The Baltimore Health Department is investigating a possible measles case in a 12-month-old child — which could be the first documented case in the city in the last decade.
Health officials said they were acting "out of an abundance of caution," but noted that the child might have had a reaction to a vaccine given earlier in the month.
"This is a quickly-evolving situation," city health commissioner Leana Wen said in a statement. Doctors and health staff were "working around the clock to gather further information about this case so that we can best protect the public and serve Baltimore."
A measles outbreak has been reported in California with connections to seven states and Mexico, health officials have said. But Baltimore officials said the city patient has not traveled anywhere, and has no known exposures to people who are ill.
The patient received a measles vaccine on Jan. 3, within federal recommendations for the first dose of a vaccination. On Jan. 21 the patient was taken to the emergency room at Good Samaritan Hospital with symptoms of measles.
The patient was then taken to Johns Hopkins Hospital — where lab work tested positive for the measles virus — and was discharged that day and placed in isolation at home.
The only way to determine if the patient has naturally-occurring measles or a reaction from the vaccine is a special laboratory test to determine the genetic code of the measles virus, the health department said. The patient's test sample was being sent to the federal Centers for Disease Control and Prevention, with results expected back late next week.
"This case may be a false alarm, and the child may not be infectious with measles," Wen said. "However, there is an outbreak on the west coast, and measles is common in other parts of the world. We urge that parents and caregivers ensure their children are immunized. This protects themselves and everyone around them."
Symptoms of measles include fever as high as 105, cough, runny nose, redness of eyes, and a rash that begins at the head and then spreads to the rest of the body. It can lead to inflammation of the brain, pneumonia and death.
Information from the Los Angeles Times was used in this report.