Ticks as vectors: taxonomy, biology and ecology

Detection of Crimean-Congo haemorrhagic fever virus in Hyalomma marginatum ticks, southern France, May 2022 and April 2023

Crimean-Congo haemorrhagic fever (CCHF), a potentially severe zoonotic viral disease causing fever and haemorrhagic manifestations in humans. As the Crimean-Congo haemorrhagic fever virus (CCHFV) has been detected in ticks in Spain and antibodies against the virus in ruminant sera in Corsica, it was necessary to know more about the situation in France. In 2022-2023, CCHFV was detected in 155 ticks collected from horses and cattle in southern France.

The diverse functions of Mu-class Glutathione S-transferase HrGSTm1 during the development of Hyalomma rufipes with a focus on the detoxification metabolism of cyhalothrin

BACKGROUND

Glutathione S-transferases (GSTs) are a superfamily of multifunctional enzymes in living organisms with metabolic and detoxification functions, which can detoxify exogenous and endogenous compounds and thereby reduce the damage caused by toxic substances to the body. Ticks are obligate blood-sucking ectoparasites that can transmit various pathogens, and the characterization of tick-derived GSTs may help improve current understanding of the molecular mechanism of tick resistance to insecticides. In this study, a novel GST gene, named HrGSTm1, was identified from Hyalomma rufipes.

METHODS

Sequence analysis was performed by using bioinformatics techniques. A prokaryotic expression system was used to obtain the recombinant expression protein rHrGSTm1. Detection of spatiotemporal expression patterns of target genes and their response to the toxicity of cyhalothrin on female H. rufipes was performed by using a quantitative PCR platform. The optimal enzymological parameters of rHrGSTm1 using glutathione as substrate were calculated. The antioxidant capacity of the recombinant protein was evaluated by DPPH• (1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl). Knockdown of the HrGSTm1 genes through RNA interference was used to analyze their effects on the physiological parameters of ticks. The changes in HrGSTm1 messenger RNA expression patterns under cypermethrin stress were analyzed.

RESULTS

The complementary DNA sequence of HrGSTm1 contained a 672-bp open reading frame, which potentially encoded 223 amino acids. The predicted molecular weight was 25.62 kDa, and the isoelectric point 8.22. HrGSTm1 is a Mu-class GST, belonging to the cytoplasmic GSTs with no signal peptide observed. The Vmax and Km of rHrGSTm1 were 3.367 ± 0.81 uM and 2.208 ± 0.76 uM, respectively, and its activities were dependent on different temperatures and pH conditions; the scavenging rate of rHrGSTm1 to DPPH• reached 76.4% at 1.25 mg/ml. Variable expressions of HrGSTm1 were observed under various treatment periods and in different tissues, with the highest appearing in eggs (analysis of variance [ANOVA], F(2, 9) = 279.9, P < 0.0001) and Malpighian tubules (ANOVA, F(3, 12) = 290.5, P < 0.0001). After knockdown of HrGSTm1, compared with the control group, the mortality in the treatment group was increased by 16.7%, the average oviposition rate decreased by 33.9%, the average engorged body weight decreased by 287.38 mg and egg weight decreased by 127.46 mg, although only the engorged body weight was significantly different (t-test, t(44) = 2.886, P = 0.006). After exposure to three sublethal concentrations (LC05, LC10, LC50) of cyhalothrin, the expression level of HrGSTm1 in the midgut, ovary and salivary gland was upregulated, whereas in Malpighian tubules, it showed a trend of upregulation at first and then downregulation, implying different functions during the detoxification in different tissues.

CONCLUSIONS

In this study, a novel GST of the Mu-class was successfully isolated from H. rufipes and systematically subjected to bioinformatic analysis and recombination identification. The variation trend of HrGSTm1 expression level in different tissues suggests that the gene has different detoxification functions in different tissues. The potential function of this gene was analyzed to provide basic research for further investigation of its detoxification mechanism.

Survey on tick infestation in stray dogs in localities of Malaysia

The close relationship between dogs and humans has led to concerns regarding the transmission of zoonotic pathogens through ectoparasites such as ticks. This study aimed to investigate the occurrence of ticks and the intensity on stray dogs with specific risk factors (size, sex, neutering status, body part). Additionally, identifying the predilection sites of ticks on stray dogs was crucial for developing an effective tick control program in Malaysia. A cross-sectional study was conducted among 64 stray dogs from Kelantan and Selangor States. These dogs were subjected to integumentary examinations, collecting 431 ticks comprising Rhipicephalus sanguineus s.l. "tropical lineage" and Haemaphysalis bispinosa from 53 infested dogs. The overall occurrence of tick infestation was 82.81% (53/64), with an average intensity of 8.13 ticks (range: 1-17) per stray dog. All the potential risk factors considered in this study showed no statistically significant result (P value >0.05). The head, ear, and neck were the most preferred attachment sites for ticks. These findings underscore the importance of implementing tick control programs for stray dogs, which serve as reservoirs of ticks and tick-borne pathogens for owned dogs and humans.

Molecular Detection and Genotyping of Theileria spp. in Deer (Cervidae) in Korea

Major clinical symptoms of Theileria infection include fever, anemia, anorexia, jaundice, and decreased milk production. Although several studies have been conducted on tick-borne pathogens, including Theileria in Korea, only a few have focused on Theileria infection in deer, including the Korean water deer. Blood samples from 160 deer were collected and subjected to DNA extraction and polymerase chain reaction (PCR). Next, PCR-positive samples were sequenced and analyzed by constructing a phylogenetic tree. The results showed that the overall infection rate of Theileria was 8.1% (13/160). Infection rates of 100% were observed in the northern and southern regions. However, the study's limitation was its small sample size, wherein five and one samples were analyzed from the northern and southern regions, respectively. The central region exhibited the lowest infection rate of 2.9% (4/140). Infection rates also differed based on seasons, with the highest (18.4%, 9/49) being observed in spring, followed by that in summer (8.9%, 4/45). However, no infection was observed during autumn and winter. A phylogenetic analysis indicated that the PCR-positive samples contained Theileria luwenshuni, which usually infects small ruminants, such as goats and sheep.

Hard ticks (Acari: Ixodidae) and tick-borne diseases of sheep and goats in Africa: A review

Ticks are leading vectors of economically important pathogens that affect small ruminants due to favourable climatic conditions across different regions of the African continent. They are responsible for both direct and indirect economic losses in the livestock industry. This review focuses on the species diversity of hard ticks, their biology, tick-borne diseases of sheep and goats including non-infectious disease, and risk factors to tick infestation in Africa. Furthermore, our review provides recent updates on distribution of ticks and tick-borne pathogens of small ruminants in Africa. It was observed that several species and subspecies of hard ticks belonging to the genera Hyalomma (Hy), Rhipicephalus (Rh), Ixodes (I) and Amblyomma (Am) were found infesting small ruminants across the different regions of the continent. Of these genera, Rhipicephalus ticks accounts for the majority of the registered species, with exactly 27 different species infesting small ruminant stocks comprising of different developmental instars and adults of the tick. Rhipicephalus decolaratus, Rh. e. evertsi and Rh. appendiculatus were the three most common Rhipicephalus species reported. Both protozoal (Babesia and Theileria) and bacterial (Anaplasma, Rickettsia, Ehrlichia, Coxiella and Mycoplasma) pathogens have being reported to be amplified in several hard tick species and/or small ruminant hosts. Furthermore, tick paralysis and lameness were non-infectious conditions attributed to tick infestations. Amblyomma hebraeum and Rh. glabroscutatum may cause lameness in goats, while Hy. rufipes is responsible for the same condition in Merino sheep. Host paralysis due to a neurotoxin released by female Rh. e. evertsi and I. rubicundus has been documented within the continent. We therefore advocate for the need of integrated control measures against tick-borne pathogens (TBPs) including their arthropod vectors, to be performed simultaneously to ease the burden of vector-borne diseases in small ruminant production.

Detection of the Crimean-Congo Hemorrhagic Fever Virus Genome in Questing Ixodes spp. and Haemaphysalis spp. in the Periurban Forestry Areas of Istanbul: Has a New Biorisk Emerged?

Background: Istanbul is one of the world's most densely populated metropolitan cities, with various geographical areas that possess distinct characteristics. These areas have different climates, vegetation, and host populations that can support the survival of diverse tick species. Turkey is a region with a high risk of Crimean-Congo hemorrhagic fever (CCHF) disease, making it crucial to screen for this risk, especially in densely populated regions such as Istanbul and its surrounding areas. However, the presence of potential vectors for CCHF virus (CCHFV) in these areas has not been studied in the past 12 years. Materials and Methods: In this study, a total of 676 ticks were collected from 6 centers using the flagging and dragging method. Ticks were identified as Ixodes ricinus (7.85%), Ixodes spp. immature form (73.22%), Haemaphysalis parva (0.89%), Haemaphysalis inermis (0.15%), and Haemaphysalis spp. immature form (17.89%). Pooled samples were screened for the CCHFV genome (S segment) by RT-nested PCR. Results: A total of 14.28% of the samples were found as positive. Phylogenetic analysis revealed that all the CCHFV sequences obtained from the positive samples were clustered in clade V: Europe/Turkey genogroup. Conclusion: This study suggests that ixodes spp. and Haemaphysalis spp. may have the potential to pose a biorisk for Crimean-Congo hemorrhagic fever.

