Powassan virus (POW) has been detected in a Maine resident in Hancock County and West Nile Virus has been detected in a bird in York County. These are both the first detections of those infections in Maine in 2025. The Maine CDC is sending this Health Alert Network (HAN) Health Advisory to alert clinicians to local arboviral disease activity and to remind clinicians to consider testing for mosquito-borne and tickborne arboviruses in patients with unexplained fever, meningitis, or encephalitis, particularly among persons with outdoor exposure or recent travel to areas with known arboviral transmission.