Your Children Mite Not be Safe at School: An Outbreak of Biting Rat Mites at a Southern California Elementary School Campus

During May, 2017, the Orange County Mosquito and Vector Control District (OCMVCD) received anonymous calls from distressed school staff and parents of children attending an elementary school (Villa Park Elementary School, VPES) in Orange County, California, about an outbreak of pruritic dermatitis that was believed to be caused by biting arthropods. The incident received intense media coverage and led to a partial closure of the campus. With no identified culprit, OCMVCD interviewed VPES staff and surveyed the school property for vertebrate pests and their ectoparasites to determine the source of the outbreak. After thorough inspections of the exterior and interior of classrooms and a carefully-placed, glue-board trap survey, OCMVCD detected signs of significant roof rat activity (feces, rub marks, and harborage sites) throughout the campus and the presence of rat mites inside multiple classrooms. OCMVCD worked with other governmental agencies (Orange County Health Care’s Environmental Health, California Department of Pesticide Regulation’s School Integrated Pest Management Program, local city officials) and the VPES administration to educate parents about the vertebrate pests on the school grounds and the complexities of controlling the rat mite infestation during the school year. OCMVCD also identified deficiencies in the school’s pest control program and developed an integrated vector management plan to address the immediate and long-term health threats to prevent rodent and rat mite outbreaks in the future. This report details the investigation and methodology used to locate and eradicate the vertebrate and ectoparasite threats on the VPES campus and the challenges encountered during the process.