Ticks and tick-borne rickettsiae from dogs in El Salvador, with report of the human pathogen Rickettsia parkeri

Twelve tick species have been reported in El Salvador; however, information regarding ticks infesting domestic dogs is lacking, and pathogenic tick-borne Rickettsia species have never been reported in El Salvador. This work evaluated ticks infesting 230 dogs from ten municipalities in El Salvador from July 2019 to August 2020. A total of 1,264 ticks were collected and identified into five species: Rhipicephalus sanguineus sensu lato (s.l.), Rhipicephalus microplus, Amblyomma mixtum, Amblyomma ovale, and Amblyoma cf. parvum. The tick R. sanguineus s.l. was the most frequent species in all localities (81.3% of sampled dogs), followed by Amblyomma mixtum (13.0%), Amblyomma ovale (10.9%) and Amblyomma cf. parvum (10.4%). The overall mean intensity of tick infestation was 5.5 ticks/dog. The highest specific mean intensity value was for R. sanguineus s.l. (4.8 ticks/dog), varying from 1.6 to 2.7 ticks/dog for the three Amblyomma species. From a random sample of 288 tick specimens tested molecularly for the presence of rickettsial agents, three spotted fever group Rickettsia were detected: Rickettsia amblyommatis in 90% (36/40) A. mixtum, 46% (11/24) A. cf. parvum, 4% (7/186) R. sanguineus s.l., and 17% Amblyomma spp.; Rickettsia parkeri strain Atlantic rainforest in 4% (1/25) A. ovale; and an unnamed rickettsia agent, designated as 'Rickettsia sp. ES-A.cf.parvum', in 4% (1/24) A. cf. parvum. Our finding of R. parkeri strain Atlantic rainforest in A. ovale is highly relevant because this agent has been associated to spotted fever illness in other Latin American countries, where A. ovale is implicated as its main vector. These findings suggest that spotted fever cases caused by R. parkeri strain Atlantic rainforest could be occurring in El Salvador.

Integrative analysis highlights molecular and immune responses of tick Amblyomma americanum to Escherichia coli challenge

Ticks are ectoparasites that can transmit various pathogens capable of causing life-threatening illnesses in people and animals, making them a severe public health threat. Understanding how ticks respond to bacterial infection is crucial for deciphering their immune defense mechanisms and identifying potential targets for controlling tick-borne diseases. In this study, an in-depth transcriptome analysis was used to investigate the molecular and immune responses of Amblyomma americanum to infection caused by the microinjection of Escherichia coli. With an abundance of differentially expressed genes discovered at different times, the analysis demonstrated significant changes in gene expression profiles in response to E. coli challenge. Notably, we found alterations in crucial immune markers, including the antimicrobial peptides defensin and microplusin, suggesting they may play an essential role in the innate immune response. Furthermore, KEGG analysis showed that following E. coli exposure, a number of key enzymes, including lysosomal alpha-glucosidase, fibroblast growth factor, legumain, apoptotic protease-activating factor, etc., were altered, impacting the activity of the lysosome, mitogen-activated protein kinase, antigen processing and presentation, bacterial invasion, apoptosis, and the Toll and immune deficiency pathways. In addition to the transcriptome analysis, we constructed protein interaction networks to elucidate the molecular interactions underlying the tick's response to E. coli challenge. Hub genes were identified, and their functional enrichment provided insights into the regulation of cytoskeleton rearrangement, apoptotic processes, and kinase activity that may occur in infected cells. Collectively, the findings shed light on the potential immune responses in A. americanum that control E. coli infection.

Genetic diversity of vector-borne pathogens in ixodid ticks infesting dogs from Pakistan with notes on Ehrlichia canis, Rickettsia raoultii and Dirofilaria immitis detection

BACKGROUND

Vector-/tick-borne pathogens (V/TBPs) pose a potential threat to human and animal health globally. Information regarding canine V/TBPs is scarce and no specific study has been conducted so far to explore the microbial diversity within ticks infesting dogs from Pakistan. Herein, this knowledge gap is addressed by assessing the genetic diversity and prevalence pattern of V/TBPs in ixodid ticks with special implications for public and canine health.

METHODS

A total of 1150 hard ticks were collected from 300 dogs across central Khyber Pakhtunkhwa (KP), Pakistan. After morpho-molecular identification, 120 tick samples were screened for the presence of V/TBPs by amplifying 16S rRNA/gltA (Rickettsia/Ehrlichia and Wolbachia sp.), 18S rRNA (Theileria sp.) and cox1 (Dirofilaria sp.) genes through PCR followed by sequencing and phylogenetic study.

RESULTS

In toto, 50 ixodid ticks (50/120, 41.7%) were found positive for V/TBPs DNA. The detected V/TBPs were categorized into five genera and eight species, viz. Ehrlichia (E. canis and Ehrlichia sp.), Rickettsia (R. massiliae, R. raoultii and Rickettsia sp.), Theileria (T. annulata), Dirofilaria (D. immitis) and Wolbachia (Wolbachia sp.). The pathogen prevalence patterns showed that R. massiliae was the most prevalent zoonotic V/TBP (19.5%), followed by E. canis (10.8%), Rickettsia sp. (7.5%), R. raoultii (6.7%), T. annulata (5.8%), D. immitis (5.8%), Wolbachia sp. (4.2%) and Ehrlichia sp. (3.3%), respectively. Among the screened tick species, most Rhipicephalus sanguineus sensu lato samples were found positive for V/TBP DNA (20/20,100%) followed by Rh. turanicus sensu stricto (13/20, 65%), Hyalomma dromedarii (8/20, 40%), Rh. haemaphysaloides (6/20, 30%), Hy. excavatum (2/20, 10%) and Rh. microplus (1/20, 5%). Co-occurrence of V/TBP was also detected in tick specimens (single V/TBP infection: 32 ticks; double and triple: 13 and 5 tick samples). The detected pathogens shared a phylogenetic relationship with similar isolates published in NCBI GenBank from Old and New World countries.

CONCLUSION

Ixodid ticks infesting dogs harbor a diverse array of V/TBPs including zoonotic agents from Pakistan. Furthermore, the presence of D. immitis in ticks that infest dogs raises the possibility that this parasite has either attained its dead-end host (i.e. the tick) while feeding on dogs or has expanded its range of intermediate/paratenic hosts. Further research work is needed to investigate the epidemiology and confirm the vector competence of screened tick species for these pathogens from Pakistan.

Characterization of bacterial communities in ticks parasitizing cattle in a touristic location in southwestern China

The purpose of this study was to investigate tick species around Mount Fanjing and analyze bacterial communities in two species - Rhipicephalus microplus and Haemaphysalis longicornis - parasitizing cattle in Tongren, Guizhou province, Southwest China, using high-throughput sequencing methods. In April 2019, ticks were collected from five sites in Jiangkou County, Yinjiang County, and Songtao County. In total, 296 ticks were collected, comprising two genera and three species: H. longicornis, Haemaphysalis flava, and R. microplus. Rhipicephalus microplus was the most representative species (57.4%) within the collected group, being the dominant species in Tongren City, followed by H. longicornis (39.5%) and H. flava (3.0%). Beta-diversity analysis revealed differences in bacterial community composition among the tick species. The bacterial community structure of R. microplus collected in the three counties was highly similar. Chlorella and Bacillus were highly abundant in H. longicornis. Rickettsia was detected at high relative abundance in R. microplus but in low relative abundance in H. longicornis, suggesting that Rickettsia is more associated with R. microplus than with H. longicornis. More in-depth investigations are needed to determine the pathogenic risk of Rickettsia and its relationship with the host. This is the first survey on tick-borne bacterial communities in this area, which is of great significance for the prevention and control of tick-borne diseases locally.

Molecular Detection of Tick-Borne Bacterial and Protozoan Pathogens in Haemaphysalis longicornis (Acari: Ixodidae) Ticks from Free-Ranging Domestic Sheep in Hebei Province, China

Ticks and tick-borne pathogens significantly threaten human and animal health worldwide. Haemaphysalis longicornis is one of the dominant tick species in East Asia, including China. In the present study, 646 Ha. longicornis ticks were collected from free-ranging domestic sheep in the southern region of Hebei Province, China. Tick-borne pathogens of zoonotic and veterinary importance (i.e., Rickettsia, Anaplasma, Ehrlichia, Borrelia, Theileria, and Hepatozoon spp.) were detected in the ticks using PCR assays and sequence analysis. The prevalence rates of these pathogens were 5.1% (33/646), 15.9% (103/646), 1.2% (8/646), 17.0% (110/646), 0.15% (1/646), and 0.15% (1/646), respectively. For Rickettsia spp., R. japonica (n = 13), R. raoultii (n = 6), and Candidatus R. jingxinensis (n = 14) were detected for the first time in the province, while several Anaplasma spp. were also detected in the ticks, including A. bovis (n = 52), A. ovis (n = 31), A. phagocytophilum (n = 10), and A. capra (n = 10). A putative novel Ehrlichia spp. was also found with a prevalence of 1.2% in the area. The present study provides important data for effectively controlling ticks and tick-borne diseases in the Hebei Province region of China.

