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What is trichomoniasis?

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Raja Narayan.

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Video transcript

- [Voiceover] Trichomonas vaginalis is responsible for a sexually transmitted infection known as trichomoniasis and as we'll talk about in a minute, the symptoms mainly occur in women in the vagina. Now this STI is not caused by a bacterium, but rather a protozoan which is a more advanced form of microorganism than a bacterium and this protozoan specifically is a parasite and it exists mainly by eating cells that they destroy, so eating cell fragments and this protozoan uses these cell fragments or these pieces of cells for nourishment. Now they typically have a pear shape to them, so I'll draw this pear shape here. So this is their body, the cell body. These trichomonas, or you can also refer to them as trichomonads have one cell to them, so this is the one cell pear body and they move around because of these protein strands, these whips that they have, that are called flagella, flagella. And finally, one of the other things you might see if you take a look at this guy under a microscope, as we will in a minute, is the nucleus. So here's the nucleus. Now because trichomoniasis is a sexually transmitted infection, we have to consider the mode of transmission, or how does it commonly spread from one person to the other, and as the name sort of sugggests, this occurs only through vaginal sex and what makes this infection very interesting is that the trichomonad protozoan can't survive anywhere else. So they can only live within the urogenital tract. Now this means they can live within women, like in the vaginal tract or in the urethra, or they can also live in men, but the tricky thing about that with men is that they rarely have symptoms. So they're asymptomatic, which means that they're carriers of this infection. So they're asymptomatic carriers that can spread this STI to women without even realizing it. So if we take a look at this woman right here, and I've drawn here urogential tract so we're taking a look at a sagittal section or if we chop them in half from head to toe down the middle through the legs, you can see here is the bladder that leads out the urethra. So here's the urethra. And here's the vagina, so the vagina. At the top of the vaginal tract is the cervix over here and this part that I won't label for our conversation, because we won't be talking much about it, this is the anus that leads up to the rectum and the rest of the GI tract. So if a woman is infected with trichomonas, they're going to spread into the vagina and spread up the vaginal walls and we can take a look at this on a larger scale here. Here are the vaginal walls and we're leading up to the cervix. Let's say that the trichomonas is climbing up the vaginal tract using its flagella right here. I'll draw these green. And it latches on there. It'll use this type of mechanism to whip itself upward and in doing so, it causes stress to the cell membrane that over time, as I'll show up here, causes the cell to die, producing fragments that used to be the cell that are scattered into the vaginal tract and eaten up by this parasite. Now your immune system will recognize this and in response to the trichomonas, white blood cells will be sent here to combat them and release toxins and try and engulf them and eat them to stop them from killing cells in our body and as a result of this, we will get inflammation. Inflammation meaning more cell death in response to the ones that have been affected by the trichomonas as well as a fever and other systemic responses and that causes irritation. If we have white blood cells fighting the trichomonads within the urethra, you can get urethritis which will cause pain when you urinate and that's referred to a dys, meaning painful, urea, meaning urinations. So painful urination. The same thing happens up here with the vagina as well as with the cervix, because you can get vaginitis as well as cervicitis, cervicitis. Irritation of these two will then make sex rather painful, causing what's referred to as dys, again, meaning pain, pareunia, dyspareunia or painful sex. And as this battle continues, you'll have more dead cells, dead white blood cells, dead protozoa falling through the vaginal tract out producing frothy, green discharge. And this also has a characteristically bad smell or it's malodorous. Over time this inflammation can actually cause some pretty bad effects as well. In women, especially those that are pregnant, chronic irritation or long-term irritation can cause them to deliver a baby earlier than they should. So that leads to preterm labor. Also, long-term inflammation can cause irregularities in cell formation or cell division at the cervix, over time producing cervical cancer. The idea though is because women tend to have symptoms, we will catch the trichomonads earlier on and we'll treat them as we'll talk about. In men, there's a greater concern though, because they're asymptomatic. So one of the things that you can get with chronic inflammation is prostate cancer which why, as we'll see in a few minutes, why it's important to treat the symptomatic patient as well as their asymptomatic sexual partner. Now, let's move on and talk about how do we diagnose trichomoniasis? Well there are two main tests that we can employ. The first is what's referred to as a wet mount, which is exactly kind of what it sounds like. You take a swab of the vaginal tract. You take a swab. Let me draw that swab right here. And if we swab the vaginal tract, we'll get a sample of cells, mucus and hopefully some of the protozoa as well. >From there, you put the sample on the slide, so you put it on the slide. So there's our sample and you take a look at it under a microscope and this is what you'll see. They'll be some squamous cells. So this simple squamous vaginal epithelial cells as well as these two guys which are actual, microscopic views of these trichomonads. Now that you can see here, there's the nucleus, the pear shaped body and the flagella that are present here. The second test you can do is a culture, a culture, or just try and grow out the trichomonads on a petri dish. So here's our petri dish over here and I've smeared our sample from this swab right there and we'll let it grow over about five days. Then, what you'll see here are these trichomonad colonies that are growing on this petri dish. Okay, so now that we've diagnosed trichomoniasis, how do we treat it? Well, here to we're going to use antibiotics and we can use the culture up here to determine what antibiotics the trichomonads will be sensitive to. So say let's put antibiotic number one down there and antibiotic two up here. Over time we will see that antibiotic two wasn't very useful. We still had these trichomonads grow even though we had it on our petri dish here, whereas down here, antibiotic one created this space where no trichomonads could grow. So that way we can have our culture determine what antibiotics the trichomonads are sensitive to. So we can have our culture determine sensitivity. And another important thing about treating infected patients with trichomoniasis, is that their sexual partner should be treated as well, because remember if their partner was a male, they may not have any symptoms, but are at risk for developing diseases down the line. Now, if we wanted to prevent trichomoniasis all together? How do we achieve prevention? Well, the trick here like most STI's is to block transmission and we do that by limiting the amount of direct contact during these modes of transmissions. So, in this case, during vaginal sex use of a condom, so condoms, can greatly reduce the rate of spreading trichomonads potentially from an asymptomatic carrier to a susceptible patient and because trchimonas vaginalis can only live within the human urogenital tract, if we treated everyone that was carrying this parasite, we could eradicate the disease from the planet.