Zoonotic Tick-Borne Pathogens in Temperate and Cold Regions of Europe-A Review on the Prevalence in Domestic Animals

A One Health Epidemiological Approach for Understanding Ticks and Tick-Borne Pathogens

Background: The control and prevention of ticks and tick borne diseases (TBDs) is often difficult, since it is necessary to disrupt a complex transmission cycle, involving ticks and vertebrate hosts, which interact in a changing environment, driven by constant environmental and ecological changes. Our view is that factors driving the spread of R. microplus are complex and intrinsically interconnected, something that has often been ignored in control strategies. Results: The aim of this review is to analyze the importance of the epidemiological surveillance of ticks and tick-borne diseases (TTBDs) for Public Health, with the One Health approach; emphasizing the knowledge, importance, and distribution of TTBDs. Conclusions: The key points for surveillance, and raising the scope and limitations of surveillance programs, to delay the emergence of acaricide resistance, to reduce toxic residues in food for human consumption and to protect animal, human, and environmental health, from a One Health perspective will require calling producers, veterinarians, academics, pharmaceutical industry, and decision makers to join efforts in order to mitigate the effects of ticks and TBDs affecting the cattle industry in Mexico.

The role of wildlife in the epidemiology of tick-borne diseases in Slovakia

Tick-borne diseases (TBD) represent an important challenge for human and veterinary medicine. In Slovakia, studies on the epidemiology of tick-borne pathogens (TBP) regarding reservoir hosts have focused on small mammals and to a lesser extent on birds or lizards, while knowledge of the role of the remaining vertebrate groups is limited. Generally, wild ungulates, hedgehogs, small- and medium-sized carnivores, or squirrels are important feeding hosts for ticks and serve as reservoirs for TBP. Importantly, because they carry infected ticks and/or are serologically positive, they can be used as sentinels to monitor the presence of ticks and TBP in the environment. With their increasing occurrence in urban and suburban habitats, wild ungulates, hedgehogs or foxes are becoming an important component in the developmental cycle of Ixodes ricinus and of TBP such as Anaplasma phagocytophilum or Babesia spp. On the other hand, it has been postulated that cervids may act as dilution hosts for Borrelia burgdorferi (sensu lato) and tick-borne encephalitis virus. In southwestern Slovakia, a high prevalence of infection with Theileria spp. (100%) was observed in some cervid populations, while A. phagocytophilum (prevalence of c.50%) was detected in cervids and wild boars. The following pathogens were detected in ticks feeding on free-ranging ungulates, birds, and hedgehogs: A. phagocytophilum, Rickettsia spp., Coxiella burnetii, Neoehrlichia mikurensis, B. burgdorferi (s.l.), and Babesia spp. The growing understanding of the role of wildlife as pathogen reservoirs and carriers of pathogen-infected ticks offers valuable insights into the epidemiology of TBP, providing a foundation for reducing the risk of TBD.

Molecular screening and genetic diversity of tick-borne pathogens associated with dogs and livestock ticks in Egypt

BACKGROUND

The Middle East and North Africa (MENA) offer optimal climatic conditions for tick reproduction and dispersal. Research on tick-borne pathogens in this region is scarce. Despite recent advances in the characterization and taxonomic explanation of various tick-borne illnesses affecting animals in Egypt, no comprehensive examination of TBP (tick-borne pathogen) statuses has been performed. Therefore, the present study aims to detect the prevalence of pathogens harbored by ticks in Egypt.

METHODOLOGY/PRINCIPAL FINDINGS

A four-year PCR-based study was conducted to detect a wide range of tick-borne pathogens (TBPs) harbored by three economically important tick species in Egypt. Approximately 86.7% (902/1,040) of the investigated Hyalomma dromedarii ticks from camels were found positive with Candidatus Anaplasma camelii (18.8%), Ehrlichia ruminantium (16.5%), Rickettsia africae (12.6%), Theileria annulata (11.9%), Mycoplasma arginini (9.9%), Borrelia burgdorferi (7.7%), Spiroplasma-like endosymbiont (4.0%), Hepatozoon canis (2.4%), Coxiella burnetii (1.6%) and Leishmania infantum (1.3%). Double co-infections were recorded in 3.0% (27/902) of Hy. dromedarii ticks, triple co-infections (simultaneous infection of the tick by three pathogen species) were found in 9.6% (87/902) of Hy. dromedarii ticks, whereas multiple co-infections (simultaneous infection of the tick by ≥ four pathogen species) comprised 12% (108/902). Out of 1,435 investigated Rhipicephalus rutilus ticks collected from dogs and sheep, 816 (56.9%) ticks harbored Babesia canis vogeli (17.1%), Rickettsia conorii (16.2%), Ehrlichia canis (15.4%), H. canis (13.6%), Bo. burgdorferi (9.7%), L. infantum (8.4%), C. burnetii (7.3%) and Trypanosoma evansi (6.6%) in dogs, and 242 (16.9%) ticks harbored Theileria lestoquardi (21.6%), Theileria ovis (20.0%) and Eh. ruminantium (0.3%) in sheep. Double, triple, and multiple co-infections represented 11% (90/816), 7.6% (62/816), and 10.3% (84/816), respectively in Rh. rutilus from dogs, whereas double and triple co-infections represented 30.2% (73/242) and 2.1% (5/242), respectively in Rh. rutilus from sheep. Approximately 92.5% (1,355/1,465) of Rhipicephalus annulatus ticks of cattle carried a burden of Anaplasma marginale (21.3%), Babesia bigemina (18.2%), Babesia bovis (14.0%), Borrelia theleri (12.8%), R. africae (12.4%), Th. annulata (8.7%), Bo. burgdorferi (2.7%), and Eh. ruminantium (2.5%). Double, triple, and multiple co-infections represented 1.8% (25/1,355), 11.5% (156/1,355), and 12.9% (175/1,355), respectively. The detected pathogens' sequences had 98.76-100% similarity to the available database with genetic divergence ranged between 0.0001 to 0.0009% to closest sequences from other African, Asian, and European countries. Phylogenetic analysis revealed close similarities between the detected pathogens and other isolates mostly from African and Asian countries.

CONCLUSIONS/SIGNIFICANCE

Continuous PCR-detection of pathogens transmitted by ticks is necessary to overcome the consequences of these infection to the hosts. More restrictions should be applied from the Egyptian authorities on animal importations to limit the emergence and re-emergence of tick-borne pathogens in the country. This is the first in-depth investigation of TBPs in Egypt.

Exposure of cattle to tick-borne encephalitis virus in the historical endemic zone in north-eastern France

BACKGROUND

Tick-borne encephalitis (TBE) is a severe human neuroinfection caused by TBE virus (TBEV). TBEV is transmitted by tick bites and by the consumption of unpasteurized dairy products from infected asymptomatic ruminants. In France, several food-borne transmission events have been reported since 2020, raising the question of the level of exposure of domestic ungulates to TBEV. In this study, our objectives were (i) to estimate TBEV seroprevalence and quantify antibodies titres in cattle in the historical endemic area of TBEV in France using the micro virus neutralisation test (MNT) and (ii) to compare the performance of two veterinary cELISA kits with MNT for detecting anti-TBEV antibodies in cattle in various epidemiological contexts. A total of 344 cattle sera from four grid cells of 100 km² in Alsace-Lorraine (endemic region) and 84 from western France, assumed to be TBEV-free, were investigated.

