I didn't know this. Could you explain the reason?
Merely exposing someone to a virus does not necessarily result in widespread infection. A low enough number of copies could be neutralized by the host's immune response before it has a chance to spread significantly. How low this number is depends on the virus. For example, COVID-19 load is higher in symptomatic patients.
Chronic viral infections are managed by reducing as much as possible the number of viral copies in circulation. Risk of transmission is mitigated when number of copies is low enough. There are studies showing risk of HIV transmission approaches zero when HIV load < 200 copies/ml. Ideal would be HIV load < 50 copies/ml or undetectable.
https://en.wikipedia.org/wiki/Viral_load
https://en.wikipedia.org/wiki/Minimal_infective_dose
https://www.virology.ws/2011/01/21/are-all-virus-particles-i...
https://royalsocietypublishing.org/doi/10.1098/rspb.2009.006...
https://www.cdc.gov/hiv/basics/livingwithhiv/protecting-othe... https://www.nejm.org/doi/full/10.1056/NEJMoa1600693#t=articl... https://pubmed.ncbi.nlm.nih.gov/27404185/
You don’t need to be a 100% sure. Once the risk becomes small enough you can spend your time worrying about other risks.
Hell, an HIV viron could be created spontaneously through quantum tunneling in your body with some non-zero probability. I think it would be legitimate to triple equal signs that to "not going to happen" though.
Time spent driving is not time spent having sex (well, hopefully).
So if risk(dying while driving) ~ risk(dying because of sex) ~ 0, you can easily ignore both of those.
Also, you can avoid having sex with a HIV-positive person. You can probably not avoid driving. So the fact that a risk may be low is not sufficient to take such risk if you can hedge against it.
Meanwhile doing some once a day with a 1 in 1,000,000,000 chance of possibility killing you in 40 years just isn’t worth considering.
Depends what your quality lifespan is. If I get sick of everything, that time isn't worth much.
There's also a "time-value" of life.
Cool stuff I can do today may be worth a lot more to me than things I can do 500B years from now. Especially since the person that would be doing them is someone I cannot identify with at all.
Yes, and I believe this is a reason why people make choices that adversely affect their 50 year old self. Who's that guy in the future going to be? Why should I care about making it better for him?
I can imagine time scales on a par with how long I've lived and to a lesser extent to the ages of people I identify with.
(500 year from now me would see the first paragraph as exceptionally foolish... and also inevitable. But that fact doesn't change the truth of what I'm saying).
The vast majority of virions seems to be killed by the immune system before they can actually take hold.
https://journals.plos.org/plospathogens/article?id=10.1371/j...
Some Sex lubes can make it easier for infections to get into the body. https://en.wikipedia.org/wiki/Personal_lubricant#Water-based
Thing is I wonder if a higher vitamin A and zinc intake can help because all epithelial cells need retinol (vitamin A), zinc is needed to move retinol around the body as Retinol Binding Protein (RBP) for epithelial cells. Alcohol can reduce fat soluble vitamins stored in the liver which can then reduce the VitA stored in the liver, you see this most easily with alcoholics and hypovitaminosis A, but even short term binge drinking can reduce levels enough to increase risks of transmission which probably explains man flu!
I found a cadaver study where they measured vitA content in the livers of dead people but didnt say how they died, knowing that you can die from ingesting too much vitA in one go like some arctic explorers did when eating polar bear livers decades ago and died. In order to get the highest amounts of vitA seen in some of these cadavers, you'd have to consume 30,000ui of VitA every day for at least a year without your body using any! Thats a lot of Vit A!!!
Anyone who paid attention to the Ebola outbreak in Africa a few years back, may remember that some viruses like Ebola can hide in parts of the body where the immune system can not go, namely the eyes and the testes and sometimes the brain, so they may have remembered that blokes testing negative for Ebola but previously had it, could still be passing it on through semen.
The thing with HIV, its typically passed through anal intercourse, not vaginal where there is sufficient lubrication, but its passed more frequently in Africa because they have a tendancy to have dry vaginal intercourse, because they actually try to reduce the wetness of the vagina which then creates microtears and sores and then its easy for HIV to get into the bloodstream, just like cuts and sores in the mouth also making it easy for HIV to get into the blood.
