A mysterious tick-borne virus may already be spreading unnoticed in the Northeast.
Researchers have confirmed New York State’s first case of Bourbon virus, a rare and potentially severe infection carried by lone star ticks. The discovery on Long Island raises concerns that additional cases may have been mistaken for more familiar tick-borne illnesses, especially because the symptoms overlap and no widely available diagnostic test exists.
The findings, led by Stony Brook Medicine and published in the American Journal of Tropical Medicine and Hygiene, suggest that the virus could be more established in the region than current case numbers indicate.
Bourbon virus was first identified in Bourbon County, Kansas, in 2014. Since then, only a small number of infections have been documented, primarily in the central United States. However, the lone star tick has expanded into much of the Northeast, creating new opportunities for the virus to spread.
Unlike many bacterial infections transmitted by ticks, Bourbon virus does not respond to antibiotics. There is also no vaccine or specific antiviral treatment. Patients may develop fever, extreme fatigue, headaches, body aches, nausea, and a rash.
Those broad symptoms make the infection difficult to distinguish from other tick-related illnesses.
Why Bourbon Virus May Be Missed
The lone star tick can transmit ehrlichiosis and tularemia and is also linked to Alpha-Gal Syndrome, an immune reaction that can cause an allergy to red meat. Doctors often consider these better-known conditions when a patient becomes sick after a tick bite. Bourbon virus may be missed because most clinicians have never encountered it and cannot order a standard commercial test to confirm the diagnosis.
“There are a lot of lone star ticks in New York and in the Northeast; we have dense populations, and when someone is infected with Bourbon virus symptoms, they are similar to other tick-borne infections,” says Luis Marcos, MD, lead author, a professor in the Departments of Medicine and Microbiology and Immunology at the Renaissance School of Medicine (RSOM) at Stony Brook University, and director of the Tick-borne Disease Clinic. “For these reasons, the Bourbon virus is likely more prevalent than we think in our region, and other cases are likely not being diagnosed.”
Suspected samples in New York must be sent to the NYS Department of Health for specialized analysis. That extra hurdle, combined with limited awareness of the virus, may allow infections to go undetected.
Blood Tests Reveal a Recent Infection
Marcos and his colleagues identified the state’s first confirmed case in April 2026 while analyzing blood from 107 patients who had experienced fever and other signs of tick-borne illness between 2019 and 2024.
Two people had neutralizing antibodies against the Bourbon virus, showing that their immune systems had encountered it. One patient experienced a fourfold increase in antibody levels, evidence of an acute or recent infection. Over one month, the patient’s antibody levels ultimately rose eightfold.
“This one case certainly was the Bourbon virus, and over a one-month period, antibody titers increased eightfold. The patient had shown some very severe symptoms and was hospitalized,” summarizes Dr. Marcos.
When Lyme Treatment Does Not Work
The patient’s illness initially resembled Lyme disease. Doctors prescribed doxycycline, the antibiotic commonly used to treat Lyme and several other bacterial tick-borne infections, but the patient’s severe headaches, fatigue, and other symptoms did not improve.
That lack of response can be an important warning sign. Antibiotics target bacteria, not viruses, meaning standard treatment for a suspected bacterial tick infection would not stop the Bourbon virus.
Although infections remain rare, the disease can be serious. The first identified case in Kansas in 2014 was fatal, and another death linked to the virus was reported in 2026.
Better Surveillance and Testing Needed
Marcos and his co-authors said the findings “highlight 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.”
He added, “Without identifying the cause of an infection, the chances of developing accurate diagnostic tests or effective treatments are minimal. That is why it is so important to first understand the true impact of the virus in high-risk areas.”
Reference: “Evidence of Heartland and Bourbon Viruses Transmitted by Ticks in Suffolk County, New York” by Victoria A. Bateman, Rudline G. Zamor, Brigitte Maczaj, Angelina Blyufer, Charles Kyriakos Vorkas, Alexander T. Ciota, Alan P. Dupuis II and Luis A. Marcos, 12 May 2026, The American Journal of Tropical Medicine and Hygiene.
DOI: 10.4269/ajtmh.26-0012
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