Protein Angst

Tuesday, February 08, 2005

You Can't Get AIDS from a Sneeze

My latest article is about aromatase inhibitors, a new class of breast cancer drugs, but a far more interesting article in today's science page is on Bexxar, a lymphoma drug that actually uses antibodies to administer radiation specifically to cancer cells.

A couple days ago, I read about someone whose health teacher didn't hang around with gay people because she was afraid she might catch AIDS. I didn't know what to say. I couldn't believe there were people so ignorant, yet it didn't surprise me. I will counter this ignorance by spreading knowledge, and I expect you to spread it yourself. Go on. Be a virus.

Diseases are spread by pathogens. These are any number of microscopic buggers: bacteria, viruses, fungi, etc. AIDS is caused by HIV, which is Human Immunodeficiency Virus.

Now, there is some controversy as to whether a virus can truly be considered alive, but for my purposes, I will consider it to be a living organism. It contains genetic information and the ability to pass it on. That's good enough for me. Also, it allows me to anthropomorphize it more easily.

Each virus is different. They like different parts of the body. They require different things to survive. From what I've learned, I'm not even certain we know why certain viruses behave the way they do, but we know they do, and that's what's important.

HIV is found in high concentrations in the blood, semen, vaginal fluid, and breast milk. These are the only bodily fluids you really need concern yourself with when worrying about "catching AIDS." It is present in very low quantities (if at all) in the saliva, sweat, tears, feces, and urine, but the concentration is so low as to be negligible (we're talking ten thousand times lower than in the blood). A person with AIDS — let's call him Bill — could pee directly into your mouth and you'd be safe. But that's really gross.

The other thing about HIV is that unlike the cold and flu viruses, it can't survive outside the body for very long at all. It's incredibly weak, and very codependent. HIV is hardly present in mucus in the first place, so a cough or sneeze spells a very lonely death for the virus. By the time it reaches you and scrambles around looking for a way to get in your nice warm body, it's too late.

That is the other consideration: the virus needs a way to get into your bloodstream. If Bill touches you, there is no way HIV from inside him could have gotten into your blood. You are safe. First of all, there was very little virus hanging out on his hand anyway. Plus, HIV is incredibly lazy, and it needs easy access. None of this epidermis business.

If Bill — no, let's switch gears and talk about his friend Karen — If Karen bleeds on you, you are also safe. Wash it off immediately, but don't flail around screaming, "I've got AIDS! I've got AIDS!" Like the process required to become a vampire, the blood needs to mix with your own. This is why blood transfusions sometimes led to HIV infection — now that we have HIV tests, it's less of an issue. In the same vein — no pun intended — sharing needles is another method of transferring the virus from infected blood to fresh blood.

The fact that HIV is so concentrated in the semen and vaginal fluid is why it is a sexually transmitted disease. During sex, the vaginal lining can be sloughed off, providing a route to the bloodstream. The reason gay men have a high rate of affliction is because the rectal lining is even thinner than the vaginal lining. You have the two conditions necessary for infection: a large supply of virus and a way to get in.

Every virus is different, and these are the quirks of HIV. It takes quite a bit of work to get, as direct access to the bloodstream is not very common. Plus, only certain bodily fluids carry a high risk of infection.

And of course, even after all that, you don't contract the disease immediately. The virus can party in your body for years before getting to work. All that time, though, you're able to pass it on.

The A in AIDS stands for Acquired. You cannot just magically get HIV; you must acquire it from someone else. You can have unprotected sex with three thousand people, and if none of them have the virus, your chance of having the virus is zero. Unless you already had it, in which case you have a lot of phone calls to make.

AIDS is a sexually transmitted disease. It is transmitted through sex. It is transmitted through direct blood-blood contact. You can't get it from a sneeze. Or a cough. Or a touch. And for God's sake, you can't get it from being around someone with AIDS.

