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.
Unfortunately, we (the global community) have failed to provide the funding for even the most basic public health measures in Africa, which would include things like public sanitation and safe drinking water, let alone autoclaves to sterilize re-usable syringes and needles and operating room equipment.
