Dermacentor Variabilis Research Articles

Comparison of the supercooling points of questing Dermacentor variabilis adults in two populations on the Canadian prairies and implications for overwinter survival.

A comparison was made of the supercooling points (SCPs) of questing Dermacentor variabilis adults from two populations located ca. 800km apart on the Canadian prairies. This is also the first study to examine whether there are seasonal fluctuations in the SCP of questing D. variabilis adults. The SCPs of adult ticks from Lizard Lake Community Pasture, a recently established population in west-central Saskatchewan, varied over spring and summer, with the median SCP warming over time. In addition, the SCPs of ticks from Lizard Lake Community Pasture were significantly higher than those of adult ticks collected from Sandy Hook in Manitoba, a population that has been established for decades. The off-host survival of adults from Sandy Hook between summer and spring has been shown previously to be significantly greater than that of adults from Lizard Lake Community Pasture. The findings of the present study suggest that there may be geographical variation in the SCPs of D. variabilis adults which may be associated with differences in overwinter survival. The relatively low SCPs of questing D. variabilis adults, and the ability of some adults to survive off-host during winter, may be factors contributing to the range expansion of this tick species in Canada.

Pharmacokinetics of intravenously and trans-dermally administered fluralaner in healthy laying shaver hens: fluralaner in chickens

Ectoparasite infestations negatively affect both backyard and commercial chicken flocks in the United States. Fluralaner is an isoxazoline shown to be efficacious in treating mite and bed bug infestations in poultry. Fluralaner is approved to treat fleas and ticks in dogs and cats in the United States and to treat mite infestations of chickens in Europe and Australia; however, the use of fluralaner in poultry is not yet approved in the United States. This study aimed to investigate the plasma fluralaner pharmacokinetic profile of intravenous and transdermal routes and apparent bioavailability of fluralaner administered trans-dermally in healthy shaver hens. A total of 12 individually housed healthy shaver hens received a single dose of either intravenous technical grade fluralaner at 0.5 mg/kg, or transdermal fluralaner (Bravecto (fluralaner transdermal solution) for dogs, 280 mg/mL, Merck Animal Health) at mean 58.7 mg/kg. Plasma from each hen was collected from the jugular, ulnar, or medial metatarsal vein at multiple intervals. Fluralaner concentrations in plasma were determined using Ultra Performance Liquid Chromatography with Mass Spectrometry (UPLC/MS). Noncompartmental analysis revealed that the geometric mean elimination half-life for intravenous and transdermal routes were 80.5 and 179.6 h, respectively. The geometric mean apparent bioavailability of transdermal routes was estimated as 3.4%. Prolonged fluralaner concentration in plasma above minimum inhibitory concentration of bed bugs following the single dose was observed in healthy shaver hens for both routes. It is important to understand the pharmacokinetic profile could be useful in determining the appropriate treatment strategy.

Molecular Evidence of Ehrlichia canis (Rickettsiales: Anaplasmataceae) in Ticks (Ixodida: Ixodidae) Associated with Dogs (Carnivora: Canidae) from Nuevo Leon, Mexico.

Background: Ehrlichia canis is transmitted by ticks causing Canine monocytic ehrlichiosis, which is considered one of the most critical tickborne pathogens. Materials and Methods: This study aimed to identify by PCR technique E. canis in ticks associated with dogs from urban and rural homes in Nuevo Leon, Mexico. The study was conducted at 13 localities in eight municipalities from 2012 to 2021. Results: A total of 1873 ticks of three species were captured: Amblyomma tenellum, Dermacentor variabilis, and Rhipicephalus sanguineus s.l. The overall infection rate of E. canis in ticks was 59.12% (149/252). Of the 15 sequences, three haplotypes were identified. Conclusion: The urban transmission cycle of canine ehrlichiosis is demonstrated, where the potential vector is the tick R. sanguineus s.l.

Differences in the reproductive output and larval survival of Rocky Mountain wood ticks (Dermacentor andersoni) and American dog ticks (Dermacentor variabilis) from prairie populations near their northern distributional limits in western Canada.

