Beyond Koplik spots: aphthous-like ulcers as a novel enanthem in adolescent and adult measles.

OBJECTIVES: Measles is re-emerging in adolescents and adults, yet its oral phenotype beyond Koplik spots is poorly characterised. We describe the oral mucosal manifestations of confirmed measles in this group, focusing on aphthous-like ulcers, a less characterised enanthem of measles. METHODS: In a prospective observational cohort at a tertiary centre in Kerala, India (June 2024 to June 2026), patients aged 12 years or older with acute fever and generalised rash were enrolled consecutively; those with measles confirmed by IgM ELISA and/or nasopharyngeal RT-PCR are reported. The oral cavity was examined systematically; ulcer-base swabs were obtained where feasible and one ulcer was biopsied. RESULTS: Of 307 patients with fever and rash, 31 had confirmed measles (median age 26 years; 30 of 31 vaccinated, 22 of them with a single infant dose). Any oral mucosal finding occurred in 21 of 31 (67.7%). Aphthous-like ulcers occurred in 11 of 31 (35.5%), spanned illness days 3 to 8, and outlasted Koplik spots (13 of 31, 41.9%), which were associated with earlier presentation (median day 4 versus 6, p=0.001). Ulcer-base swabs, obtained in three patients, were measles RT-PCR-positive in all three and negative for herpes simplex virus 1/2, enteroviruses, cytomegalovirus, Epstein-Barr virus and varicella-zoster virus; biopsy showed non-specific aphthous morphology. CONCLUSIONS: Aphthous-like oral ulcers are a frequent enanthem of measles that outlasts the Koplik window and warrants active recognition and prompt measles testing.