RESULTS

In Alsace-Lorraine, cattle were exposed to the virus with an overall estimated seroprevalence of 57.6% (95% CI: 52.1-62.8%, n = 344), varying locally from 29.9% (95% CI: 21.0-40.0%) to 92.1% (95% CI: 84.5-96.8%). Seroprevalence did not increase with age, with one- to three-year-old cattle being as highly exposed as older ones, suggesting a short-life duration of antibodies. The proportion of sera with MNT titres lower than 1:40 per grid cell decreased with increased seroprevalence. Both cELISA kits showed high specificity (> 90%) and low sensitivity (less than 78.1%) compared with MNT. Sensitivity was lower for sera with neutralising antibodies titres below 1:40, suggesting that sensitivity of these tests varied with local virus circulation intensity.

CONCLUSIONS

Our results highlight that cattle were highly exposed to TBEV. Screening strategy and serological tests should be carefully chosen according to the purpose of the serological study and with regard to the limitations of each method.

Nationwide survey of ticks on domesticated animals in Taiwan: Revealing the hidden threat to animal and public health

Ticks are not only bloodsucking ectoparasites but also important vectors of tick-borne diseases (TBDs), posing significant threats to public and animal health. Domesticated animals serve as critical hosts for numerous ticks, highlighting the importance of understanding tick infestations in Taiwan. To address this knowledge gap, we conducted a nationwide survey to identify ticks on domesticated animals and associated environments in 2018 and 2019. A total of 6,205 ticks were collected from 1,337 host animals, revealing the presence of seven tick species, with Rhipicephalus microplus, and Rhipicephalus sanguineus being the dominant species. High infestation rates and widespread distribution of ticks were observed on domesticated animals, especially on dogs and cattle (yellow cattle and angus cattle), and the neighbouring grassland of yellow cattle. While this study has certain limitations, it provides valuable insights into the distribution and prevalence of ticks on domesticated animals in Taiwan and their implications for controlling TBDs. Further research is needed to comprehensively understand the complex interactions among ticks, hosts and pathogens.

Tick-borne diseases in the North Sea region-A comprehensive overview and recommendations for diagnostics and treatment

As part of the NorthTick project, co-funded by the European Union through the European Regional Development Fund and the North Sea Region Programme, specialists in the field of tick-borne diseases from seven North Sea countries co-operated with patient organisations and governmental health care institutions to provide this comprehensive overview of diagnostics and treatment recommendations in the region for Lyme borreliosis, Borrelia miyamotoi infection, tick-borne encephalitis, human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis and babesiosis. The main conclusion is that the recommendations in these northern countries are essentially the same, with very few differences. This overview presents the current diagnostics and provides useful clinical guidance.

Frequency of Anaplasma phagocytophilum, Borrelia spp., and coinfections in Ixodes ricinus ticks collected from dogs and cats in Germany

BACKGROUND

Changing geographical and seasonal activity patterns of ticks may increase the risk of tick infestation and tick-borne pathogen (TBP) transmission for both humans and animals.

METHODS

To estimate TBP exposure of dogs and cats, 3000 female I. ricinus from these hosts were investigated for Anaplasma phagocytophilum and Borrelia species.

RESULTS

qPCR inhibition, which was observed for ticks of all engorgement stages but not questing ticks, was eliminated at a template volume of 2 µl. In ticks from dogs, A. phagocytophilum and Borrelia spp. prevalence amounted to 19.0% (285/1500) and 28.5% (427/1500), respectively, while ticks from cats showed significantly higher values of 30.9% (464/1500) and 55.1% (827/1500). Accordingly, the coinfection rate with both A. phagocytophilum and Borrelia spp. was significantly higher in ticks from cats (17.5%, 262/1500) than dogs (6.9%, 104/1500). Borrelia prevalence significantly decreased with increasing engorgement duration in ticks from both host species, whereas A. phagocytophilum prevalence decreased only in ticks from dogs. While A. phagocytophilum copy numbers in positive ticks did not change significantly over the time of engorgement, those of Borrelia decreased initially in dog ticks. In ticks from cats, copy numbers of neither A. phagocytophilum nor Borrelia spp. were affected by engorgement. Borrelia species differentiation was successful in 29.1% (365/1254) of qPCR-positive ticks. The most frequently detected species in ticks from dogs were B. afzelii (39.3% of successfully differentiated infections; 70/178), B. miyamotoi (16.3%; 29/178), and B. valaisiana (15.7%; 28/178), while B. afzelii (40.1%; 91/227), B. spielmanii (21.6%; 49/227), and B. miyamotoi (14.1%; 32/227) occurred most frequently in ticks from cats.

CONCLUSIONS

The differences in pathogen prevalence and Borrelia species distribution between ticks collected from dogs and cats may result from differences in habitat overlap with TBP reservoir hosts. The declining prevalence of A. phagocytophilum with increasing engorgement duration, without a decrease in copy numbers, could indicate transmission to dogs over the time of attachment. The fact that this was not observed in ticks from cats may indicate less efficient transmission. In conclusion, the high prevalence of A. phagocytophilum and Borrelia spp. in ticks collected from dogs and cats underlines the need for effective acaricide tick control to protect both animals and humans from associated health risks.

An Overview of Tick-Borne Encephalitis Epidemiology in Endemic Regions of Continental Croatia, 2017-2023

Tick-borne encephalitis (TBE) represents an important public health problem in Europe. We analyzed the epidemiology of TBE based on data from humans, animals, and Ixodes ricinus ticks in endemic regions of continental Croatia. In the period from 2017 to 2023, cerebrospinal fluid (CSF) and serum samples of 684 patients with neuroinvasive diseases, 2240 horse serum samples, and 300 sheep serum samples were tested for TBEV. In addition, 8751 I. ricinus ticks were collected. CSF samples were tested using RT-PCR. Serological tests (serum, CSF) were performed using commercial ELISA, with confirmation of cross-reactive samples by a virus neutralization test. Eighty-four autochthonous human TBEV cases were confirmed. The majority of patients were in the age group of 40-69 years (58.3%) with a male predominance (70.2%). TBE showed a bimodal seasonality with a large peak in April-August and a small one in October-November. In addition to humans, TBEV IgG antibodies were found in 12.2% of horses and 9.7% of sheep. Seasonal tick abundance corresponds to the reported number of human infections. Continental Croatia is still an active natural focus of TBE. Continuous monitoring of infections in humans, sentinel animals, and ticks is needed for the implementation of preventive measures.