The effects of temperature and relative humidity (RH) on female reproductive output, egg development and larval survival were determined for Rocky Mountain wood ticks (Dermacentor andersoni) from a prairie population (Chin Lakes, Alberta, Canada) near the northern distribution limit of this species. The responses of D. andersoni eggs and unfed larvae to different temperature (25 or 32°C) and RH (35, 55, 75, 85 or 95%) regimes were compared to our previously published data (Diyes et al. 2021) for a northern prairie population of American dog ticks (Dermacentor variabilis). Oviposition by D. andersoni females took 21-30 days at 25°C and 95% RH compared to 10-21 days for D. variabilis. The number of eggs laid by female ticks was strongly dependent on their engorgement weight, and D. andersoni females produced more eggs than D. variabilis females of an equivalent body weight. Eggs of D. andersoni took less time to develop at 32°C than 25°C with ≥ 85% RH, and hatched faster than those of D. variabilis. Larval survival times declined as temperature increased and RH decreased, but D. andersoni survived longer at 32°C and ≤ 75% RH than D. variabilis. The interspecific differences in responses to the same temperature and humidity regimes indicate that D. andersoni is xerophilic, whereas D. variabilis is hydrophilic. Hence, 'prairie' populations of the Rocky Mountain wood tick occur in the drier grassland ecoregions but are absent in Aspen Parklands Ecoregion which is located to the north and east of the distributional range of D. andersoni.

Effect of snow cover on the off-host survival of Dermacentor variabilis (Acari: Ixodidae) larvae.

The geographical range of the American dog tick, Dermacentor variabilis (Say), in Canada continues to expand northwards into areas with colder winter temperatures. Understanding what influences the off-host survival of D. variabilis over winter is important for predicting the northern distributional limit of this species. A field experiment was conducted to determine the effect of snow cover on the off-host survival of unfed D. variabilis larvae from a population situated near the northern distributional limit in Saskatchewan, Canada. Ticks were placed in tubes within 1 of 9 field enclosures (tickaria) in early fall. The 9 tickaria were divided into 3 equal treatment groups: no snow cover, natural snow cover (maximum depth of 25 cm) and extra snow cover (maximum depth of 32 cm). Tick survival was measured in mid-winter and in early spring (i.e., ~17 and ~26 wk after start of experiment). The results showed that snow cover had a significant impact on the relative humidity, but not temperature, in the tickaria. Larvae in tickaria with no snow cover had a higher mortality rate (27%) than larvae in tickaria with natural snow cover (6%) or extra snow cover (4%). Although snow cover enhanced off-host survival, many individuals were able to survive in sub-zero temperatures under leaf litter in the absence of continuous snow cover for a period of 108 days. These findings have implications for the construction of predictive models to determine the northern distributional limits of D. variabilis, a species that is an important vector of several pathogens.

Exploring the Larvicidal and Repellent Potential of Taurus Cedar (Cedrus libani) Tar against the Brown Dog Tick (Rhipicephalus sanguineus sensu lato).

This study investigated the potential acaricidal and repellent effects of tar obtained from the Lebanon cedar (Cedrus libani A. Rich.) against the brown dog tick species Rhipicephalus sanguineus sensu lato Latreille (Acari: Ixodidae). The goal was to find an alternative, safe, and effective way to eliminate ticks. Tar is traditionally extracted from cedar trees in the Antalya region of Türkiye. The composition of the tar is primarily characterized by a diverse mixture of terpenes, with β-himachalene (29.16%), α-atlantone (28.7%), ar-turmerone (8.82%), longifolene-(V4) (6.66%), α-himachalene (5.28%), and β-turmerone (5.12%) emerging as the predominant constituents. The toxic effects of tar on tick larvae were studied through larval immersion tests (LIT), and its repellent activity was evaluated using a new larval repellent activity test (LRAT). The results revealed significant acaricidal effects, with mortality rates of 77.7% and 82.2% for the Konyaalti and Kepez strains of the brown dog tick, respectively, in response to a 1% concentration of tar. LC50 and LC90 values were determined as 0.47% and 1.52% for the Kepez strain and 0.58% and 1.63% for the Konyaalti strain, respectively. When comparing the repellent effect of tar to the widely used synthetic repellent DEET, repellency rates of up to 100% were observed. As a result, this study establishes, for the first time, the larvicidal and repellent effects of C. libani tar on ticks.

