Tick Hosts Research Articles

The public health implications of gentrification: tick‐borne disease risks for communities of color

Gentrification operates as a social driver of health that can increase tick‐borne disease (TBD) risk for communities of color through either population displacement or land‐use change. Research on the emergence of TBDs in urban environments has primarily focused on the ecological processes of urban landscapes that facilitate favorable habitats for host reservoirs and tick vectors. However, neglecting to view infectious disease risk from a socioecological framework will continue to result in policies and planning that disadvantage communities of color. Using Lyme disease as a case study, we integrated elements of environmental epidemiology, ecology, public health, and urban planning to propose pathways of gentrification as a socioecological process with public health implications. By drawing connections between urban ecology, urban planning, and environmental racism, we seek to bring awareness to disease ecologists, policy makers, and public health managers on the potential role of gentrification as a driver of tick‐borne pathogen exposure.Front Ecol Environ 2022;

Identification and expression of potential olfactory-related genes related to Niemann-Pick C2 protein and ionotropic receptors in Haemaphysalis longicornis.

Studies have shown that the main pathway for tick host localization and perception of mating information may be chemosensory. However, chemical communication in ticks is poorly understood, especially in those other than the Ixodes ticks. Niemann-Pick C2 (NPC2) protein and ionotropic receptors (IRs) are considered to be closely related to the perception of infochemicals in arthropods. Through bioinformatic analysis, eight NPC2 and four IR candidate genes were identified through screening and identification of the transcriptome sequencing database of Haemaphysalis longicornis. Phylogenetic tree analysis indicated that H. longicornis possesses similar homology to the genus Ixodes. A comparison of the expression of NPC2 and IR in tick forelegs (first pair of legs), hind legs (fourth pair of legs), and capitula using RT-PCR revealed that, barring HlonNPC2-8, 11 candidate genes were highly expressed in the foreleg and capitulum, which are the main sensory organs of ticks. They were also expressed in the hind legs, except for six genes that were not expressed in the males. RT-qPCR analysis showed upregulation and higher relative expression of HlonNPC2-1, HlonNPC2-3, HlonNPC2-6, and HlonNPC2-8 when stimulated by ammonium hydroxide, whereas the others were downregulated and demonstrated lower relative expression. These results further support the putative role of NPC2s as a new odorant carrier in ticks and present 12 promising candidate genes for understanding tick olfactory communication, enriching the data on these genes, especially outside the genus Ixodes.

Influence of tick sex and geographic region on the microbiome of Dermacentor variabilis collected from dogs and cats across the United States

As tick-borne diseases continue to increase across North America, current research strives to understand how the tick microbiome may affect pathogen acquisition, maintenance, and transmission. Prior high throughput amplicon-based microbial diversity surveys of the widespread tick Dermacentor variabilis have suggested that life stage, sex, and geographic region may influence the composition of the tick microbiome. Here, adult D. variabilis ticks (n = 145) were collected from dogs and cats from 32 states with specimens originating from all four regions of the United States (West, Midwest, South, and Northeast), and the tick microbiome was examined via V4-16S rRNA gene amplification and Illumina sequencing. A total of 481,246 bacterial sequences were obtained (median 2924 per sample, range 399–11,990). Fifty genera represented the majority (>80%) of the sequences detected, with the genera Allofrancisella and Francisella being the most abundant. Further, 97%, 23%, and 5.5% of the ticks contained sequences belonging to Francisella spp., Rickettsia spp., and Coxiella spp., respectively. No Ehrlichia spp. or Anaplasma spp. were identified. Co-occurrence analysis, by way of correlation coefficients, between the top 50 most abundant genera demonstrated five strong positive and no strong negative correlation relationships. Geographic region had a consistent effect on species richness with ticks from the Northeast having a significantly greater level of richness. Alpha diversity patterns were dependent on tick sex, with males exhibiting higher levels of diversity, and geographical region, with higher level of diversity observed in ticks obtained from the Northeast, but not on tick host. Community structure, or beta diversity, of tick microbiome was impacted by tick sex and geographic location, with microbiomes of ticks from the western US exhibiting a distinct community structure when compared to those from the other three regions (Northeast, South, and Midwest). In total, LEfSe (Linear discriminant analysis Effect Size) identified 18 specific genera driving these observed patterns of diversity and community structure. Collectively, these findings highlight the differences in bacterial diversity of D. variabilis across the US and supports the interpretation that tick sex and geographic region affects microbiome composition across a broad sampling distribution.

