PITTSBURGH — Multiple school districts around southwestern Pennsylvania are closing school campuses as more students and staff are becoming infected with the novel coronavirus. “Over the last two weeks, we’ve reported 2,000 news cases of COVID-19 among school-age children,” said Dr. Rachel Levine, Pa. Department of Health secretary. Monday night, the Baldwin-Whitehall school district announced three elementary schools will be closed for the rest of the week after a substitute teacher who had worked at each campus tested positive for the virus. In the Quaker Valley School District, 129 students and staff are in quarantine; 14 current COVID-19 cases in the middle and high school forced the district to close both schools for the next two weeks. The McKeesport School District reported six new cases in the past 24 hours among students, teachers and staff. Officials said they believe the cases are “fully contained” and that custodians are using “spray-striker machines” to disinfect all surfaces. In Westmoreland County, Hempfield, Latrobe and Norwin schools are also grappling with a spike in coronavirus cases. Latrobe has 28 current cases, and students are in classes five days a week despite the community spread entering the “significant phase” in the county. The Pa. Department of Health’s recommendation for that district is to move 100% virtual until it’s contained. Norwin reported seven new cases Monday alone among students and staff. The district is considering transitioning from hybrid to five days a week in-person instruction next month. However, some students and board members publicly said they are not comfortable with that. State officials said it has been extremely tough to pinpoint where cases are coming from. The health secretary said two out of every three people who spoke with contact tracers between Oct. 4 and Oct. 10 refused to say whether they traveled to a business or attended a mass gathering in the prior two weeks.