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Emerging viruses

James M Hughes, MD
Section Editor
Martin S Hirsch, MD
Deputy Editor
Elinor L Baron, MD, DTMH


Most emerging viruses originate in animals and are vector-borne or zoonotic diseases. Issues related to Heartland virus, Bourbon virus, variegated squirrel bornavirus, and Oropouche virus are reviewed here. Issues related to other emerging viruses, such as Ebola virus, Zika virus, and chikungunya virus, are discussed separately. (See "Clinical manifestations and diagnosis of Ebola virus disease" and "Zika virus infection: An overview" and "Chikungunya fever".)


Heartland virus is a member of the genus Phlebovirus in the family Bunyavirus [1].

Heartland virus has been isolated from leukocytes, and virions can be visualized in infected cells by electron microscopy [1,2]. Viral antigens have been identified by immunohistochemical staining in large mononuclear cells in bone marrow aspirates [1]. Viral antigens have also been detected in postmortem spleen and mediastinal and mesenteric lymph nodes, and the virus has been detected in a postmortem blood sample by reverse-transcription polymerase chain reaction (RT-PCR) and isolation in cell culture [3].

Epidemiology — The virus was initially described in 2012; subsequently, a small number of human cases have been reported in Missouri, Oklahoma, Tennessee, and Arkansas [1,3-6]. The cases all occurred among men over 50 years of age who reported spending several hours outside each day, and most patients had a history of tick bite within two weeks prior to symptoms. Onset of illness occurred between May and September [1,3,4].

Transmission — Transmission of Heartland virus is likely tickborne. The virus has been detected via polymerase chain reaction and culture among nymphs of the lone star tick (Amblyomma americanum), which is found in a broad geographic area extending from Texas to Maine (figure 1 and figure 2) [7]. The vertebrate host has not been definitively identified; neutralizing antibodies to Heartland virus have been observed in raccoons, deer, horses, moose, coyotes, dogs, and opossums [8,9].

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Literature review current through: Nov 2017. | This topic last updated: Oct 05, 2017.
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