Serological Investigation of Heartland Virus (Bunyaviridae: Phlebovirus) Exposure in Wild and Domestic Animals Adjacent to Human Case Sites in Missouri 2012–2013

Abstract

Heartland virus (HRTV; Bunyaviridae: Phlebovirus) has recently emerged as a causative agent of human disease characterized by thrombocytopenia and leukopenia in the United States. The lone star tick (Amblyomma americanum L.) has been implicated as a vector. To identify candidate vertebrate amplification hosts associated with enzootic maintenance of the virus, sera and ticks were sampled from 160 mammals (8 species) and 139 birds (26 species) captured near 2 human case residences in Andrew and Nodaway Counties in northwest Missouri. HRTV-specific neutralizing antibodies were identified in northern raccoons (42.6%), horses (17.4%), white-tailed deer (14.3%), dogs (7.7%), and Virginia opossums (3.8%), but not in birds. Virus isolation attempts from sera and ticks failed to detect HRTV. The high antibody prevalence coupled with local abundance of white-tailed deer and raccoons identifies these species as candidate amplification hosts.

Heartland virus infection in hamsters deficient in type I interferon signaling: Protracted disease course ameliorated by favipiravir

“…The disease course was protracted with the majority of animals surviving the infection. The generally less severe HRTV infection in the immune deficient STAT2 KO hamsters is consistent with the idea that the virus, despite evidence of its presence across many eastern states (Bosco-Lauth et al, 2015; Riemersma and Komar, 2015), seldom causes severe disease that would require hospitalization in healthy individuals.…”

“…HRTV was first isolated in Missouri in 2009 from two hospitalized farmers that presented with fever, fatigue, diarrhea, leukopenia, and thrombocytopenia (McMullan et al, 2012). With less than a dozen cases reported and serological evidence of widespread prevalence of HRTV across central and eastern US (Bosco-Lauth et al, 2015; Riemersma and Komar, 2015), the virus appears to be less virulent than SFTSV causing mostly subclinical or mild illness. Death associated with HRTV disease appears to be linked to advancing age and underlying conditions that likely exacerbate the infection and disease process (2014; Fill et al, 2016; Muehlenbachs et al, 2014).…”

Vertebrate Host Susceptibility to Heartland Virus

“…Six raccoons were caught in the wild in Larimer County, Colorado, and housed in a US Department of Agriculture facility for several months before being transferred to the Animal Disease ABSL 3 Laboratory at Colorado State University for experimental inoculation. Raccoon serum samples were screened for neutralizing antibodies against HRTV/phlebovirus as described ( 3 ) and in this report. All animal handling, trapping, and care was in compliance with approved Institutional Animal Care and Use Committee protocols under the oversight of attending veterinarians.…”

“…The virus has subsequently been isolated from nymphal Amblyomma americanum ticks collected at sites adjacent to the residences of the index case-patients ( 2 ). High seroprevalence rates for HRTV have been reported in northern raccoons ( Procyon lotor ), white-tailed deer ( Odocoileus virginianus ), and horses sampled near the residences of human case-patients ( 3 ). Additional serosurveillance in wildlife has demonstrated wide-ranging antibody prevalence to HRTV across the geographic host range distribution of A. americanum ticks ( 4 ).…”

“…Given the serologic evidence that northern raccoons are commonly exposed to HRTV across the central and eastern United States ( 4 ) and near the residence of a human index case-patient ( 3 ), we performed experimental inoculations of raccoons with HRTV. In addition, on the basis of results of goat serosurveillance for SFTSV in China ( 15 ) and experimental infections ( 16 ), we performed experimental inoculation of goats with HRTV.…”