without any clue because it's happening so gradually but that virus is multiplying. Antibodies are made. The problem is, the antibodies you're making really aren't working very well. They can get rid of parts of the virus. It might get rid of some of the aspects here or there but it does not clear the entire virus out. Now those antibodies you're making, they might not be good in six months or a year from that point because the HIV virus is constantly changing. It's one of the biggest problems of why medicine cannot find a cure or a vaccine. The virus just changes too frequently for anything to keep current. Once that phase is gone then you get to phase two. It can occur about six months to anywhere to 10 years. This has a problem because now it's opportunistic infections. Opportunistic infections are any infection that in a healthy person you probably could fight off but with your immune system being compromised now these infections can take set and cause some major problems, and the reason here, the helper T cells. All the helper T cells are becoming infected, they're becoming destroyed. The numbers are slowly dwindling down. The fewer and fewer helper T cells, the slower and slower and weaker the immune response is. If untreated, this phase two will go into the next phase, the phase of AIDS. So phase three, full-blown AIDS. Now AIDS is diagnosed when the helper T cells fall below 200 cells per cubic millimeter. That means your body just cannot adequately fight infections because the cells that activate the immune response just aren't there. So phase three, this is what typically is called AIDS, is when the helper T cells are below that 200 cell per cubic millimeter count. Tuberculosis, pneumonia, mengitis, encephalitis, Kaposi's sarcoma, non-Hodgkins lymphoma, cancers, all these opportunistic infections will now come into the system and try to take over. Now any one of these is quite problematic. More often than not a healthy individual with a fully functional immune system will not have any of these be able to take hold. Well if you're thinking, hold on, I had pneumonia or hey, I had meningitis, these can take hold but usually they take hold while you're already sick with something else. For instance, I've had pneumonia. Not the end of the world. I was down and out for about a week or two, but the pneumonia was only able to take hold because I was already sick with a head cold and upper respiratory infection. That infection allowed the pneumonia infection to come in because it's opportunistic. If I didn't have that head cold and chest infection pneumonia would not have a had a chance, so that's that idea of opportunistic. Something must be affecting your immune system for these to come in and take hold. Now, if there's no treatment at this point, it's pretty much always fatal because any one of these opportunistic infections could be deadly, so treatment is pretty much essential to try to help combat these opportunistic infections. So here's a graph showing your T cell count, your antibodies, HIV in the blood, all things mixed together. Now the bottom of the graph is years. You can see within the first year, HIV in the blood spikes and gets knocked down. That's because your antibodies are fighting it. So phase one basically means the HIV has spiked, antibodies are trying to catch up. Phase two you can see, well, HIV in the blood's pretty low. The antibodies do a good a job but they're not getting rid of everything and the biggest problem is, look what's happening in phase two. The T cells are plummeting. So even though the antibodies are pretty efficient here, they're not 100% and the ones that are being missed, those HIV virus particles that are still going, they're killing and destroying more and more and more T cells. Eventually, you'll end up at a point where there's more HIV in the blood than there are T cells. It's that point that typically is where you say now it's full-blown AIDS. Now any of these behaviors can increase your chance of getting AIDS. Now these are worldwide numbers. Males, usually about 3/4 of new cases. So it's going to be sex, man with man. It can be sharing needles during intravenous drug use. Heterosexual with an HIV-infected female. What all three of these share in common is in exchanging bodily fluid. In the first two, it could be exchanging blood. In the first and third it could be exchanging semen or vaginal fluids in the female. Females, only about 1/4 of new cases, again worldwide. If a female has sex with an HIV-infected male or sharing drug needles. Now the idea of safe sex. Well, you hear all over the place, abstinence is the only way perfectly to be safe. That because it's the only 100% way. Anything beyond that, you never get more than a 99 point some percent chance. Even tube-tying, vasectomy, you name the different types of contraception, every one of them, even the best ones, are only at 99 point seven or eight percent. There's no 100% method out there, so that's why they say abstinence is the safest. Well, if that's not the choice, reduce the number of sexual partners. The fewer people you're close with, the less chance of having an infection. Low-risk behavior. Individuals that are engaging in drug use a lot of times have a higher risk because of the intravenous needle potential or someone that is constantly being with other individuals, having different partners. The idea of avoiding high-risk sexual practices. Anal-genital is a very high risk, one of the reasons being that a lot of times this will cause tearing of the anal or the rectal tissue. That tearing will be bleeding. Blood carries virus particles. Latex, polyurethane condoms, barriers are ways of helping prevent the passage of fluids but it's one of those things where even then they're not 100%. There could be a rip, there could be a tear. If anyone thinks they're exposed, thinks there might have been a risk factor, might have been an issue, get tested. It's better to catch it early because today's modern medicines, it might be a lot of medicine to take but a lot of times HIV can be put into a remissive state. There are people that have had the HIV virus for 15, 25 years at this point living a relatively normal life, just having to take an increased amount of medication to try to keep the HIV infection in check so getting tested will help answer the questions. It will help answer are you or are you not infected. It also could help catch it at an earlier stage. The key thing though is just be safe. Be smart about choices. Today's treatments, those drugs I was talking about. One of the HIV drugs is AZT, reverse transcriptase inhibitor. If you're saying, what the heck is a reverse transcriptase inhibitor, it's the way it works when your RNA from the virus is made back into DNA. The term transcription is when DNA is made into RNA, so reverse, go the other way, RNA to DNA. If you can stop the HIV virus from creating new virus particles, you can help keep the virus in check. That's AZT. Protease inhibitors, well these things are meant again to prohibit a certain pathway within the viral production. Then we have Maraviroc. It's a newer drug on the market but it helps to protect the T cells specifically. It does not allow HIV to actually enter into the T cell and destroy the T cell. The whole thing though is early treatment. The only way for early treatment is early detection to get tested. With all these drugs, people are living longer and more normal lives once they've been infected. The best thing to do obviously is don't get infected, practice safe practices but if it unfortunately occurs, click it, seek help. Go over basically to come clinic and get tested. Figure out what's going on earlier rather than later. Now they're working on a vaccine. The problem is, they can't quite pin it down. They've been working on a vaccine for the past decade or two almost. The vaccine is constantly under development but every time they identify a unique feature to target, the virus mutates. It changes. That's one of the biggest problems with HIV is how often this virus is changing. The only way a vaccine can be efficient is if what the vaccine is presenting is matched exactly with a future virus. If a virus changes, the vaccine is useless and sometimes the HIV virus is changing as frequently as every six months. So vaccines, they're trying to figure it out but so far they haven't found one thing that stays consistent.