Casual contact - why infections don't happen?
Mar 28, 2012
I' have found several contradictions in what I read about hiv and I hope you will be able to help me.. On the one hand I know that hiv cannot be transmited by casual contact. But on the other in all the books I found about HIV there is written that it can suvive outside body for few days(!) and still be able to cause an infection. The only place where I found shorter period was CDC website (several hours). You (TheBody experts) write that hiv does not live well outside the body". But what exactly does it mean? Minutes? Hours (CDC)? Days? In some posts some of TheBody experts write about minutes. I would like so much to believe in this claim but it's clearly in contradiction with other sources. Am I so unlucky with finging good/reliable booksources? I looked through many books (via google books for keywords dried blood" and hiv otside body") and many of them state that hiv can live long and doesn't loose infectivity even after drying. You write that dried blood is harmless and direct, immidiate contact is required for an infection. What's more you can find information that even unvisible amount of blood is enough to cause infction - and you are telling that "sufficient" amount is needed. What does it meen "sufficient"? I called hiv hotline in my country and they told me that although hiv can live longer (few days outside body), it's not so important, since it's hard to get infection by casual contact. But I'm still worried :( When you live with someone you often have contact with body fluids (menstrual blood in the toilet, semen on sheets etc.) and the skin of most of us is very often not so intact (broken pimples, cuts, scratches, rush after shaving). So why these infecions don't happen? Maybe you write that hiv dies quickly outside the body (despite it isn't true) because it's not the way hiv is usually transmitted and you don't want to scare anyone? I would like to belive that you cannot get HIV from casual contact, by I must know why? What is the justification for this claim? What is the true about survival/drying/minimal amount of infected blood/semen?
Some more detailed questions: 1. Can dried blood/semen cause an infecion? (why/why not) 2. What is estimated hiv survival time in room tempreture for a drop of blood of avrage viral load (minutes?hours?days?) 3. Is the survival time in semen lower than in blood? 4. I found information that 0,1 ml is estimated minimum volume of blood to cause infection, but i couldn't find any support for this claim. Is it true? Is it possible to get infection from UNVISIBLE amount of blood/semen? How much blood/semen is "sufficient" amount. 5. Why syrgine used one day after somebody is more dangerous than for example popping pimple with hands in someone's blood/semen? (I found such answer on your site) 6.why when you masturbate someone and then, after a while with the same hand (with some fluids/fluids residue on it) mastrubate yourself, or cut yourself on this hand - you can't get infected? (You are saying that it is indirect contact - but that'd definitely contact with infected fluid - i don't unterstand that)
Sorry that the email is so long - but I really want to unterstandt this stuff.I would be really greatful for an answer, because I've got this strange feeling that the more I read the less I know for sure.
Response from Dr. Wohl
This question has been answered before on this forum. To sum up, detecting virus on a surface does not mean that this virus poses a risk. There are hucksters who can correctly claim that our kitchens are awash in salmonella and E. coli and thus we should by their cutting boards, soaps and sterilizers. But there is the issue of inoculum. A few germs here and there at low concentration does not make us sick. You need a minimally infective dose of a germ in order to establish infection.
The die off rate for a virus like HIV that evolved to live in a nice warm T-cell after being left out on the cold bright world of a toilet seat or dildo surface, is huge. Can some fancy pants virologist find some viral RNA or even viable virus after awhile on these surfaces? Sure, but that does not mean there is anywhere near enough virus to infect some one. And, infection is the issue.
So, fret no more. THe books are right. HIV can live for a time outside the body, especially in wet dark bloody substances. But, the amount of virus that remains quickly falls well below the threshold for infecting people. DW
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