Detection and molecular identification of Anaplasma phagocytophilum and Babesia spp. infections in Hyalomma aegyptium ticks in Tunisia.

Tortoises of the genus Testudo are the main hosts of Hyalomma aegyptium ticks. This species serves as a vector of several zoonotic pathogens. Therefore, the present study aimed to investigate the presence of four pathogens associated with H. aegyptium ticks obtained from tortoises from Tunisia. Conventional, multiplex and nested PCRs were used for Aanaplasma phagocytophilum, Ehrlichia canis, Coxiella burnetii and Babesia spp. screening. The molecular analyses revealed the presence of A. phagocytophilum and Babesia spp. None of the ticks, were infected by E. canis or C. burnetii species. Co-infection was detected in four ticks. As a conclusion, this is the first detection of A. phagocytophilum and Babesia spp. in H. aegyptium ticks collected from tortoises, in Tunisia. Thus, considering these results, the spur-thighed tortoise constitute a potential host of H. aegyptium which plays an important role in the transmission of pathogenic agents affecting both human and animals. In term of public health, a strict control and surveillance should be carried to reduce the circulation of such pathogens between different hosts.

Fluazuron orally administered to guinea pigs: pharmacokinetic and efficacy against Amblyomma sculptum

BackgroundBrazilian spotted fever (BSF), the most lethal tick-borne disease in the Western Hemisphere, is caused by the bacterium Rickettsia rickettsii and transmitted by the bite of Amblyomma sculptum. Capybaras are considered primary hosts of this tick and amplifier hosts of R. rickettsii, generating new infected lineages of A. sculptum in BSF-endemic areas. To define a possible treatment regimen for controlling the tick A. sculptum in capybaras, the aim of this study was to establish an effective fluazuron (FLU) dose to control A. sculptum larvae in artificially infested guinea pigs.MethodsIn Study I (pharmacokinetic and pharmacodynamic analysis), 24 guinea pigs were divided into four equal groups: control group (CG; untreated) and treated groups receiving FLU administered by gavage in three doses: G1—1 mg/kg, G2—5 mg/kg and G3—10 mg/kg, once a day for 15 days (d0 to d + 14). Blood samples were collected from the animals of the treated groups before and at d + 1, + 2, + 4, + 7, + 15 and + 21. The guinea pigs were artificially infested at d + 7 with A. sculptum larvae, and specimens were recovered at d + 11 to d + 14 and kept in a climatized chamber for 14 days. In Study II (evaluation of pharmacokinetic parameters), one group of eight animals received FLU administered by gavage in a single dose of 10 mg/kg, and blood samples were collected before and on day 0 (8 h after treatment), + 1, + 4, + 7, + 15, + 21 and + 28 after single FLU administration. FLU was analyzed in plasma samples by high-performance liquid chromatography with ultraviolet detection.ResultsFLU plasma concentrations increased quickly, indicating rapid absorption, and decreased slowly. Some larvae from all treated groups exhibited morphological and behavioral changes. FLU interfered in molting, and the efficacy obtained was 100% for all treated groups.ConclusionsThe results offer promising perspectives for the development of a palatable feed cube containing FLU for free-living capybaras to control A. sculptum and also to prevent BSF in areas where capybaras have been shown to play a primary role.

Can restoration of fire-dependent ecosystems reduce ticks and tick-borne disease prevalence in the eastern United States?

