Hard ticks (Acari: Ixodidae) have been historically identified by morphological methods which require highly specialized expertise and more recently by DNA-based molecular assays that involve high costs. Although both approaches provide complementary data for tick identification, each method has limitations which restrict their use on large-scale settings such as regional or national tick surveillance programs. To overcome those obstacles, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been introduced as a cost-efficient method for the identification of various organisms, as it balances performance, speed, and high data output. Here we describe the use of this technology to validate the distinction of two closely related Dermacentor tick species based on the development of the first nationwide MALDI-TOF MS reference database described to date. The dataset obtained from this protein-based approach confirms that tick specimens collected from United States regions west of the Rocky Mountains and identified previously as Dermacentor variabilis are the recently described species, Dermacentor similis. Therefore, we propose that this integrative taxonomic tool can facilitate vector and vector-borne pathogen surveillance programs in the United States and elsewhere.

Anaplasmosis is increasingly common in the United States, with cases being reported over an expanding geographic area. To monitor for changes in risk of human infection, the U.S. Centers for Disease Control and Prevention monitors the distribution and abundance of host-seeking vector ticks (Ixodes scapularis and Ixodes pacificus) and their infection with Anaplasma phagocytophilum. While several variants of A. phagocytophilum circulate in I. scapularis, only the human-active variant (Ap-ha) appears to be pathogenic in humans. Failure to differentiate between human and non-human variants may artificially inflate estimates of the risk of human infection. Efforts to differentiate the Ap-ha variant from the deer variant (Ap-V1) in ticks typically rely on traditional PCR assays coupled with sequencing of PCR products. However, laboratories are increasingly turning to Next Generation Sequencing (NGS) to increase testing efficiency, retain high sensitivity, and increase specificity compared with traditional PCR assays. We describe a new NGS assay with novel targets that accurately segregate the Ap-ha variant from other non-human variants and further identify unique clades within the human and non-human variants. Recognizing that not all investigators have access to NGS technology, we also developed a PCR assay based on one of the novel targets so that variants can be visualized using agarose gel electrophoresis without the need for subsequent sequencing. Such an assay may be used to improve estimates of human risk of developing anaplasmosis in North America.

Feral swine, Sus scrofa L., have become a nuisance to landowners across the United States by damaging agriculture, property, and ecosystems. Additionally, these animals have been found to host various ixodid ticks including Amblyomma americanum (L.), Amblyomma maculatum Koch, Dermacentor variabilis (Say), and Ixodes scapularis Say, which can maintain and transmit several rickettsial pathogens to livestock, wildlife, and humans. Though previous research has identified the maintenance cycle of several rickettsial pathogens in ticks and native wildlife, little is known about the role S. scrofa plays in supporting ixodid ticks and the pathogens these ticks could be harboring. This study sought to identify rickettsial agents (Rickettsiales: Anaplasmataceae and Rickettsiaceae) in ticks collected from S. scrofa obtained in Florida and South Carolina. Overall, ticks from four species (A. americanum, D. variabilis, I. scapularis, and A. maculatum) totaling 258 collected individuals were obtained from S. scrofa (n = 45). We found an Ehrlichia chaffeensis Anderson et al. infection prevalence in A. americanum of 2.7% and 2.9% in Florida and South Carolina, respectively. A Rickettsia parkeri Lackman et al. prevalence of 100% and 33% was found in A. maculatum from Florida and South Carolina, respectively. Additionally, a 0.9% infection prevalence of R. parkeri was identified in A. americanum collected in South Carolina. A 1.9% Ehrlichia ewingii Anderson et al. infection prevalence was documented in collected A. americanum in South Carolina. Further studies are warranted to better understand the role S. scrofa plays in the natural maintenance of rickettsial agents in various regions of the United States. © 2022 Georgia Entomological Society Inc.. All rights reserved.

The Asian longhorned tick, Haemaphysalis longicornis, an invasive species associated with human pathogens, has spread rapidly across the eastern USA. Questing H. longicornis ticks recovered from active surveillance conducted from 1 May to 6 September, 2019 throughout Pennsylvania were tested for rickettsial pathogens. Of 265 ticks tested by PCR for pathogens, 4 (1.5%) were positive for Anaplasma phagocytophilum. Sequence analysis of the 16S rRNA gene confirmed two positives as A. phagocytophilum-human agent variant. This is the first reported detection of A. phagocytophilum-human pathogenic strain DNA in exotic H. longicornis collected in the USA.

The Asian longhorned tick, Haemaphysalis longicornis, is an invasive species, originally from eastern Asia, and was first reported in the USA in New Jersey. It is now reported in several eastern states. In 2018, researchers reported H. longicornis in northwest Arkansas (Benton County). This tick species is a proven vector of livestock and human diseases, which prompted the current survey of ticks in southwest Missouri. A tick drag in Greene County, Missouri, produced 2 H. longicornis nymphs on June 9, 2021. This is the first report of this species for both the state and county.

We identified an established population of the Gulf Coast tick (Amblyomma maculatum Koch) infected with Rickettsia parkeri in Connecticut, representing the northernmost range limit of this medically relevant tick species. Our finding highlights the importance of tick surveillance and public health challenges posed by geographic expansion of tick vectors and their pathogens.