Tick-borne zoonoses and commonly used diagnostic methods in human and veterinary medicine

Key molecules regulating the blood meals of Rhipicephalus sanguineus (Acari: Ixodidae) revealed by transcriptomics

Rhipicephalus sanguineus, a repulsive obligate blood feeder, is a three-host tick inflicting tremendous damage. Blood-sucking initiates tick-pathogen-host interactions along with alterations in the expression levels of numerous bioactive ingredients. Key molecules regulating blood meals were identified using the transcriptomic approach. A total number of 744 transcripts showed statistically significantly differential expression including 309 significantly upregulated transcripts and 435 significantly downregulated transcripts in semiengorged female ticks compared to unfed ticks, all collected in 2021. The top 10 differentially upregulated transcripts with explicit functional annotations included turripeptide OL55-like protein, valine tRNA ligase-like protein and ice-structuring glycoprotein-like protein. The top 10 differentially down-regulated transcripts were uncharacterized proteins. Gene Ontology (GO) enrichment analysis revealed four associated terms in the cellular component category and 16 in the molecular function category among the top 20 terms. Differentially expressed genes (DEGs) were enriched in GO terms ID 0000323 (lytic vacuole) and ID 0005773 (vacuole). The top 20 enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways included metabolism, cellular processes, organismal systems and human diseases. The DEGs were enriched in the KEGG term ID: ko-04142 (lysosome pathway) associated with intracellular digestion in the tick midgut epithelium. Molecular markers annotated via comparative transcriptomic profiling were expected to be candidate markers for the purpose of tick control.

Spatial and Seasonal Patterns of Tick Infestations in Kassena-Nankana Livestock

The ability of ticks to adapt to different ecological zones, coupled with the spread of infectious pathogens negatively affects livestock production and thus, there is a need for better control strategies. However, control measures within a geographical region can only be effective if there is available information on tick population dynamics and ecology. This study focused on ticks infesting livestock in the Kassena-Nankana Districts of the Upper East Region of Ghana. The ticks were morphologically identified, variables such as season, animal host, and predilection sites were recorded, and the data were analyzed using STATA version 13. Out of 448 livestock examined, tick infestation in cattle was (78.60%), followed by sheep (25%) and goats (5.88%). A total of 1,550 ticks including nymphs (303) and adults (1,247) were collected. Adult ticks were found to be significantly associated with season (p < 0.001), with a high burden in the wet season. The nymph burden and body parts of livestock hosts were significantly associated with more nymphs collected from male animals than females (p < 0.001). Three genera of ticks, Amblyomma (62.97%), Hyalomma (18.71%), and Rhipicephalus (18.32%) were morphologically identified with the most predominant tick species recorded as Amblyomma variegatum (62.97%). Matured A. variegatum was sampled primarily in the wet season with their predilection site as the udder/scrotum (p < 0.001). However, adult Hyalomma truncatum was observed to have a significant association with the anal region (p < 0.001). Findings from this study are essential for formulating tick control measures to prevent the spread of infectious pathogens.

Recombinant protein immunoblots for differential diagnosis of tick-borne relapsing fever and Lyme disease

Lyme disease (LD) is caused by a group of tick-borne bacteria of the genus Borrelia termed Lyme disease Borreliae (LDB). The detection of serum antibodies to specific LDB antigens is widely used to support diagnosis of LD. Recent findings highlight a need for serological tests that can differentiate LD from tick-borne relapsing fever (TBRF) caused by a separate group of Borrelia species termed relapsing fever Borreliae. This is because LD and TBRF share some clinical symptoms and can occur in overlapping locations. The development of serological tests for TBRF is at an early stage compared with LD. This article reviews the application of line immunoblots (IBs), where recombinant proteins applied as lines on nitrocellulose membrane strips are used to detect antibodies in patient sera, for the diagnosis and differentiation of LD and TBRF.

