A virus doctors can't easily test for and can't yet treat has been detected in Tennessee, carried by the same Lone Star ticks already swarming the state's fields and forests this summer. Bourbon virus is exceedingly rare, but it has a history of turning deadly, and its arrival lands squarely in the middle of what may be Tennessee's worst tick season yet.
The connection between Bourbon virus and Lone Star ticks in Tennessee was reported by the Knoxville News Sentinel, whose coverage notes the virus infection can include fever and fatigue, and that there is currently no commercial test or approved treatment for it. That lack of a quick diagnostic path is not a local gap — it reflects a nationwide reality. According to the CDC, no commercially available diagnostic test for Bourbon virus exists anywhere in the United States, meaning healthcare providers with a suspected case must coordinate through state health departments to send patient blood samples to the CDC Arbovirus Diagnostic Laboratory for specialized PCR and serologic testing.
The virus itself is not new to science, even if it is new to Tennessee's tick population. Bourbon virus was first identified in June 2014 in a patient from Bourbon County, Kansas, who died from a severe febrile illness — a case that made it the first member of the Thogotovirus genus known to cause human illness anywhere in the Western Hemisphere, per the CDC. It was only isolated after lab tests ruled out other, more familiar tickborne diseases.
Why Doctors Can't Just Reach for Antibiotics
One of the trickiest parts of Bourbon virus for clinicians is that it can look, at first glance, like more common bacterial tickborne illnesses. But standard antibiotics such as doxycycline do nothing against a virus, and the CDC notes that lab findings in confirmed cases consistently show leukopenia, or abnormally low white blood cell counts, along with thrombocytopenia, or low platelet counts — patterns that help distinguish it from non-viral tickborne infections.
The stakes of getting that distinction right are high. Fewer than 10 confirmed human cases of Bourbon virus disease have been reported nationwide since 2014, according to GIDEON Informatics, but several of those confirmed cases resulted in multi-organ failure and death. Cases have so far been documented primarily in Kansas, Oklahoma, Missouri, New York, and North Carolina. On the treatment front, preclinical research published in PLOS Pathogens in 2019 and the Journal of Virology in 2025 found that experimental antiviral drugs, including favipiravir and molnupiravir, effectively inhibited Bourbon virus replication and prevented fatal outcomes in laboratory mice — though favipiravir is approved for influenza use in Japan, not in the United States, and neither drug is an approved human treatment for the virus.
One Tick, Many Threats
The Lone Star tick, the primary vector for Bourbon virus, is something of a one-species health hazard. Per the Cleveland Clinic, it also transmits Heartland virus, Ehrlichiosis, Southern Tick-Associated Rash Illness, and Tularemia, and it can trigger Alpha-gal syndrome, the red-meat allergy that has drawn its own headlines this year. Female adults of the species are recognizable by a distinctive white spot on their backs.
There is at least one piece of good news buried in the tick biology. Research led by University of Tennessee entomologists established that Lone Star ticks do not transmit Lyme disease, according to ScienceDaily, because antibacterial compounds in the tick's saliva actively destroy the Borrelia burgdorferi bacteria responsible for that illness. Lyme disease in the region is instead spread primarily by blacklegged deer ticks.
A Tick Season Already Straining Tennessee
None of this is happening in isolation. Emergency medicine physicians at Vanderbilt Health reported treating a steady, month-over-month increase in tick-bite patients throughout the summer as outdoor recreation and temperatures climbed across Middle Tennessee, with six medically important tick species now active statewide. Back in June, the University of Tennessee Extension put farmers on high alert after dense tick infestations spiked across pastures and tree lines, driven by a warm, wet spring that accelerated tick reproduction and threatened livestock with anemia and worse.
The surge is not confined to Tennessee. Epidemiological studies compiled by PMC show Lone Star ticks are expanding their range further north and east out of their traditional southern strongholds, pushed along by suburban sprawl, growing white-tailed deer herds, and warming seasonal temperatures — with tick encounters nationally peaking between April and July. Because there is no vaccine, no approved antiviral, and no walk-in test for Bourbon virus, prevention remains the primary defense for anyone spending time outdoors in Tennessee this season.
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