Pop star Ariana Grande may have laughed after licking unpurchased doughnuts at a local doughnut shop last weekend, but to public health experts, the incident is no joke.

Grande could have spread an infectious disease to any customer who stopped in after her and ate one of the doughnuts she had licked, a state health official tells Breitbart News.

Diseases that can be transmitted through the ingestion of saliva include the basic common cold, strep throat and herpes. But other, potentially more serious diseases, including meningitis and mononucleosis, could also be contracted through eating someone else’s spit.

Wolfee Donuts in Lake Elsinore, site of the July 4 incident in which Grande and a male companion were caught on tape licking several doughnuts, was penalized Thursday by the Riverside County Department of Environmental Health. The shop’s health rating was downgraded to a “B” after an inspector determined that the shop had not adequately had “food separated and protected from contamination.”

The shop’s owner, Joe Marin, claimed that his employee had simply placed the tray of doughnuts on top of the counter while stocking the display case.

Barbara Cole, director of disease control at the California Department of Public Health, told Breitbart News that while the chance of transmission is low, an infectious disease could be spread through the consumption of a licked doughnut.

“It would depend on how much secretion is on the doughnut,” Cole told Breitbart News.

Other factors that could affect the risk of transmission include how long the doughnut remained on the tray before being consumed and how wet or dry the doughnut was after being licked. These variables would determine whether someone at the doughnut shop could have contracted hepatitis, a respiratory disease or any other illness that could be spread through saliva.

“Potentially, many communicable diseases could be transmittable through saliva,” a clinical professor at the David Geffen School of Medicine at UCLA told Breitbart News. “Bacteria and viruses have been shown to survive on inanimate objects for periods of time. For example: staphylococcus, oral herpes, and hepatitis A could all live in an environment outside the body and cause disease.”

The Riverside County Sheriff’s Office is still investigating the July 4 incident in the doughnut shop, and said it is “not clear at this time if the affected doughnuts were disposed of or sold to another patron.”

But Wolfee Donuts owner Joe Marin told Us magazine shortly after the incident that someone definitely ended up eating those doughnuts.

“I didn’t see who bought them because they were mixed [together],” Marin said. “Somewhere out there the doughnuts ended up with a customer because that night we ended up selling out.”

Grande issued a second apology for the incident in a video posted to YouTube on Thursday, but, like her first apology, did not address the doughnut-licking specifically.