If you know someone with AIDS, here are some things you probably shouldn't do with them:
  • have unprotected sex
  • take a blood oath
  • share needles
  • remove some of their blood with a syringe and inject it into yourself
If you know someone with AIDS, here are some things you should do with them:
  • give them a hug
  • shake their hand
  • kiss them
  • share your drink
It is literally safer to be around someone with AIDS than it is to be around someone with a cold. If the person with AIDS has a cold, though, watch out! You might get sick!

With a cold. Not AIDS.

Here are some informative pages on HIV transmission:
Honestly, if you meet someone who doesn't understand how HIV is transmitted and why, please set them straight.


  • I'm more amused by the people who think HIV can be spread by mosquitos.

    If it was easily spread by mosquitos, we'd all have it. All of us.

    Sigh. Ignorance.

    *goes off to the lab to study cancer*


    By Anonymous Anonymous, at 11:13 AM  

  • Definitely some information that needs to get out there...have you heard that some of the abstinence-only sex ed courses teach that you can (apparently easily) get AIDS from tears?

    Me-- *banging head on wall, again*

    I'll post a link to this in my lj!


    By Anonymous Anonymous, at 11:49 AM  

  • Like the process required to become a vampire, the blood needs to mix with your own.Dude, this? Is why you rock.

    People definitely need to know this information. I mean, I learned on The Daily Show that a Senator actually told people that you could get HIV from sweat and tears. Sweat and tears! I think they just want a reason to say, "Stay away from gay people!" Which, you know, is stupid, since not only gay people get AIDS.

    And hee! to your cold/HIV comparisons. The common cold is much more easily trasmitted. And there's no cure! And it keeps coming back!


    By Anonymous Anonymous, at 12:25 PM  

  • It wasn't just any old Senator who said that... it was Bill Frist, who is a medical doctor. He's either grossly incompetant or a liar.

    Or, you know, both. No reason for me to be closed-minded about the possibilities...

    By Blogger Jonathan, at 2:33 PM  

  • Bill Frist isn't a real doctor. he went to medical school and then went on to help his family run the Columbia Hospital System, not so much with the practicing of medicine. I bet he's a fifth rate doctor, otherwise he wouldn't have gone into politics.

    i have a controversial topic once more.
    two even.

    obesity: is it a genetic disorder?

    homosexuality: nature or nurture?

    run with them.

    By Blogger daedal, at 3:43 PM  

  • Since this is sort of related to your post, here's my most recent HIV question. I heard recently (maybe from CNN?) that we are very close to eliminating infant HIV in the US. I had the impression from the article that most of this is from early testing and administering drugs (not sure if the drugs go to the mom or baby) that prevent the passing of the HIV prior to and during birth. I have no idea how this would work, but I can sort of see how it might be possible.

    However, the piece when on to say that there are also drugs that you can give to the infant once they have HIV in their system that will prevent the infant from getting (or maybe keeping?) HIV. Is this possible? If it is, why can't you do the same for an adult?

    I hope this isn't a dumb question but it's been roaming around in my brain since I heard the piece a few weeks ago.

    --Steph (aka Nonian)

    By Anonymous Anonymous, at 4:26 PM  

  • Thank you-- that's a beautifully clear explaination! It worries me, though, that there are health teachers who don't know these things-- the general population, okay, some will always be ignorant, but health teachers really should be in possesion of the facts.


    By Anonymous Anonymous, at 12:14 PM  

  • I was just linked here from the Esoteric Science Resource Center. You've got a good writing style; just informal enough to be friendly, but not so simple that it's boring to read. It makes me reconsider whether or not to go into science journalism. Pleasantries aside, though, now that you've shown your competence comes the question. What's your opinion on endocrine-disrupting compounds and the so-called "Environmental Endocrine Hypothesis"? Is it a serious threat or just overreaction? Just curious.

    By Anonymous Brad, at 10:10 PM  

  • Hey, this was a great article. Its easy to understand which is how an article like this should be.

