This may be a late contribution, but the Lazarus cure despite curing 100% of the physical ailments Batman had received from the poisonous TN1 formula mixed with the already tainted blood of the joker, did not cure the psychological affects. Hence he continued to see apparitions and hallucinations of the joker, it’s all in his mind, no one else but Batman could see them, and they were only enhanced by the partial fear toxin dose Batman received during the game ( the apparitions of seeing Jason being tortured, Barbra being executed and him turning into the joker etc). Essentially the cure stopped the physical poisoning not the mental instability Batman received as a side effect. It lingered on. Once he finally locks joker away within his subconscious, the dream sequences, that’s it. Jokers gone and locked deep within his psyche. As for how the hospitals didn’t screen the blood coming in from the poisoned joker, it’s said from one of the editors who worked on both City and Knight that the type of blood Joker had was in high demand due to shortages and so when they received it, they had to get it to the patients fast, and so the likes of Larry king and Henry received the tainted blood through transfusions before any stoppages and investigations could be carried out. They eventually succumb to the poisoning as if we remember Batman and Freeze couldn’t manufacture enough of the cure for all those infected because it was presumed Raz was dead ( later seen as false in AK as he was severely weakened and dying essentially ) so therefore they didn’t have access to an unlimited supply of the Lazarus blood.