Over the past century, fire suppression has facilitated broad ecological changes in the composition, structure, and function of fire-dependent landscapes throughout the eastern US, which are in decline. These changes have likely contributed mechanistically to the enhancement of habitat conditions that favor pathogen-carrying tick species, key wildlife hosts of ticks, and interactions that have fostered pathogen transmission among them and to humans. While the long-running paradigm for limiting human exposure to tick-borne diseases focuses responsibility on individual prevention, the continued expansion of medically important tick populations, increased incidence of tick-borne disease in humans, and emergence of novel tick-borne diseases highlights the need for additional approaches to stem this public health challenge. Another approach that has the potential to be a cost-effective and widely applied but that remains largely overlooked is the use of prescribed fire to ecologically restore degraded landscapes that favor ticks and pathogen transmission. We examine the ecological role of fire and its effects on ticks within the eastern United States, especially examining the life cycles of forest-dwelling ticks, shifts in regional-scale fire use over the past century, and the concept that frequent fire may have helped moderate tick populations and pathogen transmission prior to the so-called fire-suppression era that has characterized the past century. We explore mechanisms of how fire and ecological restoration can reduce ticks, the potential for incorporating the mechanisms into the broader strategy for managing ticks, and the challenges, limitations, and research needs of prescribed burning for tick reduction.

A 15-year monitoring of Rickettsiales (Anaplasma phagocytophilum and Rickettsia spp.) in questing ticks in the city of Hanover, Germany

Rickettsiales (Anaplasma phagocytophilum and Rickettsia spp.) are regarded as potentially emerging tick-borne pathogens and may change in abundance in response to global climate change. However, continuous monitoring on their prevalence in questing ticks is only available for the northern German city of Hanover. In the presented follow-up of this long-term study, 2100 questing ticks of the Ixodes ricinus/Ixodes inopinatus-complex collected from April to October 2020 at ten different recreation sites in Hanover were individually analysed for Rickettsia and A. phagocytophilum infection by quantitative real-time PCR. Together with previous results from years 2005, 2010 and 2015, the current study allows to assess potential changes in tick infection rates with Rickettsiales over a 15-year monitoring period. In 2020, 3.0% (63/2100) of ticks were infected with A. phagocytophilum, 36.0% (756/2100) with Rickettsia spp. and 1.2% (26/2100) with both pathogens. Regarding the different developmental tick stages, nymphs showed a significantly lower A. phagocytophilum prevalence of 0.5% (5/1050) than adult ticks (5.5% [58/1050]) as well as compared to females (5.4% [38/700]) and males (5.7% [20/350]). For Rickettsia spp., nymphs also showed a lower prevalence of 33.2% (349/1050) with a significant difference to adult ticks (38.8% [407/1050]) and female ticks (40.7% [285/700]), while males had a Rickettsia infection rate of 34.9% (122/350). Comparison with previous years indicated a stable A. phagocytophilum prevalence over the 15-year monitoring period. In contrast, fluctuating Rickettsia prevalences were observed, with a peak in 2015 in all developmental stages, but similar infection rates in 2005 and 2020. Therefore, epidemiological changes in response to climate change are not (yet) evident. Nevertheless, the long-term monitoring study will be continued in the future, as climatic impacts on tick and reservoir host populations may have a delayed effect on pathogen prevalence and, consequently, transmission to humans and domestic animals.

A Transfected Babesia bovis Parasite Line Expressing eGFP Is Able to Complete the Full Life Cycle of the Parasite in Mammalian and Tick Hosts.

