The employee's firing comes just one day after Texas Children's Hospital said it was investigating the incident.
"We were made aware that one of our nurses posted protected health information regarding a patient on social media," the hospital said in a statement Tuesday night. "We take these matters very seriously as the privacy and well-being of our patients is always a top priority. After an internal investigation, this individual is no longer with the organization."
She allegedly wrote about the case on the "Proud Parents of Unvaccinated Children - Texas" Facebook page, which has since been deleted. A concerned parent posted screenshots of the unidentified nurse’s comments on the hospital's Facebook page late Friday.
“I think it’s easy for us nonvaxxers to make assumptions but most of us have never and will never see one of theses diseases,” the self-identified nurse wrote, according to the screenshots. "[F]or the first time in my career I saw measles this week. Actually most of my coworkers and the ER docs saw measles for the first time as well. And honestly, it was rough. The kid was super sick. Sick enough to be admitted to the ICU and he looked miserable.
“By no means have I changed my vax stance, and I never will. But I just wanted to share my experience and how much worse it was than I expected," she added.
The nurse claimed the patient had recently traveled to a region "where measles is very common" and speculated that he may have contracted the disease overseas.
Texas Children's Hospital responded to the parent’s post on Friday, confirming that it was aware of the post.
“Thank you for your post. We are aware of this situation and have started a thorough investigation.We take these matters very seriously,” the hospital wrote. It edited the statement later to add: “The views of this employee do not represent that of the organization.”
If confirmed, the toddler’s diagnosis would mark the state’s eighth measles case this year. More than 100 people have been diagnosed in the U.S. this year, according to the Centers for Disease Control and Prevention.
The hospital issued a longer statement on Monday, saying it had reached out to children who may have had contact with the infected toddler.
“A patient treated at Texas Children's Hospital West Campus tested positive for measles. This is a highly-contagious, vaccine-preventable infection. We know vaccination is the best protection against measles,” the hospital told Houston ABC station KTRK Monday. “Our Infection Control and Prevention team immediately identified other children who may have come in contact with this patient to assess their risk and provide clinical recommendations. We have contacted all of those families.”
It said the nurse in question was in good standing with the licensing board, but it would not comment on her vaccination status. The hospital says it strongly encourages all staff to obtain the recommended vaccines.
Measles, also known as rubeola, is a highly contagious virus that spreads through respiratory droplets, especially coughing and sneezing, according to medical officials. Early symptoms include a high fever, runny nose, cough and red eyes, preceded by red spots on the face.
"Measles is such a concern, because one, it's preventable. We have a vaccination that can prevent it," Dr. Umair Shah, executive director of the Harris County, Texas, Health System, told KTRK. "And two, it's so easily transmittable to someone else. ... Vaccines save lives.”
This report appeared in the Wednesday, Aug. 29, 2018, episode of ABC News' daily news podcast "Start Here."
"Start Here" is a daily ABC News podcast hosted by Brad Mielke featuring original reporting on stories that are driving the national conversation. Listen for FREE on the ABC News app, Apple Podcasts, TuneIn, Spotify, Stitcher, Google Play Music, iHeartRadio -- or ask Alexa: "Play 'Start Here.'"