Heartland Virus Transmission, Suffolk County, New York, USA

Alan P. Dupuis II; Melissa A. Prusinski; Collin O'Connor; Joseph G. Maffei; Kiet A. Ngo; Cheri A. Koetzner; Michael P. Santoriello; Christopher L. Romano; Guang Xu; Fumiko Ribbe; Scott R. Campbell; Stephen M. Rich; P. Bryon Backenson; Laura D. Kramer; Alexander T. Ciota

Disclosures

Emerging Infectious Diseases. 2021;27(12):3128-3132. 

In This Article

Conclusions

Evidence of widespread HRTV transmission was demonstrated throughout Suffolk County, New York. Consistent with previous studies, A. americanum ticks were implicated in local transmission of HRTV. All positive pools were nymphal stage ticks, including the tick originally submitted for testing at the University of Massachusetts. Tick minimal infection rates ranged from 0% to 1.1%. It is unclear whether flat nymphs had acquired the virus as larvae feeding on viremic hosts, through cofeeding transmission, or transovarially because each of these modes has been demonstrated in the laboratory.[7]

The lack of HRTV detection in adult ticks is notable if one considers that collections occurred at the same site across 3 seasons. Higher numbers of positive nymph pools were observed in Missouri, where 53/60 HRTV-positive tick pools collected at sites near the first described human cases were nymphs.[6] Complete genome sequence analysis of the HRTV strains isolated during this study showed >98% amino acid and >93% nucleotide identities to the original strains isolated from patients in Missouri during 2009[1] and a strain isolated in Tennessee during 2013.[2]

White-tailed deer are a sensitive sentinel model for many arboviruses, given their abundance, limited home range, and the frequency on which they are fed upon by hematophagous arthropods.[10,11,14] Approximately 10% of the deer sampled during this study were seropositive against HRTV. Our serologic testing strategy differed from those of previous studies by using a more stringent PRNT90. Suffolk County deer seropositive rates were similar to those reported in Vermont (10%), Maine (11%), and Florida (4%) deer.[12] The rates are lower than those reported for deer tested in midwestern and southeastern states, areas with burgeoning populations of A. americanum ticks.[10,11] To date, no competent vertebrate host, including deer, has been implicated in HRTV amplification.[15]

Results from this study emphasize the need to include HRTV in surveillance programs wherever A. americanum ticks are distributed. Furthermore, clinicians should be aware of this pathogen and the potential for overlapping symptomologies (fever, fatigue, and loss of appetite) with other tickborne infections. Providers should request HRTV testing for patients who have clinical symptoms, including leukopenia and thrombocytopenia, and a history of tick exposure or travel to regions where A. americanum ticks are reported.

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