Distribution characteristics and influencing factors of Haemaphysalis longicornis around goat sheds in Jinan city, East China

As one of the most important disease vectors worldwide, ticks can transmit a number of pathogenic organisms to humans and domestic animals and cause a variety of important natural focal diseases and zoonoses. Domestic livestock play a vital role in the dispersal of ticks from the field environment to the human settlement, contributing to the prevalence of tick-borne diseases. Identification of the tick control region could contribute a vital role in strategic planning and cost-effective tick control measures. However, little is known about the spatial distribution characteristics of ticks around livestock sheds, which will lead to abusage and overuse of insecticides. Therefore, this study aimed to explore spatial distribution characteristics and correlation factors of ticks around goat sheds. A total of 3898 ticks were collected from eight goat sheds from April to June in Jinan city. All the sampled ticks belonged to the same species, namely Haemaphysalis longicornis, and 88.8% of them were nymphs. A significant positive correlation was noted between free-living ticks and parasitic ticks (r = 0.411, P < 0.001). However, there was a significant negative correlation between number of free-living ticks and distance from the goat sheds (r = -0.622, P < 0.001). Within 20 m from the goat sheds, 2211 ticks were collected respectively, representing 56.7% of the total free-living ticks. At a distance of 30 m, 57.6% decline in the tick density was found with a significant difference (q = 5.534, P < 0.001). In conclusion, focusing control efforts near the goat sheds should be recommend for tick prevention and control.

Latitude and seasons influence the prevalence of Theileria orientalis and affect the hematology of non-grazed dairy cows in Korea

This pilot study aimed to investigate the effects of regional and seasonal variations on the prevalence of Theileria orientalis and the hematological profile of non-grazed dairy cows in Korea. A total of 365 clinically healthy lactating Holstein Friesian cows from 26 dairy farms in 7 provinces that were categorized into northern, central, and southern regions were sampled during the warm period from July to August and the cold period from October to December. The detection of T. orientalis major piroplasm surface protein gene and the hematology non-grazed dairy cows were analyzed using peripheral blood samples. The T. orientalis prevalence was 20.0% (73/365). The prevalence in the southern region was 35.9%, which was significantly higher than that in the central (21.6%) and northern (12.9%) regions (P < 0.05). The prevalence during warm period was higher (43.0%) than that during the cold season (13.5%). The infected cows showed significantly lower erythrocyte counts in the southern region (5.8 ± 0.6 M/µl) and during the warm period (5.8 ± 0.7 M/µl) compared with those in the central and northern regions and during the cold season, which affected the extended RBC parameters, including hematocrit and hemoglobin concentrations. Our findings revealed the prevalence of T. orientalis in Korea, highlighting its high occurrence during warm periods and in certain geographical regions. Climatic factors could contribute to the health and productivity of cattle, as evidenced by the prevalence of T. orientalis and its negative impact on animals.

Risk factors for tick attachment in companion animals in Great Britain: a spatiotemporal analysis covering 2014-2021

BACKGROUND

Ticks are an important driver of veterinary health care, causing irritation and sometimes infection to their hosts. We explored epidemiological and geo-referenced data from > 7 million electronic health records (EHRs) from cats and dogs collected by the Small Animal Veterinary Surveillance Network (SAVSNET) in Great Britain (GB) between 2014 and 2021 to assess the factors affecting tick attachment in an individual and at a spatiotemporal level.

METHODS

EHRs in which ticks were mentioned were identified by text mining; domain experts confirmed those with ticks on the animal. Tick presence/absence records were overlaid with a spatiotemporal series of climate, environment, anthropogenic and host distribution factors to produce a spatiotemporal regression matrix. An ensemble machine learning spatiotemporal model was used to fine-tune hyperparameters for Random Forest, Gradient-boosted Trees and Generalized Linear Model regression algorithms, which were then used to produce a final ensemble meta-learner to predict the probability of tick attachment across GB at a monthly interval and averaged long-term through 2014-2021 at a spatial resolution of 1 km. Individual host factors associated with tick attachment were also assessed by conditional logistic regression on a matched case-control dataset.

RESULTS

In total, 11,741 consultations were identified in which a tick was recorded. The frequency of tick records was low (0.16% EHRs), suggesting an underestimation of risk. That said, increased odds for tick attachment in cats and dogs were associated with younger adult ages, longer coat length, crossbreeds and unclassified breeds. In cats, males and entire animals had significantly increased odds of recorded tick attachment. The key variables controlling the spatiotemporal risk for tick attachment were climatic (precipitation and temperature) and vegetation type (Enhanced Vegetation Index). Suitable areas for tick attachment were predicted across GB, especially in forests and grassland areas, mainly during summer, particularly in June.

CONCLUSIONS

Our results can inform targeted health messages to owners and veterinary practitioners, identifying those animals, seasons and areas of higher risk for tick attachment and allowing for more tailored prophylaxis to reduce tick burden, inappropriate parasiticide treatment and potentially TBDs in companion animals and humans. Sentinel networks like SAVSNET represent a novel complementary data source to improve our understanding of tick attachment risk for companion animals and as a proxy of risk to humans.

Survey on tick infestation in stray dogs in localities of Malaysia

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

Isolation, identification and antimicrobial susceptibility of the bacteria isolated from Hyalomma dromedarii infesting camels in Al-Jouf province, Saudi Arabia

Ticks are important ectoparasites that transmit various pathogens causing morbidity and mortality in humans and animals. Saudi Arabia faces several challenges that can contribute to the emergence and spread of antimicrobial resistance (AMR) bacteria. These challenges require collaborative efforts to successfully achieve significant control of AMR in the country. The present study aims to isolate bacteria from camels' tick Hyalomma dromedarii in Al-Jouf province to identify and determine these isolates' antimicrobial susceptibilities. Forty-nine ticks were collected from dromedary camels and morphologically classified as H. dromedarii. Ticks were then homogenized and plated individually, which resulted in the isolation of 55 bacteria. The results showed that the bacterial isolates belong to 20 different species. About 71% (n = 39) of the total isolates were identified as Gram-positive bacteria comprised of 11 different species, while 29% (n = 16) of the total isolates were Gram-negative bacteria comprised of 9 different species. The most prevalent isolate within the total samples was Staphylococcus lentus (22.45%, 11/49), followed by Staphylococcus pseudintermedius (18.37%, 9/49) and Sphingomonas paucimobilis (16.33% 8/49). The antimicrobial susceptibility profile of Gram-positive bacteria showed that 100% (n = 31) were resistant to benzylpenicillin; 90.3% (n = 28) were resistant to oxacillin; 58.1% (n = 18) were resistant to clindamycin; 48.4% (n = 15) were resistant to vancomycin. In addition, 32.3% (n = 10) were resistant to trimethoprim/sulfamethoxazole and rifampicin; 25.8% (n = 8) were resistant to erythromycin; 16.1% (n = 5) were resistant to teicoplanin; 6.5% (n = 2) were resistant to tetracycline. All Gram-positive bacteria were 100% susceptible to linezolid, gentamicin, tobramycin, levofloxacin, moxifloxacin, tigecycline, and nitrofurantoin. In antimicrobial susceptibility tests for the Gram-negative bacteria, 57.14% (n = 8) of the identified bacteria were resistant to ampicillin, whereas 50% (n = 7) were resistant to cefoxitin and ceftazidime. About 28.57% (n = 4) of the Gram-negative bacteria were resistant to ceftriaxone, trimethoprim/sulfamethoxazole. In addition, 21.43% (n = 3) were resistant to amoxicillin/clavulanic acid and cephalothin; 14.29% (n = 2) were resistant to cefepime and nitrofurantoin; 7.14% (n = 1) were resistant to piperacillin/tazobactam and tigecycline. However, all Gram-negative bacteria were susceptible to other examined antimicrobials. This is the first study that investigates the role of the hard tick as a potential reservoir for AMR pathogens within our region.