Describing the experience of livestock producers from Ohio, USA with ticks and associated diseases

BackgroundAs tick ranges expand across North America, the risk of tick bites and tick-borne diseases (TBDs, i.e. diseases or syndromes associated with ticks) rises for humans and animals, making prevention critical. Several U.S. studies have examined knowledge, attitudes, and practices regarding ticks and TBDs for various cohorts of people. However, among occupational groups with high exposure risk from ticks and TBDs are livestock producers, of which we know little about. To help address this gap, an electronic questionnaire was distributed to livestock producers in Ohio, U.S, a state with a robust agricultural sector.MethodsWe generated descriptive statistics and conducted a multiple correspondence analysis followed by hierarchical clustering on principal components to identify producers with similar response profiles.ResultsResponses from 57 producers showed that most (52.6%) think the American dog tick (Dermacentor variabilis) is found in Ohio but are unsure about other species. Although several TBDs are present in Ohio, most (> 50%) producers were unsure or unaware of their presence. Interestingly, most (54.4%) thought ticks pose major health risks for their livestock but fewer (49.1%) thought the same for humans. Regardless, most producers did employ at least one prevention method for themselves (96.5%) and their animals (82.5%). Cluster analysis (n = 48) identified three groups: the largest (n = 21) was considered “aware and cautious” consisting primarily of farm owners. The others generally practiced less prevention and consisted primarily of farm employees.ConclusionsOur findings indicate that producers in Ohio practice prevention for themselves and their livestock, but demonstrate gaps in knowledge (e.g., TBD occurrence) and attitudes (e.g., health risks) that could be addressed via educational formats we found producers preferred (e.g., extension materials), to encourage informed prevention. This is especially important for farm employees that may practice less prevention because of lower awareness. Our study can guide others in regions faced with similar tick and TBD risks to protect occupational and livestock health.

Metagenomic exploration of endosymbionts and pathogens in the tropical lineage of Rhipicephalus sanguineus sensu lato (s.l.) ticks in Colombia

Rhipicephalus sanguineus sensu lato (s.l.), commonly known as the domestic dog tick, is a globally distributed tick. This species plays a significant role in human and animal health, as well as in economy due to its ability to infest livestock. The use of shotgun metagenomics has proven valuable in identifying tick-borne pathogens and key members of the tick microbiome, including endosymbionts. However, the application of shotgun metagenomics in R. sanguineus s.l. ticks in Latin America remains largely unexplored. Therefore, our objective aimed to explore and further analyze the metagenome of the tropical lineage of R. sanguineus s.l. ticks in Colombia. Through our analysis, we identified the three most prevalent pathogens harbored by these ticks, namely: Anaplasma phagocytophilum, Francisella tularensis, and Theileria equi. However, the most abundant microorganism detected was not a pathogen but the endosymbiont Coxiella mudrowiae. Interestingly, Coxiella mudrowiae exhibited significant negative correlations with several pathogens and other endosymbionts. Furthermore, we successfully constructed 27 medium-quality metagenome-assembled genomes (MAGs) for this microorganism, enabling us to conduct a pangenome analysis by comparing them with available genomes and identifying proteins of interest, such as those involved in vitamin B synthesis. This study represents the first implementation of shotgun metagenomics as a methodology to expand our understanding of pathogens and endosymbionts in the circulating tropical lineage of R. sanguineus s.l. ticks in Colombia. The findings of this research serve as a foundation for the development of prevention and mitigation strategies against pathogens transmitted by this tick species. Information gained from this study can contribute to the improvement of public health measures and veterinary practices aimed at controlling the impact of tick-borne diseases.