Detection, identification and genotyping of Borrelia spp. in ticks of Coastal-Karst and Littoral-Inner Carniola regions in Slovenia

The density and spread of tick vector species have increased throughout Europe in the last 30 years, leading to an increase of Lyme borreliosis cases, including in Slovenia. The aim of this study was to isolate Borrelia strains and determine the prevalence of B. burgdorferi sensu lato and B. miyamotoi in adults of Ixodes ricinus (Linnaeus) collected in 2019 in the two regions of the country (Coastal-Karst and Littoral-Inner Carniola) by cultivation and PCR. We isolated B. burgdorferi s.l. by culture method in 28/559 (5%) ticks from both regions. Culture-negative samples (531/559, i.e., 95%) were additionally tested by real-time PCR. In 155/531 (29.2%) PCR-positive samples, a fragment of flaB or glpQ was amplified and further sequenced to identify species of the Borrelia. Using both methods, cultivation and PCR, Borrelia spp. prevalence was 32.7% in the Coastal-Karst region and 33.0% in the Littoral-Inner Carniola region. Genotyping of the Borrelia spp. isolates revealed that 17/28 (60%) were B. garinii subtype Mlg2. Of all tick samples tested for B. miyamotoi 8/398 (2%) were PCR positive. Based on previous studies in these regions, we had expected more ticks to be infected with B. afzelii, but genotyping revealed that B. garinii was the most abundant.

Assessing the spatial and temporal patterns and risk factors for acquisition of Ixodes spp. by companion animals across Canada

Climatic and land use changes have contributed to substantial changes in the abundance, distribution, and activity patterns of ticks in Canada, which have led to an increased risk of tick bites and tick-borne pathogen exposure for companion animals. The objectives of this study were to describe current spatial and temporal patterns of Ixodes spp. on companion animals in Canada and explore the association between tick bites and dog and cat demographic factors. Ticks were collected for one year (April 2019 - March 2020) from 94 veterinary clinics. Included with each submission was a short questionnaire containing owner-reported information on travel history, date of removal and suspected location of tick acquisition, and animal-specific demographic factors. Ticks were identified morphologically using a stereomicroscope, standard keys, and through PCR analyses. Mixed effect multivariable logistic regression models were built to explore the association between an Ixodes scapularis bite and animal demographic factors; veterinary clinic was included as a random effect. Approximately 2300 submissions were received from clinics across Canada, totalling 4425 ticks. The most common Ixodes spp. was I. scapularis (n = 2168), followed by Ixodes pacificus (n = 172) and Ixodes cookei (n = 155). Ixodes scapularis were well distributed in regions across central and eastern Canada. Ixodes cookei was found in eastern Canada, with the greatest numbers from Quebec and New Brunswick. Ixodes pacificus submissions were restricted to British Columbia. Across eastern Canada, dogs of the herding, mixed breed (large and small), sporting, working, terrier, and toy breed groups, and spayed cats were all found to have higher odds of acquiring I. scapularis, compared to other tick species. For the dog model, significant interactions were found between predictor variables age and sex. Regional information on tick distribution, seasonality, and risk factors for acquisition contribute to evidence-based veterinary practices for tick and tick-borne disease control in Canada.

First detection and molecular identification of Rickettsia massiliae, a human pathogen, in Rhipicephalus sanguineus ticks collected from Southern Taiwan

The Rickettsia massiliae was firstly detected and identified in Rhipicephalus sanguineus ticks infested on dogs in Taiwan. A total of 1154 Rh. sanguineus ticks collected from 158 dogs of four districts of Tainan city were examined for Rickettsia infection by nested-PCR assay targeting the citrate synthase (gltA) and outer membrane protein B (ompB) genes of Rickettsia. The Rickettsia infection was detected with a general infection rate of 2.77%, and was detected in male, female and nymphal stage with an infection rate of 2.77%, 3.22% and 1.32%, respectively. Phylogenetic relationships were analyzed by comparing the gltA and ompB sequences obtained from 9 Taiwan strains and 16 other strains representing 13 genospecies of Rickettsia. Results revealed that all Taiwan strains were genetically affiliated to the same clades of R. massiliae (spotted fever group) and R. felis (transitional group), and can be discriminated from other genospecies of Rickettsia. This study provides the first evidence of R. massiliae, a pathogenic spotted fever Rickettsia, identified in Rh. sanguineus ticks and highlight the potential threat for the regional transmission of Rickettsia infection among humans in Taiwan.

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.

Epidemiological study on Ixodid tick infestation and tick borne haemopathogens on cattle in Awi Zone, northwest Ethiopia

Background

Tick and tick borne haemopathogens are the main challenge of livestock production and productivity in Ethiopia particular in northwest Ethiopia due to favourable climate condition.

Objectives

The objectives of this study was to determining the prevalence of Ixodid tick infestation and tick borne haemopathogens on cattle, identifying the existing Ixodid tick species, assessing seasonal variation and major risk factors associated with tick infestation and tick borne haemopathogens.

Methods

A cross‐sectional study was conducted from December 2020 to july 2021 on Ixodid tick infestation and tick borne haemopathogens on cattle in the northwest Ethiopia. A toatal of 384 cattle were used for this study. Tick species were identified using morphological identification keys under a stereomicroscope. Thin blood smear examination were conducted to assess tick borne haemopathogens.

Results

The overall prevalence of Ixodid tick infestation and tick borne haemopathogens were 45% and 3%, respectively. Babesia bigemina was the only haemoparasite detected in the present survey. Potential risk factors were investigated for their association with tick infestation and B. bigemina using logistic regression and chi‐square test, respectively. Accordingly, age, body condition, agroecological systems and season were significantly (p < 0.05) associated with tick infestation whereas season and body condition were significantly (p < 0.05) associated with B. bigemina infection. A total seven tick species were identified. Amblyomma varigatum (55%) and Boophilus decoloratus (15.7%) were the predominant Ixodid tick species encountered. A total of 128 blood samples were collected from Jawi district and examined using thin blood smear. Of them, 3% were infected by the B. bigemina

Conclusions

Tick infestation in this study was high and seems to play vital role for the reduction of production, productivity and for the transmission B. bigemina. Therefore, sound and effective tick control and prevention strategies are needed to mitigate the risk factors for tick infestation and B. bigemina infection in Ethiopia.

Possible Association between Selected Tick-Borne Pathogen Prevalence and Rhipicephalus sanguineus sensu lato Infestation in Dogs from Juarez City (Chihuahua), Northwest Mexico–US Border

Tick-borne bacterial pathogens (TBBPs) show a worldwide distribution and represent a great impact on public health. The brown dog tick (Rhipicephalus sanguineus) is a vector of several pathogens that affect dogs and sometimes humans as well. In addition, TBBPs represent a diagnostic challenge and imply financial resources and medical treatment for long periods of time. In the present study, R. sanguineus s. l. was identified as the main tick species naturally parasitizing dogs that inhabit. Juárez City, Chihuahua, in the Paso del Norte region, Mexico–US Border, representing 99.8% of the cases. Additionally, an end-point PCR was performed to search for whether pathogens in R. sanguineus s. l. can transmit in DNA extracted from ticks and dog blood samples. This is the first molecular detection of Rickettsia rickettsi infecting domestic dogs in Mexico; however, other pathogens were also identified, such as Ehrlichia canis and Anaplasma platys in both ticks and dog blood samples, while Anaplasma phagocytophilum was identified only in dog blood samples. Moreover, co-detection in tick pools and co-infection in the analyzed dog blood samples could be found. Similarly, this research showed that dogs were found mostly parasitized by adult female ticks, increasing the possibility of transmission of E. canis.

Hard Ticks (Ixodidae) from Wildlife in Liguria, Northwest Italy: Tick Species Diversity and Tick-Host Associations

Hard ticks’ geographical distribution and abundance are influenced by wildlife population. This work presents the results of the identification of ticks retrieved from wild animals in the framework of a Regional Plan of Monitoring and Surveillance of Wildlife health. The frequency of distribution of ticks in different hosts and their geographical patterns were also investigated. Ticks were collected from game animals (Sus scrofa, Capreolus capreolus, Dama dama, and Rupicapra rupicapra) during two hunting seasons (2018–2019 and 2019–2020) in the four provinces of the Liguria region in northwest Italy. In the same period, ticks were also collected from carcasses of Vulpes vulpes, Canis lupus, Meles meles, and Asio otus received for necropsy. Tick species were identified according to taxonomic keys. A total of 819 ticks, removed from 259 animals, were found and identified. Overall, Ixodes ricinus was the dominant species (62.6%), followed by Dermacentor marginatus (24.5%), Rhipicephalus sanguineus s.l. (12.5%), Haemaphysalis punctata (0.2%), and Ixodes hexagonus (0.1%). I. ricinus was also the prevalent species in roe deer and in fallow deer and the only species collected from the three wolf carcasses examined. In contrast, D. marginatus was the dominant species in S. scrofa. This last tick species was also more frequent in one province (Imperia), whereas Ixodes spp. were more common in another one (Savona). Wild animals proved to be useful for characterizing and monitoring tick population.

