Lone Star Ticks (Amblyomma americanum):: An Emerging Threat in Delaware

Alpha-gal syndrome: potential for a hypersensitivity reaction after the use of dental products: Literature review and case report

BACKGROUND

Alpha-gal syndrome (AGS) is associated with a potentially severe delayed immunoglobulin E-based hypersensitivity reaction produced via transmission of a salivary oligosaccharide (galactose-⍺-1,3-galactose) predominately from the bite of the lone star tick (Amblyomma americanum). Sensitized people are at an increased risk of experiencing cross-reactivity reactions to numerous foods, pharmaceuticals, and medical and dental products that could result in a spectrum of pathophysiological responses, ranging from gastrointestinal and cutaneous disturbances to anaphylaxis. The authors have summarized the relevant literature and presented a case report describing an alpha-gal (AG) reaction associated with oral health care.

TYPES OF STUDIES REVIEWED

The authors provided an overview of clinical studies, review articles, case reports, and case series of AGS obtained from PubMed and Google Scholar electronic databases. In addition, various medical and dental pharmaceuticals and health care products were reviewed for the presence of AG epitopes.

RESULTS

Factors implicated in an AGS-like event included consuming nonprimate red meat and dairy products, intake of pharmaceuticals with animal-based ingredients and excipients, and use of medical and dental products containing AG epitopes. The most common promoter of AGS-related dental events was the administration of animal-based hemostatic agents.

PRACTICAL IMPLICATIONS

Oral health care providers should be knowledgeable about the salient features of AGS and perform a thorough review of an affected patient's diagnosis, triggering events, associated adverse incidents, and therapeutic measures used. To gain greater insight into an affected patient's disorder, consultation with their attending allergist or immunologist is advised. To reduce the onset of a hypersensitivity reaction, attending clinicians must maintain strict avoidance of the use of pharmaceuticals and medical or dental products that express AG epitopes.

Ticks of Delaware revisited: an updated checklist of hard ticks (Ixodidae) and first records of soft ticks (Argasidae) in the First State

It has been more than three-quarters of a century since the inaugural report of Delaware's ticks was published. To provide an updated checklist of tick species currently known to occur in Delaware, we reviewed the scientific literature, examined tick collections, accessed archived tick specimen data, and analyzed findings from the state's ongoing tick surveillance program, initiated in 2019. We report here a total of 15 established hard tick species (Ixodidae), as well as additional Ixodidae and 2 soft tick species (Argasidae) that are not yet confirmed as established. We summarize the phenology of each species and its known distribution in Delaware and public health importance. We also provide a table of known tick-host associations for Delaware.

Statewide surveillance of tick-borne pathogens in ticks collected in Delaware using novel multiplex PCR assays

Tick-borne pathogens are responsible for most vector-borne human diseases in the United States. With the growing recognition of tick-borne diseases and the expanding range of ticks, it is imperative to understand which pathogens, and in what prevalence, are carried by tick species in areas populated by humans. Few studies exist surveying the presence and distribution of tick-borne pathogens in the state of Delaware. The goal of this study was to create multiplex real-time PCR assays to identify Borrelia burgdorferi sensu stricto, Babesia microti, Anaplasma phagocytophilum, Ehrlichia chaffeensis, and Ehrlichia ewingii from their respective tick vectors collected across the state of Delaware. Two multiplex, real-time PCR assays were developed and tested on 1027 ticks comprising Ixodes scapularis and Amblyomma americanum, two species of ticks commonly encountered in Delaware. The results showed that in a sample of 500 Ixodes scapularis ticks, 30.20 % were positive for Borrelia burgdorferi, 2.60 % were positive for Babesia microti, and 1 % were positive for Anaplasma phagocytophilum. Testing of 527 A. americanum ticks showed that 4.74 % were positive for E. chaffeensis and 1.14 % were positive for E. ewingii. These findings suggest that these five tick-borne pathogens are present across the state of Delaware and therefore pose a risk to the public.

