Related Experiment Video
Updated: Apr 27, 2026
Author Spotlight: Controlled Human Exposure Model for Tick Research and Lyme Disease Studies
Published on: December 1, 2023
Spotted fever group rickettsiae in multiple hard tick species from Fairfax County, Virginia
Tyler C Henning1, John M Orr, Joshua D Smith
11 The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland.
Abstract:
Spotted fever group rickettsiosis (SFGR) is a potentially fatal disease that has displayed increasing incidence in the United States in recent years. The most well-known and severe type of this disease is Rocky Mountain spotted fever, but there are other mild forms that occur. Recently, human infection with Rickettsia parkeri has been reported and linked with the tick Amblyomma maculatum. In 2010, a population of R. parkeri-infected A. maculatum was discovered in Fairfax County, Virginia, leading to increased surveillance of tick species. In this study, we report the presence of R. parkeri in Rhipicephalus sanguineus, Haemaphysalis leporispalustris, and Dermacentor variabilis in Fairfax County. R. parkeri was discovered in two Rh. sanguineus, one H. leporispalustris, and 17 D. variabilis. These findings suggest that spillover infections of R. parkeri may be occurring in tick species not typically associated with this pathogen; however, vector competence studies need to be conducted to determine if these tick species can serve as potential vectors for human SFGR.
Insights
Spotted fever group rickettsiosis (SFGR) is rising in the US. This study found Rickettsia parkeri in new tick species in Virginia, suggesting potential new disease transmission routes.
Area of Science:
- Veterinary Entomology
- Infectious Diseases
- Public Health
Background:
- Spotted fever group rickettsiosis (SFGR) is a significant and growing public health concern in the United States.
- Rickettsia parkeri, a cause of SFGR, has been primarily associated with the Gulf Coast tick, Amblyomma maculatum.
- Previous findings of R. parkeri in A. maculatum in Fairfax County, Virginia, prompted further investigation into local tick populations.
Purpose of the Study:
- To investigate the presence and distribution of Rickettsia parkeri in various tick species within Fairfax County, Virginia.
- To identify potential novel tick vectors for R. parkeri beyond its typically associated species.
- To assess the implications of these findings for the epidemiology of SFGR in the region.
Main Methods:
- Tick surveillance was conducted in Fairfax County, Virginia.
- Collected ticks were identified to species level.
- Molecular methods were used to detect the presence of Rickettsia parkeri DNA within individual ticks.
Main Results:
- Rickettsia parkeri was detected in three tick species previously not commonly associated with this pathogen: Rhipicephalus sanguineus (two ticks), Haemaphysalis leporispalustris (one tick), and Dermacentor variabilis (17 ticks).
- The pathogen was found in tick populations within Fairfax County, Virginia.
- These findings indicate a broader host range for R. parkeri than previously understood.
Conclusions:
- The detection of R. parkeri in Rh. sanguineus, H. leporispalustris, and D. variabilis suggests potential spillover infections into new tick species.
- Further vector competence studies are essential to confirm if these newly identified tick species can effectively transmit R. parkeri to humans, posing a risk for SFGR.
- This research highlights the need for ongoing surveillance and research to understand the evolving landscape of tick-borne diseases.
Related Concept Videos
01:10Intracellular Movement of Viruses and Bacteria
01:30Bacterial Phylum Spirochaetes