Questing Ixodes ricinus ticks and Borrelia spp. in urban green space across Europe: A review

For more than three decades, it has been recognized that Ixodes ricinus ticks occur in urban green space in Europe and that they harbour multiple pathogens linked to both human and animal diseases. Urban green space use for health and well‐being, climate mitigation or biodiversity goals is promoted, often without consideration for the potential impact on tick encounters or tick‐borne disease outcomes. This review synthesizes the results of over 100 publications on questing I. ricinus and Borrelia spp. infections in ticks in urban green space in 24 European countries. It presents data on several risk indicators for Lyme borreliosis and highlights key research gaps and recommendations for future studies. Across Europe, mean density of I. ricinus in urban green space was 6.9 (range; 0.1–28.8) per 100 m² and mean Borrelia prevalence was 17.3% (range; 3.1%–38.1%). Similar density estimates were obtained for nymphs, which had a Borrelia prevalence of 14.2% (range; 0.5%–86.7%). Few studies provided data on both questing nymph density and Borrelia prevalence, but those that did found an average of 1.7 (range; 0–5.6) Borrelia‐infected nymphs per 100 m² of urban green space. Although a wide range of genospecies were reported, Borrelia afzelii was the most common in most parts of Europe, except for England where B. garinii was more common. The emerging pathogen Borrelia miyamotoi was also found in several countries, but with a much lower prevalence (1.5%). Our review highlights that I. ricinus and tick‐borne Borrelia pathogens are found in a wide range of urban green space habitats and across several seasons. The impact of human exposure to I. ricinus and subsequent Lyme borreliosis incidence in urban green space has not been quantified. There is also a need to standardize sampling protocols to generate better baseline data for the density of ticks and Borrelia prevalence in urban areas.

Scenes From Tick Physiology: Proteins of Sialome Talk About Their Biological Processes

Ticks are blood-sucking parasites with different strategies of feeding depending on the tick family. The major families are Ixodidae or Argasidae, being slow or fast feeders, respectively. In the recent years, the advances in molecular sequencing techniques have enabled to gain knowledge about the proteome of the tick's salivary glands. But an holistic view of the biological processes underlying the expression of the sialome has been neglected. In this study we propose the use of standard biological processes as a tool to draw the physiology of the tick's salivary glands. We used published data on the sialome of Rhipicephalus sanguineus s.l. (Ixodidae) and Ornithodoros rostratus (Argasidae). A partial set of proteins obtained by these studies were used to define the biological process(es) in which proteins are involved. We used a directed network construction in which the nodes are proteins (source) and biological processes (target), separately for the low-level processes ("children") and the top-level ones ("parents"). We applied the method to feeding R. sanguineus at different time slices, and to different organs of O. rostratus. The network connects the proteins and the processes with a strength directly proportional to the transcript per millions of each protein. We used PageRank as a measure of the importance of each biological process. As suggested in previous studies, the sialome of unfed R. sanguineus express about 30% less biological processes than feeding ticks. Another decrease (25%) is noticed at the middle of the feeding and before detachment. However, top-level processes are deeply affected only at the onset of feeding, demonstrating a redundancy in the feeding. When ixodid-argasid are compared, large differences were observed: they do not share 91% of proteins, but share 90% of the biological processes. However, caution must be observed when examining these results. The hypothesis of different proteins linked to similar biological process(es) in both ticks is an extreme not confirmed in this study. Considering the limitations of this study, carried out with a selected set of proteins, we propose the networks of proteins of sialome linked to their biological processes as a tool aimed to explain the biological processes behind families of proteins.

Ticks and Tick-Borne Pathogens in Domestic Animals, Wild Pigs, and Off-Host Environmental Sampling in Guam, USA

Background: Guam, a United States of America (USA) island territory in the Pacific Ocean, is known to have large populations of ticks; however, it is unclear what the risk is to wildlife and humans living on the island. Dog (Canis familiaris), cat (Felis catus), and wild pig (Sus scrofa) sentinels were examined for ticks, and environmental sampling was conducted to determine the ticks present in Guam and the prevalence of tick-borne pathogens in hosts.

Methods and Results: From March 2019-November 2020, ticks were collected from environmental sampling, dogs, cats, and wild pigs. Blood samples were also taken from a subset of animals. A total of 99 ticks were collected from 27 environmental samples and all were Rhipicephalus sanguineus, the brown dog tick. Most ticks were collected during the dry season with an overall sampling success rate of 63% (95% CI: 42.4–80.6). 6,614 dogs were examined, and 12.6% (95% CI: 11.8–13.4) were infested with at least one tick. One thousand one hundred twelve cats were examined, and six (0.54%; 95% CI: 0.20–1.1) were found with ticks. Sixty-four wild pigs were examined and 17.2% (95% CI: 9.5–27.8) had ticks. In total, 1,956 ticks were collected and 97.4% of ticks were R. sanguineus. A subset of R. sanguineus were determined to be the tropical lineage. The other tick species found were Rhipicephalus microplus (0.77%), Amblyomma breviscutatum (0.77 %), and a Haemaphysalis sp. (0.51%). Blood samples from 136 dogs, four cats, and 64 wild pigs were tested using polymerase chain reaction (PCR) and DNA sequencing methods. Five different tick-borne pathogens with the following prevalences were found in dogs: Anaplasma phagocytophilum 5.9% (95% CI: 2.6–11.3); Anaplasma platys 19.1% (95% CI: 12.9–26.7); Babesia canis vogeli 8.8% (95% CI: 4.6–14.9); Ehrlichia canis 12.5% (95% CI: 7.5–19.3); Hepatozoon canis 14.7% (95% CI: 9.2–28.8). E. canis was detected in one cat, and no tick-borne pathogens were detected in wild pigs. Overall, 43.4% (95% CI: 34.9–52.1) of dogs had at least one tick-borne pathogen. Serological testing for antibodies against Ehrlichia spp. and Anaplasma spp. showed prevalences of 14.7% (95% CI: 9.2–28.8) and 31.6% (95% CI: 23.9–40), respectively.

Conclusion: Four different tick species were found in Guam to include a Haemaphysalis sp., which is a previously unreported genus for Guam. Dogs with ticks have a high prevalence of tick-borne pathogens which makes them useful sentinels.

The bioactive compound carvacrol as a potential acaricide: An assessment of its effects on the integument of female Rhipicephalus sanguineus sensu lato ticks

Studies seeking control methods for infestation of Riphicephalus sanguineus sensu lato (s.l.) ticks (dog ticks) have been carried out in order to minimize damage to both the tick's hosts and the environment, the latter due to the misuse of acaricide products. In this regard, carvacrol has been used as a natural alternative against ticks as it displays several properties including acaricidal. In this context, the present study aimed to evaluate the ultramorphology and morphohistochemistry of the integument of semi-engorged R. sanguineus s.l. females exposed to different carvacrol concentrations. The findings indicate that the integument surface of females exposed to the highest carvacrol concentration (25 μl/ml) became wrinkled, suggesting dehydration or the result of integument cuticular and epithelial layer disorganization in response to the toxic product. Morphohistochemical integument layer alterations were more significant and intense in females exposed to the highest carvacrol concentration (25 μl/ml), confirming dose-dependent carvacrol action. Among other cell and tissue alterations, changes in epithelial cell shape, size, and arrangement (epidermal layer) were noted, alongside altered and pyknotic-shaped nuclei, suggesting a death process for these cells. This epithelium changed from simple cubic to stratified, also in response to the presence of the evaluated bioactive compound. Thus, the findings reported herein demonstrate that carvacrol may be an alternative for an efficient and more sustainable tick control in the near future.

First detection and genetic identification of Rickettsia infection in Rhipicephalus sanguineus (Acari: Ixodidae) ticks collected from Southern Taiwan

The prevalence and genetic identity of Rickettsia infection in Rhipicephalus sanguineus sensu lato (s.l.) ticks were determined in Taiwan. In total 1153 ticks were examined for Rickettsia infection by PCR assay targeting the citrate synthase gene (gltA) of Rickettsia. The prevalence of Rickettsia infection in R. sanguineus s.l. ticks with a general infection rate of 2.2%, and was detected in nymph, male and female stages of R. sanguineus s.l. ticks with an infection rate of 3.1, 2.0 and 1.1%, respectively. Phylogenetic relationships were analyzed by comparing the gltA sequences obtained from four Taiwan strains and 16 other strains representing 13 genospecies of Rickettsia. Phylogenetic analyses reveal that one Taiwan strain was genetically affiliated with the Japan isolate (GRA-1 strain) which belongs to the spotted fever group (R. parkeri/R. honei) and three Taiwan strains were genetically affiliated with the transitional group of Rickettsia (R. felis). Intra- and inter-species analysis also indicated the genetic distance (GD) of the Taiwan strains with a lower level of GD < 0.011, 0.023 and 0.003 as compared with the type strains of R. parkeri, R. honei and R. felis, respectively. Our findings reveal the first detection of Rickettsia infections (R. parkeri/R. honei and R. felis) in R. sanguineus s.l. ticks of Taiwan. These results also highlight the epidemiological significance of diverse Rickettsia species existed in R. sanguineus s.l. ticks and the potential threat for the geographical transmission of Rickettsia infection in Taiwan.