An investigation of Haemaphysalis longicornis (Ixodida:Ixodidae) habitat and pathogen overlap with resident tick species in Southeastern Pennsylvania forests

The long-horned tick, Haemaphysalis longicornis Neumann (Ixodida: Ixodidae) was recently introduced to the United States from its native range in Asia. Although H. longicornis transmits numerous disease-causing pathogens in its native range, it is unclear to what extent H. longicornis will act as a disease vector in the United States. The ability of H. longicornis to acquire pathogens likely depends on overlap with resident tick species in both habitat and pathogens transmitted within its introduced range. To assess the potential overlap in habitat and pathogens between invasive H. longicornis and resident tick species, we field-collected ticks across southeastern Pennsylvania and tested them for pathogens. We then contextualized the risk of pathogen transmission to and by H. longicornis at sites where it overlaps with the current vector species using a network of vectored pathogens. None of the collected H. longicornis individuals tested positive for any pathogens. However, we found significant overlap in habitat use among H. longicornis and resident tick nymphs, as well as several overlaps in the pathogens vectored by resident ticks and those carried by H. longicornis in Asia. These findings indicate a high but yet-to-be-realized potential for H. longicornis to acquire North American tick-borne pathogens.

Alpha-gal syndrome and the gastrointestinal reaction: a narrative review

Gastrointestinal (GI) disturbances such as abdominal pain, nausea, and diarrhea are infrequently attributed to food allergies as an initial diagnosis in the absence of more traditional allergic reactions like hives, angioedema, or anaphylaxis. Alpha-gal syndrome (AGS) is an atypical and under-recognized allergy characterized by a delayed hypersensitivity reaction to the oligosaccharide galactose-α-1,3-galactose, a carbohydrate found in non-primate mammalian meat and derived products. This review of the current literature on AGS focuses on GI manifestations and diagnostic challenges. While clinical presentations of AGS vary widely, predominant or isolated GI symptoms, when manifested, can overlap with other disorders, thus making a timely and accurate diagnosis challenging. Here we provide an updated review of the epidemiology, pathophysiology, clinical presentation, and management of AGS. Current diagnostic approaches, treatment strategies, and areas requiring further research are also discussed.

A simple improved method for extracting DNA from ethanol-preserved hard ticks and its applications

Hard tick exoskeletons, composed primarily of chitin, pose a significant challenge for researchers attempting to extract genetic material. This study presents a simple modified, alternative method for extracting DNA from ethanol-preserved hard ticks. The extracted DNA was further used for PCR amplification of phylogenetic markers for population genetics studies. The study also improvises the DNA extraction methods from commercial kits. We have used four DNA extraction methods: Modified Simple Alkaline Lysis, and other commercial kit-based methods (Kit X, Kit Y & Kit Z). The modified method for DNA extraction yielded comparable results in terms of concentration, and purity from all the life stages (adult, nymph, and larvae). The extracted DNA from each method was quantified and subjected to PCR amplification of molecular markers, ITS-1 and ITS-2. The nucleotide sequences from both markers were characterized for the first time and used for phylogenetic analysis of Amblyomma integrum, which is a potential vector for Kyasanur Forest Disease Virus (KFDV), causing monkey fever disease in India. These results demonstrate a cost-effective approach for isolating genomic DNA suitable for PCR amplification and subsequent nucleotide sequencing. Importantly, this simple method offers an option for population genetics study in resource-limited settings, facilitating field research with minimal equipment requirements. Additionally, the study showed tick homogenization can significantly improve DNA yield from commercial kits.

