Recent rumors of "measles parties" in northern California have prompted concern among parents nationally and locally.

The fears are unfounded, as there isn’t proof that such parties existed and many reports appear to have all relied on a single mother’s account in Marin County, near San Francisco.

California Department of Public Health spokesperson Anita Gore told TODAY.com there is no “information to share about the existence or frequency of [measles] parties.” But, the CDPH strongly recommends against the intentional exposure of children to measles under circumstances, Gore said.

Experts agree that an event where unvaccinated kids are exposed to measles in order to build their immunity is a terrible idea. Measles kills more than 140,000 people a year globally, according to the World Health Organization and is so contagious that if one person has it, 90 percent of the people close to that individual, who are not immune, will become infected with the virus.

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The measles party rumors started when California public news outlet KQED quoted a Marin County mother of two unvaccinated kids as saying she was approached by a friend who offered to set up a play date with a child who has measles. But the mom, Julie Schiffman, told KQED, “I would never do that to my child.”

Schiffman told TODAY.com that, to her knowledge, there were no measles parties or play dates that had occurred or were planned for the future. Schiffman’s two sons, age 5 and 8, are unvaccinated on the advice of her doctor because of the family’s medical history.

According to Schiffman, the current measles parties rumors have all been based on a casual remark she posted in a private Facebook group and then repeated to KQED.

“Someone asked me in passing if I wanted to expose my kids because she knew a family who had measles,” Schiffman wrote in an email to TODAY. But, she added, the friend — who vaccinates her own kids — hadn’t even asked the family of the infected child if they would be willing to host an unvaccinated kid in their home.

The concept of “natural immunity” parties isn’t new and could be why rumors of measles parties struck a public nerve.

In recent years, parents throwing “chicken pox parties” have been reported in New York and Seattle, for example, as a way of exposing unvaccinated children to the disease without having to give a child the chickenpox vaccine.

Parents who either wanted to get chicken pox “over with” or who believe the vaccine comes with health risks intentionally exposed their kid to the disease, as they called it, “the natural way.”

But even a "measles playdate" could bring significant health risk to an unvaccinated child, as the virus can cause severe complications, especially for those under five, according to the Centers for Disease Control and Prevention.

This article was originally published Feb. 10, 2015 at 7:49 p.m. ET.