Urban woodland habitat is important for tick presence and density in a city in England

Urban green spaces provide an opportunity for contact between members of the public and ticks infected with pathogens. Understanding tick distribution within these areas and the drivers for increased tick density or Borrelia infection are important from a risk management perspective. This study aimed to generate data on tick presence, nymph density and Borrelia infection across a range of urban green space habitats, in order to identify those that may potentially present a higher risk of Lyme borreliosis to members of the public. Several sites were visited across the English city of Bath during 2015 and 2016. Tick presence was confirmed in all habitats surveyed, with increased likelihood in woodland and woodland edge. Highest nymph densities were also reported in these habitats, along with grassland during one of the sampling years. Adult ticks were more likely to be infected compared to nymphs, and the highest densities of infected nymphs were associated with woodland edge habitat. In addition to Lyme borreliosis causing Borrelia genospecies, Borrelia miyamotoi was also detected at several sites. This study adds to the growing evidence that urban green space habitats present a public health risk from tick bites, and this has implications for many policy areas including health and wellbeing, climate adaptation and urban green space planning.

Soft ticks (Acari: Argasidae) in the island nations of Southeast Asia: A review on their distribution, associated hosts and potential pathogens

Soft ticks (Acari: Argasidae) are the second major family of the blood feeding metastriates and vectors of a number of viral and bacterial pathogens for both humans and animals. Despite the growing effort on tick surveillance and studies worldwide, there is still limited information on the soft tick distribution in the island nations of Southeast Asia, especially species that are medically and veterinarily important. With the aim to provide an overview of the current status of knowledge on soft tick distribution in the island nations of Southeast Asia (Malaysia, Singapore, Brunei, Indonesia, the Philippines and Timor-Leste), this article reviews the species of soft ticks (Acari: Argasidae) and their associated hosts and pathogens, with the addition of a pictorial summary and list of tick species discovered in this region. The most prevalent soft tick genus is Carios, and the host species most associated with findings of soft ticks in this region are bats, particularly of the Pteropodidae and Vespertilionidae families. Furthermore, the only known pathogen originating from soft ticks in the island nations of Southeast Asia was the Keterah virus, which was isolated from Argas pusillus tick in Malaysia.

Symbiont-regulated serotonin biosynthesis modulates tick feeding activity

Ticks are obligate hematophagous arthropods. Blood feeding ensures that ticks obtain nutrients essential for their survival, development, and reproduction while providing routes for pathogen transmission. However, the effectors that determine tick feeding activities remain poorly understood. Here, we demonstrate that reduced abundance of the symbiont Coxiella (CHI) in Haemaphysalis longicornis decreases blood intake. Providing tetracycline-treated ticks with the CHI-derived tryptophan precursor chorismate, tryptophan, or 5-hydroxytryptamine (5-HT; serotonin) restores the feeding defect. Mechanistically, CHI-derived chorismate increases tick 5-HT biosynthesis by stimulating the expression of aromatic amino acid decarboxylase (AAAD), which catalyzes the decarboxylation of 5-hydroxytryptophan (5-HTP) to 5-HT. The increased level of 5-HT in the synganglion and midgut promotes tick feeding. Inhibition of CHI chorismate biosynthesis by treating the colonized tick with the herbicide glyphosate suppresses blood-feeding behavior. Taken together, our results demonstrate an important function of the endosymbiont Coxiella in the regulation of tick 5-HT biosynthesis and feeding.

Identification and Prevalence of Ixodid Ticks of Cattle in case of Haramaya Eastern Hararghe, Ethiopia

A cross-sectional study was conducted from December 2017 to April 2018 to determine the prevalence and identify major species of ixodid ticks of cattle and tick burden of different sex, age, breed, and body condition of cattle. Standard physical and direct stereomicroscopy techniques were employed for identification of tick species. During the study period, a total of 353 cattle were examined for presence of ticks and around 447 ticks were collected. The study showed that 34.3% cattle were infested with one or more tick species. The study reported different species of ticks in the order of their prevalence: A. variegatum (46.3%), Rh. decoloratus (20.1%), A. cohaerens (15.7%), A. gemma (11.9%), and Rh. pulchellus (6.04%), respectively. The prevalence of tick infestation between different risk factors such as sex, age, and body condition of cattle was statistically significant (p < 0.05). The overall male-to-female ratio of ticks was 2.29 : 1. Also, it was reported that, in A. variegatum, A. cohaerens, and A. gemma, the number of male exceeded that of female, but female number exceeded male number in case of Rh. decoloratus. The result also reported difference in attachment site preference, for example, Amblyomma genus was attached mostly to the scrotum/udder and axial and Rh. pulchellus was specified on the ear and perianal area, while Rh. decoloratus was non site selective. In conclusion, findings of this study suggest that ticks were the most important problems of cattle of the study areas. Therefore, the increasing threat of ticks warrants urgent strategic control including application of acaricides and creation of awareness among livestock owners about the veterinary importance of ticks for the integrated tick control.

Grappling with the tick microbiome

Ixodes scapularis and Ixodes pacificus are the predominant vectors of multiple human pathogens, including Borrelia burgdorferi, one of the causative agents of Lyme disease in North America. Differences in the habitats and host preferences of these closely related tick species present an opportunity to examine key aspects of the tick microbiome. While advances in sequencing technologies have accelerated a descriptive understanding of the tick microbiome, molecular and mechanistic insights into the tick microbiome are only beginning to emerge. Progress is stymied by technical difficulties in manipulating the microbiome and by biological variables related to the life cycle of Ixodid ticks. This review highlights these challenges and examines avenues to understand the significance of the tick microbiome in tick biology.

Comparative population genetic structure of two ixodid tick species (Acari:Ixodidae) (Ixodes ovatus and Haemaphysalis flava) in Niigata prefecture, Japan

Ixodid ticks (Acari:Ixodidae) are essential vectors of tick-borne diseases in Japan. In this study, we characterized the population genetic structure and inferred genetic divergence in two widespread and abundant ixodid species, Ixodes ovatus and Haemaphysalis flava. Our hypothesis was that genetic divergence would be high in I. ovatus because of the low mobility of their small rodent hosts of immature I. ovatus would limit their gene flow compared to more mobile avian hosts of immature H. flava. We collected 320 adult I. ovatus from 29 locations and 223 adult H. flava from 17 locations across Niigata Prefecture, Japan, and investigated their genetic structure using DNA sequences from fragments of two mitochondrial gene regions, cox1 and the 16S rRNA gene. For I. ovatus, pairwise F_ST and analysis of molecular variance (AMOVA) analyses of cox1 and 16S sequences indicated significant genetic variation among populations, whereas both markers showed non-significant genetic variation among locations for H. flava. A cox1 gene tree and haplotype network revealed three genetic groups of I. ovatus. One of these groups consisted of haplotypes distributed at lower altitudes (251-471 m.a.s.l.). The cox1 sequences of I. ovatus from Japan clustered separately from I. ovatus sequences reported from China, suggesting the potential for cryptic species in Japan. Our results support our hypothesis and suggest that the host preference of ticks at the immature stage may influence the genetic structure of the ticks. This information may be important for understanding the tick-host interactions in the field to better understand the tick-borne disease transmission and in designing an effective tick control program.

Ixodes ricinus and Borrelia burgdorferi sensu lato in the Royal Parks of London, UK

Assessing the risk of tick-borne disease in areas with high visitor numbers is important from a public health perspective. Evidence suggests that tick presence, density, infection prevalence and the density of infected ticks can vary between habitats within urban green space, suggesting that the risk of Lyme borreliosis transmission can also vary. This study assessed nymph density, Borrelia prevalence and the density of infected nymphs across a range of habitat types in nine parks in London which receive millions of visitors each year. Ixodes ricinus were found in only two of the nine locations sampled, and here they were found in all types of habitat surveyed. Established I. ricinus populations were identified in the two largest parks, both of which had resident free-roaming deer populations. Highest densities of nymphs (15.68 per 100 m²) and infected nymphs (1.22 per 100 m²) were associated with woodland and under canopy habitats in Richmond Park, but ticks infected with Borrelia were found across all habitat types surveyed. Nymphs infected with Borrelia (7.9%) were only reported from Richmond Park, where Borrelia burgdorferi sensu stricto and Borrelia afzelii were identified as the dominant genospecies. Areas with short grass appeared to be less suitable for ticks and maintaining short grass in high footfall areas could be a good strategy for reducing the risk of Lyme borreliosis transmission to humans in such settings. In areas where this would create conflict with existing practices which aim to improve and/or meet historic landscape, biodiversity and public access goals, promoting public health awareness of tick-borne disease risks could also be utilised.

