Early Babesia canis transmission in dogs within 24 h and 8 h of infestation with infected pre-activated male Dermacentor reticulatus ticks

Attachment sites of Ixodes ricinus, Ixodes hexagonus/Ixodes canisuga and Dermacentor reticulatus ticks and risk factors of infestation intensity and engorgement duration in dogs and cats

BACKGROUND

Over the last decades, climatic and environmental changes have led to an expanding seasonal activity pattern and increasing distribution of ticks across Europe. In particular, Dermacentor reticulatus is now commonly found on dogs in central Europe. The present study compared attachment sites between Ixodes spp. and Dermacentor reticulatus ticks collected by veterinarians from dogs and cats, and investigated risk factors associated with tick infestation intensity and engorgement duration.

RESULTS

The dataset comprised 6,335 dogs harbouring 10,287 ticks (8,095 Ixodes ricinus, 1,860 D. reticulatus, 218 Ixodes hexagonus/Ixodes canisuga, 114 of other tick species) respectively 4,248 cats harbouring 8,005 ticks (7,344 I. ricinus, 56 D. reticulatus, 505 I. hexagonus/I. canisuga, 100 of other tick species). Differing sites of tick attachment were not only found between the different host and tick species, but also between the tick developmental stages. Regarding the risk of infestation with multiple ticks, dogs and cats living in rural areas harboured significantly more often multiple than single specimens. Further, a long coat in cats was associated with a higher probability of multiple infestation, while this was not observed in dogs. However, there was a tendency towards a potential influence of the density of the undercoat (p = 0.051). In dogs, a tall to very tall body size as well as folded ears increased the risk of multiple infestation, while in cats, increasing age and increasing body size were negatively associated with multiple infestations. Ticks with an engorgement duration of > 48 h were found significantly more often on senior dogs and cats than on younger individuals, as well as on working/utility dog breeds, while engorgement duration was negatively correlated with infestation intensity in dogs. In cats, female gender and a rural residence were significantly associated with longer attachment duration.

CONCLUSIONS

Individual as well as breed specific characteristics can lead to a higher tick infestation intensity or longer engorgement duration. The knowledge of tick attachment sites and specific risk factors can help to raise awareness among owners concerning the importance of tick control with licensed acaricides, as recommended e.g. by the European Scientific Counsel Companion Animal Parasites (ESCCAP), and may aid in early tick removal to decrease the risk of pathogen transmission to dogs and cats whose owners nonetheless refuse acaricidal drugs.

Tick Control Strategies: Critical Insights into Chemical, Biological, Physical, and Integrated Approaches for Effective Hard Tick Management

Ticks and tick-borne diseases significantly impact animal health, public health, and economic productivity globally, particularly in areas where the wildlife-livestock interface complicates management. This review critically examines the current control strategies, focusing on chemical, biological, physical, and integrated pest management (IPM) approaches. Chemical acaricides, while effective, are increasingly challenged by resistance development and environmental concerns. Biological approaches, including natural predators and entomopathogenic fungi, and physical interventions, such as habitat modification, provide sustainable alternatives but require further optimization. IPM stands out as the most promising long-term solution, integrating multiple approaches to enhance efficacy while reducing environmental risks. Emerging innovations, such as nanotechnology-enhanced acaricides and next-generation vaccines, offer promising avenues for improved tick control. Addressing the complex challenges of tick management requires tailored strategies, interdisciplinary collaboration, and sustained research investment in both veterinary and public health contexts.

Contrasting pathogen prevalence between tick and dog populations at Chornobyl

BACKGROUND

The 1986 disaster at the Chornobyl Nuclear Power Plant released massive amounts of radioactive material into the local environment. In addition to radiation, remediation efforts and abandonment of military-industrial complexes contributed to contamination with heavy metals, organics, pesticides and other toxic chemicals. Numerous studies have evaluated the effects of this contamination on the local ecology. However, few studies have reported the effect of this contamination on vector-borne pathogens and their hosts. In this manuscript, we characterize tick-borne pathogen presence at two sample locations within the Chornobyl Exclusion Zone, one at the Nuclear Power Plant (NPP) and another 16 km away in Chornobyl City (CC).

METHODS

Ticks and whole-blood samples were collected from free-breeding dogs captured at the NPP and CC. Endpoint PCR and quantitative PCR were used to identify tick species and to assess the presence of specific tick-borne pathogens, including Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, Babesia spp., Bartonella spp., Francisella tularensis and general Anaplasmataceae. A droplet digital PCR assay was developed for Babesia canis and A. phagocytophilum to evaluate their presence in dogs from the two populations. Pathogen prevalences between the two sample populations were compared by calculating Z-scores.