Dermatologic manifestations of zoonotic diseases transmitted by dogs: "Spot" could give you spots

The bond between humans and dogs is precious and has been treasured since ancient times. Dog ownership is linked to numerous health benefits, such as increased physical activity and social functioning and decreased depression and cardiovascular events. However, dogs can transmit zoonotic diseases to humans, many of which present with cutaneous findings. This review summarizes the dermatologic manifestations, transmission routes, diagnosis, and treatment of zoonotic diseases transmitted by dogs, including vector-borne, bacterial, viral, fungal, and parasitic infections. This review emphasizes the significance of clinicians obtaining a comprehensive exposure history when patients exhibit a rash of unknown origin. Such an approach can provide valuable epidemiological clues related to diagnosing a zoonotic disease transmitted by a pet dog. Furthermore, identifying the dog as an infection source and subsequent veterinary treatment can help prevent recurrent infections in dermatologic patients.

Analysis of Amblyomma americanum microRNAs in response to Ehrlichia chaffeensis infection and their potential role in vectorial capacity

Background

MicroRNAs (miRNAs) represent a subset of small noncoding RNAs and carry tremendous potential for regulating gene expression at the post-transcriptional level. They play pivotal roles in distinct cellular mechanisms including inhibition of bacterial, parasitic, and viral infections via immune response pathways. Intriguingly, pathogens have developed strategies to manipulate the host's miRNA profile, fostering environments conducive to successful infection. Therefore, changes in an arthropod host's miRNA profile in response to pathogen invasion could be critical in understanding host-pathogen dynamics. Additionally, this area of study could provide insights into discovering new targets for disease control and prevention. The main objective of the present study is to investigate the functional role of differentially expressed miRNAs upon Ehrlichia chaffeensis, a tick-borne pathogen, infection in tick vector, Amblyomma americanum.

Methods

Small RNA libraries from uninfected and E. chaffeensis-infected Am. americanum midgut and salivary gland tissues were prepared using the Illumina Truseq kit. Small RNA sequencing data was analyzed using miRDeep2 and sRNAtoolbox to identify novel and known miRNAs. The differentially expressed miRNAs were validated using a quantitative PCR assay. Furthermore, a miRNA inhibitor approach was used to determine the functional role of selected miRNA candidates.

Results

The sequencing of small RNA libraries generated >147 million raw reads in all four libraries and identified a total of >250 miRNAs across the four libraries. We identified 23 and 14 differentially expressed miRNAs in salivary glands, and midgut tissues infected with E. chaffeensis, respectively. Three differentially expressed miRNAs (miR-87, miR-750, and miR-275) were further characterized to determine their roles in pathogen infection. Inhibition of target miRNAs significantly decreased the E. chaffeensis load in tick tissues, which warrants more in-depth mechanistic studies.

Conclusions

The current study identified known and novel miRNAs and suggests that interfering with these miRNAs may impact the vectorial capacity of ticks to harbor Ehrlichia. This study identified several new miRNAs for future analysis of their functions in tick biology and tick-pathogen interaction studies.

Analysis of Amblyomma americanum microRNAs in response to Ehrlichia chaffeensis infection and their potential role in vectorial capacity

Background

MicroRNAs (miRNAs) represent a subset of small noncoding RNAs and carry tremendous potential for regulating gene expression at the post-transcriptional level. They play pivotal roles in distinct cellular mechanisms including inhibition of bacterial, parasitic, and viral infections via immune response pathways. Intriguingly, pathogens have developed strategies to manipulate the host's miRNA profile, fostering environments conducive to successful infection. Therefore, changes in an arthropod host's miRNA profile in response to pathogen invasion could be critical in understanding host-pathogen dynamics. Additionally, this area of study could provide insights into discovering new targets for disease control and prevention. The main objective of the present study is to investigate the functional role of differentially expressed miRNAs upon Ehrlichia chaffeensis, a tick-borne pathogen, infection in tick vector, Amblyomma americanum.

Methods

Small RNA libraries from uninfected and E. chaffeensis-infected Am. americanum midgut and salivary gland tissues were prepared using the Illumina Truseq kit. Small RNA sequencing data was analyzed using miRDeep2 and sRNAtoolbox to identify novel and known miRNAs. The differentially expressed miRNAs were validated using a quantitative PCR assay. Furthermore, a miRNA inhibitor approach was used to determine the functional role of selected miRNA candidates.

