There are several factors which determine the severity of a needlestick exposure.
The first factor is the infectivity of the source. If a patient doesn't have HIV, of course you can't get AIDS from exposure to his blood. If the patient is dying of AIDS, you would expect the infectivity of his blood to be somewhat higher. My patient, despite our best efforts, died of AIDS-related complications at age 19 the very next day after I injected his blood into my palm. His hepatitis tests were negative.
The next most important factor is the type of needle involved. Hollow bore needles are well known to be more infective than solid suture needles, presumedly because the hollow needle can hold (and transmit) more blood. Larger bore needles create bigger wounds too, so the thick pipe of a 14 gauge needle is a significantly more concerning vector than a flimsy 27 gauge.
Other factors are the location and depth of the injury. A deep needlestick into a vascular area is thought to be more infective than a superficial prick into the pad of a fingertip or the sole of a foot.
Considering all of those factors, I assessed my risk to be not much better than if I had been sharing a heroin syringe while mainlining in a back alley with this guy. Of course I scrubbed and irrigated the wound like crazy, and my palm finally stopped bleeding after I held pressure for a bit. So I went ahead and made rounds with my team for the next couple of hours, thinking about my fate instead of my patients.
After rounds, I hurried down to the ER where I was fortunate to find one of the Infectious Disease fellows moonlighting as faculty. He tried his best to reassure me that the odds were in my favor, but freaking hell, I had just been badly stuck with a dirty needle carrying the blood of a critically ill AIDS patient. Of course
I was going to take the PEP (post-exposure prophylaxis)
The research at that time was inconclusive; there just weren't enough cases of HIV conversion after needlesticks to know if PEP really helped, and there weren't any blinded placebo-controlled studies either. For all I know, there still aren't any.
The only preventive option at that time was AZT
, so I eagerly filled the prescription and started taking the medication five times per day, as directed. The GI side effects were so intolerable that I only lasted one week of the recommended six, deciding to take my chances instead. Blessedly, my wife and I had already conceived our first child less than a month before my needlestick (which was also the very first month we had stopped using contraception). Otherwise, we would have had to wait another year.
Still, it was a pretty stressful year wondering if I was going to convert, and it was probably harder for my wife than it was for me. Every kiss was subtly tainted by the spectre of AIDS hovering overhead, transforming an expression of love into a grim reminder of the dangers of this job and the fragility of our false sense of invulnerability. As I mentioned
, we sort of take AIDS for granted now, but back then it was a certain death sentence.
Fortunately, my tests came back negative, my wife delivered a healthy son, and all was well in my world....until my next HIV exposure, which was potentially even worse than this one.