RESULTS

Ticks were identified as Ixodes ricinus (n = 102) and Dermacentor reticulatus (n = 4). Overall, 56.9% of I. ricinus ticks were positive for at least one pathogen. A significantly higher prevalence of A. phagocytophilum and B. burgdorferi was found in ticks at the NPP (44.0% and 42.0%, respectively) compared to CC (23.1% and 19.2%, respectively). Babesia spp. (including B. canis and B. caballi) were detected in 8.8% ticks at similar proportions for both populations. Interestingly, we found a significantly lower level of A. phagocytophilum in dogs at the NPP (1.8%) than in dogs at CC (11.7%). In total, 24.3% of dogs were positive for B. canis, evenly distributed across the two populations.

CONCLUSIONS

The results of this study show contrasting pathogen prevalence in both ticks and dogs at the NPP and CC, which may reflect the differential exposures at the two locations. This work adds an important new component to our understanding of the consequences of prolonged exposure to environmental contamination on the wildlife and ecology within the Chornobyl Exclusion Zone.

New paradigms in the prevention of canine vector-borne diseases

The prevention of canine vector-borne diseases (CVBDs) is pivotal for the health and welfare of dogs as well as for reducing their zoonotic risk to humans. Scientific knowledge gained in recent years contributed to the development of new strategies for the control of these diseases in different social and cultural contexts. Here, we discuss recent advances in the prevention of vector-borne pathogens (VBPs) affecting dogs with a focus on those of zoonotic relevance.

Evidence of Incomplete Feeding Behaviors among South Carolina Tick Populations

Dynamic environmental conditions, such as climate change and host availability, have greatly influenced the expansion of medically relevant tick vectors into new regions throughout the southeastern United States of America. As tick populations migrate into new areas, it has been suggested they can exhibit a phenomenon known as incomplete feeding. With this phenomenon, tick vectors feed on more than one host at each life stage, thus increasing the likelihood of pathogen transmission. Although this behavior is not well understood, it presents an important threat to human health. Here we present evidence of incomplete feeding behaviors in multiple tick species in South Carolina. Engorged, blood-fed female ticks were collected from feral dogs at animal shelters across South Carolina in 2022. All ticks were tested for human blood meals using rapid stain identification blood tests. Approximately one third (33.78%) of all ticks tested positive for a human blood meal, with various patterns seen across species, geographic location, and collection month. The results of this pilot study follow the current national trend of increasing rates of tick-borne disease incidence in the southeastern United States of America and warrant further investigation into the relationship between seasonality, geographic distribution, species, and incomplete feeding among tick populations in South Carolina.

Comparative Evaluation of the Efficacy of Two Ectoparasiticides in Preventing the Acquisition of Borrelia burgdorferi by Ixodes scapularis and Ixodes ricinus: A Canine Ex Vivo Model

In dogs, tick infestation can cause damage ranging from a simple skin irritation to severe diseases and/or paralysis leading to animal death. For example, Ixodes ricinus and I. scapularis are among the tick species incriminated the most in the transmission of Borrelia burgdorferi, the agent of human and canine Lyme borreliosis (LB). In this study, we aimed to compare the efficacy of two products designed for dogs-an oral systemic ectoparasiticide and a topical repellent ectoparasiticide-against the acquisition of B. burgdorferi by adult I. scapularis and I. ricinus using an ex vivo model. Thirty-two beagle dogs were included in a parallel-group-designed, randomized, single-center, negative-controlled efficacy study. The dogs were allocated to three groups based on gender and body weight: a fluralaner (F, Bravecto®) treatment group (n = 8), administered a single oral treatment on day 0 at the recommended dose; a dinotefuran-permethrin-pyriproxyfen (DPP, Vectra® 3D) treatment group (n = 8), topically treated on day 56 at the recommended dose; and an untreated control group (n = 16). Blood and hair were collected from each dog on days 58, 63, 70, 77, and 84. Hair was added to the silicone-based membrane separating two glass chambers forming the feeding unit (FU). Chamber 1 was filled with blood spiked with B. burgdorferi sensu stricto, strain B31 (105 cells/mL). Chamber 2, glued below chamber 1, was seeded with 20 adult I. scapularis or I. ricinus. The FUs (n = 240) were incubated at 37 °C with a humidity >90%. Tick survival, attachment, and feces presence were observed from 1 h up to 72 h after tick seeding. The uptake of B. burgdorferi was determined in ticks using nested polymerase chain reaction (nPCR). The acaricidal efficacy of DPP-treated hair was 100% within 1 h of tick release on every study day for both I. ricinus and I. scapularis. The speed of kill associated with DPP was sufficiently fast to prevent tick attachment and engorgement, and, consequently, to prevent the acquisition of B. burgdorferi. In the F-treated group, the acaricidal efficacy observed at 12 h, throughout the study, was <20% and <28% for I. scapularis and I. ricinus, respectively. Furthermore, tick feces were observed in the FUs, and several female ticks (I. scapularis (n = 55) and I. ricinus (n = 94)) tested positive for B. burgdorferi. The results provide proof of concept for the use of an ex vivo model based on an artificial feeding system to compare two ectoparasiticides against the acquisition of B. burgdorferi by I. ricinus and I. scapularis. In addition, our results demonstrate the superiority of DPP compared to F in the speed of acaricidal activity against ticks, as well as in preventing the acquisition of B. burgdorferi.