Bovine babesiosis is caused by apicomplexan pathogens of the genus Babesia, including B. bovis. This protozoan parasite has a complex life cycle involving dynamic changes to its transcriptome during the transition between the invertebrate and vertebrate hosts. Studying the role of genes upregulated by tick stage parasites has been hindered by the lack of appropriate tools to study parasite gene products in the invertebrate host. Herein, we present tfBbo5480, a transfected B. bovis cell line, constitutively expressing enhanced green fluorescent protein (eGFP) created by a whole gene replacement transfection strategy, that was capable of completing the parasite’s entire life cycle in both the vertebrate and invertebrate hosts. tfBbo5480 was demonstrated to respond to in vitro sexual stage induction and upon acquisition by the female tick vector, Rhipicephalus microplus, the tick specific kinete stage of tfBbo5480 was detected in tick hemolymph. Larvae from tfBbo5480 exposed R. microplus female ticks successfully transmitted the transfected parasite to a naïve calf. The development of the whole gene replacement strategy will permit a deeper understanding of the biology of parasite-host-vector triad interactions and facilitate the evaluation of upregulated genes during the parasite’s journey through the tick vector leading to new intervention strategies for the control of bovine babesiosis.

Bacterial microbiota analysis demonstrates that ticks can acquire bacteria from habitat and host blood meal.

Ticks have a diversity of habitats and host blood meals. Whether and how factors such as tick developmental stages, habitats and host blood meals affect tick bacterial microbiota is poorly elucidated. In the present study, we investigated the bacterial microbiotas of the hard tick Haemaphysalis longicornis, their blood meals and habitats using 16S rRNA gene high-throughput sequencing. The bacterial richness and diversity in ticks varied depending on the tick developmental stage and feeding status. Results showed that fed ticks present a higher bacterial richness suggesting that ticks may acquire bacteria from blood meals. The significant overlap of the bacteria of fed ticks and the host blood also supports this possibility. Another possibility is that blood meals can stimulate the proliferation of certain bacteria. However, most shared bacteria cannot transmit throughout the tick life cycle, as they were not present in tick eggs. The most shared bacteria between ticks and habitats are members of the genera Staphylococcus, Pseudomonas, Enterobacter, Acinetobacter and Stenotrophomonas, suggesting that these environmental bacteria cannot be completely washed away and can be acquired by ticks. The predominant proportion of Coxiella in fed females further demonstrates that this genus is involved in H. longicornis physiology, such as feeding activity and nutritional provision. These findings further reveal that the bacterial composition of ticks is influenced by a variety of factors and will help in subsequent studies of the function of these bacteria.

Seroprevalence and detection of Rickettsia spp. in wild birds of Arauca, Orinoquia region, Colombia.

Wild birds have an important role as hosts of ticks infected by rickettsiae. However, the role of birds as reservoirs of tick-borne rickettsiae is unknown and poorly understood. This is particularly relevant in several tropical and subtropical areas, where migration influences the global spread of ectoparasites and pathogens of public health importance. This research aimed to detect and evaluate the exposure to spotted fever group rickettsiae in wild birds that could represent reservoirs in the Department of Arauca in the Colombian Orinoquia region. Sampling was conducted in three municipalities of the Department of Arauca (Colombia). Blood samples were collected from 255 birds and processed to obtain serum (n=155) and DNA (n=255) samples. The serum samples were processed for indirect immunofluorescence assays (IFA) for the detection of antibodies to Rickettsia rickettsii, Rickettsia parkeri, Rickettsia amblyommatis, Rickettsia rhipicephali, and Rickettsia bellii. Additionally, we investigated rickettsiae DNA in blood samples by amplification of the citrate synthase gene (gltA). The IFA results revealed seropositivity in 97 samples from 54 species of resident and migratory birds. No sample was positive for rickettsial DNA. The presence of antibodies in 62.5% of the sera indicates previous exposure of these birds to rickettsiae. The null detection of rickettsiae in the blood of seropositive birds is possibly due to a short period of bacteremia. Experimental studies are required to improve our understanding of the role of wild birds as sources of rickettsial infections in ticks.

Protozoan and Rickettsial Pathogens in Ticks Collected from Infested Cattle from Turkey.

