Brault, Aaron C.Savage, Harry M.Duggal, Nisha K.Eisen, Rebecca J.Staples, J. Erin2018-09-212018-09-212018-09-14Brault, A.C.; Savage, H.M.; Duggal, N.K.; Eisen, R.J.; Staples, J.E. Heartland Virus Epidemiology, Vector Association, and Disease Potential. Viruses 2018, 10, 498.http://hdl.handle.net/10919/85082First identified in two Missouri farmers exhibiting low white-blood-cell and platelet counts in 2009, Heartland virus (HRTV) is genetically closely related to severe fever with thrombocytopenia syndrome virus (SFTSV), a tick-borne phlebovirus producing similar symptoms in China, Korea, and Japan. Field isolations of HRTV from several life stages of unfed, host-seeking <i>Amblyomma americanum</i>, the lone star tick, implicated it as a putative vector capable of transstadial transmission. Laboratory vector competence assessments confirmed transstadial transmission of HRTV, demonstrated vertical infection, and showed co-feeding infection between <i>A. americanum</i>. A vertical infection rate of 33% from adult females to larvae in the laboratory was observed, while only one of 386 pools of molted nymphs (1930) reared from co-feeding larvae was positive for HRTV (maximum-likelihood estimate of infection rate = 0.52/1000). Over 35 human HRTV cases, all within the distribution range of <i>A. americanum</i>, have been documented. Serological testing of wildlife in areas near the index human cases, as well as in widely separated regions of the eastern United States where <i>A. americanum</i> occur, indicated many potential hosts such as raccoons and white-tailed deer. Attempts, however, to experimentally infect mice, rabbits, hamsters, chickens, raccoons, goats, and deer failed to produce detectable viremia. Immune-compromised mice and hamsters are the only susceptible models. Vertical infection augmented by co-feeding transmission could play a role in maintaining the virus in nature. A more complete assessment of the natural transmission cycle of HRTV coupled with serosurveys and enhanced HRTV disease surveillance are needed to better understand transmission dynamics and human health risks.application/pdfenCreative Commons Attribution 4.0 InternationalHeartland virusAmblyomma americanumlone star ticktransmissionthrombocytopeniaArticle - Refereed2018-09-21https://doi.org/10.3390/v10090498