Year-round tick exposure of dogs and cats in Germany and Austria: results from a tick collection study

BACKGROUND

Ticks and tick-borne diseases play a major role in companion animal health. Additionally, the European tick fauna is changing, for instance due to the spread of Dermacentor reticulatus, displaying a higher likelihood of winter activity than Ixodes ricinus. Therefore, we investigated current tick infestations in dogs and cats in Germany and in parts of Austria and the seasonal infestation risk.

METHODS

Overall, 219 veterinary practices were invited to collect ticks from cats and dogs on a monthly basis. Ticks were morphologically identified and female I. ricinus specimens were measured to estimate attachment duration.

RESULTS

In total, 19,514 ticks, 17,789 (91.2%) from Germany and 1506 (7.7%) from Austria, were received between March 2020 and October 2021, with 10,287 specimens (52.7%) detached from dogs, 8005 from cats (41.0%) and 1222 from other species (6.3%). In Germany, the most common tick species collected from dogs were I. ricinus (78.0%) and D. reticulatus (18.8%), while cats mainly harboured I. ricinus (91.3%) and I. hexagonus (5.5%) and only few D. reticulatus (0.6%). In Austria, collected I. ricinus reached similar proportions in dogs (90.4%) and cats (95.3%), followed by D. reticulatus in both dogs (5.2%) and cats (1.5%), with I. hexagonus (0.9%) collected only marginally from cats. The average infestation intensity amounted to 1.62 ticks/dog and 1.88 ticks/cat. The single to multiple infestation ratio was 79.1% to 20.9% in dogs and 69.0% to 31.0% in cats, with cats being significantly more often multiple infested than dogs, while the proportion of mixed-species infestations was 2.0% for both dogs and cats. The average attachment duration of female I. ricinus specimens amounted to 78.76 h for dogs and 82.73 h for cats. Furthermore, year-round tick exposure was confirmed, with 108 D. reticulatus and 70 I. ricinus received on average per month during December 2020 to February 2021.

CONCLUSIONS

The study shows a year-round tick infestation risk, with activity of both D. reticulatus and I. ricinus during winter, and confirms the widespread occurrence of D. reticulatus in Germany. Additionally, long average attachment durations and frequent multiple infestations underline the need for adequate year-round tick control, even during the winter months.

Autochthonous Babesia canis infections in 49 dogs in Germany

BACKGROUND

Vector-borne diseases are of increasing importance in Germany. Since 2015, autochthonous cases have been increasingly documented in Berlin/Brandenburg.

OBJECTIVES

Describe autochthonous Babesia canis infection in the Berlin/Brandenburg region.

ANIMALS

Forty-nine dogs with autochthonous B. canis infection.

METHODS

Evaluation of history, clinical signs, laboratory abnormalities, treatment, and outcome.

RESULTS

Dogs were presented between March and August (9) and September and January (40) in the years 2015-2021. Historical and clinical findings were lethargy (100%), pale mucous membranes (63%), fever (50%), and pigmenturia (52%). Common clinicopathological findings were thrombocytopenia (100%), anemia (85%), intravascular hemolysis (52%), pancytopenia (41%), and systemic inflammatory response syndrome (SIRS; 37%). Babesia detection was based on blood smear evaluation (n = 40) and PCR targeting the 18S rRNA gene of piroplasms (n = 49). Sequencing indicated 99.47% to 100% identity to B. canis sequences from GenBank. All dogs were treated with imidocarb (2.4-6.3 mg/kg; median, 5 mg/kg); 8 dogs received 1, 35 received 2, and 1 dog each received 3, 4, or 5 injections, respectively. Continued PCR-positive results were detected in 7 dogs after the 1st, in 5 after the 2nd, in 2 after the 3rd, and in 1 28 days after the 4th injection. Four dogs were euthanized and 3 dogs died.