First record of Rhipicephalus (Boophilus) microplus in Ghana, a potential risk to livestock production

Ticks are a public health threat due to their tendency to spread pathogens that affect humans and animals. With reports of Rhipicephalus (Boophilus) microplus invasion in neighbouring countries, there is the risk of this species invading Ghana through livestock trade. Previous identification of tick species in Ghana has been based on morphological identification, which can be ineffective, especially with damaged tick specimens or engorged nymphs. This study focused on the Kassena-Nankana District, which serves as a trade route for cattle into Ghana, to determine the presence of R. microplus. Three genera of ticks were identified as Amblyomma (70.9%), Hyalomma (21.3%) and Rhipicephalus (7.8%). The engorged nymphs that could not be identified morphologically were analyzed using primers that target the mitochondrial 16S rRNA gene. This study reports the first record of R. (B.) microplus in Ghana. Furthermore, R. microplus constituted 54.8% of the Boophilus species collected in this study. This finding is an addition to the diverse tick species previously collected in Ghana, most of which are of veterinary and public health importance. With reports of acaricide resistance in R. microplus and its role in spreading infectious pathogens, the detection of this species in Ghana cannot be overlooked. Nationwide surveillance will be essential to ascertain its distribution, its effects on cattle production, and the control measures adopted.

Molecular Epidemiology and Species Diversity of Tick-Borne Pathogens of Animals in Egypt: A Systematic Review and Meta-Analysis

Ticks and tick-borne pathogens (TTBPs) are listed among the most serious concerns harming Egyptian livestock’s productivity. Several reports on tick-borne pathogens (TBPs) from various geographical regions in the country were published. However, data on the molecular characterization of TBPs are the most beneficial for understanding the epidemiology of this important group of pathogens. In this study, we present the first meta-analysis on the molecular epidemiology and species diversity of TBPs infecting animals in Egypt. All published studies on TBPs were systematically collected from various databases (PubMed, Scopus, ScienceDirect, the Egyptian Knowledge Bank, and Google Scholar). Data from eligible papers were extracted and subjected to various analyses. Seventy-eight studies were found to be eligible for inclusion. Furthermore, ticks infesting animals that were molecularly screened for their associated pathogens were also included in this study to display high species diversity and underline the high infection risk to animals. Theileria annulata was used as parasite model of TBPs to study the genetic diversity and transmission dynamics across different governorates of Egypt. This study extends cross-comparisons between all published molecular data on TBPs in Egypt and provides resources from Egyptian data in order to better understand parasite epidemiology, species diversity, and disease outcome as well as the development and implementation of prevention and control methods for public health, veterinary care practitioners, and animal owners all over the country.

Recent Advances in the Immunologic Method Applied to Tick-Borne Diseases in Brazil

Zoonotic-origin infectious diseases are one of the major concerns of human and veterinary health systems. Ticks, as vectors of several zoonotic diseases, are ranked second only to mosquitoes as vectors. Many ticks’ transmitted infections are still endemic in the Americas, Europe, and Africa and represent approximately 17% of their infectious diseases population. Although our scientific capacity to identify and diagnose diseases is increasing, it remains a challenge in the case of tick-borne conditions. For example, in 2017, 160 cases of the Brazilian Spotted Fever (BSF, a tick-borne illness) were confirmed, alarming the notifiable diseases information system. Conversely, Brazilian borreliosis and ehrlichiosis do not require notification. Still, an increasing number of cases in humans and dogs have been reported in southeast and northeastern Brazil. Immunological methods applied to human and dog tick-borne diseases (TBD) show low sensitivity and specificity, cross-reactions, and false IgM positivity. Thus, the diagnosis and management of TBD are hampered by the personal tools and indirect markers used. Therefore, specific and rapid methods urgently need to be developed to diagnose the various types of tick-borne bacterial diseases. This review presents a brief historical perspective on the evolution of serological assays and recent advances in diagnostic tests for TBD (ehrlichiosis, BSF, and borreliosis) in humans and dogs, mainly applied in Brazil. Additionally, this review covers the emerging technologies available in diagnosing TBD, including biosensors, and discusses their potential for future use as gold standards in diagnosing these diseases.

Current and Future Molecular Diagnostics of Tick-Borne Diseases in Cattle

Ticks and tick-borne diseases such as babesiosis, anaplasmosis, ehrlichiosis, Lyme disease, Crimean Congo hemorrhagic fever, and Rocky Mountain spotted fever pose a significant threat to animal and human health. Tick-borne diseases cause billions of dollars of losses to livestock farmers annually. These losses are partially attributed to the lack of sensitive, robust, cost effective and efficient diagnostic approaches that could detect the infectious pathogen at the early stages of illness. The modern nucleic acid-based multiplex diagnostic approaches have been developed in human medicine but are still absent in veterinary medicine. These powerful assays can screen 384 patient samples at one time, simultaneously detect numerous infectious pathogens in each test sample and provide the diagnostic answer in a few hours. Development, commercialization, and wide use of such high throughput multiplex molecular assays in the cattle tick-borne disease surveillance will help in early detection and control of infectious pathogens in the animal reservoir before community spread and spillover to humans. Such approaches in veterinary medicine will save animal life, prevent billions of dollars of economic loss to cattle herders and reduce unwanted stress to both human and animal health care systems. This literature review provides recent updates on molecular diagnostics of tick-borne pathogens and discusses the importance of modern nucleic acid high throughput multiplex diagnostic approaches in the prevention of tick-borne infection to livestock.

