Bourbon Virus Cases Widen as Lone Star Tick Pushes North

Michael Larkin pulled two lone star ticks off his leg after landscaping work in Brookhaven Town, on the eastern end of Long Island. What followed was a rash, spiking fever, night sweats and headaches severe enough to put him in a hospital bed. Doctors treated him for Lyme disease with doxycycline. He did not improve. Years later, laboratory testing finally named the cause: Bourbon virus, a pathogen that had been recorded in only a handful of patients, all of them in three Midwestern states.

Stony Brook Medicine published the case in the American Journal of Tropical Medicine and Hygiene and announced the finding on July 21, 2026. It is the first confirmed Bourbon virus infection ever documented in New York State, and it landed in the middle of the heaviest tick season the Northeast has recorded in close to a decade.

Luis Marcos, professor in the departments of medicine and of microbiology and immunology at the Renaissance School of Medicine at Stony Brook University and director of the university's Tick-borne Disease Clinic, led the work. "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 are similar to other tick-borne infections," Marcos said. In the university's announcement of the findings he added that "the Bourbon virus is likely more prevalent than we think in our region." Speaking to CBS New York about the same patient, he was blunter: "this may be the very, very tip of the iceberg."

Long Island Case Redraws Bourbon Virus Map

Until the Stony Brook paper, the entire published human record of the disease ran to fewer than a dozen infections, confined to Kansas, Oklahoma and Missouri, plus a 2024 serological study in North Carolina that found antibodies without matching any of them to a diagnosed illness. Adding a New York patient moves the northern edge of confirmed human infection several hundred miles up the Atlantic seaboard.

Bourbon virus cases have killed three of the patients on record. The index patient died in Kansas in 2014. A Missouri state park official, a 58-year-old woman, died in 2017. In 2026, a lethal infection in a 63-year-old man with diabetes was reported in Kansas, the same state where the virus was first isolated. Against a denominator of only a few confirmed illnesses, that ratio says less about true lethality than about the severity threshold required to get tested at all.

The New York finding matters for a second reason. Bourbon virus was already known to be circulating in Long Island ticks. State laboratory scientists detected it there in 2021 and published the result in January 2023. What was missing was a person. The Stony Brook study supplied one, and closed the loop between a virus in the field and a virus in a patient.

Kansas Index Patient Set Grim Baseline in 2014

Bourbon virus was isolated in June 2014 from a previously healthy man over 50 years old living in Bourbon County, Kansas. According to the comprehensive review published in the January 2023 issue of Emerging Infectious Diseases, the journal of the Centers for Disease Control and Prevention, he removed an engorged tick from his shoulder and developed nonspecific symptoms within days.

Three days of worsening fever, muscle pain, joint pain and diarrhea took him to his primary care physician, who prescribed doxycycline on the reasonable assumption of a bacterial tickborne infection. He was admitted to hospital the following day with dehydration and syncope. The antibiotic continued. He did not respond. His organs began to fail and he died 11 days after his first symptom. Blood work showed depressed white blood cell and platelet counts, the leukopenia and thrombocytopenia pattern that has since become the laboratory signature of the disease.

Sequencing placed the pathogen in the genus Thogotovirus, within the family Orthomyxoviridae, the same family that contains influenza viruses. Its genome is segmented, roughly 10 to 11 kilobases of single-stranded negative-sense RNA spread across six gene segments, and its nearest known relatives are Thogoto and Dhori viruses, neither of which is native to North America.

In 2015 a resident of Payne County, Oklahoma, tested positive for antibodies after a febrile illness and recovered. In 2017 the virus killed again. Tamela Wilson, assistant superintendent at Meramec State Park in Missouri, was bitten near her home outside Sullivan, spent 24 days at Barnes-Jewish Hospital in St. Louis and died on June 23, 2017, as the St. Louis Post-Dispatch and CBS News reported at the time. Hers was the first Missouri infection, and fewer than a half-dozen Bourbon virus cases had been diagnosed nationally when she died. Researchers later used the viral strain recovered from her to screen candidate treatments.

