New York has recorded its first confirmed case of Bourbon virus, a rare and potentially deadly tick-borne infection that can resemble Lyme disease and other more familiar illnesses, raising concerns that additional cases may be going undiagnosed.
The case was identified by researchers at Stony Brook Medicine after analyzing blood samples from 107 people in Suffolk County who developed acute fever after a recent tick bite between 2019 and 2024.
Two patients had antibodies that neutralized Bourbon virus, and one showed a fourfold rise in antibody levels, indicating an acute or recent infection.
A Virus That Can Look Like Lyme Disease
Bourbon virus was first identified in 2014 in Bourbon County, Kansas. It is believed to spread through bites from infected ticks and has no vaccine or specific antiviral treatment.
The infection can cause fever, fatigue, rash, headache, body aches, and nausea. Those symptoms overlap with several other tick-borne diseases, creating a diagnostic challenge for doctors who may not immediately suspect such a rare virus.
Luis Marcos, a professor at Stony Brook University's Renaissance School of Medicine and director of its Tick-borne Disease Clinic, said the region's tick population could mean the virus is more widespread than current case numbers suggest.
"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," Marcos said.
"For these reasons, the Bourbon virus is likely more prevalent than we think in our region and other cases are likely not being diagnosed."
The concern is particularly significant because there is currently no commercial test specifically available to confirm Bourbon virus infection. In New York, suspected samples must be sent to the state Department of Health for analysis.
'The Patient Had Shown Some Very Severe Symptoms'
The New York case also illustrates how difficult the infection can be to recognize.
According to Stony Brook researchers, the patient was initially diagnosed with Lyme disease and treated with doxycycline, a commonly used antibiotic for bacterial tick-borne infections. However, the patient did not improve and experienced symptoms including fatigue and severe headaches.
"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," Marcos said.
Unlike Lyme disease, Bourbon virus is caused by a virus, meaning antibiotics such as doxycycline are not expected to directly treat the infection.
The virus has also been linked to fatal illness. A 2014 case in Kansas resulted in a patient's death, while researchers noted another fatal case occurred in 2026.
Researchers Are Watching the Lone Star Tick
The lone star tick can transmit multiple pathogens and is established across parts of the Northeast. It is also associated with ehrlichiosis, tularemia, and alpha-gal syndrome, an allergy to certain mammalian meats.
Researchers say the overlap between symptoms caused by these conditions could make rare viral infections difficult to identify without specialized testing.
The study's findings point to a broader need for surveillance and better diagnostic tools as tick-borne diseases continue to pose challenges for clinicians.
The researchers said their work "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."
Marcos said identifying the virus is an essential first step toward developing better ways to diagnose and treat it.
"Without identifying the cause of an infection, the chances of developing accurate diagnostic tests or effective treatments are minimal," he said. "That is why it is so important to first understand the true impact of the virus in high-risk areas."
For people spending time outdoors, the discovery is another reminder of the importance of preventing tick bites and seeking medical attention if unexplained fever, rash, severe headache, or other symptoms develop after possible tick exposure.