Molecular Detection and Genetic Identification of Rickettsia Infection in Ixodes granulatus Ticks, an Incriminated Vector for Geographical Transmission in Taiwan

Tick-borne Rickettsia pathogens have become an emerging source of zoonotic infections and have a major impact on human health worldwide. In this study, the prevalence and genetic identity of Rickettsia infections in Ixodes granulatus ticks was firstly determined in Kinmen Island of Taiwan. A total of 247 I. granulatus ticks were examined for Rickettsia infection by nested-PCR assay targeting the citrate synthase (gltA) gene of Rickettsia. The Rickettsia infection was detected with a general infection rate of 4.86%, and was detected in nymph, male and female stages with an infection rate of 3.81%, 0% and 6.84%, respectively. Phylogenetic relationships were analyzed by comparing the gltA sequences obtained from four Taiwan strains and 19 other strains representing 13 genospecies of Rickettsia. Phylogenetic analyses reveal that all Taiwan strains were genetically affiliated to the genospecies of spotted fever (R. parkeri) and transitional (R. felis) groups of Rickettsia. Our findings reveal the first detection of R. parkeri-like and R. felis in I. granulatus ticks from Kinmen Island. As a tourist island between Taiwan and mainland China, these results demonstrate the epidemiological significance of diverse Rickettsia species existed in I. granulatus ticks and highlight the potential threat of geographical transmission among humans in the Taiwan area.

Tick (Acari: Ixodidae) infestation of cuscuses from Maluku Province, Indonesia

Background and Aim:

Cuscuses are one of the endemic Indonesian marsupials, which needs to be protected and revived in terms of the numbers and range of species. Ectoparasites of ticks (Ixodidae) are one potential obstacle to cuscus conservation. Tick infestation can cause blood loss in the host, even being a predisposing factor for infection with pathogenic organisms. This study aimed to determine the prevalence, infestation intensity, and species of ticks present on cuscuses in Maluku Province, Indonesia.

Materials and Methods:

Ticks were collected from cuscuses origin of the four regions in Maluku Province, namely the island of Ambon, Seram Island, Romang Island, and Wetar Island. Cuscuses were captured at night, with ticks being collected from them from the head to the tip of the tail. The tick samples obtained from the cuscuses were preserved, identified, and counted. Cuscuses were released back into their habitat after collecting the ticks. The obtained ticks were observed using an Olympus BX51 microscope with an Olympus DP12 digital camera and prepared for examination under a scanning electron microscope (SEM). Infestation rate, infestation intensity, and morphology of the species were described.

Results:

The cuscuses were found to be infested with Ixodes cordifer ticks. Cuscuses in Maluku Province had a low tick infestation rate. The range of infestation prevalence of island origin cuscuses in Maluku was between 14.28% and 16.67%. Simultaneously, I. cordifer infestation level was mildly infested based on the intensity of thick infestation ranged from 1 to 1.2 ticks per cuscus. From observation of the tick surface structure under SEM, sexual dimorphism and various specific characteristics of the ticks were identified.

Conclusion:

The low infestation rate of I. cordifer ticks in cuscus was influenced by the up and down movement of the conscious activity in the tree, which allowed minimal contact with the ticks. The infestation prevalence rates on each island studied were similar. Such similarities of infestation are related to the similarity of cuscus species among Ambon, Lakor, Seram, and Romang islands, which are all included in the Phalangeridae family, and their similar habitats, behaviors, climatic conditions, and geographical areas.

Entomopathogenic Fungi and Bacteria in a Veterinary Perspective

Simple Summary

Several fungal species are well suited to control arthropods, being able to cause epizootic infection among them and most of them infect their host by direct penetration through the arthropod’s tegument. Most of organisms are related to the biological control of crop pests, but, more recently, have been applied to combat some livestock ectoparasites. Among the entomopathogenic bacteria, Bacillus thuringiensis, innocuous for humans, animals, and plants and isolated from different environments, showed the most relevant activity against arthropods. Its entomopathogenic property is related to the production of highly biodegradable proteins. Entomopathogenic fungi and bacteria are usually employed against agricultural pests, and some studies have focused on their use to control animal arthropods. However, risks of infections in animals and humans are possible; thus, further studies about their activity are necessary.

Abstract

The present study aimed to review the papers dealing with the biological activity of fungi and bacteria against some mites and ticks of veterinary interest. In particular, the attention was turned to the research regarding acarid species, Dermanyssus gallinae and Psoroptes sp., which are the cause of severe threat in farm animals and, regarding ticks, also pets. Their impact on animal and human health has been stressed, examining the weaknesses and strengths of conventional treatments. Bacillus thuringiensis, Beauveria bassiana and Metarhizium anisopliae are the most widely employed agents. Their activities have been reviewed, considering the feasibility of an in-field application and the effectiveness of the administration alone or combined with conventional and alternative drugs is reported.

Morphometrics of Amblyomma mixtum in the State of Veracruz, Mexico

The tick Amblyomma mixtum is an ectoparasite of veterinary and public health importance because of its role as a vector of zoonotic pathogens. However, little is known about A. mixtum intraspecific variability and if morphological differentiation exists between populations across its geographic range. This study aimed to determine by electron microscopy the morphological variability of A. mixtum populations in the state of Veracruz, which has a large livestock population among states in Mexico. Forty male and 40 female A. mixtum collected from the 10 natural regions of Veracruz state were analyzed microscopically to accomplish main component analysis for each sex. Clusters were calculated with the out-tree method and a dendrogram produced to group the specimens according to their morphometric characteristics. Using 10 main components, 77% of the morphological variation of the ticks was explained. This is a reflection of scarce intraspecific variation between females. The dendogram for females grouped six clusters of specimens with similar characteristics. Morphometric variability in males was described using eight main components. Limited intraspecific variation was also observed between males. In males, the dendogram yielded six groups with similar morphometric characteristics. Morphometric analyses confirmed that the only species from the Amblyomma cajennense complex that are parasites to livestock in Veracruz state is A. mixtum. The eryxenous nature of A. mixtum combined with the frequent movement of livestock hosts may contribute to the apparent homogeneous phenotype of this tick species in Mexico.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry: an emerging tool for studying the vectors of human infectious diseases

Arthropod vectors have historically been identified morphologically, and more recently using molecular biology methods. However, both of these methods are time-consuming and require specific expertise and equipment. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry, which has revolutionized the routine identification of microorganisms in clinical microbiology laboratories, was recently successfully applied to the identification of arthropod vectors. Since then, the robustness of this identification technique has been confirmed, extended to a large panel of arthropod vectors, and assessed for detecting blood feeding behavior and identifying the infection status in regard to certain pathogenic agents. In this study, we summarize the state-of-the-art of matrix-assisted laser desorption ionization time-of-flight mass spectrometry applied to the identification of arthropod vectors (ticks, mosquitoes, phlebotomine sand-flies, fleas, triatomines, lice and Culicoides), their trophic preferences and their ability to discriminate between infection statuses.

A knowledge, attitudes, and practices study on ticks and tick-borne diseases in cattle among farmers in a selected area of eastern Bhutan

Livestock farming plays an important role in supporting the livelihood of resource-poor subsistence farmers in Bhutan. However, ticks and tick-borne diseases (TBDs) are one of the major constraints to livestock farming due to their negative effect on health and production. To date, no study has been conducted in Bhutan to assess farmers' knowledge, attitude, and practices (KAP) about ticks and TBDs in cattle, although such information is essential in ensuring the development and adoption of effective prevention and control measures. Therefore, a KAP survey was conducted among 246 cattle owners in the Samkhar sub-district of eastern Bhutan in June 2019, using a structured questionnaire. Based on our scoring criteria, 52% [95%CI: 45.5-58.4] had adequate knowledge about ticks as potential vectors of diseases. Logistic regression analysis showed that the individuals who practiced a stall-feeding system of cattle rearing were 2.8 times [OR = 2.8 (95%CI: 1.66-4.78)] more likely to have adequate knowledge than others. Sixty-eight percent [95%CI: 62.5-74.4] had a favorable attitude toward tick prevention and control programs. Men were 1.95 times [OR = 1.95 (95%CI: 1.09-3.55)] more likely to have a favorable attitude than women, and the individuals who practiced a stall-feeding system were 2.59 times [OR = 2.59 95%CI: 1.45-4.78)] more likely to have a favorable attitude than others, after adjusting for the effect of other variables in the model. Overall, only 38% [95%CI 32.5-45] of the respondents reported tick infestation as one of the most important animal health problems, but 100% reported using acaricides to control ticks in cattle. Despite a high level of acaricide usage, the level of knowledge was low among the farmers interviewed. Findings from this study underline the importance of considering identified knowledge gaps and initiating education efforts to improve the adoption of effective tick prevention and control measures among farmers.