HPB P48 Liver Abscess Secondary to Cocktail Stick Migration Following Accidental Ingestion

Abstract Background Liver abscess formation following foreign body ingestion is rare. This may occur if the foreign body is lodged in the upper gastrointestinal tract and persists. Initial management consists of antibiotics with or without percutaneous abscess drainage. However, referral to the regional HPB unit may need to be considered to discuss foreign body retrieval, especially if it is located within the liver parenchyma itself, in order to treat persistent sepsis or prevent abscess recurrence in the future. Methods A 38-year-old gentleman, previously healthy, presented to the emergency department of a district general hospital with nausea, upper abdominal pain, and fever. He stated that he had accidentally ingested a piece of a wooden cocktail stick while eating some weeks back. Leucocytosis and raised inflammatory markers were present on bloodwork. Computed tomography revealed a 6 cm hypoattenuating lesion in the left lobe of the liver, which demonstrated features of a hepatic abscess on magnetic resonance imaging. Abdominal ultrasound visualised a 4 cm linear hyperechoic structure within the hypoechoic lesion, raising the suspicion of foreign body retention with abscess formation. Results The fever subsided, and symptoms resolved with antibiotics. Follow-up imaging revealed abscess resolution with foreign body persistence in the liver. He was referred to the regional HPB unit and underwent laparoscopy for foreign body removal. A fistulous communication between liver segment II and lesser curvature of the stomach was seen and disconnected using diathermy. Minimal pus was drained and the foreign body retrieved. The gastric perforation was sealed using a linear stapling device. A nasogastric tube was left in the stomach until the patient tolerated a liquid diet and discharged on the first post-operative day. He remains well on follow-up. Conclusions This case highlights that scrupulous history taking and imaging review are required for a timely diagnosis of foreign body retention.

Egg hatching success is influenced by the time of thermal stress in four hard tick species.

Ticks are blood-feeding arthropods responsible for the transmission of disease-causing pathogens to a wide range of vertebrate hosts, including livestock and humans. Tick-borne diseases have been implicated in significant economic losses to livestock production, and this threat will increase as these obligate parasites widen their geographical ranges. Similar to other ectotherms, thermal stress due to changing global temperatures has been shown to influence tick survival and distribution. However, studies on the influence of extreme temperatures in ticks have focused on advanced, mobile stages, ignoring immobile stages that cannot move to more favorable microhabitats. In this study, low- and high-temperature regimens were assessed in relation to egg viability for hard tick species-Amblyomma maculatum (Gulf Coast tick), Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), and Rhipicephalus sanguineus (Brown dog tick). Tick eggs exposed early in development (freshly laid during early embryo development) were significantly more susceptible to thermal stress when compared with those exposed later in development (late embryo development denoted by a fecal spot). Based on our studies, differences in egg hatching success among treatments were greater than in hatching success when comparing species. Lastly, there was evidence of extreme thermal exposure significantly altering the hatching times of tick eggs for specific treatments. These results provide insights into the critical period for tick egg viability in relation to thermal exposure and tick survival associated with stress and climate change.

POTENTIAL SHARED DISEASE RISK AMONG DOGS AND COYOTES (CANIS LATRANS) EXEMPLIFIED BY THE ECOLOGY OF RICKETTSIOSIS IN A ROCKY MOUNTAIN SPOTTED FEVER-EPIDEMIC REGION IN NORTHERN MEXICO.

Rocky Mountain spotted fever (RMSF), caused by the bacterium Rickettsia rickettsii, is a re-emerging tick-borne zoonosis in North America, with hundreds of human fatalities in multiple outbreaks in northern Mexico and the southwestern US in the past few decades. Free-roaming dogs are key because they are reservoirs for the pathogen and the main hosts of the brown dog tick (Rhipicephalus sanguineus), which vectors RMSF in this region. Because coyotes (Canis latrans) can be infected with R. rickettsii and infested with Rh. sanguineus, we hypothesized that space sharing among dogs and coyotes could enhance disease risks. In summer 2021, we captured and sampled 11 coyotes at two sites in Baja California, Mexico, near population centers with human cases of RMSF, and fitted seven individuals with GPS logging collars. We also tested tissue samples, sera, and ectoparasites for DNA of R. rickettsii with PCR and used serology to detect antibodies to R. rickettsii. Finally, we deployed an array of cameras to document dog-coyote interactions. Mean home range size was 40.37 km2. Both GPS and camera data showed considerable home range overlap both between individual coyotes and between coyotes and dogs. Coyotes were active in areas where dogs occur including the domestic interface surrounding human settlements. Although none of our samples were positive for R. rickettsii on PCR, 72.7% (8/11) of the samples were seropositive with titers ≥64. Our data confirm shared space use and risk of shared parasites and disease between coyotes and dogs.