CONCLUSIONS AND CLINICAL IMPORTANCE

Autochthonous B. canis infections in Berlin/Brandenburg were associated with severe clinicopathological changes, SIRS, and multiorgan involvement. Testing by PCR during and after treatment is advisable to monitor treatment success. Screening of blood donors in high-risk areas and year-round tick protection is strongly recommended.

Prevalence and geographic distribution of Babesia conradae and detection of Babesia vogeli in free-ranging California coyotes (Canis latrans)

Babesia species are intraerythrocytic piroplasms that can result in disease characterized by hemolytic anemia and thrombocytopenia. Of the 5 species that are known to infect canids in the United States, Babesia conradae is most frequently diagnosed in California, and Babesia vogeli is prevalent in the US. Despite the recent re-emergence of B. conradae, the mechanism of transmission is not known. Coyotes (Canis latrans) have been a proposed reservoir of disease, and previous work has shown that dogs with known aggressive interactions with coyotes are at greater risk for infection. This study aimed to determine the prevalence of B. conradae in wild coyote populations in California to assess the viability of coyotes as a potential source of infection for domestic dogs. Four hundred and sixty-one splenic samples were obtained during post-mortem examination of coyote carcasses from Southern California, Fresno, and Hopland. Demographic data including age, sex, cause of death, and urbanity were collected for each coyote. DNA was extracted from samples and amplified using real-time PCR with primers specific for the B. conradae ITS-2 gene. The 18S gene was amplified and sequenced using conventional PCR primers specific to the Babesia genus from any coyotes positive for B. conradae. In total, 22 coyotes tested positive for B. conradae in Fresno (n = 15), Orange (n = 4), San Bernardino (n = 1), and Los Angeles counties (n = 1) with an overall prevalence of 4.8%. Coyotes from Fresno (P<.01) and rural coyotes (P<.01) were significantly more likely to be infected with B. conradae. Ten of 14 samples sequenced were 99-100% homologous to B. conradae, and 4 samples were 100% homologous with B. vogeli DNA indicating co-infection with both pathogens. This study demonstrates that coyotes can become infected and harbor B. conradae and B. vogeli and should be investigated as a possible source of infection in domestic dogs.

[Occurrence of canine babesiosis in dogs in the Rhine-Main area of Hesse, Germany - a case study of 81 dogs]

OBJECTIVE

Canine babesiosis, an infectious disease transmitted by Dermacentor reticulatus, is exhibiting growing importance in Germany. The aim of this study was to display the increased incidence of canine babesiosis in the Rhine-Main area in Hesse, with special focus on the accumulation in the district of Groß-Gerau.

MATERIAL AND METHODS

The retrospective study included dogs presented to the veterinary hospital between October 2018 and December 2020 and diagnosed with canine babesiosis on the basis of a positive Babesia spp.-PCR.

RESULTS

A total of 697 dogs were tested by Babesia spp.-PCR during this time period. Of these, 81 (12 %) were positive.Sequencing was performed in 14 of the 81 dogs (17 %) (B. canis n = 13, B, vulpes n = 1). A simultaneous anaplasmosis infection was detected in 2 dogs. Strikingly, babesiosis cases occurred throughout the year with accumulations in March/April as well as in October.Evaluation of a complete blood cell count revealed pancytopenia in 44 of the 81 animals (54 %). Anemia was present in 66 (82 %), thrombocytopenia in 76 of the 81 patients (94 %). Only 2 of the 81 positive cases showed no hematological changes. Hyperbilirubinemia was found in 66 of 73 measured bilirubin levels (90 %).All animals were treated with two injections of imidocarb-diproprionate (Carbesia^®) in 14-day intervals. Follow-up PCR was performed in 37 of the 81 patients (46 %). In the majority of cases (92 %), successful therapy was confirmed by a negative Babesia-PCR. A total of 6 of the 81 patients (7 %) were euthanized during the treatment period. The reasons for euthanasia were progressive renal disease, high-grade intravascular hemolysis necessitating multiple blood transfusions, and development of splenic and renal abscesses.

CONCLUSION

In dogs with clinical signs such as apathy, pyrexia and hemoglobinuria, as well as hematologic abnormalities comprising anemia, thrombocytopenia as well as pancytopenia, babesiosis needs to be included in the list of differential diagnoses. Testing should be initiated accordingly regardless of the season, however especially in spring and autumn.

