Published research and ongoing projects
Our ongoing research into tick ecology and tick-borne pathogen surveillance centers on the public-facing TickReport tick testing service. Anonymized data produced by that testing are uploaded daily to the TickReport statistics page to provide a one-of-a-kind source of current and historical tick infection rates. But what we learn from TickReport testing also drives publications in peer-reviewed scientific journals. We highlight several of those publications below.
*note: Bold text in author lists indicate present or past members of the TickReport “lab family,” most notably faculty and staff at the University of Massachusetts Amherst that provided TickReport testing while we were on campus from 2006-2020.
Passive surveillance of Powassan virus in human biting ticks and health outcomes of associated bite victims
In this 2024 letter published in Clinical Microbiology and Infection, Siegel and colleagues analyzed 14,730 Ixodes scapularis ticks tested through the TickReport passive surveillance service from 2015 to 2023, identifying Powassan virus in 42 ticks, 38 of which came from humans. The authors noted a fourfold increase in reported human Powassan cases, from 64 (2004–2013) to 270 (2014–2023). Critically, none of the followed-up bite victims whose ticks tested positive reported symptoms, despite attachment times averaging well above the presumed minimum for transmission. Powassan-positive ticks also harbored co-infecting pathogens including Borrelia burgdorferi (60%), Babesia microti (17%), and Anaplasma phagocytophilum(5%). Using back-calculations based on Lyme incidence and tick infection rates, the authors estimated 3,000–5,000 people per year in the U.S. are bitten by Powassan-carrying ticks, suggesting that most such bites cause nonspecific symptoms that do not prompt healthcare visits or testing— a pattern compared to West Nile virus, where severe disease represents only a fraction of infections..
Siegel EL, Xu G, Killinger P, Brown C, and SM Rich. (2024) Passive surveillance of Powassan virus in human biting ticks and health outcomes of associated bite victims. Clin Micro Infect 30: 1332-1334. https://doi.org/10.1016/j.cmi.2024.06.012
What a Tick Can Tell a Doctor: Using the Human-Biting Tick in the Clinical Management of Tick-Borne Disease.
This 2023 viewpoint by Rich, Siegel, and Xu in the Journal of Clinical Medicine argues that pathogen testing of human-biting ticks should be recognized as a valuable complement to the clinical diagnostic pipeline for tick-borne diseases. The authors note that tick-borne disease incidence is rising dramatically in the U.S., yet diagnosis remains difficult due to non-specific symptoms, limited and unstandardized serological tests (especially unreliable in early infection), and the complicating factor of co-infections from pathogens like Borrelia burgdorferi, Babesia, and Anaplasma. They propose that three exposure indices drawn from the tick itself — species identification, pathogen detection via PCR, and estimation of feeding duration through physical measurement of the tick's body — can together inform pretest probability and guide clinical decision-making during the critical window between a bite and symptom onset. While acknowledging the CDC's concerns about quality control standards and potential misinterpretation of both positive and negative tick test results, the authors counter that these objections are logically inconsistent and that the better path forward is establishing regulated quality assurance frameworks rather than discouraging the practice altogether, drawing an analogy to post-mortem rabies testing in animals to guide prophylaxis decisions..
Rich SM, Siegel EL, Xu G. (2023) What a Tick Can Tell a Doctor: Using the Human-Biting Tick in the Clinical Management of Tick-Borne Disease. Journal of Clinical Medicine. 12(20):6522. https://doi.org/10.3390/jcm12206522
Borrelia miyamotoi in Human-biting ticks, United States, 2013-2019
Borrelia miyamotoi is a species in the relapsing fever group within the Borrelia genus. This bacterium is pathogenic to humans and can be transmitted through the bite of an infected Ixodes tick. Between 2013 and 2019, the TickReport lab tested over 36,000 I. scapularis and I. pacificus ticks for this pathogen, and found nationwide infection rates of 1.72% and 0.94% in these two species respectively. Borrelia miyamotoi was detected in ticks submitted from 19 states in the Northeastern U.S., Great Lakes region, and West Coast (California and Oregon).
Xu, G., Luo, C.-Y., Ribbe, F., Pearson, P., Ledizet, M., & Rich, S. M. (2021). Borrelia miyamotoi in Human-Biting Ticks, United States, 2013–2019. Emerging Infectious Diseases, 27(12), 3193–3195.
Bourbon virus detected in Amblyomma americanum ticks on Long Island, NY.
In July 2019, TickReport testing detected Bourbon virus and Ehrlichia ewingii in a partially-fed adult female Lone star tick (Amblyomma americanum). State and county agencies had collected and tested Lone star ticks in the region since 2016 with no positive results. The positive result from TickReport testing was validated externally, and TickReport molecular assays were used in a follow-up study in 2021 that confirmed the presence of Bourbon virus RNA. The assays developed by TickReport researchers detected virus RNA that was not found by the state/county assays used previously.
Dupuis, A. P., Prusinski, M. A., O’Connor, C., Maffei, J. G., Koetzner, C. A., Zembsch, T. E., Zink, S. D., White, A. L., Santoriello, M. P., Romano, C. L., Xu, G., Ribbe, F., Campbell, S. R., Rich, S. M., Backenson, B., Kramer, L.D., & Ciota, A. T. (2023). Bourbon Virus Transmission, New York, USA. Emerging Infectious Diseases, 29(1), 145-148. https://doi.org/10.3201/eid2901.220283.
Development of a TaqMan Real-Time PCR for the Identification of Haemaphysalis longicornis (Acari: Ixodidae)
The Asian longhorned tick (Haemaphysalis longicornis) is a hard tick species native to Asia that has emerged as an invasive species in the United States in recent years. The first officially-documented H. longicornis identified in the U.S. were removed from sheep in New Jersey in 2017. TickReport developed a qPCR molecular identification method to facilitate unambiguous species identification and confirm traditional morphological methods. Retroactive testing of over 76,000 ticks in the TickReport archive revealed that this invasive species was in the United States by 2015 or earlier.
Xu, G., Ribbe, F., McCaffery, J., Luo, C.-Y., Li, A. Y., & Rich, S. M. (2022). Development of a TaqMan Real-Time PCR for the Identification of Haemaphysalis longicornis (Acari: Ixodidae). Journal of Medical Entomology, 59(4), 1484–1487.
Heartland Virus detected in Amblyomma americanum tick on Long Island, NY.
In August 2018, TickReport tested a Lone star (Amblyomma americanum) nymph sent from Long Island. Previously, public health officials in New York had sampled ticks through flagging and dragging in 2016 and 2018. This fieldwork helped to measure established populations of Amblyomma americanum ticks in the state, but testing of those samples had not detected Heartland Virus RNA. Following the positive result from TickReport, increased active surveillance efforts led to additional tick collection. Between 2019 and 2020, public health officials in New York found Heartland virus RNA in 5 pools of A. americanum unengorged nymphs collected from Brookhaven, NY. The human bitten by the tick did in fact contract Heartland Virus, reinforcing the public health need for both passive and active surveillance of A. Americanum ticks in this region.
Dupuis, A. P., 2nd, Prusinski, M. A., O'Connor, C., Maffei, J. G., Ngo, K. A., Koetzner, C. A., Santoriello, M. P., Romano, C. L., Xu, G., Ribbe, F., Campbell, S. R., Rich, S. M., Backenson, P. B., Kramer, L. D., & Ciota, A. T. (2021). Heartland Virus Transmission, Suffolk County, New York, USA. Emerging infectious diseases, 27(12), 3128–3132. https://doi.org/10.3201/eid2712.211426
Passive Surveillance of Ixodes scapularis (Say), Their Biting Activity, and Associated Pathogens in Massachusetts
Since 2006, the TickReport testing lab has received and tested ticks submitted by individuals across the United States and over twenty other countries across the globe. This study considers 3,500 ticks submitted for testing between 2006 and 2012. Ixodes scapularis ticks were tested for the presence of Borrelia burgdorferi, Babesia microti, and Anaplasma phagocytophilum. The study also observes when submitters were bitten (by month), where submitters were bitten (body part), and age of submitters to enrich our understanding of how people are exposed to ticks and the pathogens they may carry.
Xu G, Mather TN, Hollingsworth CS, Rich SM. Passive Surveillance of Ixodes scapularis (Say), Their Biting Activity, and Associated Pathogens in Massachusetts. Vector Borne Zoonotic Dis. 2016 Aug;16(8):520-7. doi: 10.1089/vbz.2015.1912. Epub 2016 Jun 1. PMID: 27248292; PMCID: PMC4960492.