Results

The sequencing of small RNA libraries generated >147 million raw reads in all four libraries and identified a total of >250 miRNAs across the four libraries. We identified 23 and 14 differentially expressed miRNAs in salivary glands, and midgut tissues infected with E. chaffeensis, respectively. Three differentially expressed miRNAs (miR-87, miR-750, and miR-275) were further characterized to determine their roles in pathogen infection. Inhibition of target miRNAs significantly decreased the E. chaffeensis load in tick tissues, which warrants more in-depth mechanistic studies.

Conclusions

The current study identified known and novel miRNAs and suggests that interfering with these miRNAs may impact the vectorial capacity of ticks to harbor Ehrlichia. This study identified several new miRNAs for future analysis of their functions in tick biology and tick-pathogen interaction studies.

Heartland Virus Disease-An Underreported Emerging Infection

First recognized 15 years ago, Heartland virus disease (Heartland) is a tickborne infection contracted from the transmission of Heartland virus (HRTV) through tick bites from the lone star tick (Amblyomma americanum) and potentially other tick species. Heartland symptoms include a fever <100.4 °F, lethargy, fatigue, headaches, myalgia, a loss of appetite, nausea, diarrhea, weight loss, arthralgia, leukopenia and thrombocytopenia. We reviewed the existing peer-reviewed literature for HRTV and Heartland to more completely characterize this rarely reported, recently discovered illness. The absence of ongoing serosurveys and targeted clinical and tickborne virus investigations specific to HRTV presence and Heartland likely contributes to infection underestimation. While HRTV transmission occurs in southern and midwestern states, the true range of this infection is likely larger than now understood. The disease's proliferation benefits from an expanded tick range due to rising climate temperatures favoring habitat expansion. We recommend HRTV disease be considered in the differential diagnosis for patients with a reported exposure to ticks in areas where HRTV has been previously identified. HRTV testing should be considered early for those matching the Heartland disease profile and nonresponsive to initial broad-spectrum antimicrobial treatment. Despite aggressive supportive therapy, patients deteriorating to sepsis early in the course of the disease have a very grim prognosis.

Identification, Baculoviral Expression, and Biochemical Characterization of a Novel Cholinesterase of Amblyomma americanum (Acari: Ixodidae)

A cDNA encoding a novel cholinesterase (ChE, EC 3.1.1.8) from the larvae of Amblyomma americanum (Linnaeus) was identified, sequenced, and expressed in Sf21 insect cell culture using the baculoviral expression vector pBlueBac4.5/V5-His. The open reading frame (1746 nucleotides) of the cDNA encoded 581 amino acids beginning with the initiation codon. Identical cDNA sequences were amplified from the total RNA of adult tick synganglion and salivary gland, strongly suggesting expression in both tick synganglion and saliva. The recombinant enzyme (rAaChE1) was highly sensitive to eserine and BW284c51, relatively insensitive to tetraisopropyl pyrophosphoramide (iso-OMPA) and ethopropazine, and hydrolyzed butyrylthiocholine (BuTCh) 5.7 times as fast as acetylthiocholine (ATCh) at 120 µM, with calculated K_M values for acetylthiocholine (ATCh) and butyrylthiocholine of 6.39 µM and 14.18 µM, respectively. The recombinant enzyme was highly sensitive to inhibition by malaoxon, paraoxon, and coroxon in either substrate. Western blots using polyclonal rabbit antibody produced by immunization with a peptide specific for rAaChE1 exhibited reactivity in salivary and synganglial extract blots, indicating the presence of AaChE1 antigenic protein. Total cholinesterase activities of synganglial or salivary gland extracts from adult ticks exhibited biochemical properties very different from the expressed rAaACh1 enzyme, evidencing the substantial presence of additional cholinesterase activities in tick synganglion and saliva. The biological function of AaChE1 remains to be elucidated, but its presence in tick saliva is suggestive of functions in hydrolysis of cholinergic substrates present in the large blood mean and potential involvement in the modulation of host immune responses to tick feeding and introduced pathogens.

