Jyana

I was in a similar situation and almost died from an infection in a tooth, and coincidentally it was last year when I was 28.

I had a wisdom tooth that never erupted that had been infected for presumably years. I felt great one day and then within 24 hours my jaw and neck had swollen out by a few inches and I was in incredible pain. The swelling put pressure in my TMJ on that side and I could only open my mouth to where my teeth were about 1/4" apart.

At the ER, they told me that the swelling could have put enough pressure on my trachea to suffocate me. Normally in this case they would do a tracheotomy, but they said that until they had the results from the scans it could be fatal because my trachea had been pushed the left by the swelling and there was a chance that they could miss. I remember those hours where any breath could have been my last and then seeing myself in a bathroom mirror and not even recognizing the face that was warped from all of the swelling. It was so surreal to experience how quickly our bodies could fall apart and confront us with our imminent mortality.

Once the scans came back, things were a little less urgent, but I had to wait in the ICU for days while they waited for the pressure in my TMJ to go down so they could open my mouth for surgery. I was pumped full of IV antibiotics the entire time, but it had little effect. They were worried that the infection could easily spread to by heart of my brain, at which point there wouldn't be much hope.

Strangely, the time in the ICU was some of most peaceful I'd ever been, even with all of the pain. Ever since, I've had a resilience to day-to-day stress and anxiety, although I've lost that sense of urgency to live to the fullest that I had right after I was released. This post gave me chills when I read the headline, and it's bringing back those feeling of just how close I came to not making it and how lucky I am to still be around.

Edit: Some sloppy wording.

This seems like a good opportunity to show off my favorite equation.

What is the probability P(n) that you'll be infected if you have unprotected sex n times? It's the same as saying the opposite of never getting infected, so it's 1 minus the probability that you don't get infected even once after n exposures.

Let p be the probability of infection on a single incident. The probability of dodging the bullet is just the product of getting lucky every time, (1-p)^n. Then,

P(n) = 1 - (1 - p)ⁿ

So if you have unprotected vaginal sex 50 times, assuming p = 0.1%, then P(50) = 1 - (1 - .001)⁵⁰ = 1 - (.999)⁵⁰ ≈ 4.9%

Here are a few others:

P(1)   =  0.1% (obviously) 
P(10)  ≈  1%
P(50)  ≈  5%
P(100) ≈  9.5%
P(200) ≈ 18%
P(500) ≈ 39%

If we solve for n, we can find out how many times before our probability of getting infected is greater than a certain percentage, say 50%. Solving for n,

n = log(1-P) / log(1-p)

So, P(n) = 50% when n ≈ 693 times.

Now things change a lot for anal sex, where p = 1%:

P(1)   =  1%
P(10)  ≈  9.5%
P(50)  ≈ 39%
P(100) ≈ 63%
P(200) ≈ 87%

And, for anal sex, the number of times before there is a 90% chance of catching HIV would be about 229.

Of course, this is all assuming the little "p"s are accurate, and even if they are, those would apply to the averages over a broad population, and there are many contributing factors that would make the numbers vary significantly by the individual person and encounter. So don't go thinking you're "probably" safe having unprotected vaginal sex 692 times because the guy on Reddit who took a Discrete Math class in college said so. Please take travis_of_the_cosmos' advice about the trigger-happy cabby to heart as well.

edit: added emphasis on the disclaimer at the end.

Do you mind it?