I don't know about Polio, but I just saw something last week where a doctor was stressing how important it is to keep your kids' immunizations up and she mentioned that they thought Measles and Whooping cough were both pretty much gone, but then people stopped getting the vaccines for them and suddenly there was another surge, so they are doing those vaccines again. I know whooping cough was bad here about 10 years ago. My son was 3 weeks old and got sick, and was coughing...I couldn't get him to eat because he kept coughing. And he had a really high fever...he was too young for the vaccine. But then, my MIL had been coughing, so we figured he got it from her, and then it turned out that her Sister-in-law had been over a week or so before and she had whooping cough, so my MIL had been exposed, which meant my 3 week old baby had been exposed as well. My nephew was 2, his doctor gave him meds as a precaution because he had been exposed, but our doctor wouldn't even take a look at DS. He just said babies get higher fevers than adults, and his cough didn't sound like a whooping cough over the phone in the background, so no, he was probably fine. DH made a nuissance of himself calling back until we got meds for both the kids. They never did test them to see if they had it, but at least we got the antibiotics. But whooping cough has certainly made the rounds here in the last 10 years. I don't know if ANY of these diseases are necessarily ever gone gone.