A social-ecological systems approach to tick bite and tick-borne disease risk management: Exploring collective action in the Occitanie region in southern France

Ticks are amongst the most important zoonotic disease vectors affecting human and animal health worldwide. Tick-borne diseases (TBDs) are rapidly expanding geographically and in incidence, most notably in temperate regions of Europe where ticks are considered the principal zoonotic vector of Public Health relevance, as well as a major health and economic preoccupation in agriculture and equine industries. Tick-borne pathogen (TBP) transmission is contingent on complex, interlinked vector-pathogen-host dynamics, environmental and ecological conditions and human behavior. Tackling TBD therefore requires a better understanding of the interconnected social and ecological variables (i.e., the social-ecological system) that favor disease (re)-emergence. The One Health paradigm recognizes the interdependence of human, animal and environmental health and proposes an integrated approach to manage TBD. However, One Health interventions are limited by significant gaps in our understanding of the complex, systemic nature of TBD risk, in addition to a lack of effective, universally accepted and environmentally conscious tick control measures. Today individual prevention gestures are the most effective strategy to manage TBDs in humans and animals, making local communities important actors in TBD detection, prevention and management. Yet, how they engage and collaborate within a multi-actor TBD network has not yet been explored. Here, we argue that transdisciplinary collaborations that go beyond research, political and medical stakeholders, and extend to local community actors can aid in identifying relevant social-ecological risk indicators key for informing multi-level TBD detection, prevention and management measures. This article proposes a transdisciplinary social-ecological systems framework, based on participatory research approaches, to better understand the necessary conditions for local actor engagement to improve TBD risk. We conclude with perspectives for implementing this methodological framework in a case study in the south of France (Occitanie region), where multi-actor collaborations are mobilized to stimulate multi-actor collective action and identify relevant social-ecological indicators of TBD risk.

Ixodid tick species found in northern Sweden - Data from a frontier area

Environmental and climatic changes in northern Europe have shaped a geographical area in which new tick species may become established and introduce new tick-borne pathogens. In recent decades, ticks have expanded their latitudinal and altitudinal range limits in northern Sweden. In this study, ticks were collected in 2018 and 2019 in northern Sweden from different hosts, mainly from dogs, cats and humans. The ticks in 2018 (n = 2141, collected from 65 municipalities in 11 provinces) were identified as Ixodes ricinus (n = 2108, 98.5%), Ixodes persulcatus (n = 18, 0.8%), Ixodes trianguliceps (n = 14, 0.7%) and Hyalomma marginatum (n = 1, 0.05%). The ticks collected in 2019 (n = 519, across a smaller area than in 2018, i.e. Sweden's four northernmost provinces) were identified as I. ricinus (n = 242, 46.6%) and I. persulcatus (n = 277, 53.4%). Among those collected in 2019, the majority of I. ricinus (n = 111, 45.9%) were submitted from the province of Västerbotten, while most I. persulcatus (n = 259, 93.5%) were collected in the province of Norrbotten. This study provides updated figures on the geographical distribution of two Ixodes species in northern Sweden. The results confirmed I. ricinus to be the dominant species and that I. persulcatus has enlarged its distributional area compared with previous reports. Updated knowledge of tick distribution is fundamental for the creation of risk maps and will allow relevant advice to be provided to the general public, suggesting measures to prevent tick bites and consequently tick-borne diseases.

Evidence of Horse Exposure to Anaplasma phagocytophilum, Borrelia burgdorferi, and Leishmania infantum in Greece through the Detection of IgG Antibodies in Serum and in an Alternative Diagnostic Sample-The Saliva

Among the various zoonotic pathogens that infect horses, Anaplasma phagocytophilum, Borrelia spp. and Leishmania spp. have gained scientific interest, and relevant molecular and serological studies in horses have been conducted worldwide. Moreover, human and veterinary medicine have extensively applied alternatives to serum diagnostic samples-such as saliva-for detecting pathogens or antibodies. In this study, we investigated the exposure of horses in Greece to A. phagocytophilum, B. burgdorferi, and L. infantum, and we assessed the diagnostic accuracy of saliva compared to serum in detecting IgG antibodies against the abovementioned pathogens. Paired saliva and serum samples were collected from 317 horses from different regions in Greece. The paired samples were examined using the indirect fluorescent antibody test (IFAT) for detecting IgG antibodies against A. phagocytophilum, B. burgdorferi, and L. infantum. Sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were determined to assess the validity of saliva as an alternative to serum. The receiver operating characteristic (ROC) curve revealed that the optimal cut-off value for detecting antibodies against all the examined pathogens in saliva was 1/10. Higher seropositivity rates were found for B. burgdorferi (15.14%) and A. phagocytophilum (14.19%) compared to L. infantum (1.26%). The detection of IgG antibodies using IFAT in saliva samples had a good test performance compared to serum. The two sample types had a substantial to almost perfect agreement. Although the sensitivity was moderate (70.83-75.56%) in all cases, the specificity was almost perfect to perfect (99.63-100%). This study provides the first evidence that horses in Greece are exposed to A. phagocytophilum and B. burgdorferi and confirms that the seroprevalence of L. infantum in horses in Greece remains low. Our findings suggest that saliva sampling coupled with IFAT could be successfully applied for detecting IgG antibodies against these important zoonotic pathogens in large-scale epidemiological studies in horses, at the population level, as an alternative to serum.

Molecular Evidence of Rickettsia conorii subsp. raoultii and Rickettsia felis in Haemaphysalis intermedia Ticks in Sirumalai, Eastern Ghats, Tamil Nadu, South India

Rickettsia is an important pathogenic entity among tick-borne diseases (TBD), which are considered serious emerging public health problems globally. In India, though the widespread distribution of ticks and TBD has been documented, its real burden remains underreported. In a preliminary attempt, rickettsial surveillance was carried out in ticks collected from Sirumalai, Eastern Ghats in Tamil Nadu, India by using pathogen genome-based phylogenetic inferences generated through multi-locus sequence typing (MLST), targeting the genes 16s rRNA, OmpA, OmpB, and gltA by nested PCR. The laboratory evidence confirms the circulation of Rickettsia in Haemaphysalis intermedia species collected from this area. Analysis of the four gene sequences detected demonstrates their closest identity to the spotted fever group (SFG) available in the GenBank database. Further, multiple sequence alignment with other sequences derived from the GenBank database showed close relatedness to Rickettsia conorii subsp. raoultii (16s rDNA-99.32%, OmpA-93.38%, OmpB-97.39%, and gltA-98.57%) and Rickettsia felis (16s rDNA 99.54%, OmpA-100%, OmpB-100% and gltA-99.41%). With this genomic evidence, the circulation of rickettsial pathogens in the pools of H. intermedia ticks infesting livestock in the Sirumalai foothill area has been demonstrated and to complement the microscopic identification of the tick species, DNA barcodes were generated for H. intermedia using the mitochondrial cytochrome c oxidase subunit I gene (COI). Nevertheless, R. raoultii and R. felis were found to be the aetiological agents of tick-borne lymphadenopathy and flea-borne spotted fever in human cases, respectively, further study on the determination of their diversity, distribution, clinical relevance, and potential risk to the local community in these areas is highly warranted.