Identification, Distribution, and Habitat Suitability Models of Ixodid Tick Species in Cattle in Eastern Bhutan

Tick infestation is the most reported parasitological problem in cattle in Bhutan. In May and June 2019, we collected ticks from 240 cattle in two districts of Eastern Bhutan. Tick presence, diversity, and infestation prevalence were examined by morphological identification of 3600 live adult ticks. The relationships between cattle, geographic factors, and infestation prevalence were assessed using logistic regression analyses. Habitat suitability for the tick species identified was determined using MaxEnt. Four genera and six species of ticks were found. These were Rhipicephalus microplus (Canestrini) (70.2% (95% confidence interval (CI): 68.7-71.7)), Rhipicephalus haemaphysaloides Supino (18.8% (95% CI: 17.5-20.1)), Haemaphysalis bispinosa Neumann (8.2% (95% CI: 7.3-9.1)), Haemaphysalis spinigera Neumann (2.5% (95% CI: 2-3)), Amblyomma testudinarium Koch (0.19% (95% CI: 0.07-0.4)), and a single unidentified Ixodes sp. Logistic regression indicated that the variables associated with infestation were: longitude and cattle age for R. microplus; latitude for R. haemaphysaloides; and altitude and cattle breed for H. bispinosa and H. spinigera. MaxEnt models showed land cover to be an important predictor for the occurrence of all tick species examined. These findings provide information that can be used to initiate and plan enhanced tick surveillance and subsequent prevention and control programs for ticks and tick-borne diseases in cattle in Bhutan.

Parasites of wombats (family Vombatidae), with a focus on ticks and tick-borne pathogens

Ticks (Arachnida: Acari) are vectors for pathogens and the biggest threat to animal health. Many Australian ticks are associated with pathogens that impact humans, domestic animals and livestock. However, little is known about the presence or impact of tick-borne pathogens in native Australian wildlife. Wombats are particularly susceptible to the effects of the ectoparasite Sarcoptes scabiei which causes sarcoptic mange, the reason for which is unknown. Factors such as other ectoparasites and their associated pathogens may play a role. A critical understanding of the species of ectoparasites that parasitise wombats and their pathogens, and particularly ticks, is therefore warranted. This review describes the ectoparasites of wombats, pathogens known to be associated with those ectoparasites, and related literature gaps. Pathogens have been isolated in most tick species that typically feed on wombats; however, there are minimal molecular studies to determine the presence of pathogens in any other wombat ectoparasites. The development of next-generation sequencing (NGS) technologies allows us to explore entire microbial communities in ectoparasite samples, allowing fast and accurate identification of potential pathogens in many samples at once. These new techniques have highlighted the diversity and uniqueness of native ticks and their microbiomes, including pathogens of potential medical and veterinary importance. An increased understanding of all ectoparasites that parasitise wombats, and their associated pathogens, requires further investigation.

Coexistence of Tick-Borne Pathogens in Ticks Collected from their Hosts in Sardinia: an Update

PURPOSE

In recent decades, the incidence and distribution of tick-borne diseases have increased worldwide, attracting the attention of both clinicians and veterinarians. In Sardinia, notifiable tick-borne diseases are spreading and Mediterranean spotted fever (MSF) rickettsiosis continues to be endemic with an incidence of 10/10,000 inhabitants per year. Furthermore, ticks can transfer more than one pathogen after a single blood meal from a coinfected host or after multiple feeding on different infected hosts. The aim of this study was to update information on ticks and tick-borne diseases, focusing also on the presence of coinfection in Sardinian ticks.

METHODS

The presence of protozoan (Theileria and Babesia species) and bacterial pathogens (Rickettsia spp., Anaplasma spp., Ehrlichia canis, Chlamydia spp., Bartonella spp., and Coxiella burnetii) was evaluated in 230 ticks collected from different hosts in Sardinia.

RESULTS

PCR and sequencing analyses highlighted that the 59% of ticks were infected with at least one pathogen while the 15% resulted in coinfection by double and triple pathogens. Among the double co-infections, those of E. canis/C. burnetii, Babesia sp. Anglona/Ch. psittaci and Babesia sp. Anglona/C. burnetii revealed a statistically significant index of coinfection.

CONCLUSION

This study identifies new pathogens in Sardinian ticks and updates the information about tick-borne diseases in the island. We also provide new results on the presence of coinfections in collected ticks. The knowledge about the diversity of ticks and tick-borne diseases circulating in Sardinia is a necessary step toward implementing effective tick-borne disease prevention and control programs.

Ticks and tick-borne pathogens in animals and humans in the island nations of Southeast Asia: A review

Ticks are blood-feeding ectoparasites and major vectors of pathogens that cause infectious diseases in humans and animals worldwide including mammals, birds and reptiles. Despite the growing scientific effort in the 20th century, there is still limited information on ticks and tick-borne pathogens in Southeast Asia, especially concerning medical, veterinary, socioeconomic and agricultural aspects in the island nations. This review provides an overview of the current state of knowledge of ticks and their pathogens in the island nations of Southeast Asia and peninsular Malaysia. We aim to stimulate further research studies on ticks and tick-borne pathogens of human and veterinary importance in this geographical region.

Seasonal abundance and activity of the tick Dermacentor everestianus (Acari: Ixodidae) in the Tibetan Plateau, China

Dermacentor everestianus is an important vector for several pathogens endemic in the Qinghai-Tibet Plateau. However, knowledge of its seasonal activity and abundance is limited. Hence, the seasonal dynamics of questing and host-feeding D. everestianus were investigated from March 2014 to February 2016 in Damxung County, north of Lhasa City in Tibet. During the 2-year period, questing ticks were collected weekly from two habitats (grassland and shrubs) by flag-dragging. Host-feeding ticks were removed weekly from sheep and their attachment sites were recorded. Plateau pikas (Ochotona curzoniae) captured by traps were examined for immature ticks from May to September 2014. Results revealed that questing D. everestianus were primarily distributed in grassland, whereas host-feeding adults and nymphs were mainly found on sheep, and larvae usually were on plateau pikas. Dermacentor everestianus can complete one generation per year with population overlap between the larvae and nymphs. Adults were mainly observed from February to April with the major peak occurring in late March. Additionally, unfed adults were detected on sheep from August to next February. Nymphs were found from late May to July and reached their peak in late June. Larvae collected during May and June reached peak numbers in late May.

Biological parameters for Rhipicephalus microplus in the field and laboratory and estimation of its annual number of generations in a tropical region

The present study aimed to evaluate biological parameters of Rhipicephalus microplus in the non-parasitic phase in both field and laboratory conditions. It also aimed to assess correlations between duration (in days) of these parameters and climatic variables (humidity, rainfall, and soil temperature) and to estimate the annual number of generations of R. microplus in a tropical region. The non-parasitic phase of R. microplus in field and laboratory conditions was evaluated throughout the course of two years. A pasture was infested with engorged female of R. microplus, and biological parameters, including female pre-oviposition, female oviposition, egg mass incubation, larval pre-hatching phase, larval maturation, and larval longevity, were evaluated concomitantly with the collection of data on climatic conditions. The same parameters were also evaluated in a climatized chamber in the laboratory. The total duration of the non-parasitic phase in the field was longer in the dry season (1st and 4th life-cycle repetitions) than in the rainy season (2nd, 3rd, and 5th repetitions). Tick biological parameters for the non-parasitic phase in the laboratory were similar to those obtained in the field during the rainy season. The evaluated biological parameters were influenced mainly by environmental and ground-level temperatures, which modified egg mass incubation, larval pre-hatching, and larval longevity periods and, consequently, the total duration of the non-parasitic phase of the tick. The annual number of generations for the tick was estimated at five per year, which is alarming because it represents an increase, and so new studies into strategic control are needed.

New Records of Ticks of Genus Amblyomma Koch, 1844 (Acari: Ixodidae) for Ecuador

PURPOSE

In Ecuador, knowledge of the diversity and geographic distribution of ticks, as well as their importance as vectors, is scarce. Within the family Ixodidae, the genus Amblyomma is the most diverse and parasitizes wild and domestic animals. This genus is represented by 19 species in Ecuador, 12 of which occur in the continental territory and 7 in the Galapagos Islands. In this way, the objective of this work was to update the diversity of ticks reported for Ecuador on wild and domestic animals.

METHODS

The specimens were collected manually on mammals and birds, in four localities belonging to the Sierra and Amazon of Ecuador and were kept in tubes with 96% ethyl alcohol. After that, all specimens were separated into immatures, males and females and were identified using their morphological characters.

RESULTS

This study records Amblyomma coelebs Neumann, 1899, Amblyomma longirostre (Koch, 1844) Neumann, 1905 and Amblyomma varium Koch, 1844 for the first time in Ecuador. Thus, the genus Amblyomma is currently represented by 22 species. In addition, their hosts, distribution, and importance are also discussed.

CONCLUSIONS

Knowing the diversity of ticks that wildlife possesses, its interrelation with the domestic fauna, and the possible pathogens that could be transmitting could significantly contribute to wildlife's conservation.

