A quarantine order was issued Thursday for hundreds of students and staff at two Los Angeles universities who may have been exposed to measles and either have not been vaccinated or can't verify that they have immunity. (Damian Dovarganes/AP)

Hundreds of students, staff and faculty at two Los Angeles universities have been quarantined because they may have been exposed to measles, according to Los Angeles County health officials, the latest development in a resurgence of the highly contagious disease that was declared eliminated in 2000.

Officials at California State University at Los Angeles alerted its students and staff that the exposure may have occurred at a campus library on April 11 from 11 a.m. to 3 p.m. Those at the library during that time were asked to provide immunization records or be checked for immunity at the health center, the university said in a statement Thursday.

As of Friday afternoon, the university said 550 students and 106 staff members have been instructed to stay at home and avoid contact with others under quarantine orders, according to the university. An additional 110 students and 21 staff have been cleared, the school said.

The University of California at Los Angeles also warned students and staff of potential exposure, saying Thursday that a student infected with measles attended classes at two campus buildings on April 2, 4 and 9. He did not enter any other buildings while on campus, but the school determined that more than 500 students and staff may have been exposed or come into contact with the sick student.

The school said that one student was still quarantined on campus on Friday, with “fewer than 50 students and faculty members” asked to stay at their off-campus residences because they have not yet confirmed their immunizations.

Quarantined students and staff are asked to notify the department if they develop symptoms, the Los Angeles County Department of Public Health said in a statement.

The quarantines could last for up to 21 days, the department said. The announcement comes just days after public health officials declared a measles outbreak in the county. The quarantine is one of the largest in the state’s history, according to the Los Angeles Times.

[How does measles spread? Do I need another MMR vaccine shot? How dangerous is measles? FAQ on the outbreaks.]

The orders come amid a surge of measles outbreaks across the country — a reported 695 cases overall spanning 22 states — the highest number in a single year since the disease was declared eliminated in 2000, the Centers for Disease Control and Prevention reported Wednesday.

In a statement late Wednesday, Health and Human Services Secretary Alex Azar said the United States is seeing “a resurgence of measles, a disease that had once been effectively eliminated from our country. . . . Measles is not a harmless childhood illness, but a highly contagious, potentially life-threatening disease.”

The CDC cited misinformation about the safety of the measles vaccine as a contributing factor to the uptick in places such as New York. However, the Los Angeles Times notes that high vaccination rates in California have prevented small outbreaks from proliferating.

Lena H. Sun contributed to this report.

This story has been updated.

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