Use of In-Clinic Diagnostic Kits for the Detection of Seropositivity to Leishmania infantum and Other Major Vector-Borne Pathogens in Healthy Dogs

Canine Vector-Borne Diseases (CVBDs) are widespread in Europe and enzootic in many other countries. Though severe illnesses may occur, dogs living in enzootic areas often show vague or no clinical signs of CVBDs. Undiagnosed infections/co-infections in subclinically infected animals favor the spread of CVBDs and increase the risk of transmission to other animals and, in some cases, humans. This study has evaluated the exposure of dogs living in key enzootic countries, i.e., Italy and Greece, to major CVBDs via the use of in-clinic diagnostic kits. Overall, 300 privately owned dogs without/with single mild clinical signs living in different regions of Italy (n. 150) and Greece (n. 150) were included in the study. As part of a clinical examination, a blood sample was collected from each dog and subjected to two serological rapid tests, i.e., the SNAP^® 4Dx^®Plus (IDEXX Laboratories Inc.) for the detection of antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi s.l. and Dirofilaria immitis antigen and the SNAP^®Leishmania (IDEXX Laboratories Inc.) for the detection of antibodies against Leishmania infantum. In all, 51 dogs (17%; 95% CI 12.9-21.7) were seropositive to at least 1 pathogen, i.e., 4 in Italy (2.7%; 95% CI 1.4-13.1) and 47 in Greece (31.3%; 95% CI 24-39.4). Dirofilaria immitis antigens were found in 39 dogs (13%; 95% CI 9.4-17.3), while antibodies against Ehrlichia, Anaplasma and Leishmania were detected in 25 (8.3%; 95% CI 5.5-12.1), 8 (2.7%; 95% CI 1.2-5.2) and 5 (1.7%; 95% CI 0.5-3.8) dogs, respectively. None of the dogs tested seropositive for B. burgdorferi s.l. Statistical analyses were performed to evaluate associations between exposure to CVBDs and possible risk factors. The present results indicate that dogs living in enzootic areas may be seropositive for one or more CVBDs in absence of clinical signs. Rapid kits are among first line tools for the detection of CVBDs in clinical settings, as they are cost-effective, straightforward and quick to use. Also, in-clinic tests used herein allowed detection of co-exposure to CVBDs investigated.

Seroexposure to Zoonotic Anaplasma and Borrelia in Dogs and Horses That Are in Contact with Vulnerable People in Italy

Equine and canine anaplasmosis and borreliosis are major tick-borne zoonotic diseases caused by Anaplasma phagocytophilum and various species of Borrelia (the most important being Borrelia burgdorferi s.l.), respectively. This study evaluated the seroexposure to Anaplasma and Borrelia in dogs and horses used in Animal-Assisted Interventions or living in contact with children, elderly people or immunocompromised persons. A total of 150 horses and 150 dogs living in Italy were equally divided into clinically healthy animals and animals with at least one clinical sign compatible with borreliosis and/or anaplasmosis (present at clinical examination or reported in the medical history). Serum samples were tested with ELISA and immunoblot for the presence of antibodies against A. phagocytophilum and B. burgdorferi s.l., and the association between seropositivity and possible risk factors was analyzed using multivariate and univariate tests. Overall, 13 dogs (8.7%) and 19 horses (12.7%) were positive for at least one of the two pathogens. In addition, 1 dog (0.7%) and 12 horses (8%) were positive for antibodies against A. phagocytophilum, while 12 dogs (8.0%) and 10 horses (6.7%) had antibodies against B. burgdorferi s.l. Tick infestation in the medical history of the dogs was significantly associated with seropositivity to at least one pathogen (p = 0.027; OR 7.398). These results indicate that, in Italy, ticks infected with A. phagocytophilum and/or B. burgdorferi circulate in places where horses and dogs are in contact with people at risk of developing severe diseases. Awareness should be increased, and adequate control plans need to be developed to protect human and animal health, especially where vulnerable, at-risk individuals are concerned.

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.

Natural Co-Exposure to Borrelia burgdorferi s.l. and Anaplasma phagocytophilum: Unraveling the Hematological Profile in Sheep

The occurrence of co-infected hosts and questing ticks with more than one tick-borne pathogen-as in the case of Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato-is expected in endemic regions. Their synergy-in terms of pathogenesis and disease severity-has been suggested previously in humans. Limited data exist on the clinicopathological alterations in co-infected sheep. In this study, we investigated the impact of A. phagocytophilum and B. burgdorferi s.l. seropositivity, alone and in combination, on the hematological parameters of naturally infected sheep. A complete blood count was performed, and indirect immunofluorescence assays were used to detect IgG antibodies against A. phagocytophilum and IgG and IgM antibodies against B. burgdorferi s.l. Single natural exposure to B. burgdorferi s.l. was characterized by low Packed Cell Volume (PCV) values and platelet (PLT) counts, while single exposure to A. phagocytophilum was characterized by low PCV values, low white blood cell (WBC) counts, and an increased risk for leukopenia and neutropenia. Co-exposure resulted in the most severe blood abnormalities; all the blood parameters decreased, and the sheep presented an increased risk for anemia. Our study showed that natural co-exposure to A. phagocytophilum and B. burgdorferi s.l. in sheep leads to more severe blood abnormalities and enhances the pathogenic processes. More studies are needed to clarify the possible background mechanisms.

Clinical, diagnostic and epidemiological implications of Hepatozoon spp., Babesia spp. and Leishmania infantum infection in cats and dogs in a Mediterranean periurban setting

Hepatozoon spp., Babesia spp. and Leishmania infantum are common parasites of dogs in Mediterranean countries and are less frequent in cats, particularly Babesia spp. and L. infantum. Moreover, there is limited information on coinfections between these parasites and on L. infantum's distribution in blood, skin and lymphoid tissue in cats. We used PCR and DNA sequencing to investigate the prevalence of these parasites and the aetiology of Hepatozoon spp. and Babesia spp., in blood, skin, spleen and lymph node samples from up to 212 stray cats and 82 abandoned dogs in southeast Spain. All except 2 dogs were healthy; instead, 112 cats had clinical signs. The estimated PCR prevalences (95% confidence interval) were 25% (19-31%) Hepatozoon felis in cats, 13% (6-21%) Hepatozoon canis in dogs, 1% (0-4%) Babesia vogeli in dogs, 0% Babesia spp. in cats and 21% (15-26%) and 44% (33-55%) L. infantum in cats and dogs, respectively, and infections were not associated with each other. Leishmania infantum prevalence in lymphoid tissue was significantly higher in dogs than in cats (p < 0.001), and dogs had higher parasite loads than cats (p = 0.012). Moreover, L. infantum prevalence was significantly higher in the skin and lymphoid tissue compared to blood in infected, asymptomatic animals but it was similar in cats with clinical signs, which also had higher parasite loads compared to infected, asymptomatic cats (p < 0.05). The study highlights significant differences between sympatric dogs and cats with respect to the parasite infections investigated, as well as the need to examine both lymphoid tissue and skin samples to maximise the sensitivity of L. infantum infection diagnosis.