Poor Unstable Midgut Microbiome of Hard Ticks Contrasts With Abundant and Stable Monospecific Microbiome in Ovaries

Culture-independent metagenomic methodologies have enabled detection and identification of microorganisms in various biological systems and often revealed complex and unknown microbiomes. In many organisms, the microbiome outnumbers the host cells and greatly affects the host biology and fitness. Ticks are hematophagous ectoparasites with a wide host range. They vector a number of human and animal pathogens and also directly cause major economic losses in livestock. Although several reports on a tick midgut microbiota show a diverse bacterial community, in most cases the size of the bacterial population has not been determined. In this study, the microbiome was quantified in the midgut and ovaries of the ticks Ixodes ricinus and Rhipicephalus microplus before, during, and after blood feeding. Although the size of bacterial community in the midgut fluctuated with blood feeding, it was overall extremely low in comparison to that of other hematophagous arthropods. In addition, the tick ovarian microbiome of both tick species exceeded the midgut 16S rDNA copy numbers by several orders of magnitude. This indicates that the ratio of a tick midgut/ovary microbiome represents an exception to the general biology of other metazoans. In addition to the very low abundance, the tick midgut diversity in I. ricinus was variable and that is in contrast to that found in the tick ovary. The ovary of I. ricinus had a very low bacterial diversity and a very high and stable bacterial abundance with the dominant endosymbiont, Midichloria sp. The elucidation of this aspect of tick biology highlights a unique tissue-specific microbial-invertebrate host interaction.

Comparative vector competence of North American Lyme disease vectors

BACKGROUND

Understanding the drivers of Lyme disease incidence at broad spatial scales is critical for predicting and mitigating human disease risk. Previous studies have identified vector phenology and behavior, host community composition, and landscape features as drivers of variable Lyme disease risk. However, while the Lyme disease transmission cycles in the eastern and western USA involve different vector species (Ixodes scapularis and Ixodes pacificus, respectively), the role of vector-specific differences in transmission efficiency has not been directly examined. By comparing the performance of traits involved in vector competence between these two species, this study aims to identify how vector competence contributes to variable Lyme disease risk.

METHODS

We used a suite of laboratory experiments to compare the performance of traits related to vector competence for the two USA Lyme disease vectors. For each species, we measured the rate of attachment to a common rodent host, the engorgement weight, and the efficiency of pathogen acquisition (host to tick) and pathogen transmission (tick to host) from laboratory mice. In measuring pathogen acquisition and transmission, we used two different pathogen strains, one sympatric with I. scapularis and one sympatric with I. pacificus, to assess the importance of vector-pathogen coevolutionary history in transmission dynamics.

RESULTS

We found I. pacificus had significantly higher host attachment success and engorgement weights, but significantly lower pathogen transmission efficiency relative to I. scapularis. Molting success and pathogen acquisition did not differ between these two species. However, pathogen acquisition efficiency was significantly higher for both sympatric vector and pathogen strains than the allopatric pairings.

CONCLUSIONS

This study identified species-specific vector traits as a potential driver of broad scale variation in Lyme disease risk in the USA. In particular, the exceedingly low rates of pathogen transmission from tick to host observed for I. pacificus may limit Lyme disease transmission efficiency in the western USA. Further, observed variation in pathogen acquisition between sympatric and allopatric vector-pathogen strains indicate that vector-pathogen coevolutionary history may play a key role in transmission dynamics. These findings underscore the need to consider vector traits and vector-pathogen coevolution as important factors governing regional Lyme disease risk.

Bats and ticks: host selection and seasonality of bat-specialist ticks in eastern Europe

Background

Parasites may actively seek for hosts and may use a number of adaptive strategies to promote their reproductive success and host colonization. These strategies will necessarily influence their host specificity and seasonality. Ticks are important ectoparasites of vertebrates, which (in addition to directly affecting their hosts) may transmit a number of pathogens. In Europe, three hard tick species (Ixodidae: Ixodes ariadnae, I. simplex and I. vespertilionis) and at least two soft tick species (Argasidae: Argas transgariepinus and A. vespertilionis) are specialized for bats.

Methods

Here we report data on the host range of these ticks and the seasonality of tick infestation on wild caught bats in south-east Europe. We collected 1803 ticks from 30 species of bats living in underground shelters (caves and mines) from Romania and Bulgaria. On the basis of tick–host associations, we tested several hypotheses on host–parasite evolutionary adaptations regulating host specificity, seasonality and sympatric speciation.

Results

We observed significant differences in host specificity and seasonality of abundance between the morphologically different bat specialist ticks (I. simplex and I. vespertilionis) likely caused by their host choice and their respective host-seeking behavior. The two highly generalist, but morphologically similar tick species (I. ariadnae and I. vespertilionis) showed temporal differences in occurrence and activity, thus exploiting significantly different host communities while occurring in geographical sympatry.

Conclusions

We conclude that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry.

Immunomodulatory effects of Rhipicephalus haemaphysaloides serpin RHS2 on host immune responses

Background

Rhipicephalus haemaphysaloides is a widespread tick species in China and other South East Asian countries, where it is the vector of many pathogens. The objective of this study was to study the role of serpin (serine protease inhibitor) during the tick-host interaction.

Methods

The differentiation of bone marrow-derived dendritic cells (BMDC) was induced in vitro, and the effect of RHS2 on the maturation of DCs was evaluated. The effects of RHS2 on T cell activation and cytotoxic T lymphocytes’ (CTLs) activity were analyzed by flow cytometry. Antibody subtypes after immunization of mice with RHS2 and OVA were determined.

Results

RHS2 can inhibit the differentiation of bone marrow-derived cells into DCs and promote their differentiation into macrophages. RHS2 can inhibit the maturation of DCs and the expression of CD80, CD86 and MHCII. The number of CD3⁺CD4⁺ and CD3⁺CD8⁺ T cells secreting IFN-γ, IL-2 and TNF-α was decreased, and the number of CD3⁺CD4⁺ T cells secreting IL-4 was increased, indicating that RHS2 can inhibit the activation of CD4 T cells and CD8 T cells, leading to inhibition of Th1 immune response. RHS2 inhibits the elimination of target cells by cytotoxic T lymphocytes. After immunization of mice with RHS2 and OVA, serum IgG2b was significantly reduced and IgM was increased.

Conclusions

The results show that RHS2 has an inhibitory effect on the host immune response. Ticks have evolved various ways to circumvent adaptive immunity. Their serpin inhibits BMDC differentiation to reduce immune responses.

Seroprevalence of Borrelia burgdorferi in forest workers from inspectorates with different forest types in Lower Silesia, SW Poland: preliminary study

To estimate the Lyme borreliosis (LB) risk for forest workers, totally 646 blood samples were tested for IgG and IgM anti-Borrelia burgdorferi s.l. (anti-B.b.) antibody occurrence using ELISA tests confirmed with western blot. To clarify the varied LB risk, additionally, the data from the Forest Data Bank determining the detailed forest habitat type in particular forest inspectorates were used. The occurrence of the anti-B.b. antibody was confirmed in 22% (8.7% IgM, 17.8% IgG) of forest workers. Analysis of the influence of the habitat type (forest types) indicated the significant positive impact of the occurrence of the deciduous and mixed-deciduous forests on the seroprevalence of anti-B.b. IgG level among forestry workers. However, the share of forest type cannot be the only factor taken into account when assessing risk.

A national survey of Ixodidae ticks on privately owned dogs in Italy

BACKGROUND

The geographical distribution of ticks on companion animals needs to be monitored to develop and plan effective control measures, as suggested by the European Scientific Counsel on Companion Animal Parasites. The aim of this study was to conduct the first Italian national survey of tick distribution on privately owned dogs.

METHODS

The study was performed over 20 months (February 2016 - September 2017) and involved 153 veterinary practices in 64 different provinces covering 17/20 (85%) Italian regions. Participating practitioners were asked to examine five different dogs per month at random and complete a questionnaire for each dog. Differences in tick infestation associated with: sex, age and hair length (long and short); the dog's habitat (indoor or outdoor/kennel); and the dog's environment (urban or rural/sylvatic) were evaluated. The attachment site of ticks on the dog was also recorded. Acaricide efficacy was evaluated for the subset of dogs for which complete information on product used, date of sampling and date of last ectoparasiticide treatment was available.

RESULTS

Of the 3026 dogs examined, 1383 (45.7%) were carrying at least one tick. Overall, 2439 tick samples were collected and a total of 14 tick species identified. Rhipicephalus sanguineus group were the most predominant ticks (63.6%), followed by Ixodes ricinus (30.6%) and I. hexagonus (5.6%). Twenty-four dogs had mixed tick infestations. Long-haired dogs had a higher tick infestation risk as did dogs with outdoor and rural/sylvatic lifestyles. Ticks were located on the head (37.4%), the neck (28.8%), the muzzle (15.5%) and the back (15.3%). A higher prevalence of Rhipicephalus was found in the interdigital spaces (10.8%) compared to Ixodes (0.2%). Finally, ectoparasiticide treatments were found significantly protective against tick infestation, especially orally administered formulations.

CONCLUSIONS

Privately owned dogs in Italy have a high prevalence (45.7%) of infestation with ixodid ticks and this risk varies by dog phenotype and lifestyle.