Diseases caused by tick-transmitted pathogens including bacteria, viruses, and protozoa are of veterinary and medical importance, especially in tropical and subtropical regions including Turkey. Hence, molecular surveillance of tick-borne diseases will improve the understanding of their distribution towards effective control. This study aimed to investigate the presence and perform molecular characterization of Babesia sp., Theileria sp., Anaplasma sp., Ehrlichia sp., and Rickettsia sp. in tick species collected from cattle in five provinces of Turkey. A total of 277 adult ticks (males and females) were collected. After microscopic identification, tick pools were generated according to tick species, host animal, and sampling sites prior to DNA extraction. Molecular identification of the tick species was conducted through PCR assays. Out of 90 DNA pools, 57.8% (52/90) were detected to harbor at least 1 pathogen. The most frequently-detected pathogens were Babesia bovis, with a minimum detection rate of 7.9%, followed by Ehrlichia sp. (7.2%), Theileria annulata (5.8%), Coxiella sp. (3.3%), Anaplasma marginale (2.5%), Rickettsia sp. (2.5%), and B. occultans (0.7%). Rickettsia sp. identified in this study include Candidatus Rickettsia barbariae, R. aeschlimannii, and Rickettsia sp. Chad. All sequences obtained from this study showed 99.05–100% nucleotide identity with those deposited in GenBank (query cover range: 89–100%). This is the first molecular detection of Rickettsia sp. Chad, a variant of Astrakhan fever rickettsia, in Turkey. Results from this survey provide a reference for the distribution of ticks and tick-borne pathogens in cattle and expand the knowledge of tick-borne diseases in Turkey.

White-Tailed Deer Spatial Distribution in Relation to '4-Poster' Tick Control Devices in Suburbia.

Deer are keystone hosts for adult ticks and have enabled the spread of tick distributions. The ‘4-Poster’ deer bait station was developed by the United States Department of Agriculture to control ticks feeding on free-ranging deer. Although effective in certain scenarios, ‘4-Poster’ deer treatment stations require the use of bait to attract deer to one location, which may cause increased deer disease transmission rates and habitat damage. To better understand and manage the impact of baited ‘4-Poster’ stations on deer movements, we captured and GPS-monitored 35 deer as part of an integrated pest management project. Fifteen ‘4-Poster’ stations were deployed among three suburban county parks to control ticks. To quantify the effects of ‘4-Poster’ stations, we calculated deer movement metrics before and after feeders were filled with whole kernel corn, and we gathered information on visitation rates to feeders. Overall, 83.3% of collared deer visited a feeder and revisited approximately every 5 days. After feeders were refilled, collared deer were ~5% closer to feeders and conspecifics than before filling. Males used a higher percentage of available feeders and visited them more throughout the deployment periods. Although these nuanced alterations in behavior may not be strong enough to increase local deer abundance, in light of infectious diseases affecting deer populations and effective ‘4-Poster’ densities, the core range shifts and clustering after refilling bait may be a cause for concern. As such, trade-offs between conflicting management goals should be carefully considered when deploying ‘4-Poster’ stations.

Improving Widescale Monitoring of Ectoparasite Presence in Northern Canadian Wildlife with the Aid of Citizen Science