Managing host-parasite interactions in humans and wildlife in times of global change

Global change in the Anthropocene has modified the environment of almost any species on earth, be it through climate change, habitat modifications, pollution, human intervention in the form of mass drug administration (MDA), or vaccination. This can have far-reaching consequences on all organisational levels of life, including eco-physiological stress at the cell and organism level, individual fitness and behaviour, population viability, species interactions and biodiversity. Host-parasite interactions often require highly adapted strategies by the parasite to survive and reproduce within the host environment and ensure efficient transmission among hosts. Yet, our understanding of the system-level outcomes of the intricate interplay of within host survival and among host parasite spread is in its infancy. We shed light on how global change affects host-parasite interactions at different organisational levels and address challenges and opportunities to work towards better-informed management of parasite control. We argue that global change affects host-parasite interactions in wildlife inhabiting natural environments rather differently than in humans and invasive species that benefit from anthropogenic environments as habitat and more deliberate rather than erratic exposure to therapeutic drugs and other control efforts.

Epidemiological Survey of the Main Tick-Borne Pathogens Infecting Dogs from the Republic of Moldova

Despite the significant burden of tick-borne diseases (TBDs), epidemiologic studies are missing, and TBD awareness is low in the Republic of Moldova. Our study is the first to assess the prevalence of the main tick-borne pathogens (TBPs) infecting dogs in this country and associated risk factors. In this cross-sectional, multi-centre study (June 2018-July 2019), blood samples were collected from dogs presenting in veterinary clinics (Chişinău: N = 30) and hosted in public dog shelters (Cahul: N = 42; Chişinău: N = 48). TBPs were assessed by molecular techniques and risk factors by the logistic regression model. Hepatozoon canis was the most prevalent TBP (15.8% [19/120]), followed by Babesia canis (11.7% [14/120]), Anaplasma phagocytophilum (5.8% [7/120]), and Bartonella spp. (0.8% [1/120]). Blood samples tested negative for Borrelia spp., Rickettsia spp., Francisella tularensis, Anaplasma platys, and Ehrlichia canis. Dogs originating from the veterinary clinics had a higher prevalence of A. phagocytophilum infection than those from the shelters (16.6% versus 2.2%, respectively, p = 0.0292; OR: 27.0 [95%CI: 1.4-521.9]). Dogs from Chișinău had a higher prevalence of Hepatozoon canis infection versus those from Cahul (19.2% versus 9.5%, respectively, p = 0.0295; OR: 3.9 [95%CI: 1.1-13.4]). We recommend routine use of acaricides and deworming of dogs to prevent or/and limit TBD spread. Further TBD surveillance studies are needed.

Tick-Borne Encephalitis Virus Prevalence in Sheep, Wild Boar and Ticks in Belgium

Tick-borne encephalitis virus (TBEV) is the most important tick-borne zoonotic virus in Europe. In Belgium, antibodies to TBEV have already been detected in wildlife and domestic animals, but up-to-date prevalence data for TBEV are lacking, and no studies have assessed its seroprevalence in sheep. Serum samples of 480 sheep from all over Belgium and 831 wild boar hunted in Flanders (northern Belgium) were therefore screened for TBEV antibodies by ELISA and plaque reduction neutralization test (PRNT), respectively. The specificity of positive samples was assessed by PRNTs for TBEV and the Louping Ill, West Nile, and Usutu viruses. TBEV seroprevalence was 0.42% (2/480, CI 95%: 0.11-1.51) in sheep and 9.27% (77/831, CI 95%: 7.48-11.43) in wild boar. TBEV seroprevalence in wild boar from the province of Flemish Brabant was significantly higher (22.38%, 15/67) compared to Limburg (7.74%, 34/439) and Antwerp (8.61%, 28/325). Oud-Heverlee was the hunting area harboring the highest TBEV seroprevalence (33.33%, 11/33). In an attempt to obtain a Belgian TBEV isolate, 1983 ticks collected in areas showing the highest TBEV seroprevalence in wild boars were tested by real-time qPCR. No TBEV-RNA-positive tick was detected. The results of this study suggest an increase in TBEV prevalence over the last decade and highlight the need for One-Health surveillance in Belgium.

Vector-borne pathogens of zoonotic concern in hunting dogs of southern Italy

Dogs are commonly exposed to vector-borne pathogens (VBPs), yet few data are available on hunting dogs, which are often at high risk of infection due to their involvement in field activities. To investigate the occurrence of VBPs and evaluate the relative performance of different diagnostic tools, blood and serum samples were collected from hunting dogs (n = 1,433) in rural areas of southern Italy. All samples were tested by Knott's technique for filarioids, serologically (SNAP® 4Dx® Plus) for Anaplasma spp., Borrelia burgdorferi sensu lato, Dirofilaria immitis and Ehrlichia spp. and molecularly (qPCR) for all except B. burgdorferi of the above pathogens plus Babesia spp. and Leishmania infantum. Logistic regression was run to evaluate the statistical associations between the risk of VBP infection and independent variables (such as geographic area of provenience, age class and sex) and K-Cohen formula for assessing the concordance among diagnostic tests. Overall, out of 321 dogs (22.4%) positive to at least one VBP, 28 (1.9%) were infected by filarial species at the Knott's technique. In particular, Acanthocheilonema reconditum was the most prevalent (1.6%), followed by D. immitis (0.2%) and Dirofilaria repens (0.1%). One hundred forty (9.8%) and 231 (16.1%) dogs scored positive to VBPs by serological and molecular methods, respectively. The most prevalent pathogens detected were Ehrlichia spp. (7.3%) with SNAP® 4Dx® Plus, and A. reconditum (7.7%) by qPCR. Statistics revealed a significant association (p < 0.001) between A. reconditum infestation and both Ehrlichia spp. seropositivity and geographical origin of dogs. An agreement of 99.9%, 94.0% and 95.7% for Knott - SNAP® 4Dx® Plus, Knott - qPCR and SNAP® 4Dx® Plus - qPCR for D. immitis was found, respectively. Data demonstrate a high prevalence of VBPs in hunting dogs, indicating that this group of animals is largely exposed to several arthropod vector species and suggesting the transmission risk of pathogens to humans in rural areas of southern Italy. A multi-diagnostic approach and a deeper cooperation among healthcare and stakeholders are required to prevent VBP infections to animals and humans.

