Tick-borne arboviruses: Evidence and awareness of Heartland, Bourbon, and Powassan viruses circulating in Virginia

Ticks are expanding both in population-size and geographical range. They are also biological vectors for a range of pathogens, including viruses. Powassan virus (family Flaviviridae), Bourbon virus (family Orthomyxoviridae), and Heartland virus (family Phenuiviridae) are rare but serious emerging arboviruses concerning public health, with potential for fatal illness or neurological sequelae. Bourbon and Heartland virus, transmitted by Amblyomma americanum (lone-star tick) were only primarily described in the last 15 years. Powassan virus, vectored by Ixodes scapularis (black-legged tick), first isolated 1958, is endemic in parts of northeastern USA. Little was known about tick-virus presence in Virginia, with a single clinical case each of Powassan(2009) and Heartland virus(2021) recorded.  Here we present data on tick species in Southwest Virginia, wildlife and livestock surveillance across western Virginia, and evidence that all three tick-borne viruses are circulating broadly in the region. Together, the studies uncover insights into the ecology/epidemiology of these viruses, revealing patterns of infection across different species and local regions. Molecular viral RNA evidence was detected in environment- and host-collected ticks. Seropositivity against Powassan (ranging 1-18%), Bourbon (1.2-8%), and Heartland (5-8%) was detected via virus neutralization assays. Elevated seropositivity against Powassan virus was noted in white-tailed deer and in counties of northwestern Virginia. By identifying circulation of tick-borne viruses, we can better predict and mitigate infection risk. Such findings are useful for devising intervention strategies, such as tick-bite prevention and physician/public awareness campaigns (we highlight an example of outreach material produced by our lab), enabling effective response to potential arbovirus exposure.