Title Early Identification of Tick Species from Eschar Lesions: A Potential Strategy for Pre-Symptomatic Intervention in Tick-Borne Diseases

In endemic regions where simultaneous larval tick bites are common, early species-level information obtained from eschar lesions can meaningfully change pre-symptomatic triage. We report a 78-year-old woman found after ~24 hours of wandering with multiple clustered eschars on the legs and attached ticks on the trunk. PCR and Sanger sequencing of two removed ticks and ten representative eschars identified Amblyomma testudinarium in all samples. Because A. testudinarium is a known vector of severe fever with thrombocytopenia syndrome (SFTS) virus but not of Rickettsia japonica, we deprioritized Japanese spotted fever and focused targeted monitoring on early SFTS features. The patient remained asymptomatic and was transferred to long-term care. This case illustrates that, particularly in high-incidence settings with numerous bite sites, selective PCR of representative eschars provides a rapid and resource-sparing means to infer vector species and tailor risk assessment before symptom onset. Emphasizing eschar-based species identification in endemic areas can concentrate testing where pretest probability is highest, streamline surveillance, and support shared decision-making in frontline practice.