Evidence of Heartland and Bourbon Viruses Transmitted by Ticks in Suffolk County, New York.

A cohort of 107 subjects (2019-2024) between the ages of 20 and 93 years old with an acute febrile illness after a recent tick bite in Suffolk County, New York, was assessed for infection with Powassan, Heartland, and Bourbon viruses. The available blood samples collected from these subjects were sent to the New York State Department of Health for screening using a plaque-reduction neutralization test. Of the 107 subjects analyzed, two had neutralizing antibodies to Bourbon virus, and one had neutralizing antibodies to Heartland virus. A fourfold rise in neutralizing antibody titer in two of these patients (one Bourbon virus and one Heartland virus) indicated an acute or recent infection with these viruses. No subjects were positive for neutralizing antibodies to Powassan virus. This serologic evidence indicates that these patients were infected with emerging viral tick-borne pathogens and further highlights the need for expanded viral surveillance, clinical testing, and assay development to improve clinical decision-making and inform tick-borne disease epidemiology and vector management.