Pete... FWIW, the AIDS epidemic came along well after the greatest push of smallpox and polio vaccination in Africa. Hep A is spread by fecal-oral contamination (human fecal contamination of drinking water), not by dirty needles.
That's not to say that poor medical hygiene doesn't play a role. The first known Ebola outbreak WAS due to nurses in central Africa re-using non-sterilized needles/syringes, the big Zaire Ebola outbreak in 1995 was greatly amplified by non-sterile surgeries, and the current west African outbreak has been amplified by non-sterile medical procedures as well.
Doc,
Sorry, I got my Hep A and B mixed up.
Regardless, poor hygiene practices in various African vaccine programmes are now thought to have spread AIDS, plus other diseases as you noted with Ebola.
As the timeline for the emergence of HIV1 and HIV2 in Africa goes back to at least the 1950's although the "explosion" was indeed later.
There was another simian virus (SV-40)that transferred from monkeys to humans via contamination polio vaccines back in the late 150s early 1960's in the US. This same contamination has been detected in Soviet oral Polio vaccines into the late 1970's.
SV-40 is now common in humans, although is said to lie dormant. However, in other animals, its been linked to many different cancers especially in tumours, and has in fact been isolated in many human cancers.
Regardless, it was contaminated vaccine production that allowed it to jump from monkeys to humans...
Other vaccines have allegedly been contaminated with female hormones which potentially could have reduced fertility in a population of male recipients..
So while I don't buy into all the various vaccination conspiracies, vaccination programs have been far from straight forward, and their potential downsides are not always obvious or immediate..
Regards,
Peter