Seasonal differences in the intensity of acute phase response in dogs infected with Babesia canis

The highest number of acute Babesia canis cases in dogs is recorded over the February-May (Feb-May) period, which also represents the optimal climate conditions for tick activity in Belgrade, Serbia. A possibility that the acute phase response is more intense in dogs developing the disease in the Feb-May period compared with the response in other time periods of the year was tested. A total of 63 client-owned dogs with acute B. canis infection were enrolled and the routine hematology and biochemistry parameters-serum amyloid A (SAA), IgG against B. canis, level of parasitemia, ceruloplasmin (CER), paraoxonase-1 (PON-1), and fibrinogen-were measured. Acute phase indexes (API) were calculated as (SAA×CER)/(Iron×PON-1) and (SAA×CER)/(Albumin×Iron). Statistics included Kruskal-Wallis test and logistic regression analysis. The results showed that in the Feb-May period, the following parameters were lower: creatinine, albumin, iron, and level of parasitemia. Furthermore, increased API values were more probable in the Feb-May than in the other periods. Together, higher acute phase response intensity and presumptive hemodilution in the Feb-May period indicate a more acute course of B. canis infection than in other time periods of the year.

Field trial investigating the efficacy of a long-acting imidacloprid 10%/flumethrin 4.5% polymer matrix collar (Seresto®, Elanco) compared to monthly topical fipronil for the chemoprevention of canine tick-borne pathogens in Cambodia

The tropical brown dog tick, Rhipicephalus linnaei, commonly infests canines in the tropics and is an important vector for disease-causing and sometimes lethal pathogens including Babesia spp., Ehrlichia canis, Hepatozoon canis and Anaplasma platys. In tropical climates ticks and their pathogens exert an extremely high infection pressure on unprotected dogs. To protect canines in such regions, effective acaricidal products possessing a speed of kill that blocks pathogen transmission is paramount. We conducted a 12-month community trial to compare the chemoprophylactic efficacy of two topical commercial acaricidal formulations: an imidacloprid 10% and flumethrin 4.5%, 8-month acting collar (Seresto®) against a monthly spot-on containing 12% w/v fipronil (Detick, Thailand). In a separate analysis, we used baseline data collected at the start of the trial to quantify tick-borne pathogen (TBP) infection status in dogs with a prior history of being administered a systemically-acting (isoxazoline) versus a topically-acting ectoparasiticide. We found that both topical products in the community trial demonstrated high efficacy at protecting dogs from ticks and TBP, with Seresto® demonstrating a moderate increase in protection at 3 (95% confidence interval (CI): 1–5) TBP-positive dogs per 100 dog-years at risk compared to 11 (95% CI: 4–26) TBP-positive dogs per 100 dog-years at risk for those on fipronil. Additionally, at baseline dogs treated with commercial systemic isoxazoline acaricides prior to the trial’s commencement were 2.7 (95% CI: 0.5–15.0) times more likely to be TBP-positive compared to dogs that had been topically treated, highlighting such isoxazoline products as being less efficacious than topical products at preventing canine TBP acquisition in a tropical setting.

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Chemopreventive products against ectoparasite infestation are essential for dog health in the tropics.

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Prevalence of canine tick-borne pathogens was higher in dogs on systemic ectoparasiticides than those on topical ones.

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Seresto® demonstrated better protection against canine tick-borne pathogen infection than a fipronil formulation.

Wild Rabbit Exposure to Leishmania infantum, Toxoplasma gondii, Anaplasma phagocytophilum and Babesia caballi Evidenced by Serum and Aqueous Humor Antibody Detection

Wild rabbits (Oryctolagus cuniculus) can be important sentinel species for the presence of zoonotic pathogens. Therefore, we collected blood samples from wild rabbits harvested by hunters during the hunting season 2019–2020 on the island of Lemnos, to determine exposure of wild rabbits to the zoonotic pathogens Leishmania infantum, Toxoplasma gondii, Anaplasma phagocytophilum and Babesia caballi, as well as aqueous humor to assess its diagnostic performance in terms of sensitivity, specificity, positive and negative likelihood ratios. Antibodies against these pathogens were detected by Indirect Immunofluorescence Antibody (IFA) assay. Out of the 72 wild rabbits included in the study, 4.2%, 5.5%, 18% and 9.7% were seropositive to L. infantum, T. gondii, A. phagocytophilum and B. caballi, respectively. Although less frequently, antibodies were also detected in aqueous humor of wild rabbits. The antibody detection in aqueous humor presented 100% specificity but decreased sensitivity compared to serum suggesting that aqueous humor could be successfully used in epidemiological studies to confirm exposure at the population level but has little diagnostic value at the individual level. This is the first report on the seropositivity of wild rabbits to A. phagocytophilum and B. caballi and the detection of antibodies against A. phagocytopylum, L. infantum, T. gondii and B. caballi in the aqueous humor.

