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Current time:0:00Total duration:10:37

Video transcript

so we know a little bit about HIV now it's a virus that attacks your immune system and if untreated it will cause a state of the immune failure immune deficiency in a person and that immune deficiency state is referred to as AIDS it's essentially late stage of an untreated HIV infection so I just want to talk a little bit about some of the ways that HIV is transmitted some of the different ways you can possibly get HIV into your bloodstream and thus develop an HIV infection and let's actually do this in a bit of a simplistic way because it turns out that HIV is most often transmitted through contact with three different types I guess of body fluid from an HIV infected person so contact with their blood with their sexual or genital fluid and I'll expand on what that means in a minute or so and from breastmilk contact and let's actually look at this in terms of four fairly common scenarios these will be the most common situations that HIV is spread via these groups of fluid here and let me just make it clear that these infected body fluids would need to come into contact with broken skin or directly with your bloodstream maybe by an injection or something like that or they'd have to come into contact with one of your mucous membranes which are just parts of your body that aren't protected by normal skin so for example inside your your mouth or inside the vagina or the rectum or at the opening of the penis HIV can cross into your body through these mucous membranes you won't just become infected by say just looking at these fluids or just being near them or anything like that one of these fluids would have to make it inside your bloodstream or make it through one of your mucous membranes by physical contact for you to possibly develop an infection okay so top left up here will make this sexual fluid contact which is actually the most common way that HIV is spread typically when having unprotected sexual intercourse with someone who has HIV and don't let these pictures scare you these are just cross sections of pelvises so a female pelvis on the left here and a male pelvis on the right so we can use these to look at the sexual organs so contact with sexual fluids like semen or pre-seminal fluid or vaginal fluid or even rectal fluid can spread HIV because there's often a fairly high amount of viral particles within these fluids particularly within the first few weeks of a new HIV infection when the infected person's viral load in their blood or in their sexual fluids is up at extremely high levels but in terms of actual sexual activities in general unprotected anal sex with either a man or a woman is the highest risk sexual behavior because not only is there exposure of HIV infected sexual fluids to mucous membranes right the opening at the tip of the penis and the inside of the rectum in a woman or a man our mucous membranes but if there's any trauma to the involved body parts there can be some blood there as well and that might have virus in it and thus increase the risk of infection virus from infected sexual fluid or blood can get across the mucous membranes of an uninfected person or it can just get directly into a person's bloodstream through an area that might be bleeding now this is not to say that unprotected vaginal sex is not risky as well it turns out that unprotected vaginal sex is the second highest risk sexual behavior because again there's exposure of sexual fluids right semen and vaginal fluid to mucous membranes which HIV loves to hop across when it can and again there could be although less likely than in anal sex there could be trauma to the involved body parts so there can be some blood involved as well of course containing the HIV and just so that I'm perfectly clear here anal sex I said had the highest risk of transmission and vaginal sex the second highest risk but vaginal sex is the way HIV is transmitted most frequently overall because overall more people have vaginal sex over anal sex and so last in this sexual themed quadrant I just want to mention that oral sex of any kind so using the mouth to stimulate the penis the vagina or the anus carries a risk of transmitting HIV for much the same reasons as before mucous membranes of the mouth being exposed to sexual fluids and mucous membranes of the penis or the vagina or the anus being exposed to possibly blood may be the person's mouth has some open sores in it which happens to be one of the symptoms that can happen in an HIV infection and on that note actually having untreated sexually transmitted infections like chlamydia or syphilis or herpes vastly increases your risk of transmitting or becoming infected with HIV and risky scenarios because you're more likely to have breaks in your skin or your mucosal surfaces from symptoms of these sti's like sores or ulcers and through these HIV can more easily infect you all right next quadrant here so after sexual transmission right the most frequent mode of transmission exposure to infected blood that's the next most frequent mode of transmission and in particular procedures involving needles contaminated by someone else's blood so for example using intravenous drugs and then sharing needles with an HIV infected person in that case HIV is just one of the many viruses you might pick up by sharing needles in an IV drug use because you're essentially transferring tiny droplets of an infected person's blood directly into your bloodstream on a needle other needle related procedures needle stick injury let's say you're a healthcare worker and you're working with an hiv-positive patient right maybe you're drawing some blood or something like that you might accidentally get stuck by the needle after it's been contaminated with their blood and this does occasionally happen unfortunately there's a risk of HIV transmission from them to you there and remember to keep in mind that risk of transmission depends on some extent to a person's viral load so these risks are all sort of modified to be higher or lower depending on how much HIV is in the person's blood typically very low amounts of HIV if they're being treated with specific medications and typically pretty high amounts of HIV if they're not being treated last thing I'll say here is contaminated blood transfusions and this isn't so much of an issue these days at least not in most countries because some seriously rigorous screening of donor blood and the blood supply that blood banks have on hand but back in the olden days you know before the sort of late 80s Early 90s donated blood was not routinely tested for HIV as crazy as that sounds so contaminated transfusions don't happen very often these days in most countries but worth a mention here because it's still something to be aware of now third quadrant what's the third most frequent route of HIV transmission well it's actually from an HIV infected mom to her baby during childbirth and kind of alarmingly around 90% of the HIV that we see in kids they actually got it in this way from their mom during their birth which is also called vertical transmission mom to child during gestation or during birth and we're not 100% sure how the transmission happens but the thought is just because they're being exposed to Mom's blood and vaginal fluid on the way out of the birth canal and because they while newborn babies are essentially all mucous membrane at birth they just have really thin skin so it's not too hard for HIV to jump on board so to speak luckily there's all sorts of medications that we can give to mom before and after her pregnancy in labor and there's medication that the baby can take as well and and all of that drastically reduces the risk of mom passing HIV on to her baby from a risk of about 25 to 30 percent HIV transmission without medication all the way down to only about 1/2 percent with medications so around a 20-fold reduction in moms chances of passing HIV on to her baby with the proper medication now last quadrant this one also involves mom and baby it's transmission of HIV via breast feeding breast milk and in an infected mom will contain HIV particles so when the baby feeds it'll be ingesting lots and lots of HIV particles which obviously mom is not intending and it's not clear how the HIV gets into the breast milk in the first place but when the baby ingests it it can infect the baby by being absorbed through the digestive tract so before we wrap up I just want to briefly mention two things so first the risk of transmission in at least this quadrant here it goes way down if the if the infected person is using condoms to sort of physically block HIV transfer and also properly taking their HIV medication to reduce the viral load in their in their body in their blood and the fluids that we mentioned in this scenario here but also that second one the properly taking the HIV medications that will vastly reduce the risk of transmission in needle sharing and in mom to newborn transmission and in breast milk all these scenarios here the second thing is that these are all ways you can contract an HIV infection but I think it's worth mentioning a few ways you can't contract an HIV infection that might not be well known or there might be some myths around around these so unless any of these has been contaminated by infected blood HIV is not transmitted by body fluids like saliva or tears or sweat or urine or feces and it is not spread through the air like say tuberculosis is so being around people with HIV won't somehow transmit the virus through the air to cause an infection in another person and it's not spread from casual contact either say from shaking hands with or hugging someone who has HIV it actually doesn't even survive very well outside a human body so you can't become infected by sharing plates with an infected person in a restaurant or touching a toilet seat at a public restroom or anything like that but there you go the main routes of transmission unprotected sexual activity contaminated needles from mom to newborn and five breast milk