    By Blogger maysa, at 3:28 PM  

  • Love it. Well written, informative, entertaining. Great work, Sunil!

    I have a question, too: flu shots, worth it or not? I've always felt that even healthy people should get 'em, so as to get a nice herd effect going to protect our weaker herd-mates. However, I know a lot of people think otherwise (including your dork of a president), what say you?


    By Anonymous Anonymous, at 1:30 PM  

  • I just want to say thank you. Honestly, while I wasn't all "Don't touch me, you have AIDS" prior to reading this, I wasn't 100% clear on the facts. I appreciate that you clearly laid it all out there and in a way that makes it easy to pass on the proper information when faced with ignorance and/or misinformation. You're the bestest! Ever. So there.

    By Blogger Syd/GP, at 12:34 PM  

  • Breast Cancer charities
    Common Breast Cancer Myths

    The first myth pertaining to this disease is that it only affects women.

    Second myth that is associated with this disease is that if one has found a lump during an examination, it is cancer.

    Third is that it is solely hereditary

    The next myth associated with breast cancer is downright ridiculous. Would you believe, that in this day and age, some individuals still think that breast cancer is contagious?

    Conversely, some individuals foolishly believe that breast size determines whether or not one gets cancer.

    Finally, another myth that is associated with this disease is that it only affects older people. This is not so. Although the chance of getting breast cancer increases with age, women as young as 18 have been diagnosed with the disease.

    You can find a number of helpful informative articles on Breast Cancer charities at

    Breast Cancer charities

    By Anonymous Anonymous, at 2:55 AM  

  • Six months ago I peed in a toilet that had some mestrual period and pee, i couldn't flush, because it was broken, so I peed and I got splash a little bit, can I get aids from that?

    By Anonymous Anonymous, at 8:33 PM  

  • thank you

    By Anonymous Anonymous, at 4:27 AM  

  • Like the article says:The virus can't live on the outside word for so song.

    By Anonymous Jon, at 3:31 AM  

  • long ,i meant.

    By Anonymous Jon, at 3:32 AM  

  • I am considering living with a gay man who has hiv as flatmates. My mind is almost positive about it but I know little about him and hiv so I have had too many doubts lately. Enough too many to make my brain work overtime. I was busy googling and landed here. I like your article.

    By Blogger phry, at 1:38 AM  

  • What if a sex worker covers her mouth with the condom she used when she sneezed?? In other words she covered the sneeze with the open condom?

    By Anonymous Anonymous, at 2:19 AM  

  • So you mean to tell me i can have people with aids spit in my mouth and swallow it or spit in my food and i won't get it?!?! awesome

    But if you lied i will suuuuuue yooooou jk..

    By Blogger timm fields, at 4:18 AM  

  • I had a patient who came to me with nasolacrimal duct block and I did syringing. the mistake i did was not to wear gloves because i find it troublesome to retract the upper eyelid with it, the mistake my patient did was not tell me she was on ART for two years for HIV infection. i have cleaned all the instruments and sterilized them thoroughly, but i have two questions, 1. what are my chances of exposure? i had not cuts on my fingers but had hang nails & 2. what precautions do i need to take for her surgery, Endoscopic DCR, under General Anaesthesia?

    By Anonymous Anonymous, at 10:28 PM  

  • Hi,

    First off, I came across your site and wanted to say thanks for providing a great HIV/AIDS resource to the community.

    I thought you might find this HIV infographic interesting, as it shows detailed information about the effects of HIV in an interactive format:

    Naturally, I’d be delighted if you share this embeddable graphic on , and/or share it with your followers. Either way, keep up the great work !

    All the best,

    Nicole Lascurain | Assistant Marketing Manager
    p: 415-281-3100 | e:

    660 Third Street, San Francisco, CA 94107 | @Healthline

    By Anonymous, at 12:39 PM  

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