Year-round efficacy of a single treatment of fluralaner injectable suspension (Bravecto Quantum™) against repeated infestations with Rhipicephalus sanguineus (sensu lato) and Ctenocephalides felis in dogs

BackgroundPoor owner compliance with monthly control measures means that dogs in Australia can remain susceptible to infestations with fleas, present throughout the whole year, and brown dog ticks, which thrive in tropical and subtropical areas. A 150 mg/ml injectable fluralaner suspension (Bravecto Quantum™) was developed to help ensure year-round protection against these parasites. A study investigated the persistent efficacy of this formulation against repeated challenges with Rhipicephalus sanguineus (sensu lato) and Ctenocephalides felis throughout 12 months following a single subcutaneous treatment.MethodsTwenty dogs were blocked by pre-treatment R. sanguineus s.l. counts and randomized to an untreated control group or to a group treated once, on day 0, with the fluralaner injection (15 mg/kg). Infestations of 50 mixed-sex, unfed adult R. sanguineus s.l. and up to 100 C. felis were done on days 7, 14, 35, 63, 91, 126, 154, 182, 210, 245, 273, 301, 336 and 365. Live flea and tick counts were completed 48 h post-infestation. Flea infestations were also done on day −1, with counts on day 2. Infestations were considered adequate if at each evaluation, at least six dogs in the control group retained at least 20% of tick challenges and 25% of flea challenges.ResultsThe fluralaner injectable suspension was well tolerated. Efficacy against existing flea infestations was > 99% (arithmetic and geometric means) at 48 h post-treatment. At all subsequent assessments throughout the year following treatment, efficacy against fleas remained at 100%. Arithmetic mean tick count reductions relative to the control group ranged from 97.6% to 100% from day 7 through 11 months and was 92.6% at 12 months (geometric means 95.2% to 100% through 12 months).ConclusionThe injectable fluralaner suspension was effective against fleas and brown dog ticks for 12 months following a single treatment. Compared with more frequently administered products where compliance may be suboptimal, the year-round efficacy of this veterinarian-administered fluralaner formulation has the potential to improve owner compliance for control of fleas and ticks. In turn, by reducing the detrimental effects of flea and tick infestations and risk of transmission of flea- and tick-borne pathogens, canine health can be enhanced.Graphical

Establishment and range expansion of Dermacentor variabilis in the northern Maritimes of Canada: Community participatory science documents establishment of an invasive tick species.

Tick populations are dependent on a complex interplay of abiotic and biotic influences, many of which are influenced by anthropic factors including climate change. Dermacentor variabilis, the wood tick or American dog tick, is a hardy tick species that feeds from a wide range of mammals and birds that can transmit pathogens of medical and agricultural importance. Significant range expansion across North America has been occurring over the past decades;this study documents northwards range expansion in the Canadian Maritime provinces. Tick recoveries from passive surveillance between 2012 and 2021 were examined to assess northward population expansion through Atlantic Canada. At the beginning of this period, D. variabilis was abundant in the most southerly province, Nova Scotia, but was not considered established in the province to the north, New Brunswick. During the 10-year span covered by this study, an increasing number of locally acquired ticks were recovered in discrete foci, suggesting small established or establishing populations in southern and coastal New Brunswick. The pattern of population establishment follows the climate-driven establishment pattern of Ixodes scapularis to some extent but there is also evidence of successful seeding of disjunct populations in areas identified as sub-optimal for tick populations. Dogs were the most common host from which these ticks were recovered, which raises the possibility of human activity, via movement of companion animals, having a significant role in establishing new populations of this species. Dermacentor variabilis is a vector of several pathogens of medical and agricultural importance but is not considered to be a competent vector for Borrelia burgdorferi, the etiological agent of Lyme disease; our molecular analysis of a subset of D. variabilis for both B. burgdorferi and B. miyamotoi did not confirm any with Borrelia. This study spans the initial establishment of this tick species and documents the pattern of introduction, providing a relatively unique opportunity to examine the first stages of range expansion of a tick species.

Forest-associated habitat variables influence human-tick encounters in the southeastern United States.