Simple SummarySurveying ticks on wildlife hosts consistently over time and across space presents many challenges. In Yukon, Canada, the winter tick, Dermacentor albipictus, is a blood-feeding parasite that can cause significant losses of hair and blood in moose and other wildlife. The impacts of winter tick infestation in wildlife hosts in this northern region are not well documented. To enhance existing surveillance of winter ticks in Yukon, we implemented a three-year citizen science program, the Yukon Winter Tick Monitoring Project (YWTMP) to engage hunters in the collection of underrepresented moose and caribou samples. Social media, participation incentives, and hide-sampling kits distributed to hunters increased the combined number of annual moose and caribou hide submissions almost 100-fold, and the geographical range of samples by almost 500 km, compared with submission numbers in the previous seven years. Citizen science samples were also used to detect previously unknown infection localities on moose in southeastern Yukon that are spatially separate to known infestations found on elk and deer, helping to build a better picture of infection dynamics on different host animals. Engaging with key demographic groups using structured citizen science programs like the YWTMP can significantly expand sampling efforts in remote areas while maintaining systematic sampling methods to monitor parasites of wildlife health concern.Sampling hides from harvested animals is commonly used for passive monitoring of ectoparasites on wildlife hosts, but often relies heavily on community engagement to obtain spatially and temporally consistent samples. Surveillance of winter ticks (Dermacentor albipictus) on moose (Alces alces) and caribou (Rangifer tarandus caribou) hosts in Yukon, Canada, has relied in part on voluntary submission of hides by hunters since 2011, but few samples were submitted. To enhance sampling efforts on underrepresented moose and caribou hosts, we implemented a three-year citizen science program, the Yukon Winter Tick Monitoring Project (YWTMP), to better engage with hunters in hide sample collection. A combination of in-person and social media outreach, incentivized engagement, and standardized hide sampling kits increased voluntary submissions of moose and caribou hides almost 100-fold since surveillance began. Citizen science samples expanded the northernmost geographic extent of existing sampling efforts for moose by 480 km and for caribou by 650 km to reach 67.5° N latitude. Samples also resulted in new detections of winter ticks on moose hides that are spatially separate to those submitted for other cervids in Yukon. Findings from the YWTMP have provided an essential baseline to monitor future winter tick host–parasite dynamics in the region and highlighted priority areas for ongoing tick surveillance.

Transmission patterns of tick-borne pathogens among birds and rodents in a forested park in southeastern Canada

Ixodes scapularis ticks are expanding their range in parts of northeastern North America, bringing with them pathogens of public health concern. While rodents like the white-footed mouse, Peromyscus leucopus, are considered the primary reservoir of many emerging tick-borne pathogens, the contribution of birds, as alternative hosts and reservoirs, to local transmission cycles has not yet been firmly established. From 2016 to 2018, we collected host-seeking ticks and examined rodent and bird hosts for ticks at 48 sites in a park where blacklegged ticks are established in Quebec, Canada, in order to characterize the distribution of pathogens in ticks and mammalian and avian hosts. We found nearly one third of captured birds (n = 849) and 70% of small mammals (n = 694) were infested with I. scapularis. Five bird and three mammal species transmitted Borrelia burgdorferi to feeding larvae (n larvae tested = 2257) and we estimated that about one fifth of the B. burgdorferi-infected questing nymphs in the park acquired their infection from birds, the remaining being attributable to mice. Ground-foraging bird species were more parasitized than other birds, and species that inhabited open habitat were more frequently infested and were more likely to transmit B. burgdorferi to larval ticks feeding upon them. Female birds were more likely to transmit infection than males, without age differentiation, whereas in mice, adult males were more likely to transmit infection than juveniles and females. We also detected Borrelia miyamotoi in larvae collected from birds, and Anaplasma phagocytophilum from a larva collected from a white-footed mouse. This study highlights the importance of characterising the reservoir potential of alternative reservoir hosts and to quantify their contribution to transmission dynamics in different species assemblages. This information is key to identifying the most effective host-targeted risk mitigation actions.

Host in reserve: The role of common shrews (Sorex araneus) as a supplementary source of tick hosts in small mammal communities influenced by rodent population cycles.

Rodents often act as important hosts for ticks and as pathogen reservoirs. At northern latitudes, rodents often undergo multi‐annual population cycles, and the periodic absence of certain hosts may inhibit the survival and recruitment of ticks. We investigated the potential role of common shrews (Sorex araneus) to serve as a supplementary host source to immature life stages (larvae and nymphs) of a generalist tick Ixodes ricinus and a small mammal specialist tick I. trianguliceps, during decreasing abundances of bank voles (Myodes glareolus). We used generalized mixed models to test whether ticks would have a propensity to parasitize a certain host species dependent on host population size and host population composition across two high‐latitude gradients in southern Norway, by comparing tick burdens on trapped animals. Host population size was defined as the total number of captured animals and host population composition as the proportion of voles to shrews. We found that a larger proportion of voles in the host population favored the parasitism of voles by I. ricinus larvae (estimate = −1.923, p = .039) but not by nymphs (estimate = −0.307, p = .772). I. trianguliceps larvae did not show a lower propensity to parasitize voles, regardless of host population composition (estimate = 0.875, p = .180), while nymphs parasitized shrews significantly more as vole abundance increased (estimate = 2.106, p = .002). These results indicate that common shrews may have the potential to act as a replacement host during periods of low rodent availability, but long‐term observations encompassing complete rodent cycles may determine whether shrews are able to maintain tick range expansion despite low rodent availability.

