Vector competence of Rhipicephalus sanguineus sensu stricto for Anaplasma platys

Human granulocytotropic anaplasmosis-A systematic review and analysis of the literature

Human granulocytotropic anaplasmosis (HGA) is a zoonotic tick-borne bacterial infection caused by Anaplasma phagocytophilum. While most cases are reported from North America, HGA has been recognized as an emerging disease in several regions of the world in recent decades. Most available data comes from case reports, case series and retrospective studies, while prospective studies and clinical trials are largely lacking. To obtain a clearer picture of the currently known epidemiologic distribution, clinical and paraclinical presentation, diagnostic aspects, complications, therapeutic aspects, and outcomes of HGA, we systematically reviewed the literature and analyzed and summarized the data. Cases of HGA are reported from all continents except from Antarctica. HGA primarily presents as an unspecific febrile illness (88.5% of the cases) often accompanied by thrombocytopenia (71.8% of the cases), abnormal liver injury tests (66.7% of the cases), and leukopenia (49.8% of the cases). Although we found complications reported in a total of 40.5% of the reviewed cases and severe and even life-threatening complications are not infrequent (e.g. acute renal failure 9.8%, multi organ failure 7.5%, ARDS 6.3%, a.o.), sequelae are rare (2.1% of the cases) and lethality is low (3.0% of the cases). Treatment with doxycycline shows a rapid response, with the fever subsiding in the majority of patients within one day of starting treatment. Unlike in human monocytotropic ehrlichiosis (HME), reports of opportunistic infections complicating HGA are rare. HGA during pregnancy does not appear to be associated with unfavorable outcomes. In addition, our analysis provides some evidence that HGA may differ in clinical aspects and laboratory characteristics in different regions of the world. Overall, the data analyzed indicates a non-negligible bias in reporting/publication, so a certain degree of caution is required when generalizing the data.

Island hitchhikers: pathogen agents of Madeira and Azores ticks

Ticks are blood-sucking arthropods that can transmit pathogens to their host. As insular ecosystems can enhance tick-host interactions, this study aimed to understand tick diversity, pathogen presence, and their respective associations in the Azores and Madeira archipelagos. Unfed or partially engorged ticks (n = 120) were collected from 58 cats and dogs in the Azores (n = 41 specimens) and Madeira (n = 79 specimens) from November 2018 to March 2019. Vector identification was based on morphology and molecular criteria. For pathogen sequencing, 18S gene fragment for Babesia/Hepatozoon and gltA for Rickettsia were performed. Sequence data was explored using BLAST and BLAST and phylogenetic inference tools. In the Azores, Ixodes hexagonus, I. ventalloi, and Rhipicephalus sanguineus (n = 6; 14.6%, n = 6; 14.6%, and n = 29; 70.7% respectively) were found and in Madeira I. ricinus and R. sanguineus (n = 78, 98.7%; and n = 1, 1.3%; respectively) were identified. Tick COI markers confirmed species highlighting confirmation of R. sanguineus s.s. and genotype A of I. ventalloi. In the Azores Islands, the detected Rickettsia massiliae was linked to R. sanguineus (dogs and cats) and I. hexagonus (dogs), and in Madeira Island, R. monacensis (dogs) and Hepatozoon silvestris (cats) were found associated with I. ricinus. Further, I. ventalloi presence in the Azores expands west its known range, and Hepatozoon silvestris in Madeira may suggest that I. ricinus could have a role as a potential vector. Finally, as R. massiliae and R. monacensis presence underlines public health risks, surveillance by health authorities is crucial as pathogen-tick interactions may drive disease spread, therefore monitoring remains pivotal for disease prevention.