Lethal Effects of Imergard WP, a Perlite-based Dust, on Amblyomma americanum (Ixodida: Ixodidae) Larvae and Nymphs

As resistance in economically and medically important ixodids (hard ticks, Ixodida: Ixodidae) to conventional synthetic toxin-based acaricides has become increasingly widespread, research efforts to identify alternative control tactics have intensified. Laboratory bioassays on the lone star tick, Amblyomma americanum (L.), as a model for other ixodid species, were conducted to assess the efficiency of Imergard WP perlite-based dust versus CimeXa, a silica gel-based insecticidal product that is highly effective against ixodid larvae and nymphs. Each of the two inert desiccant dusts immobilized A. americanum larvae and nymphs within 4-6 h, and killed 100% of the ixodids by 24 h after contact by brief immersion in dry dusts, and after they crawled ≈7.3 cm across a filter paper disc treated with the dusts. Contact by crawling on a dried aqueous film of the dusts, however, did not immobilize and kill the ixodids by 24 h. Similar to silica gel-based desiccant dust, dry perlite-based Imergard WP dust might prophylactically protect cattle and other animals from medically and agriculturally important ixodid pests. Perlite can potentially be stored indefinitely, it can retain its lethal properties for as long as adequate amounts remain on a substrate, and it might be acceptable for limited application in environmentally sensitive habitats.

Seasonal Dynamics of Tick Species in the Ecotone of Parks and Recreational Areas in Middlesex County (New Jersey, USA)

People often use parks and other forested areas for outdoor activities such as hiking and walking their dogs. Areas of primary use are paths or grassy meadows on the edges of the forests that constitute transitional areas between different plant communities (aka ecotones). In this study, we monitored the seasonal dynamics of questing ticks in forest/meadow and forest/path ecotones in five areas in Middlesex County, New Jersey (NJ). We found anthropophilic species such as Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis coexisting with Haemaphysalis longicornis, an invasive tick species first detected in NJ in 2017. Surveillance was conducted weekly from March to November 2020, and collected ticks were identified. The most abundant tick species was H. longicornis (83%), followed by A. americanum (9%), I. scapularis (7%), and D. variabilis (<1%). The seasonal dynamics of A. americanum and I. scapularis in the ecotone were similar to previous surveys in forest habitats. The presence of anthropophilic ticks, particularly I. scapularis, suggests the need for specific control approaches to target these habitats. In addition, the extraordinarily high numbers of H. longicornis collected in ecotones (1.70 ticks/m2) and frequent reports of this species on dogs highlight the importance of monitoring its expansion due to its potential as a vector of animal and human diseases.

Comprehensive Review of Emergence and Virology of Tickborne Bourbon Virus in the United States

This novel human pathogenic tickborne thogotovirus is found in the eastern and central regions of the country.

The emergence of SARS-CoV-2 and the worldwide COVID-19 pandemic triggered considerable attention to the emergence and evolution of novel human pathogens. Bourbon virus (BRBV) was first discovered in 2014 in Bourbon County, Kansas, USA. Since its initial discovery, several cases of BRBV infection in humans have been identified in Kansas, Oklahoma, and Missouri. BRBV is classified within the Thogotovirus genus; these negative-strand RNA viruses appear to be transmitted by ticks, and much of their biology remains unknown. In this review, we describe the emergence, virology, geographic range and ecology, and human disease caused by BRBV and discuss potential treatments for active BRBV infections. This virus and other emerging viral pathogens remain key public health concerns and require continued surveillance and study to mitigate human exposure and disease.