Babesia gibsoni

Babesia gibsoni is an intraerythrocytic apicomplexan parasite that causes babesiosis in dogs. Since its first report in India in 1910, B. gibsoni has spread globally. It is transmitted mainly by tick bite but many reports have demonstrated transmission by dog fighting, and blood transfusion, and a few reports have mentioned transplacental transmission to the developing fetus. The parasite life cycle consists of a sexual developmental phase in the midgut lumen of tick vectors (gamogony) and two asexual developmental phases occurring in the tick salivary glands (sporogony) and host red blood cells (merogony).

Host Immune Responses to Salivary Components - A Critical Facet of Tick-Host Interactions.

Tick sialome is comprised of a rich cocktail of bioactive molecules that function as a tool to disarm host immunity, assist blood-feeding, and play a vibrant role in pathogen transmission. The adaptation of the tick’s blood-feeding behavior has lead to the evolution of bioactive molecules in its saliva to assist them to overwhelm hosts’ defense mechanisms. During a blood meal, a tick secretes different salivary molecules including vasodilators, platelet aggregation inhibitors, anticoagulants, anti-inflammatory proteins, and inhibitors of complement activation; the salivary repertoire changes to meet various needs such as tick attachment, feeding, and modulation or impairment of the local dynamic and vigorous host responses. For instance, the tick’s salivary immunomodulatory and cement proteins facilitate the tick’s attachment to the host to enhance prolonged blood-feeding and to modulate the host’s innate and adaptive immune responses. Recent advances implemented in the field of “omics” have substantially assisted our understanding of host immune modulation and immune inhibition against the molecular dynamics of tick salivary molecules in a crosstalk between the tick–host interface. A deep understanding of the tick salivary molecules, their substantial roles in multifactorial immunological cascades, variations in secretion, and host immune responses against these molecules is necessary to control these parasites. In this article, we reviewed updated knowledge about the molecular mechanisms underlying host responses to diverse elements in tick saliva throughout tick invasion, as well as host defense strategies. In conclusion, understanding the mechanisms involved in the complex interactions between the tick salivary components and host responses is essential to decipher the host defense mechanisms against the tick evasion strategies at tick-host interface which is promising in the development of effective anti-tick vaccines and drug therapeutics.

Antiphospholipid autoantibodies in Lyme disease arise after scavenging of host phospholipids by Borrelia burgdorferi.

A close association with its vertebrate and tick hosts allows Borrelia burgdorferi, the bacterium responsible for Lyme disease, to eliminate many metabolic pathways and instead scavenge key nutrients from the host. A lipid-defined culture medium was developed to demonstrate that exogenous lipids are an essential nutrient of B. burgdorferi, which can accumulate intact phospholipids from its environment to support growth. Antibody responses to host phospholipids were studied in mice and humans using an antiphospholipid ELISA. Several of these environmentally acquired phospholipids including phosphatidylserine and phosphatidic acid, as well as borrelial phosphatidylcholine, are the targets of antibodies that arose early in infection in the mouse model. Patients with acute infections demonstrated antibody responses to the same lipids. The elevation of antiphospholipid antibodies predicted early infection with better sensitivity than did the standardized 2-tier tests currently used in diagnosis. Sera obtained from patients with Lyme disease before and after antibiotic therapy showed declining antiphospholipid titers after treatment. Further study will be required to determine whether these antibodies have utility in early diagnosis of Lyme disease, tracking of the response to therapy, and diagnosis of reinfection, areas in which current standardized tests are inadequate.