Stony Brook Cohort Turned Up Two Antibody Signals

Marcos and colleagues were not hunting for one patient. They analyzed stored blood from 107 people who presented with fever and other signs of tick-borne illness between 2019 and 2024, then routed candidate samples to the New York State Department of Health, which holds the only regional capacity to run the neutralization assay.

Two of the 107 carried Bourbon virus neutralizing antibodies. One showed a fourfold rise in titer between paired samples, the conventional serological threshold for recent rather than historical infection. "Over a one-month period antibody titers increased eightfold," Marcos said of the confirmed case, which had required hospitalization. Researchers identified it in April 2026.

The clinical path is the detail clinicians outside the Midwest should register. Larkin, 67 when the diagnosis was announced, received doxycycline for presumed Lyme disease, which is the correct empirical choice for the bacterial infections that blacklegged and lone star ticks transmit. He was later admitted for intravenous antibiotics and supportive care. Bourbon virus is a virus and does not respond to any of it. His fever, exhaustion and headaches ground on. "I just keep feeling worse and worse," he told CBS New York, describing the stretch before anyone reached the right answer. "Three or four hours later, I would hit rock bottom and can't get off the couch."

The lag is the other striking feature. Larkin's illness began in 2021, within about five days of the tick bite, with an extreme headache, severe night sweats and a spiking fever that pushed him into emergency care. Confirmation did not come until stored serum was pulled for a research cohort and shipped to the state laboratory five years later. No surveillance system counts an infection that takes half a decade to name, and nothing in the standard workup that a Long Island emergency department runs in July would have caught it.

Serosurveys in Ticks, Deer and Blood Banks

The groundwork for the New York diagnosis was laid by field surveillance. Alan P. Dupuis II and colleagues at the New York State Department of Health, with the Suffolk County Department of Health Services, the University of Massachusetts Amherst and the SUNY Albany School of Public Health, reported Bourbon virus RNA in five pools of unengorged nymphs collected on Long Island during 2021. Three pools came from a single Smithtown site sampled on May 3, and one pool each came from two Brookhaven sites on June 9 and July 8. Infectious virus was isolated from the positive pools.

That result followed five years of negative sampling. Between 2016 and 2020 the same program tested 1,265 tick pools representing 4,189 adults, 7,227 nymphs and 97 larvae, and found nothing. The 2021 expansion covered 1,058 pools holding 4,406 adults and 9,972 nymphs from 12 Suffolk County sites. The work was supported by CDC cooperative agreement U01CK000509 and National Institutes of Health grant R01AI142572.

Deer blood told a parallel story. Of 881 white-tailed deer sampled statewide, 37.7 percent were seropositive for Bourbon virus. In Suffolk County the figure reached 66.5 percent. Elsewhere in New York the numbers collapsed: 3.8 percent in the west, 1.7 percent in the Hudson Valley, 1.2 percent in central New York. The virus, in other words, is concentrated exactly where the lone star tick is dense.

In North Carolina, a team led by Diana L. Zychowski with Gayan Bamunuarachchi, Scott P. Commins, Ross M. Boyce and Adrianus C.M. Boon screened 1,036 serum samples and reported the results in the November 2024 issue of Emerging Infectious Diseases. Four of 518 North Carolina residents with variable tick exposure, or 0.77 percent, carried neutralizing antibodies, with titers between 1:100 and 1:200. One positive came from a cohort of 162 alpha-gal syndrome patients and three from 156 heart valve recipients. The authors concluded the virus may be an underappreciated cause of vector-borne disease in the state.

Animal serology from the Midwest reinforces that the virus is broadly seeded in wildlife. Domestic dogs, eastern cottontail rabbits, horses, raccoons and white-tailed deer have all tested seropositive, with raccoons and deer most often positive, suggesting they function as amplifying hosts.

Lone Star Tick Behavior Drives Human Exposure

Amblyomma americanum, the lone star tick, is the presumed vector. Bourbon virus has been detected in all three feeding life stages, larvae, nymphs and adults, in surveyed Missouri areas, which points to transmission passing between generations of ticks rather than depending solely on infected hosts. A 2017 report in Emerging Infectious Diseases first documented the virus in field-collected Missouri ticks. A 2022 addendum recorded detection in Haemaphysalis longicornis, the Asian longhorned tick, in Virginia.

Unlike the blacklegged tick, the lone star is an aggressive host-seeker that will move toward a target rather than wait on vegetation. Its nymphs are small enough to feed for days without being noticed. CDC surveillance through 2025 lists established lone star populations across Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, New Jersey, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Virginia and West Virginia, with additional counties in Kansas, Maine, Michigan, Minnesota, Nebraska, New Hampshire, New York, Oklahoma, South Dakota, Texas, Vermont and Wisconsin. Arizona, Colorado and North Dakota have each logged at least one detection.

Exposure pressure in 2026 is high. CDC emergency department data show tick bite visits running at the highest level for this point in the year since 2017 in every US region except the South Central states. The Northeast leads at 58 visits per 100,000 emergency department visits across the season, ahead of the Midwest at 40, and the weekly figure for the Northeast peaked at 104 per 100,000 as of June 21.

Suffolk County built dedicated infrastructure for this problem before Bourbon virus entered the picture. Stony Brook Southampton Hospital opened the Northeast's first standalone tick clinic in Hampton Bays on August 14, 2023, after the county logged close to 2,700 Lyme disease cases in a single year. The center, overseen by Sharon Nachman, director of pediatric infectious diseases at Stony Brook Medicine, combines medical evaluation, laboratory testing, tick identification under microscopy and removal kits. "We are one stop shopping for all things tick," a clinic administrator told CBS New York at the opening. That referral pipeline is what produced the 107-patient sample from which the state's first Bourbon virus infection emerged.

Diagnostic Vacuum Around Bourbon Virus Cases

No commercial laboratory in the United States offers a Bourbon virus test. Suspected samples in New York go to the state health department. Nationally, testing runs through CDC, which publishes joint guidance for Heartland and Bourbon virus specimens and asks clinicians to consider the pair when a patient with recent tick exposure has fever, leukopenia and thrombocytopenia and fails to improve on doxycycline. Because no commercial assay exists, Bourbon virus cases enter the record only after a state laboratory runs a neutralization assay on paired serum samples, the procedure that took Stony Brook's cohort work to confirm a single Long Island infection.

That workflow filters out mild disease by design. A patient who recovers in a week is never tested, which is why the published Bourbon virus cases skew toward hospitalization and death and why serosurveys keep finding antibodies in people who were never diagnosed. Symptoms appear roughly two to seven days after exposure and include fever, fatigue, anorexia, nausea, vomiting, weakness, muscle and joint pain, diarrhea and a maculopapular rash. There is no vaccine, no licensed antiviral and no specific therapy. Management is supportive.

Separating Bourbon Virus, Heartland Virus and Alpha-gal

Three distinct conditions are now attributed to the same tick, and they are routinely conflated. Heartland virus disease shares the lone star vector and a similar transmission cycle, and it produces the same fever plus low white cell and platelet counts. It is further along in surveillance terms: more than 60 cases had been identified as of November 2022 across roughly 14 states in the eastern, southeastern and south-central United States, including Arkansas, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Missouri, New York, North Carolina, Oklahoma, Pennsylvania, Tennessee and Virginia. Like Bourbon virus, it has no treatment.

