Diphtheria and polio are generally considered historical relics, diseases to go along with consumption as plot devices for period piece movies and historical fiction novels. For some kids, though, these bacterial menaces could become very much a part of their lives.

The reason? More and more parents are opting to not get their vaccinated, seeking exemptions from those shots required by many school districts, according to an Associated Press report.

Other diseases which are prevented by common vaccines -- which parents are foregoing in some cases -- include measles, mumps, rubella and whooping cough.

Around 1 in 20 kids entering kindergarten do not get the supposedly required vaccines, according to The AP report.

Why would parents opt to not get their children vaccinated? There are a variety of reasons, ranging from religious to health reasons.

Many of the vaccines are unnecessary and public health officials don't honestly know what the effect of giving so many vaccines to such small children really are, Jennifer Margulis, a mother and author of a book on parenting from Ashland, Ore., told the AP.

One common reason given for the past several years is the idea that vaccines can cause autism. According to a 2010 MSNBC report, one in four parents believed that there was some link between immunizing shots and autism.

The 1998 British study that linked immunizing shots and autism has since been retracted and roundly criticized, but the legacy lives on as many people continue to write about the possible connection between the two, MSNBC reported.

One doctor who has studied the effects of vaccine refusal said that every one's children could be affected by one parents choice.

Your child's risk of getting disease depends on what your neighbors do, Saad Omer, an Emory University doctor, told The AP.