Nebraska becomes ninth state with Heartland or Bourbon virus in its ticks, and there is still no...

Nebraska has become the ninth US state to detect Heartland virus, Bourbon virus or both in local ticks, and New York has reported its first human Bourbon virus infection ^[1][2][3]. Between them the two viruses have killed at least seven people in the US, and there is no commercial test for either, so a case is only found when a hospitalised patient's blood is sent to a specialised laboratory such as the Centers for Disease Control and Prevention ^[1][4].

Both viruses are carried by the lone star tick, Amblyomma americanum ^[5]. That tick was historically confined to southeastern states but has been pushing north and west, which New Scientist attributes to factors including climate change and reforestation of previously cleared land ^[6]. Heartland or Bourbon virus has now been found in lone star ticks in Missouri, Kansas, Illinois, Alabama, Georgia, New York, Pennsylvania and Virginia ^[7]; adding Nebraska makes nine ^[1][1].

The Nebraska finding came from screening more than 7000 lone star ticks collected by the state Department of Health and Human Services at multiple locations between 2022 and 2026 ^[8]. Both viruses turned up in ticks from Sarpy County, and Heartland virus in ticks from Richardson County, both in the southeast of the state, consistent with ticks arriving from neighbouring Missouri and Kansas ^[9]. No Nebraskan is known to have caught either virus, but Joseph Fauver of the University of Nebraska Medical Center says there is a "very real possibility" that infections have occurred and gone undiagnosed, because the symptoms look like other tick-borne or ordinary viral illnesses: fever, fatigue, headache, appetite loss, muscle or joint aches and nausea ^[10][11][12].

The surveillance gap is the operative problem. Only a small proportion of infected people become severely unwell ^[13], and blood samples from hundreds of people in Missouri found almost 1 per cent with neutralising antibodies to Heartland and Bourbon virus, indicating past infection ^[14]. Fauver cautions that this does not mean 1 per cent of Missourians have had these illnesses ^[15]. Against that background, more than 80 Heartland infections have been identified across central and eastern states, with at least four deaths ^[16] - a crude ratio of roughly 5 per cent among detected cases, which says more about who gets tested than about the virus ^[2].

The severe cases are what drives detection. Heartland virus was named for the Heartland Regional Medical Center in St Joseph, Missouri, where it was found in 2012 in two farmers hospitalised after tick bites; both recovered, one with fatigue and headaches lasting years ^[17][18]. The most recent Heartland death, reported last October, was a 32-year-old Connecticut woman who died of cardiac arrest after a hiking trip; an autopsy found the virus in her brain ^[19]. Bourbon virus is named for Bourbon County, Kansas, where a man who found a tick on his shoulder in 2014 died of multi-organ failure ^[20]. The New York patient, a man in his 60s bitten by multiple ticks while working outdoors on Long Island, recovered, and was identified only because his blood went to the state Department of Health ^[21][22].

Watch whether Nebraska logs a first human case now that clinicians there have a reason to ask, whether tick-positive counties move beyond the two southeastern ones, and whether any diagnostic reaches clinicians outside the referral-to-CDC pathway.