The geographic limits and life history of the tropical brown dog tick, Rhipicephalus linnaei (Audouin, 1826), in Australia with notes on the spread of Ehrlichia canis

The tropical brown dog tick, Rhipicephalus linnaei, is a tick of much medical, veterinary, and zoonotic importance. This tick has a nearly world-wide distribution due to its ability to survive and propagate in kennels and houses. Rhipicephalus linnaei is the vector of Ehrlichia canis, the causative agent of canine monocytic ehrlichiosis, an often debilitating disease of canids and, occasionally, humans. To prevent incursion of E. canis into Australia, dogs entering Australia have been required to have a negative immunofluorescence antibody test for E. canis. In May 2020 however, E. canis was detected in Western Australia. The detection of E. canis in Australia prompted disease investigation and concerted surveillance for R. linnaei and E. canis in regions across Australia. These investigations revealed that R. linnaei was established far beyond the previously recognised geographic range limits of this tick. In the present paper, using records from various collections, published data, and data from our network of veterinarian collaborators and colleagues, we update the current geographic range of R. linnaei in Australia. Our analyses revealed that the geographic range of R. linnaei in Australia is much wider than was previously supposed, particularly in Western Australia, and in South Australia. We also map, for the first time, where E. canis has been detected in Australia. Last, we discuss the possible routes of incursion and subsequently the factors which may have aided the spread of E. canis in Australia which led to the establishment of this pathogen in Australia.

Molecular survey of Piroplasmida, Hepatozoon spp. and Anaplasmataceae in anemic and thrombocytopenic dogs from Uruguay

Canine tick-borne diseases, such as babesiosis, rangeliosis, hepatozoonosis, anaplasmosis and ehrlichiosis, are of veterinarian relevance, causing mild or severe clinical cases that can lead to the death of the dog. The aim of this study was detecting tick-borne protozoan and rickettsial infections in dogs with anemia and/or thrombocytopenia in Uruguay. A total of 803 domestic dogs were evaluated, and 10% were found positive (detected by PCR) at least for one hemoparasite. Sequence analysis confirmed the presence of four hemoprotozoan species: Rangelia vitalii, Babesia vogeli, Hepatozoon canis and Hepatozoon americanum, and the rickettsial Anaplasma platys. The most detected hemoparasite was R. vitalii, followed by H. canis and A. platys. This is the first report of B. vogeli in Uruguay and the second report of H. americanum in dogs from South America. The results highlight the importance for veterinarians to include hemoparasitic diseases in their differential diagnosis of agents causing anemia and thrombocytopenia.

Immune protection of three serine protease inhibitors vaccine in mice against Rhipicephalus sanguineus

Bioactive molecules in tick saliva are considered to be key to successful feeding and further the transmission of tick-borne pathogens. Problems such as pathogen transmission and animal weight loss result in tick infestation can cause tremendous economic losses to the livestock industry. Therefore, the development of a universal tick vaccine is urgently needed. In this paper, three serine protease inhibitor (serpin) proteins RMS-3, L7LRK7 and L7LTU1 were analyzed with bioinformatics methods. Subsequently the proteins were expressed and purified, and inoculated into Kunming mice for immune protection analysis. The amino acid sequence similarities between RMS-3, L7LRK7 and L7LTU1 were up to 90% in Rhipicephalus sanguineus. The recombinant RMS-3 + L7LRK7 + L7LTU1 showed anticoagulant reaction function and could inhibit the activity of CD4+ lymphocytes, when inoculated into Kunming mice. Additionally, After the immunized mice were challenged with Rhipicephalus sanguineus, the percentage of larvae and nymphs that were fully engorged dropped to 40.87% (P < 0.05) and 87.68% (P > 0.05) in the RmS-3 + L7LRK7 immune group, 49.57% (P < 0.01) and 52.06% (P < 0.05) in the RmS-3 + L7LTU1 group, and 45.22% (P < 0.05) and 60.28% (P < 0.05) in the RmS-3 + L7LRK7 + L7LTU1 immune group, in comparison with the control group. These data indicate that RmS-3 + L7LRK7 + L7LTU1 has good immune protection and has the potential to be developed into a vaccine against the larvae and nymphs of R. sanguineus.

Seasonal dynamics and genetic characterization of bovine arthropod-borne parasites in Nan Province, Thailand with molecular identification of Anaplasma platys and Trypanosoma theileri

Virulent species or strains of hematophagous borne pathogens such as Anaplasma spp., