University of Wisconsin–Madison Medical College of Wisconsin

Ixodes scapularis: Vector to an Increasing Diversity of Human Pathogens in the Upper Midwest

Matthew J. Wolf, MS; Hannah R. Watkins, BS; William R. Schwan, PhD

WMJ. 2020;119(1):16-21.

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Introduction: The black-legged tick, Ixodes scapularis (I scapularis), is now recognized as the deadliest tick vector in the United States. The Upper Midwest, particularly Wisconsin and Minnesota, are endemic to a diversity of tick-transmitted infectious diseases. Although Borrelia burgdorferi, the agent of Lyme disease, still accounts for the majority of diagnosed infections, I scapularis is known to transmit other bacterial, viral, and parasitic agents.

Objective: To provide an overview of the array of pathogenic microorganisms carried by I scapularis ticks in the Upper Midwest.

Methods: A literature review was conducted to collect and analyze current information about I scapularis lifestyle, transmission, microorganisms carried by the arthropod vector, and the diseases that occur as a result of infections with these microorganisms in the Upper Midwest.

Results: Diagnosis of co-infection from tick-borne zoonosis in humans has increased over the last 2 decades. Since I scapularis can transmit multiple pathogens, it is clinically important because different diagnostic testing and treatment strategies may need to be implemented for a patient with I scapularis-borne infection(s).

Conclusions: This review has concentrated on I scapularis-transmitted diseases affecting the Upper Midwest and has explored the ecology of the I scapularis vector and its role in pathogen transmission.

Author Affiliations: Department of Microbiology, University of Wisconsin-La Crosse, La Crosse Wis (Wolf, Watkins, Schwan).
Corresponding Author: William R. Schwan, PhD, Department of Microbiology, University of Wisconsin-La Crosse, 1725 State St, La Crosse, WI 54601; phone 608.785.6980; email; ORCID ID 0000-0003-3076-1815.
Acknowledgement: The authors wish to thank Bobbi Pritt for critical reading of the manuscript.
Funding/Support: Dr Schwan was supported by a grant AI065432 from the National Institutes of Health.
Financial Disclosures: None declared.
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