Alpha-gal syndrome is not an infection at all. It is an IgE-mediated allergy to a sugar molecule carried in the tick's saliva, and it leaves patients reacting to red meat and, in some cases, dairy, often hours after eating. CDC has estimated that as many as 450,000 Americans may be affected, against more than 110,000 suspected cases identified between 2010 and 2022. A CDC analysis of 3,000 residual blood donor samples collected across 10 states during 2024 and 2025 put alpha-gal IgE seroprevalence at 24.0 percent in the five highest states: Arkansas, Kentucky, Missouri, Tennessee and Virginia.

Alpha-gal is also no longer a nuisance diagnosis. In November 2025, researchers at the University of Virginia School of Medicine and Hackensack Meridian Health reported what they believe to be the first death attributed to the syndrome: a 47-year-old New Jersey airline pilot who died of anaphylaxis roughly four hours after eating a hamburger at a barbecue in September 2024. He had experienced abdominal pain, vomiting and diarrhea hours after a steak dinner two weeks earlier on a family camping trip, and had decided against seeing a doctor.

The practical distinction for a clinician is timing and test availability. Alpha-gal has a commercial IgE assay. Lyme, ehrlichiosis, anaplasmosis and babesiosis have commercial assays. Bourbon virus cases do not, which is precisely why the New York patient waited years for a name.

Antivirals With Proof Only in Mice

Therapeutic work has advanced further than diagnostics. A team at Washington University School of Medicine in St. Louis led by Jacco Boon tested favipiravir, an influenza antiviral approved in Japan but not in the United States, against Bourbon virus in mice and published the results in PLOS Pathogens in 2019. "Without the flu drug, 100 percent of the infected mice died, and with the treatment, 100 percent survived," Boon said of the work. Favipiravir prevented mortality in immunocompromised mice both as prophylaxis and when started three days after infection.

Neutralizing monoclonal antibodies have also protected mice, raising the prospect of a licensable biologic. Laboratory studies have flagged interferon alfa, ribavirin and the plant flavonoid myricetin as additional candidates. None of these has been tested in a human patient with Bourbon virus disease, and with a case count in the single digits, no conventional efficacy trial is feasible. Any future approval would have to run through an animal-rule or compassionate-use pathway, which requires a confirmed diagnosis fast enough to matter clinically, the one thing the current testing system cannot deliver.

Testing Capacity Sets the Case Count

Lone star adults and nymphs stay active into September across the mid-Atlantic and the Northeast, so exposure in Suffolk County and the surrounding region continues for several more weeks. CDC updates its emergency department tick bite tracker weekly through the season, and the Northeast figure is the number to watch as August progresses. The infected pools New York State scientists recovered in 2021 came from Smithtown and Brookhaven, both in Suffolk County, and no comparable positive pool has yet been reported west of there.

Prevention guidance has not changed and does not depend on a diagnostic test existing. Clinicians advising patients in lone star territory point to permethrin-treated clothing, full skin inspection after time outdoors, and prompt removal of attached ticks. "Ticks are very tiny. Use a bright light, mirror. Have a friend do it," Marcos told CBS New York. Because Bourbon virus has been recovered from larvae, nymphs and adults alike, a bite from a tick too small to notice carries the same theoretical risk as a bite from an engorged adult.

New York's Department of Health issues an annual tick-borne disease surveillance report; the 2025 edition documented the state's Lyme, anaplasmosis and babesiosis burden, and the 2026 edition will be the first with a confirmed human Bourbon virus infection on the books. New York City reported 2,928 preliminary Lyme cases among residents in 2025, alongside 98 babesiosis and 107 anaplasmosis reports, an indication of how much tick-borne illness passes through the region's clinics annually without any Bourbon testing.

Marcos and the North Carolina authors identified the same binding constraint: no validated assay a clinician can order directly. Stony Brook's tick-borne disease cohort keeps enrolling, and further positives drawn from it would settle whether the Long Island infection was an isolated event or the visible edge of steady transmission. Absent either, the count of Bourbon virus cases will keep measuring testing capacity rather than the number of people the virus infects.