Experimental Infection of Ticks: An Essential Tool for the Analysis of Babesia Species Biology and Transmission

Babesiosis is one of the most important tick-borne diseases in veterinary health, impacting mainly cattle, equidae, and canidae, and limiting the development of livestock industries worldwide. In humans, babesiosis is considered to be an emerging disease mostly due to Babesia divergens in Europe and Babesia microti in America. Despite this importance, our knowledge of Babesia sp. transmission by ticks is incomplete. The complexity of vectorial systems involving the vector, vertebrate host, and pathogen, as well as the complex feeding biology of ticks, may be part of the reason for the existing gaps in our knowledge. Indeed, this complexity renders the implementation of experimental systems that are as close as possible to natural conditions and allowing the study of tick-host-parasite interactions, quite difficult. However, it is unlikely that the development of more effective and sustainable control measures against babesiosis will emerge unless significant progress can be made in understanding this tripartite relationship. The various methods used to date to achieve tick transmission of Babesia spp. of medical and veterinary importance under experimental conditions are reviewed and discussed here.

Vectra 3D (dinotefuran, pyriproxyfen and permethrin) prevents acquisition of Borrelia burgdorferi sensu stricto by Ixodes ricinus and Ixodes scapularis ticks in an ex vivo feeding model

BACKGROUND

We evaluated the efficiency of an ex vivo feeding technique using a silicone membrane-based feeding chamber to (i) assess the anti-feeding and acaricidal efficacy of a spot-on combination of dinotefuran, pyriproxyfen and permethrin (DPP, Vectra® 3D) against adult Ixodes scapularis and Ixodes ricinus ticks, and to (ii) explore its effect on blocking the acquisition of Borrelia burgdorferi sensu stricto.

METHODS

Eight purpose-bred dogs were randomly allocated to two equal-size groups based on body weight assessed on day 2. DPP was administered topically, as spot-on, to four dogs on day 0. Hair from the eight dogs was collected individually by brushing the whole body on days 2, 7, 14, 21, 28 and 35. On each day of hair collection, 0.05 g of sampled hair was applied on the membrane corresponding to each feeding unit (FU). Seventy-two FU were each seeded with 30 adults of I. scapularis (n = 24 FU) or I. ricinus ticks (n = 48 FU). Bovine blood spiked with B. burgdorferi sensu stricto (strain B31) was added into each unit and changed every 12 h for 4 days. Tick mortality was assessed 1 h after seeding. One additional hour of incubation was added for live/moribund specimens and reassessed for viability. All remaining live/moribund ticks were left in the feeders and tick engorgement status was recorded at 96 h after seeding, and the uptake of B. burgdorferi s.s. was examined in the collected ticks by applying quantitative real-time PCR.

RESULTS

Exposure to DPP-treated hair was 100% effective in blocking B. burgdorferi s.s. acquisition. The anti-feeding efficacy remained stable (100%) against both Ixodes species throughout the study. The acaricidal efficacy of DPP evaluated at 1 and 2 h after exposure was 100% throughout the study for I. ricinus, except the 1-h assessment on day 28 (95.9%) and day 35 (95.3%). The 1-h assessment of acaricidal efficacy was 100% at all time points for I. scapularis.

CONCLUSIONS

The ex vivo feeding system developed here demonstrated a protective effect of DPP against the acquisition of B. burgdorferi without exposing the animals to the vectors or to the pathogen.

Early onset of pre-lethal effects of lotilaner (Credelio®) on Amblyomma americanum ticks on experimentally infested dogs

Background

The speed with which acaricides paralyze and kill ticks is relevant to impeding pathogen transmission. The objective of this study was to assess early-onset lotilaner effects on the motility and weights of Amblyomma americanum ticks collected from treated dogs.

Methods

Twelve healthy dogs were randomized between two groups to receive either lotilaner (Credelio^®) on Day 0 or to be sham treated. On Day 7, 25 male and 25 female A. americanum were placed under bandages, two on each flank of each dog. After 30 or 45 min, all unattached ticks were removed and T = 0 was set. At T = 2, 4, 8 and 24 h post attachment, 5 attached ticks removed from each bandage on each dog were weighed, assessed by blinded observers for righting ability and movement recorded.