Influence of ecological and climatic conditions on the spread of Borrelia burgdorferi in domestic dogs in Ukraine

Lyme-borreliosis is a zoonotic, infectious disease that has a complex chain of transmission of the pathogen Borrelia burgdorferi sensu lato and includes the relationship between ixodid ticks, vertebrate hosts, humans and companion animals in the environment. The article shows general trends in the prevalence of canine Lyme-borreliosis in Ukraine depending on environmental, climatic and physiographic factors. The results of a comparative cartographic analysis of the prevalence of Lyme borreliosis among domestic dogs in Ukraine are presented by systematizing, mathematical and statistical processing of the data obtained by surveying veterinarians engaged in clinical veterinary practice. The paper includes generalized data on the clinical manifestations, methods of diagnosis and treatment of Lyme borreliosis in dogs. We determined the dependence of the prevalence of Lyme borreliosis in dogs on the types of physical and geographical territories – natural zones of Ukraine. Each of the natural zones differs in types of relief, climatic conditions, soil types, composition of fauna and flora, which affect the epizootic chain of Lyme disease. There is a clear correlation between the incidence of Lyme borreliosis in dogs and the types of natural areas. The highest incidence of Lyme borreliosis in dogs was observed in the forest-steppe zone and the zone of broad-leaved forests. A sharp decrease in the incidence of dogs was recorded in areas of mixed forests, the Ukrainian Carpathians and in the South of Ukraine in the steppe zone. The study also confirmed that the prevalence of Lyme disease among domestic dogs was influenced by the climatic factors, in particular: gross moisture of territories, average annual air temperature and soil temperature. In Ukraine, veterinarians in the vast majority of cases use serological diagnostic methods: immunochromatographic analysis, immunoenzymatic assay, and western blot, which are insufficient, since the presence of antibodies to the Lyme borreliosis pathogen is only a confirmation of the animal's contact with the antigen and may not indicate the presence of the disease in the clinical form. The generalized data on the use of antimicrobial drugs in the treatment of Lyme borreliosis in dogs indicate the predominant use of tetracycline antibiotics and cephalosporins. The majority of veterinarians reported symptoms of Lyme arthritis, somewhat fewer reported Lyme nephritis, neuroborreliosis, Lyme carditis and in rare cases, veterinarians observed erythema at the site of tick bite. About half of the veterinarians in Ukraine observed an increase in the incidence of Lyme disease in dogs, indicating a probable deterioration of the epizootic and epidemiological situation regarding Lyme borreliosis, especially in areas with favourable conditions for the circulation of Lyme borreliosis pathogens in natural and urban ecotopes. The results substantiate the need for the further study of the circulation of Borrelia burgdorferi sensu lato and their ability to cause disease in humans and animals, as well as the need to implement the principles of the One Health concept for the control and management of Lyme borreliosis.

Molecular epidemiological study on ticks and tick-borne protozoan parasites (Apicomplexa: Cytauxzoon and Hepatozoon spp.) from wild cats (Felis silvestris), Mustelidae and red squirrels (Sciurus vulgaris) in central Europe, Hungary

Background

Among live wild mammals adapted to urban and peri-urban habitats in Europe, members of the families Felidae, Mustelidae and Sciuridae deserve special attention as pathogen reservoirs because all of these families include members that are kept as pets. We report here the results of our study on two important groups of tick-borne protozoan parasites in ticks and tissues of wild cats, mustelids and red squirrels.

Methods

DNA was extracted from the tissues of carnivores (wild cats, mustelids; n = 16) and red squirrels (n = 4), as well as from ixodid ticks (n = 89) collected from these hosts. These DNA extracts were screened for piroplasms and Hepatozoon spp. using conventional PCR analysis and sequencing. In addition, 53 pooled samples of 259 questing Haemaphysalis concinna ticks were evaluated for the presence of Hepatozoon DNA, followed by phylogenetic analyses.

Results

One wild cat was found to be coinfected with Cytauxzoon europaeus and a new genotype of Hepatozoon felis, and two additional wild cats were infected with H. felis from a different phylogenetic group. In mustelids, Hepatozoon martis and two further Hepatozoon genotypes were detected. The latter clustered separately, close to others reported from eastern Asia. In addition, Hepatozoon sciuri was detected in red squirrels. Morphologic and molecular analyses verified eight tick species. One wild cat was infected with a H. felis genotype that was significantly different from that in Ixodes ricinus females infesting this cat. Only three pools of questing H. concinna nymphs tested positive for Hepatozoon, one of which contained H. martis.

Conclusions

This study provides the first evidence of the occurrence of any Cytauxzoon species and of three Hepatozoon species in Hungary. In addition to H. martis, two further mustelid-associated Hepatozoon genotypes were detected, one of which was new in terms of phylogenetic and broader geographical contexts. This may be the first indication that H. felis genotypes from both of its phylogenetic groups occur in Europe. This also appears to be the first evidence of H. felis and C. europaeus coinfection in felids in Europe, and of autochthonous H. felis infection in wild cats north of the Mediterranean Basin. New tick–host associations were also observed in this study. Based on the results, H. felis and H. martis might survive transstadially in I. ricinus and H. concinna, respectively.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05271-1.

One Health Approach to Tick and Tick-Borne Disease Surveillance in the United Kingdom

Where ticks are found, tick-borne diseases can present a threat to human and animal health. The aetiology of many of these important diseases, including Lyme disease, bovine babesiosis, tick-borne fever and louping ill, have been known for decades whilst others have only recently been documented in the United Kingdom (UK). Further threats such as the importation of exotic ticks through human activity or bird migration, combined with changes to either the habitat or climate could increase the risk of tick-borne disease persistence and transmission. Prevention of tick-borne diseases for the human population and animals (both livestock and companion) is dependent on a thorough understanding of where and when pathogen transmission occurs. This information can only be gained through surveillance that seeks to identify where tick populations are distributed, which pathogens are present within those populations, and the periods of the year when ticks are active. To achieve this, a variety of approaches can be applied to enhance knowledge utilising a diverse range of stakeholders (public health professionals and veterinarians through to citizen scientists). Without this information, the application of mitigation strategies to reduce pathogen transmission and impact is compromised and the ability to monitor the effects of climate change or landscape modification on the risk of tick-borne disease is more challenging. However, as with many public and animal health interventions, there needs to be a cost-benefit assessment on the most appropriate intervention applied. This review will assess the challenges of tick-borne diseases in the UK and argue for a cross-disciplinary approach to their surveillance and control.

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

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

Canine Tick-Borne Encephalitis: Clinical Features, Survival Rate and Neurological Sequelae: A Retrospective Study of 54 Cases (1999-2016)

Tick-borne encephalitis (TBE) is one of the most important infectious diseases of the central nervous system in dogs from endemic areas. While in humans survival rate and long-term outcomes are well described, these data are lacking in veterinary literature. The aim of the present paper is to characterize the clinical aspects of TBE and to investigate fatality rate, long-term outcome and the long-term neurological sequelae in a population of dogs infected with TBE. We performed a retrospective analysis of 54 dogs diagnosed with TBE at the veterinary hospital of the University of Zurich between 1999 and 2016. Medical data such as signalment, clinical presentation, results of diagnostic procedures, treatment and outcome were collected and analyzed. Statistical analysis including a cox proportional hazard model using a backward stepwise regression approach was performed. In 62% of the TBE cases unspecific signs were described before the onset of neurological signs, resembling a biphasic appearance that is well known in human TBE. Case fatality rate was 33% and all dogs died within the first 4 months after diagnosis. Long-term neurological sequalae were detected in 17% of the TBE cases. For each day of clinical signs before hospital entry the odds of sequalae increased by a factor of 1.88 (CI 1.04–3.15). Older dogs and dogs presented with seizure activity had an increased hazard risk of death (Hazard ration = 1.2, p = 0.03; and 9.38, p = 0.001, respectively). In conclusion, despite TBE being a life-threatening disease with severe clinical signs, the survival rate in our study was 67%. However, long-term sequalae can be of concern especially in dogs with longer clinical course.

