It's not a crime though-
Any more than it would be for children living in the same home to all experience a childhood disease together.
Criminal transmission of contagious disease IS a crime under some jurisdictions and circumstances.
I just did a very quick search. These first 2 links pertain to HIV and STDs. The last one is draft language from the Iowa Legislature on Senate Bill 2297, which appear to have also had a companion House bill (which gives it a better chance of passing, and indicates the seriousness and validity of the issue across parties.) The language in the bill specifies a number of communicable diseases. IDK if it became law, but there it is, and I wouldn't be surprised if other states either have laws on the books, or are considering them. My point is that it isn't 1950, when there were no effective vaccines. These "chicken pox parties" and "measles parties" are an intentional effort to spread communicable disease, which "could" be criminally prosecuted. All it takes is for one immunocompromised person to be infected, or one healthy baby who is infected and has complications, and I could easily see criminal charges applied.
Intentionally spreading communicable diseases is shocking and appalling behavior, IMO-- and I really think it does rise to the level of criminal behavior. It is not ''victimless" behavior.
And we have ALL heard about the potential for intentional spread of communicable disease as a bio-terrorist act, so this affects all of us. All it would take is a few suicide terrorists to infect themselves and become weapons, and travel to infect as many people as possible. I'm not saying the "measles party mommies" are terrorists, but the
behavior is
exactly the same-- intentional exposure and infection of themselves and/or their kids, and then intentionally moving about freely in society while contagious. The bio-terrorist tries to expose and infect as many people as possible; the "measles mommies and kids"
don't care who they expose and infect. That's reckless endangerment, IMO.
http://en.wikipedia.org/wiki/Criminal_transmission_of_HIV
http://www.ganfyd.org/index.php?title=Criminal_transmission_of_an_infectious_disease
http://coolice.legis.iowa.gov/linc/85/external/H8118_Introduced.pdf