Results

After the infestation period significantly fewer treated than control dogs had 20 ticks attached (50.0% versus 91.7%, P = 0.0015). At 24 h post attachment, mean weights of ticks from treated dogs (males 1.69 mg; females 2.72) were significantly less than ticks from controls (males 2.66 mg; females 4.67) (P_male = 0.0002; P_female < 0.0001). Mean tick weights from the treated group were significantly lower at 24 h than at earlier time points (P_male < 0.0307; P_female = 0.0021). At 4 and 8 h, significantly fewer ticks from treated (14.3%, 0.0%, respectively) than from control dogs could right (73.3%, 70.0%) (P_4h < 0.0001; P_8h = 0.0024) (at 24 h, all ticks from treated dogs were dead), and distance moved was significantly less at all time points (P_2h = 0.0413; P_4h, P_8h < 0.0001). Mean and maximum velocity of ticks from treated dogs were significantly lower, relative to controls, at 4 and 8 h (P ≤ 0.0001). Within the treated group, collected ticks had significantly lower mean and maximum velocities at 4 and 8 h compared to 2 h (P_mean < 0.0042; P_max < 0.0194).

Conclusion

The observed changes indicate that lotilaner may disrupt tick attachment. In ticks that attached, a progressive impairment of neuromuscular processes began within 2 h. Those irreversible changes could substantially reduce the risk of pathogen transmission from tick to host.

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for studies evaluating the efficacy of parasiticides in reducing the risk of vector-borne pathogen transmission in dogs and cats

These guidelines are intended to provide an in-depth review of current knowledge and assist the planning and implementation of studies for evaluating the efficacy of parasiticides in reducing transmission of vector-borne pathogens (VBPs) to dogs and cats. At present, the prevention of VBP transmission in companion animals is generally achieved through the administration of products that can repel or rapidly kill arthropods, thus preventing or interrupting feeding before transmission occurs. The present guidelines complement existing guidelines, which focus on efficacy assessment of parasiticides for the treatment, prevention and control of flea and tick infestations, but also give guidance for studies focused on other vectors (i.e. mosquitoes and phlebotomine sand flies). The efficacy of parasiticides in reducing VBP transmission can be evaluated through laboratory or field studies. As such, the present guidelines provide recommendations for these studies, representing a tool for researchers, pharmaceutical companies and authorities involved in the research, development and registration of products with claims for reducing VBP transmission in dogs and cats, respecting the overall principles of the 3Rs (replacement, reduction and refinement). Gaps in our current understanding of VBP transmission times are herein highlighted and the need for further basic research on related topics is briefly discussed.

Vectors of disease at the northern distribution limit of the genus Dermacentor in Eurasia: D. reticulatus and D. silvarum

The two ixodid tick species Dermacentor reticulatus (Fabricius) and Dermacentor silvarum Olenev occur at the northern distribution limit of the genus Dermacentor in Eurasia, within the belt of [Formula: see text] latitude. Whilst the distribution area of D. reticulatus extends from the Atlantic coast of Portugal to Western Siberia, that of D. silvarum extends from Western Siberia to the Pacific coast. In Western Siberia, the distribution areas of the two Dermacentor species overlap. Although the two tick species are important vectors of disease, detailed information concerning the entire distribution area, climate adaptation, and proven vector competence is still missing. A dataset was compiled, resulting in 2188 georeferenced D. reticulatus and 522 D. silvarum locations. Up-to-date maps depicting the geographical distribution and climate adaptation of the two Dermacentor species are presented. To investigate the climate adaptation of the two tick species, the georeferenced locations were superimposed on a high-resolution map of the Köppen-Geiger climate classification. The frequency distribution of D. reticulatus under different climates shows two major peaks related to the following climates: warm temperate with precipitation all year round (57%) and boreal with precipitation all year round (40%). The frequency distribution of D. silvarum shows also two major peaks related to boreal climates with precipitation all year round (30%) and boreal winter dry climates (60%). Dermacentor silvarum seems to be rather flexible concerning summer temperatures, which can range from cool to hot. In climates with cool summers D. reticulatus does not occur, it prefers warm and to a lesser extent hot summers. Lists are given in this paper for cases of proven vector competence for various agents of both Dermacentor species. For the first time, the entire distribution areas of D. reticulatus and D. silvarum were mapped using georeferenced data. Their climate adaptations were quantified by Köppen profiles.

