Determining the Prevalence and Distribution of Tick-Borne Pathogens in Southeastern Virginia and Exploring the Transmission Dynamics of Rickettsia Parkeri in Amblyomma Maculatum

Tick-borne pathogens are an increasing threat to human and animal health worldwide. In the United States, cases of Lyme disease, spotted fever rickettsioses, ehrlichiosis and anaplasmosis are on the rise. Factors related to emergence include appearance of a new pathogen, recognition of an existing pathogen and environmental changes that result in new exposure events. Despite the rise in tick-borne disease incidence within many states, including Virginia, there is a paucity of data related to the prevalence and distribution of ticks and tick-borne pathogens. The first aim of this dissertation research was to determine the tick-borne pathogen composition within tick populations in southeastern Virginia. Since 2009, the vector ecology laboratory at Old Dominion University has been conducting year-round surveillance of tick populations within Hampton Roads. This research explores the pathogen composition within these tick populations, with a particular focus on emerging pathogens, including Rickettsia parkeri and Ehrlichia chaffeensis. The second aim of this research was to determine the transmission dynamics of Rickettsia parkeri within its vector, Amblyomma maculatum. Although some rickettsiae are transovarially transmitted in ticks, little is known about the frequency and efficiency of this transmission route, and nothing is known regarding the transmission strategy of R. parkeri in A. maculatum. By understanding the dynamics of pathogen transmission within the tick, a broader knowledge of the disease system can be attained, and mathematical models to explore these dynamics can be parameterized. The third aim of this research was to explore the potential for R. parkeri to spill over from A. maculatum populations into populations of Amblyomma americanum. A. americanum is an aggressive human-biting tick, represents 95% of the ticks encountered in southeastern Virginia, and is the most common tick found attached to humans in the southeastern and mid-Atlantic United States. Because of its common association with humans, A. americanum and the pathogens it transmits are an important threat to human health in southeastern states. The competence of A. americanum as a vector of R. parkeri was also investigated in this study

Prevalence of Ehrlichia chaffeensis and Ehrlichia ewingii in Amblyomma americanum and Dermacentor variabilis Collected From Southeastern Virginia, 2010-2011

Amblyomma americanum is the most commonly-encountered tick species in southeastern Virginia, representing approximately 95% of the human-biting tick population in this area. Here we investigated the prevalence of Ehrlichia chaffeensis and Ehrlichia ewingii in questing Amblyomma americanum and Dermacentor variabilis ticks collected from multiple sites in southeastern Virginia from 2010–2011. Although both Ehrlichia species were detected in Amblyomma americanum, no evidence of either pathogen was found in Dermacentor variabilis. Prevalence of E. chaffeensis varied by location, ranging from 0 – 5.08% among Amblyomma americanum populations. Ehrlichia ewingii prevalence was slightly higher, ranging from 0 – 8.20% among A. americanum populations. We conclude that both pathogens are established in southeastern Virginia A. americanum populations, and that although there are no apparent temporal trends in Ehrlichia prevalence, there is variation among locations, suggesting the potential for disease hotspots

Ixodes affinis (Acari: Ixodidae) in Southeastern Virginia and Implications for the Spread of Borrelia burgdorferi, the Agent of Lyme Disease

Ixodes affinis Neumann is a hard-bodied (ixodid) tick known to be a competent vector for Borrelia burgdorferi, the agent of Lyme disease, and agents of other human diseases (Keirans et al. 1999). Ixodes affinis has been reported in Florida, Georgia, and South Carolina and throughout coastal North Carolina (Clark et al. 1998, Harrison et al. 2010). Harrison et al. (2010) indicated that I. affinis was established throughout the coastal plain of North Carolina up to the Virginia border and suggested that I. affinis might occur in Virginia

Qualitative Health Research Involving Indigenous Peoples: Culturally Appropriate Data Collection Methods

Historically, health research involving Indigenous peoples has been fraught with problems, including researchers not addressing Indigenous research priorities and then subsequently often failing to utilize culturally appropriate methods. Given this historical precedence, some Indigenous populations may be reluctant to participate in research projects. In response to these concerns, the Government of Canada has developed the Tri-Council Policy Statement (TCPS2): Research Involving the First Nations, Inuit and Métis Peoples of Canada, which stipulates the requirements for research collaborations with Indigenous communities. Utilizing this policy as an ethical standard for research practices, this paper describes, critiques and synthesizes the literature on culturally appropriate oral-data collection methods, excluding interviews and focus groups, for use with Indigenous people in Canada. Results suggest that photovoice, symbol-based reflection, circles and story-telling can be methodologically rigorous and culturally appropriate methods of collecting data with this population. Suggestions are made for researchers wishing to use these methods to promote respectful and collaborative research partnerships with Indigenous peoples in Canada