Associating Land Cover Changes with Patterns of Incidences of Climate-Sensitive Infections: An Example on Tick-Borne Diseases in the Nordic Area

Some of the climate-sensitive infections (CSIs) affecting humans are zoonotic vector-borne diseases, such as Lyme borreliosis (BOR) and tick-borne encephalitis (TBE), mostly linked to various species of ticks as vectors. Due to climate change, the geographical distribution of tick species, their hosts, and the prevalence of pathogens are likely to change. A recent increase in human incidences of these CSIs in the Nordic regions might indicate an expansion of the range of ticks and hosts, with vegetation changes acting as potential predictors linked to habitat suitability. In this paper, we study districts in Fennoscandia and Russia where incidences of BOR and TBE have steadily increased over the 1995-2015 period (defined as 'Well Increasing districts'). This selection is taken as a proxy for increasing the prevalence of tick-borne pathogens due to increased habitat suitability for ticks and hosts, thus simplifying the multiple factors that explain incidence variations. This approach allows vegetation types and strengths of correlation specific to the WI districts to be differentiated and compared with associations found over all districts. Land cover types and their changes found to be associated with increasing human disease incidence are described, indicating zones with potential future higher risk of these diseases. Combining vegetation cover and climate variables in regression models shows the interplay of biotic and abiotic factors linked to CSI incidences and identifies some differences between BOR and TBE. Regression model projections up until 2070 under different climate scenarios depict possible CSI progressions within the studied area and are consistent with the observed changes over the past 20 years.

Simultaneous Exposure to Angiostrongylus vasorum and Vector-Borne Pathogens in Dogs from Italy

Several drivers have recently fostered the expansion of Angiostrongylus vasorum throughout Europe, where Vector-Borne Pathogens (VBPs) are also spreading. However, the level of simultaneous risk of infection is still unknown in canine populations. This study evaluated the simultaneous exposure to A. vasorum and major canine VBPs in dogs of Italy. Sera of 294 dogs were subjected to two ELISAs, detecting A. vasorum circulating antigens and antibodies against the parasite, and to the following assays: (i) SNAP® 4DX (IDEXX Laboratories Inc.) detecting Dirofilaria immitis antigens, and antibodies vs. Borrelia burgdorferi, Anaplasma spp. and Ehrlichia spp. and (ii) IFAT for the detection of antibodies vs. Leishmania infantum, Babesia canis and Rickettsia conorii. Twenty-two (7.5%, CI: 4.8-11.1%) and six (2%, CI: 0.7-4.4%) dogs scored positive for circulating A. vasorum antibodies and antigens, respectively. Seventeen dogs (5.8%, CI: 3.4-9.1%) were positive for A. vasorum antibodies + at least one VBP, three (1%, CI: 0.2-3%) for A. vasorum antigen + at least one VBP, while one dog (0.3%, CI: 0.01-1.88%) was positive for A. vasorum antigen + A. vasorum antibodies + B. canis antibodies. These results show that dogs living in different regions of Italy are at risk of simultaneous infections with both A. vasorum and VBPs. Despite the same scenario being likely in other countries of Europe, the current knowledge is scant. Therefore, further studies are warranted to amplify current epizootiological information and to understand whether control programs should be improved.

Seropositivity to canine tick-borne pathogens in a population of sick dogs in Italy

BACKGROUND

Canine vector-borne diseases (CVBDs) associated to ticks are among the most important health issues affecting dogs. In Italy, Ehrlichia canis, Anaplasma spp., Rickettsia conorii and Borrelia burgdorferi (s.l.) have been studied in both healthy canine populations and those clinically ill with suspected CVBDs. However, little information is currently available on the overall prevalence and distribution of these pathogens in the country. The aim of this study was to assess the prevalence and distribution of tick-borne pathogens (TBPs) in clinically suspect dogs from three Italian macro areas during a 15-year period (2006-2020).

METHODS

A large dataset (n = 21,992) of serological test results for selected TBPs in three macro areas in Italy was analysed using a Chi-square test to evaluate the associations between the categorical factors (i.e. macro area, region, year, sex and age) and a standard logistic regression model (significance set at P = 0.05). Serological data were presented as annual and cumulative prevalence, and distribution maps of cumulative positive cases for TBPs were generated.

RESULTS

Of the tested serum samples, 86.9% originated from northern (43.9%) and central (43%) Italy. The majority of the tests was requested for the diagnosis of E. canis (47%; n = 10,334), followed by Rickettsia spp. (35.1%; n = 7725), B. burgdorferi (s.l.) (11.6%; n = 2560) and Anaplasma spp. (6.2%; n = 1373). The highest serological exposure was recorded for B. burgdorferi (s.l.) (83.5%), followed by Rickettsia spp. (64.9%), Anaplasma spp. (39.8%) and E. canis (28.7%). The highest number of cumulative cases of Borrelia burgdorferi (s.l.) was recorded in samples from Tuscany, central Italy. Rickettsia spp. was more prevalent in the south and on the islands, particularly in dogs on Sicily older than 6 years, whereas Anaplasma spp. was more prevalent in the north and E. canis more prevalent in the south and on the islands.

CONCLUSIONS

The results of this study highlight the high seroprevalence and wide distribution of the four TBPs in dogs with clinically suspected CVBDs from the studied regions of Italy. The very high seroprevalence of B. burgdorferi (s.l.) exemplifies a limitation of this study, given the use of clinically suspect dogs and the possibility of cross-reactions when using serological tests. The present research provides updated and illustrative information on the seroprevalence and distribution of four key TBPs, and advocates for integrative control strategies for their prevention.

Exposure to Major Vector-Borne Diseases in Dogs Subjected to Different Preventative Regimens in Endemic Areas of Italy

Vector-borne diseases (VBDs) are globally widespread arthropod-transmitted diseases with a significant impact on animal and human health. Many drivers have recently spurred the geographic spread of VBDs in dogs. This study has evaluated the exposure to most important VBDs in dogs under different preventative treatments in different regions of Italy, i.e., Veneto, Friuli Venezia-Giulia, Umbria, Giglio Island (Tuscany), Abruzzo and Latium. Serological analyses were performed to detect antibodies against Leishmania infantum, Babesia canis, Anaplasma phagocytophilum/Anaplasma platys, Ehrlichia canis/Ehrlichia ewingii, Borrelia burgdorferi, Rickettsia conorii and the circulating antigen of Dirofilaria immitis. Dogs were categorized according to the treatment schedule usually received, and the association between seropositivity and possible risk factors was statistically evaluated. Overall, 124/242 (51.2%) dogs tested positive for at least one pathogen, while 34 (14.0%) were exposed to two or more pathogens. The most detected seropositivity was against R. conorii, followed by Anaplasma spp., L. infantum, B. canis, and the other pathogens under study. Significant statistical associations were found according to geographical provenance, history of tick infestation, lifestyle and inadequate prophylactic treatments. Random/irregular treatments have been identified as a clear risk factor. These results show that adequate prophylactic treatment protocols are overlooked by dog owners, despite the availability of several effective products, with possible implications in veterinary medicine and on public health.