Due to the increased frequency of human-tick encounters and expanding ranges of ticks in the United States, there is a critical need to identify environmental conditions associated with tick populations and their likelihood to contact human hosts. In a passive tick surveillance partnership with the US Department of Agriculture Forest Inventory and Analysis (FIA) program, we identified environmental variables associated with tick encounters by forestry personnel. Ticks were identified by species and life stage, and site-specific variables were associated with each tick using FIA forest inventory datasets and generalized linear models with negative binomial distributions. Of the 55 FIA variables available, we identified biotic and abiotic environmental variables associated with Amblyomma americanum L. (carbon in litter material and standing dead tree aboveground dry biomass), Dermacentor variabilis Say (seedling species unevenness and elevation), and Ixodes scapularis L. (carbon in dead woody material and seedling species unevenness). We propose conducting future treatment-control studies using these forestry-related environmental variables to test their ability to alter tick abundance at sites. Land management decisions not only affect common flora and fauna, but changes to these habitats can also alter the way ticks parasitize hosts and use vegetation to find those hosts. These results can be used with land management decisions to prevent future human-tick encounters and highlight risk areas.

Post-traumatic Leuconostoc mesenteroides scleral infection: A rare case scenario

We herein report a case of Leuconostoc mesenteroides scleral infection after trauma. A young male developed pain and redness following trauma to the right eye with a wooden stick. A mildly elevated scleral abscess was noted, which was surgically drained, and Leuconostoc mesenteroides were isolated. There was a favorable anatomical outcome after topical and oral antibiotics therapy guided by culture and sensitivity. Post-trauma scleral infection with Leuconostoc mesenteroides is a rare possibility, which can be managed with topical and oral antibiotics therapy with favorable outcomes.

Monthly infestation characteristics of ticks in dogs in Turkish Thrace: Possible urbanization trends in some sylvatic tick species

In recent decades, significant increases and/or drastic changes have been recorded in the prevalence, intensity, and distribution of ticks worldwide, which are known to be fueled by the climate change. However, there are many intertwined drivers affecting ticks, the degree of their influence of which is contingent and difficult to determine, and it is known that elucidating the factors is crucial to understand the current tick ecology and predicting the future trend. This study was carried out to determine monthly dynamics of tick infestation in owned and stray dogs under the influence of hot dry summer sub-type of the Mediterranean climate in Thrace region, European part of Turkey. During the survey performed in 2017 on monthly basis, 1605 different dogs from ten different localities in Thrace were examined for ticks. Infestation was determined in 137 (8.54%) dogs. The highest monthly prevalence (34.03%) was recorded in May. In total, 1033 ticks (1008 adults, 25 nymphs) belonging to the following species have been identified with different monthly and total prevalence and intensity: Rhipicephalus sanguineus sensu lato, Haemaphysalis parva, Ixodes ricinus, Ixodes acuminatus, and Ixodes kaiseri. The results indicated that degradation and destruction of natural habitats under the influence of human effect seem likely to cause/facilitate/accelerate the entering some wild animal species, and therefore their ticks, to the urbanized environments via afforested woodlands and gardens in the periurbans, and dogs in such areas seem to play a supportive role in the maintenance of some tick species, including those with primarily sylvatic cycle, such as I. acuminatus and I. kaiseri.

Evidence on the prevalence of emerging and re-emerging tick- and flea-borne rickettsial agents in acute encephalitis syndrome endemic areas of northeast Uttar Pradesh, India.

