Measles has been confirmed at a school in Allegheny County, the Pittsburgh Post-Gazette reports, as the county health department logged a second case of the virus. The new case marks the outbreak's spread into a school setting, according to the Post-Gazette.
The Pennsylvania outbreak is now the largest recorded in the United States in 35 years, the Wall Street Journal reports. Nationwide, measles cases have passed 4,000, well above last year's total, according to CBS News, citing the CDC.
The scale of the outbreak has changed daily practice for some clinicians. A pediatrician at Penn State Health told the Pittsburgh Post-Gazette that he had never expected to encounter measles in his career and now treats it routinely.
Allegheny County health officials confirmed the second local case, WTAE reports. The Post-Gazette's reporting on the school case followed that confirmation.
The figures cited by CBS News and the Wall Street Journal indicate that the current national count has already exceeded the total recorded during the previous year, a threshold the CDC tracks as part of its routine measles surveillance.
What to watch next: whether Allegheny County health officials identify additional linked cases or issue new exposure notices for schools and other sites.
