A child with a terminal illness was exposed to measles while being treated at a California hospital in March, and now his mother is criticizing parents’ “irresponsible decision” to not vaccinate their child.

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Rayna Bell took her 7-year-old son, Jackson Souza, to the University of California Davis Medical Center on March 17 after he began having seizures, KTXL-TV reported.

Jackson was diagnosed with tuberous sclerosis when he was 4 months old -- a rare disease that has caused tumors to grow throughout his body. He’s been in and out of hospitals his whole life.

Days after his hospital visit in March, doctors called Bell and told her Jackson had been exposed to measles.

"When I found I felt mortified. My son's already terminal," she said. "I don’t have any area to risk any potential anything with him because I’m just, like, walking around him with a plastic bubble just trying to keep him here as long as I can."

Bell said doctors told her a child with measles had been at the hospital at the same time as Jackson -- though, at the time, doctors didn’t know the child had the measles. The child with the measles hadn’t been vaccinated against the disease, Bell said.

"Jackson was in the room, the emergency department room, where this other patient was seen," said UC Davis Health Chief of Pediatric Infectious Diseases Dr. Dean Blumberg. "It was less than an hour separation between them. So, there was potentially still measles virus in the air."

Because of the exposure, Jackson was quarantined at the hospital for 18 days. His first day home was Tuesday.

Blumberg said that even though Jackson was exposed, he doesn’t believe the boy has the measles. But Bell said she still worries.

"People making irresponsible decisions for their family and their child need to really, really look and see how that could affect other people, because I still could lose my son," Souza said.