Vector Surveillance and Pathogen Detection in the Working Areas of Military Working Dogs in Eastern Austria

Vector-borne diseases play a major role in human and veterinary medicine worldwide. A previous study detected asymptomatic vector-borne pathogens in military working dogs stationed at a military base in eastern Austria, and a follow-up survey of potential arthropod vectors was conducted in spring 2019 and 2020 in the vicinity of the base to evaluate the presence of vectors and their carrier status for a range of canine and zoonotic pathogens. A total of 1324 ticks (nymphs and adults of Ixodes ricinus, comprising 92.9% of the collected specimens, and adults of Haemaphysalis inermis, a tick previously only rarely described in Austria, Haemaphysalis concinna, and Dermacentor reticulatus) were collected by flagging. In 44.1% (125/284) of all pools (n = 284), one infectious agent was found; in 27.8% (79/284) and in 1.1% (3/284), two and three different agents, respectively, could be identified. Overall, 72.9% of the pools contained at least one pathogen (Borrelia spp., Rickettsia spp., Bartonella spp., and Babesia microti). Borrelia mijamotoi, B. lustinaniae, and B. microti were previously only described in single cases in Austria. Mosquitoes were collected with BG-Sentinel traps monthly during the summer of 2019. A total of 71 individuals from 11 species were collected. No filarioid DNA was detected in the mosquito sample pools, although Dirofilaria repens had been present in the dogs from the military site. In conclusion, vector surveillance should be combined with the surveillance of an exposed population whenever possible to estimate the infection risks for dogs and their handlers.

Evaluation of two artificial infection methods of live ticks as tools for studying interactions between tick-borne viruses and their tick vectors

Up to 170 tick-borne viruses (TBVs) have been identified to date. However, there is a paucity of information regarding TBVs and their interaction with respective vectors, limiting the development of new effective and urgently needed control methods. To overcome this gap of knowledge, it is essential to reproduce transmission cycles under controlled laboratory conditions. In this study we assessed an artificial feeding system (AFS) and an immersion technique (IT) to infect Ixodes ricinus ticks with tick-borne encephalitis (TBE) and Kemerovo (KEM) virus, both known to be transmitted predominantly by ixodid ticks. Both methods permitted TBEV acquisition by ticks and we further confirmed virus trans-stadial transmission and onward transmission to a vertebrate host. However, only artificial feeding system allowed to demonstrate both acquisition by ticks and trans-stadial transmission for KEMV. Yet we did not observe transmission of KEMV to mice (IFNAR^-/- or BALB/c). Artificial infection methods of ticks are important tools to study tick-virus interactions. When optimally used under laboratory settings, they provide important insights into tick-borne virus transmission cycles.

Molecular detection of Rickettsia sp. cf. Rickettsia monacensis in Ixodes sp. cf. Ixodes affinis collected from white-tailed deer in Campeche, Mexico

Deer encompass a group of large-sized vertebrates that serve as hosts for a wide variety of ectoparasites, mainly ticks. In Mexico, ticks have relevance as vectors of pathogenic microorganisms, and 20 species of hard ticks are associated with four species of deer, although only a single study has been conducted to detect bacterial agents associated with ticks from deer in the country. In February, 2019 three white-tailed deers (Odocoileus virginianus) were hunted from the locality of Chiná from the municipality of Campeche, Mexico. The sampled deers were parasitized by 26 ticks belonged to three species: Amblyomma mixtum (5♀, 1♂), Amblyomma ovale (2♀, 1♂), and Ixodes sp. cf. Ixodes affinis (15♀, 2♂). Specimens were screened individually for Anaplasma, Borrelia, Ehrlichia, and Rickettsia DNA by the amplification of several fragments of 16S rRNA, gltA, 17-kDa, and flaB genes. This study report for the first time the presence of Rickettsia sp. cf. Rickettsia monacensis in Ixodes sp. cf. Ixodes affinis in Mexico.