Outbreak of Neisseria meningitidis Conjunctivitis in Military Trainees - Texas, February-May 2025

Viral and allergic conjunctivitis are more common than bacterial conjunctivitis in healthy immunocompetent adults. Neisseria meningitidis is an uncommon cause of bacterial conjunctivitis. During February-May 2025, an outbreak of 41 meningococcal conjunctivitis cases occurred among healthy, communally housed, military trainees at Joint Base San Antonio-Lackland in San Antonio, Texas; all had received the quadrivalent meningococcal vaccine. One patient was hospitalized with periorbital cellulitis and received intravenous antibiotics; all other patients were treated successfully with topical antibiotics. Whole genome sequencing of isolates from the first two cases suggested that the organism was unencapsulated (nongroupable) and that the cases were related. After the identification of two cases of N. meningitidis conjunctivitis among military trainees within a 3-week period in February 2025, an investigation was initiated by the base health surveillance team. Investigation of basic trainee hygiene and cleaning practices found that all protocols were followed; no source for the outbreak was found. When outbreaks of mucopurulent conjunctivitis occur in congregate living settings, culturing exudate can identify outbreak etiology, and whole genome sequencing can help guide treatment and response. Previous studies indicated that systemic antimicrobial therapy might be needed to prevent invasive infections of N. meningitidis cases; findings from this investigation suggest that nongroupable N. meningitidis conjunctivitis in otherwise healthy persons might be successfully treated with topical antimicrobials.