Modeling the invasion and establishment of a tick-borne pathogen

We develop a discrete-time tick–host–pathogen model to describe the spread of a disease in a hard-bodied tick species. This model incorporates the developmental stages for a tick, the dependence of the tick life-cycle and disease transmission on host availability, and three sources of pathogen transmission. We first establish the global dynamics of the disease-free system. We then apply the model to two pathogens, Borellia burgdorferi and Anaplasma phagocytophila, using Ixodes ricinus as the tick species to study properties of the invasion and establishment of a disease numerically. In particular, we consider the basic reproduction number, which determines whether a disease can invade the tick-host system, as well as disease prevalence and time to establishment in the case of successful disease invasion. Using Monte Carlo simulations, we calculate the means of each of these disease metrics and their elasticities with respect to various model parameters. We find that increased tick survival may help enable disease invasion, decrease the time to disease establishment, and increase disease prevalence once established. In contrast, though disease invasion is sensitive to tick-to-host transmission and tick searching efficiencies, neither disease prevalence nor time to disease establishment is sensitive to these parameters. These differences emphasize the importance of developing approaches, such as the one highlighted here, that can be used to study disease dynamics beyond just pathogen invasion, including transitional and long-term dynamics.

A Review of Tick and Tick Control Strategies in Pakistan

Background: In Pakistan, ticks are a major problem for livestock and humans. These can spread a wide range of infections including protozoan, viruses, and bacteria such as spirochetes and rickettsiae. Ticks are found in all ecological and geographic zones of Pakistan. Bovine Babesiosis and Theileriosis have been documented in Pakistan. Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral disease that affects those who work with cattle, like slaughterhouse workers, vets, and hospitals. There are at least 40 tick species, mostly Haemaphysalis, Hyalomma, and Rhipicephalus. In Pakistan, CCHF is spread by Hyalomma ticks, posing a severe risk to human health. Ticks are most prevalent in the summer (June–September) and goats rather than sheep in Pakistan. Tick-borne infections include Anaplasma, Babesia, and Theileria spp., more common in sheep than goats. In the previous sixteen years, occasional CCHF outbreaks have been documented in Pakistan, with a 24% fatality rate. Mass tick control efforts have been initiated in Punjab and Sind provinces to control tick populations and zoonotic disease spread. These tick control campaigns use a lot of Deltamethrin and Ivermectin. Deltamethrin and Ivermectin can harm the ecosystem and suggested alternate tick control approaches. Deltamethrin can damage the kidneys of insect-eating birds and disrupt the life cycle of aquatic organisms when mixed with stream water. This is because roughly 60%-80% of the whole dose is excreted by the animal and is not metabolized by the animal. Dung deterioration can be hampered by a reduction of dung beetles. Tick control methods have been used for decades worldwide. But only chemical technique is still practised in Pakistan. Each method's efficacy varies with tick number, dispersion, morphology, and host species. Results: The goal of the literature review was to discuss ticks and tick management measures used on domestic animals in Pakistan and offer new and successful techniques. This article reviews the most widely used tick management methods in Pakistan. According to studies, ticks and tick-borne diseases cause significant economic losses to livestock globally. Chemicals (acaricides) are overused to treat ticks on domestic and wild animals. Tickbots, bait boxes, vaccines, natural fauna, and bio-pesticides should be promoted and used to control ticks. Conclusion: The literature concluded that tick and tick-borne diseases are a significant cause of economic losses to the livestock throughout the globe. The chemicals (acaricides) are excessively applied against ticks on domestic and wild animals. Other new techniques like tickbot, bait boxes, the discovery of vaccines, natural fauna and biopesticides should be promoted and applied to control the ticks. These strategies will have an extreme outcome on reducing the tick population. Keywords: Ticks, Ectoparasites, Congo Haemorrhagic Fever, Wild animals, Integrated tick management, Pakistan