A wide range of pathogens, such as bacteria, viruses, and parasites can be transmitted by ticks and can cause diseases, such as Lyme disease, anaplasmosis, or Rocky Mountain spotted fever. Landscape and climate changes are driving the geographic range expansion of important tick species. The morphological identification of ticks is critical for the assessment of disease risk; however, this process is time-consuming, costly, and requires qualified taxonomic specialists. To address this issue, we constructed a tick identification tool that can differentiate the most encountered human-biting ticks, Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis, by implementing artificial intelligence methods with deep learning algorithms. Many convolutional neural network (CNN) models (such as VGG, ResNet, or Inception) have been used for image recognition purposes but it is still a very limited application in the use of tick identification. Here, we describe the modified CNN-based models which were trained using a large-scale molecularly verified dataset to identify tick species. The best CNN model achieved a 99.5% accuracy on the test set. These results demonstrate that a computer vision system is a potential alternative tool to help in prescreening ticks for identification, an earlier diagnosis of disease risk, and, as such, could be a valuable resource for health professionals.

Ticks are vectors of many human and animal zoonotic disease-causing agents causing significant global health and economic strain. Repellents and acaricides are integral to the human capacity for personal protection from tick bites. Nootkatone, a naturally occurring sesquiterpene found in the Alaskan cedar tree, grapefruit, and other sources, has been documented to be a potent acaricide. Research has also noted repellent effects against some tick species. In this study, our aim was to investigate the effect of synthetic, high-purity (+)-nootkatone on adult Ixodes scapularis, Dermacentor variabilis, and Amblyomma americanum ticks in an in vitro, vertical filter paper bioassay. (+)-nootkatone showed compelling tick repellency, but median effective concentrations (EC₅₀) significantly differed among species. Ixodes scapularis were repelled at very low concentrations (EC₅₀ = 0.87 ± 0.05 µg/cm²). Higher concentrations were required to repel D. variabilis (EC₅₀ = 252 ± 12 µg/cm²) and A. americanum (EC₅₀ = 2313 ± 179 µg/cm²). Significant post-exposure mortality, assessed 24 h after repellency trials, was also observed in I. scapularis but was absent entirely in D. variabilis and A. americanum. These tests demonstrate that nootkatone has a promising dual-action personal protection capacity against adult I. scapularis ticks, warranting further investigation in more natural environments and in the presence of host cues.

Borrelia burgdorferi, the causative agent of Lyme disease, has a highly reduced genome and relies heavily on glycolysis for carbon metabolism. As such, established inhibitors of lactate dehydrogenase (LDH) were evaluated in cultures to determine the extent of their impacts on B. burgdorferi growth. Both racemic and enantiopure (AT-101) gossypol, as well as oxamate, galloflavin, and stiripentol, caused the dose-dependent suppression of B. burgdorferi growth in vitro. Racemic gossypol and AT-101 were shown to fully inhibit spirochetal growth at concentrations of 70.5 and 187.5 μM, respectively. Differences between racemic gossypol and AT-101 efficacy may indicate that the dextrorotatory enantiomer of gossypol is a more effective inhibitor of B. burgdorferi growth than the levorotatory enantiomer. As a whole, LDH inhibition appears to be a promising mechanism for suppressing Borrelia growth, particularly with bulky LDH inhibitors like gossypol.

Deer keds (Lipoptena spp. and Neolipoptena ferrisi) are hematophagous ectoparasites that primarily infest white-tailed deer (Odocoileus virginianus) and other cervids in the United States. The distribution of deer keds in the northeastern United States and the pathogens they harbor remains relatively unexplored. In this study, we examined the geographical distribution and pathogen prevalence of deer keds in Massachusetts by collecting samples from white-tailed deer and testing for tick-borne pathogens. Deer keds were collected across the state, including in four previously unrecorded counties, indicating a wide distribution. Pathogen screening revealed the presence of Anaplasma phagocytophilum DNA in 30% of the keds, but no other pathogens were detected. The medical and biological significance of detecting A. phagocytophilum DNA in deer keds requires future studies. This research provides a baseline for the distribution and pathogen prevalence of deer keds in Massachusetts and highlights the potential of deer keds as sentinels for monitoring deer-associated microbes.

Tick-borne diseases and a tick-induced red meat allergy have become increasingly common in the northeastern USA and elsewhere. At the scale of local communities, few studies have documented tick densities or infection levels to characterize current conditions and provide a baseline for further monitoring. Using the town of Nantucket, MA, as a case study, we recorded tick densities by drag sampling along hiking trails in nature preserves on two islands. Nymphal blacklegged ticks (Ixodes scapularis Say) were most abundant at shadier sites and least common in grasslands and scrub oak thickets (Quercus ilicifolia). Lone star ticks (Amblyomma americanum L.) were common on Tuckernuck Island and rare on Nantucket Island, while both tick species were more numerous in 2021 compared to 2020 and 2022. We tested for pathogens in blacklegged nymphs at five sites over two years. In 2020 and 2021, infection levels among the four Nantucket Island sites averaged 10% vs. 19% for Borrelia burgdorferi, 11% vs. 15% for Babesia microti, and 17% (both years) for Anaplasma phagocytophilum, while corresponding levels were significantly greater on Tuckernuck in 2021. Our site-specific, quantitative approach represents a practical example of how potential exposure to tick-borne diseases can be monitored on a local scale.

Spotted fever group (SFG) rickettsioses are increasingly recognized worldwide as threats to public health. Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia rickettsii subspecies californica cause spotted fever rickettsioses, including Rocky Mountain spotted fever. These disease agents are transmitted to humans by various tick vectors in the United States. There is growing concern that other tick species, such as Haemaphysalis leporispalustris, may also transmit new and potentially unrecognized SFG rickettsial pathogens. In this study, we found that 6.1 % of 296 questing H. leporispalustris ticks (21 larvae, 260 nymphs, 9 males, and 6 females) collected from 38 towns across nine counties in Maine, USA, were positive for Rickettsia spp. Further multilocus sequence typing and phylogenetic analysis revealed that this is a new Rickettsia genotype (Rickettsia sp. ME2023) belonging to the SFG group and close to Candidatus Rickettsia lanei. Tick vectors and rickettsial species associated with SFG rickettsioses in New England warrant further investigation. Additionally, the role of H. leporispalustris in pathogen enzootic cycles and transmission requires further study.