<i>Notes from the Field</i>: School-Based Surveillance of <i>Mycoplasma pneumoniae</i> Trends and Impact on School Attendance by Students and Staff Members — Missouri, Fall 2024

Acute respiratory illnesses (ARIs) occur frequently in school students and staff members.These infections are mostly caused by respiratory viruses; however, some are caused by bacteria, including Mycoplasma pneumoniae.Primarily affecting young adults and school-aged children, M. pneumoniae typically causes mild upper respiratory infections, but can progress to a pneumonia commonly known as "walking pneumonia" (1).Currently, no vaccine is available to prevent M. pneumoniae infection.After a period of low incidence during the COVID-19 pandemic, M. pneumoniae incidence increased in 2023.*Since spring 2024, CDC has reported increasing M. pneumoniae diagnoses in U.S. emergency departments, especially among children and adolescents (2).This report describes recent trends in M. pneumoniae activity observed in a school-based ARI surveillance program, including macrolide resistance in positive specimens.Macrolide resistance in M. pneumoniae infections might limit treatment options, potentially worsen patient outcomes, and facilitate the spread of resistant strains in community settings (3).This activity was reviewed by Children's Mercy Hospital and CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy. * The number of M. pneumoniae infections has varied over time, and infections might occur more frequently in summer and early fall.Cyclical peaks have been noted to occur every 3-7 years.