The whole 80's govt advice/warnings on HIV were directed at everyone because they didnt want to stigmatise those engaging in non vaginal intercourse.
The biggest risk from HIV is getting it into the blood, like most things which are pathogenic.
Now you can still have a highly effective immune system which can lock down viruses, but there is always the risk it gets into those parts of a body where the immune system cant go and I dont know what they test now a days.
Gay people were so stigmatized at the time that the government did nothing when they thought it was a 'gay disease'; they just let an epidemic spread and people die. Very few in the 1980s worried about offending gay people. Once it was spreading to people who weren't gay, then I'm sure health information was provided to those people.
But I just have to laugh out loud at the thought of governments in the 80s not stigmatizing the disease and specifically queer people having anal sex.
Just so laughably the opposite of the real experience of an entire lost generation of gay men.
There's no excuse for it in todays day and age, but what can you do? I sometimes think democracy is a soap opera for serious people, whilst the military run the real show.
There was a thing not long ago where talcum powder, I think Johnson & Johnson, had some asbestos contamination (asbestos being another mineral that can come from the same mines, apparently). And people were suing because it gave them cancer of the uterus and other internal parts of the female reproductive system. Which makes you go: Wait a second. How the hell does that happen?
That's how.
When I first heard about asbestos in children talc powder, I simply thought it was just one of these "bad pharma" conspiracy theories (there was another one - about asbestos in sanitary towels). It seemed so far-fetched - who in their right mind wouldn't make sure to thoroughly check a product designed to have long-term contact with babies' skin against well-known carcinogenic substance? Well, it turns out this time it happened not in China but right in the heart of the USA.
You might find this interesting, the "few years back" might be now again: https://www.nature.com/articles/s41586-021-03901-9
I think this Hollywood film Dont Look Up will be a poignant message to everyone.
I would not use Wikipedia for health information with serious consequences.
I mean, technically, there's always a possibility of getting HIV. Particles in your body could spontaneously quantum tunnel at the same time into the form of an HIV virus. This is basically impossible, but not actually (p = 0.00) impossible.
At some point you have to look at a probability and say - that's basically not transmissible.
You generally can't measure infectious dose directly without a highly unethical challenge study. You can sometimes know concentrations that did or didn't result in infection in various real world scenarios, and sometimes you have circumstantial evidence (e.g. you can know how much virus a person sheds, and what proportion of a room with certain ventilation quantities got infected).
Infection requires virus particles to be physically present in transmission vectors (fluids, droplets, etc). There's generally also a dose-response effect where more particles means more chance of evading the immune system well enough to establish replication in the victim.
So a lack of anything to detect, means a lack of anything to spread an infection.
One should add that for that the threshold for detection has to be lower than the threshold for infection.
Example: let the detection threshold be 10 particles/ml and the infection threshold be 100 particles/ml (*) -> then undetectable implies that it is very improbable that an infection will take place.
(*) This is a very crude description. Think of it like this: Every single virion (virus particle) has a very low probability of causing an infection itself but there is a high number of them and for one them it might just work out (higher viral load -> higher risk of successful infection)
This statement is logical and makes perfect sense - but it's narrower than the original one.
We're quite good at detecting viruses if we really want to. PCR can amplify DNA so much that we can detect even 50 viruses per milliliter of blood. A milliliter seems like actually a lot of blood to get into someone else and your innate immune system is capable of finding and neutralizing small amounts of contagions relatively well even if it's never seen it before. I do suspect this is a statistical impossibility though probably you could somehow get incredibly unlucky, for example in your blood momentarily all the free floating viruses end up in the same bit of blood and that somehow gets into someone else, but I think we can all realize that probability is tiny and in practice I don't think there are any examples of transmission with undetectable levels of HIV.
1 cm^3 is indeed pretty big. That’s 1,000 little millimetre cubes, and we can detect as few as 50 virions in that space!
I will point out though that 1 ml is low for semen (more like 2.5 ml or more).
Think of it like chemistry. Sure, two covalently bonded hydrogen atoms at STP could have nuclei 1cm from each other due to random chance. However, the probability of this happening is so low that it is effectively 0.
If one bounds the risk from HIV from an undetectable partner to an unmeasurably small epsilon, dwarfed by other risks by many orders of magnitude--- the edges where the assertion are false don't matter.