Outbreaks of acute encephalitis syndrome (AES) with unknown aetiology are reported every year in Gorakhpur district, Uttar Pradesh, India, and Orientia tsutsugamushi, the rickettsial pathogen, responsible for scrub typhus has been attributed as the primary cause of AES problem. However, information on the prevalence of other rickettsial infections is lacking. Hence, this study was carried out to assess any occurrence of tick- and flea-borne rickettsial agents in villages reporting AES cases in this district. In total, 825 peridomestic small mammals were trapped, by setting 9254 Sherman traps in four villages with a trap success rate of 8.9%. The Asian house shrew, Suncus murinus, constituted the predominant animal species (56.2%) and contributed to the maximum number (87.37%) of ectoparasites. In total, 1552 ectoparasites comprising two species of ticks and one species each of flea and louse were retrieved from the trapped rodents/shrews. Rhipicephalus sanguineus, the brown dog tick, was the predominant species retrieved from the trapped rodents/shrews, and the overall infestation rate was 1.75 per animal. In total, 4428 ectoparasites comprising five tick species, three louse species and one flea species were collected from 1798 domestic animals screened. Rhipicephalus microplus was the predominant tick species collected from the domestic animals. The cat flea, Ctenocephalides felis, constituted 1.5% of the total ectoparasites. Of all the ectoparasite samples (5980) from domestic animals and rodents, tested as 1211 pools through real-time PCR assays, 64 pools were positive for 23S rRNA gene of rickettsial agents. The PCR-positive samples were subjected to multi-locus sequence typing (MLST). In BLAST and phylogenetic analysis, the ectoparasites were found to harbour Rickettsia asembonensis (n = 9), Rickettsia conorii (n = 3), Rickettsia massiliae (n = 29) and Candidatus Rickettsia senegalensis (n = 1). A total of 22 pools were detected to have multiple rickettsial agents. The prevalence of fleas and high abundance of tick vectors with natural infections of rickettsial agents indicates the risk of transmission of tick- and flea-borne rickettsial diseases in rural villages of Gorakhpur. Further epidemiological studies are required to confirm the transmission of these agents to humans.

Omnivore diet composition alters parasite resistance and host condition.

Diet composition modulates animals' ability to resist parasites and recover from stress. Broader diet breadths enable omnivores to mount dynamic responses to parasite attack, but little is known about how plant/prey mixing might influence responses to infection. Using omnivorous deer mice (Peromyscus maniculatus) as a model, we examine how varying plant and prey concentrations in blended diets influence resistance and body condition following infestation by Rocky Mountain wood ticks (Dermacentor andersoni). In two repeated experiments, deer mice fed for 4 weeks on controlled diets that varied in proportions of seeds and insects were then challenged with 50 tick larvae in two sequential infestations. The numbers of ticks successfully feeding on mice declined by 25% and 66% after the first infestation (in the first and second experiments, respectively), reflecting a pattern of acquired resistance, and resistance was strongest when plant/prey ratios were more equally balanced in mouse diets, relative to seed-dominated diets. Diet also dramatically impacted the capacity of mice to cope with tick infestations. Mice fed insect-rich diets lost 15% of their body weight when parasitized by ticks, while mice fed seed-rich diets lost no weight at all. While mounting/maintaining an immune response may be energetically demanding, mice may compensate for parasitism with fat and carbohydrate-rich diets. Altogether, these results suggest that a diverse nutritional landscape may be key in enabling omnivores' resistance and resilience to infection and immune stressors in their environments.

Factors influencing abundance of 3 tick species across a gradient of urban development intensity in the US Great Plains.

Urbanization alters abiotic conditions, vegetation, and wildlife populations in ways that affect tick abundance and tick-borne disease prevalence. Likely due to such changes, tick abundance has increased in many US urban areas. Despite growing public health importance of tick-borne diseases, little is known about how ticks are influenced by urbanization in North America, especially in the central United States where several pathogens occur at or near their highest incidences. To identify factors influencing tick abundance across a gradient of urbanization intensity, we used CO2 traps and flagging to sample ticks at 16 parks across Oklahoma City, Oklahoma, USA over 2 yr, conducted vegetation surveys, and used trail cameras to estimate a deer abundance index. Our results indicate there is a risk of encountering ticks across the entire urbanization gradient from exurban areas to the urban core, although some species (Dermacentor variabilis (Say)) appear less-common in heavily-urbanized areas. Vegetation variables were also associated with tick abundance. For example, Amblyomma maculatum Koch decreased with increasing woody plant and leaf litter cover, and there was a weak positive relationship between D. variabilis abundance and cover of understory eastern redcedar (Juniperus virginiana L.), indicating this native encroaching tree may increase tick populations in urban areas of the Great Plains. The deer abundance index was positively correlated with A. maculatum and D. variabilis abundance but unrelated to A. americanum (L.) abundance. Public health officials and land managers can use such information about parks/greenspaces and their surroundings to focus public education and land management efforts designed to reduce tick-borne disease prevalence.

Brown dog tick attached to lower eyelid

Brown dog tick attached to lower eyelid