Case in point: Polio is endemic in only three countries today: Afghanistan, Pakistan and Nigeria. While in Afghanistan it'd be possible for it to be down to the war, in Pakistan and Nigeria it is down to skepticism and misinformation from religious groups (often based in past experiences) that are often amongst the most important information bearers in their communities. When people don't have other sources than a government they don't trust and other biased groups giving them false information, it's no wonder many misinformation proliferate.