A Systematic Review of the Distribution of Tick-Borne Pathogens in Wild Animals and Their Ticks in the Mediterranean Rim between 2000 and 2021

Tick-borne pathogens (TBPs) can be divided into three groups: bacteria, parasites, and viruses. They are transmitted by a wide range of tick species and cause a variety of human, animal, and zoonotic diseases. A total of 148 publications were found on tick-borne pathogens in wild animals, reporting on 85 species of pathogens from 35 tick species and 17 wild animal hosts between 2000 and February 2021. The main TBPs reported were of bacterial origin, including Anaplasma spp. and Rickettsia spp. A total of 72.2% of the TBPs came from infected ticks collected from wild animals. The main tick genus positive for TBPs was Ixodes. This genus was mainly reported in Western Europe, which was the focus of most of the publications (66.9%). It was followed by the Hyalomma genus, which was mainly reported in other areas of the Mediterranean Rim. These TBPs and TBP-positive tick genera were reported to have come from a total of 17 wild animal hosts. The main hosts reported were game mammals such as red deer and wild boars, but small vertebrates such as birds and rodents were also found to be infected. Of the 148 publications, 12.8% investigated publications on Mediterranean islands, and 36.8% of all the TBPs were reported in seven tick genera and 11 wild animal hosts there. The main TBP-positive wild animals and tick genera reported on these islands were birds and Hyalomma spp. Despite the small percentage of publications focusing on ticks, they reveal the importance of islands when monitoring TBPs in wild animals. This is especially true for wild birds, which may disseminate their ticks and TBPs along their migration path.

Northward Expansion of Amblyomma americanum (Acari: Ixodidae) into Southwestern Michigan

Amblyomma americanum (Linnaeus) (Acari: Ixodidae) (lone star tick) is an aggressive, generalist parasite that vectors numerous important human and animal pathogens. In recent decades its geographic range has expanded northwards from endemic regions in the southeastern and southcentral United States. In 2019 five questing A. americanum ticks, comprising two life stages were detected at one site in southwestern Michigan, satisfying one CDC criterium for an established population for the first time in recent history in the state. To better characterize the extent of emerging A. americanum, we conducted active surveillance (i.e., drag sampling) in summer 2020 throughout Michigan's southern counties and detected one adult A. americanum from each of six widespread sites, including where they had been detected in 2019. A larger established population was identified at another site in Berrien County, which yielded 691 A. americanum comprising three life stages, and questing phenologies here were similar to that reported for other endemic regions. Statewide surveillance in 2021 revealed no A. americanum outside of Berrien County, but establishment criteria were met again at the two sites where established populations were first detected respectively in 2019 and 2020. These observations may represent the successful invasion of A. americanum into Michigan. Data from passive (1999-2020) and active surveillance (2004-2021) efforts, including a domestic animal sentinel program (2015-2018), are reported to provide context for this nascent invasion. Continued active surveillance is needed to help inform the public, medical professionals, and public health officials of the health risks associated with this vector.

Eight years' advances on Bourbon virus, a tick-born Thogotovirus of the Orthomyxovirus family

Bourbon virus (BRBV) was first isolated from a blood sample collected from a male patient living in Bourbon county, Kansas, during the spring of 2014. The patient later died due to complications associated with multiorgan failure. Currently, several BRBV infection-caused deaths have been reported in the United States, and misdiagnosed cases are often undercounted. BRBV is a member of the genus Thogotovirus of the Orthomyxoviridae family, and is transmitted through the Lone Star tick, Amblyomma Americanum, in North America. Currently, there are no specific antivirals or vaccinations available to treat or prevent BRBV infection. Several small molecular compounds have been identified to effectively inhibit BRBV infection of in vitro cell cultures at a single- or sub-micromolar level. Favipiravir, an RNA-dependent RNA polymerase inhibitor, prevented the death of Type I interferon receptor knockout mice infected with BRBV infection.