Multiple cases of the measles virus have been confirmed at a South Florida elementary school, with the outbreak coming weeks after a nationwide alert went out to physicians about an uptick in cases.

A sixth case of the highly contagious virus was confirmed Tuesday evening at Manatee Bay Elementary School in Weston, just west of Fort Lauderdale, a Broward County Public Schools official said. The first case was detected on Thursday.

As preventative measures, proactive cleanings at the school continue to take place daily. In addition, over the weekend, the District conducted a deep cleaning of the school premises and replaced its air filters, John J. Sullivan, chief communications and legislative affairs officer for BCPS, which is the second largest school system in Florida, said in a statement.

Manatee Bay has nearly 1,100 students, and 86 of them are not vaccinated against measles, CBS News reported citing the school district.