Interrupted Blood Feeding in Ticks: Causes and Consequences

Ticks are obligate hematophagous arthropods and act as vectors for a great variety of pathogens, including viruses, bacteria, protozoa, and helminths. Some tick-borne viruses, such as Powassan virus and tick-borne encephalitis virus, are transmissible within 15–60 min after tick attachment. However, a minimum of 3–24 h of tick attachment is necessary to effectively transmit bacterial agents such as Ehrlichia spp., Anaplasma spp., and Rickettsia spp. to a new host. Longer transmission periods were reported for Borrelia spp. and protozoans such as Babesia spp., which require a minimum duration of 24–48 h of tick attachment for maturation and migration of the pathogen. Laboratory observations indicate that the probability of transmission of tick-borne pathogens increases with the duration an infected tick is allowed to remain attached to the host. However, the transmission time may be shortened when partially fed infected ticks detach from their initial host and reattach to a new host, on which they complete their engorgement. For example, early transmission of tick-borne pathogens (e.g., Rickettsia rickettsii, Borrelia burgdorferi, and Babesia canis) and a significantly shorter transmission time were demonstrated in laboratory experiments by interrupted blood feeding. The relevance of such situations under field conditions remains poorly documented. In this review, we explore parameters of, and causes leading to, spontaneous interrupted feeding in nature, as well as the effects of this behavior on the minimum time required for transmission of tick-borne pathogens.

Transmission of Anaplasma phagocytophilum (Foggie, 1949) by Ixodes ricinus (Linnaeus, 1758) ticks feeding on dogs and artificial membranes

Background

The interplay of speed of activity of acaricidal products and tick-borne pathogen transmission time is the major driver for disease prevention. This study aimed to investigate the time required for transmission of Anaplasma phagocytophilum by adult Ixodes ricinus ticks in vivo on dogs, and to confirm the time required for transmission observed in vivo, in vitro.

Methods

Nymphs of I. ricinus were experimentally infected with an A. phagocytophilum strain of canine origin. Dogs were allocated to 6 groups of 3 dogs each. Groups 1–5 were infested with 50 A. phagocytophilum-infected female adult ticks on Day 0. Ticks were removed post-infestation at 3, 6, 12, 24 and 48 h. Dogs in Group 6 were infested with 60 A. phagocytophilum-infected female adult ticks (left on dogs until engorged). Dogs were observed daily for general health and clinically examined on Day 0, and weekly from Day 14. Blood was collected for qPCR and serological analysis on Day 0 (pre-challenge) and weekly thereafter. In the in vitro study each artificial feeding chamber was seeded with 10 adult ticks (5 male/5 female), attachment assessed, and blood pools sampled for qPCR at 6 h intervals up to 72 h after first tick attachment.

Results

Anaplasma phagocytophilum specific antibodies and DNA were detected in all 3 dogs in Group 6. No A. phagocytophilum-specific antibodies or DNA were detected in any dogs in Groups 1–5. All dogs remained healthy. Female tick attachment in 60 artificial feeding chambers over 72 h ranged between 20–60%. Anaplasma phagocytophilum DNA was detected in the blood collected from 5% of chambers sampled at 6 h, with the highest number of positive samples (16.3%) observed at 36 h.

Conclusions

Transmission of A. phagocytophilum by I. ricinus ticks starts within a few hours after attachment but establishment of infections in dogs is apparently dependent on a minimum inoculation dose that was only observed when ticks attached for greater than 48 h. These findings highlight the need for acaricidal products to exert a repellent and/or rapid killing effect on ticks to forestall transmission and subsequent disease.

A study on the long-term efficacy of Seresto® collars in preventing Babesia canis (Piana & Galli-Valerio, 1895) transmission to dogs by infected Dermacentor reticulatus (Fabricius, 1794) ticks

BACKGROUND

An imidacloprid/flumethrin collar (Seresto®) was previously shown to prevent infection with Babesia canis, transmitted by Dermacentor reticulatus, in dogs for up to 1 month after application. The present study evaluated the prevention of transmission throughout the claimed efficacy period of 8 months.

METHODS

Eight animals each were randomly included in groups 1 (negative control) and 2 (Seresto® collar), respectively. Animals in group 2 received the Seresto® collar on Day 0. Tick challenges were performed monthly from the 2nd to the 8th month. Assessment criteria included in situ tick counts 48 hours post-challenge, polymerase chain reaction (PCR) analyses and immunofluorescence assays (IFA). Whenever dogs were diagnosed with babesiosis they were "rescue-treated", excluded and replaced. Consequently, 24 replacement animals were introduced at various time points throughout the study in the control group; thus data for a total of 32 dogs were available in the latter group at study termination.

RESULTS

Acaricidal efficacy for in situ counts was 93% on Day 30, and ranged from 97 to 100% thereafter. No B. canis specific DNA or antibodies were detected in any Seresto®-treated dog at any time. Babesia canis-specific DNA and antibodies were detected in 2-6 of 8 control dogs after each challenge, confirming the validity of the challenge model.

CONCLUSIONS

The Seresto® collar was highly effective against challenges with D. reticulatus ticks for up to 8 months. The high sustained acaricidal efficacy over this period prevented transmission of B. canis, thus fully protecting dogs against infection in this experimental infestation model.