Heartland Virus Disease in the United States, 2018–2024

ABSTRACT. Heartland virus (HRTV), a tick-borne virus, was first discovered as a cause of human disease in Missouri in 2011. Heartland virus disease presents similarly to other tick-borne infectious diseases, with acute febrile illness accompanied by thrombocytopenia, leukopenia, and elevated liver enzymes. In 2018, diagnostic testing for HTRV disease by reverse transcriptase polymerase chain reaction, IgM microsphere immunosorbent assay, and plaque reduction neutralization test became routinely available at the CDC. We describe the demographics and geographic distribution of patients tested for evidence of HRTV disease, and we note the clinical outcomes of patients with HRTV disease identified during 2018–2024. Of 279 patients tested, we identified 38 patients with laboratory evidence of HRTV disease (median of 5 patients per year). Patients resided in 13 states located in the eastern, southeastern, and central United States. All patients were ages 50 years old and older, 29 (76%) were male, and most ( n = 36; 95%) had illness onset during April to September. Among patients with HRTV disease, 92% were hospitalized, and 13% died. Compared with patients with no evidence of HRTV disease, HRTV disease patients were older (median age = 68 versus 51 years old, P <0.05) and more limited in their geographic distribution. Through routine diagnostic testing, the number of HRTV disease cases identified in the United States has more than doubled, but the disease remains relatively uncommon. Continued surveillance and increased awareness among clinicians and public health officials can help improve understanding of the epidemiology and public health burden of HRTV disease.