Ticks and Spotted Fever Group Rickettsiae of Southeastern Virginia

The incidence of tick-borne rickettsial disease in the southeastern United States has been rising steadily through the past decade, and the range expansions of tick species and tick-borne infectious agents, new and old, has resulted in an unprecedented mix of vectors and pathogens. The results of an ongoing 4-year surveillance project describe the relative abundance of questing tick populations in southeastern Virginia. Since 2009, more than 66,000 questing ticks of 7 species have been collected from vegetation in a variety of habitats, with Amblyomma americanum constituting over 95% of ticks collected. Other species represented included Ixodes scapularis, Dermacentor variabilis, Amblyomma maculatum, Ixodes affinis, Haemaphysalis leporispalustris, and Ixodes brunneus. We found that 26.9–54.9% of A. americanum ticks tested were positive for Rickettsia amblyommii, a non-pathogenic symbiont of this tick species. We also found no evidence of R. rickettsii in D. variabilis ticks, although they did show low infection rates of R. montanensis (1.5–2.0%). Rickettsia parkeri and Candidatus R. andeanae were found in 41.8–55.7% and 0– 1.5% A. maculatum ticks, respectively. The rate of R. parkeri in A. maculatum ticks is among the highest in the literature and has increased in the 2 years since R. parkeri and A. maculatum were first reported in southeastern Virginia. We conclude that tick populations in southeastern Virginia have recently undergone dramatic changes in species and abundance and that these populations support a variety of rickettsial agents with the potential for increased risk to human health

In Vitro Propagation of Candidatus Rickettsia andeanae Isolated From Amblyomma maculatum

Candidatus Rickettsia andeanae was identified during an investigation of a febrile outbreak in northwestern Peru (2002). DNA sequencing from two ticks (Amblyomma maculatum, Ixodes boliviensis) collected during the investigation revealed a novel Rickettsia agent with similarity to the spotted fever group rickettsiae. Since then, Candidatus R. similar to andeanae has been detected in A. maculatum ticks collected in the southeastern and southcentral United States, Argentina, and Peru. To date, Candidatus R. andeanae has not been successfully cultivated in the laboratory. We present evidence for the continuous cultivation in three cell lines of Candidatus R. similar to andeanae isolated from an A. maculatum tick (Portsmouth, Virginia)

Single-Tube Real-Time PCR Assay for Differentiation of Ixodes Affinis and Ixodes scapularis

Ixodes affinis Neumann (1899) and Ixodes scapularis Say (1821) are tick vectors of the etiologic agent of Lyme disease, Borrelia burgdorferi sensu stricto. Ixodes affinis and I. scapularis are morphologically very similar, and as they are sympatric in the mid- and south-Atlantic U.S. coastal states, their accurate identification is crucial to studies of disease and vector ecology in this area. This work describes a rapid, single-tube SYBR® Green-based real-time PCR assay for differentiation of I. affinis and I. scapularis at all life stages. The assay employs 2 pairs of species specific primers directed against the internal transcribed spacer 2 (ITS2) region of the nuclear rRNA operon. Amplification products for these primer pairs differ in size and may be differentiated with a melt curve analysis. This tool is intended as a supplement to morphological methods for accurate identification of these ticks

Framing the future for taxonomic monography: Improving recognition, support, and access

No abstract available

Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ∼30% of γ -ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ , and driving amplitudes on short timescales σ . Imposing cuts on minimum τ and σ allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several arcminute error ellipses of γ -ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E ≥ 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other γ -ray blazars and is likely to be the γ -ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ∼3 years in the rest frame of the jet, in contrast with the ∼320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics

TOI-5126: A hot super-Neptune and warm Neptune pair discovered by TESS\textit{TESS} and CHEOPS\textit{CHEOPS}

We present the confirmation of a hot super-Neptune with an exterior Neptune companion orbiting a bright (V = 10.1 mag) F-dwarf identified by the $\textit{Transiting Exoplanet Survey Satellite}$ ($\textit{TESS}$). The two planets, observed in sectors 45, 46 and 48 of the $\textit{TESS}$ extended mission, are $4.74^{+0.16}_{-0.14}$ $R_{\oplus}$ and $3.86^{+0.17}_{-0.16}$ $R_{\oplus}$ with $5.4588385^{+0.0000070}_{-0.0000072}$ d and $17.8999^{+0.0018}_{-0.0013}$ d orbital periods, respectively. We also obtained precise space based photometric follow-up of the system with ESAs $\textit{CHaracterising ExOplanets Satellite}$ ($\textit{CHEOPS}$) to constrain the radius and ephemeris of TOI-5126 b. TOI 5126 b is located in the "hot Neptune Desert" and is an ideal candidate for follow-up transmission spectroscopy due to its high predicted equilibrium temperature ($T_{eq} = 1442^{+46}_{-40}$ K) implying a cloud-free atmosphere. TOI-5126 c is a warm Neptune ($T_{eq}= 971^{+31}_{-27}$ K) also suitable for follow-up. Tentative transit timing variations (TTVs) have also been identified in analysis, suggesting the presence of at least one additional planet, however this signal may be caused by spot-crossing events, necessitating further precise photometric follow-up to confirm these signals.Comment: Accepted in MNRAS, 18 pages, 14 figure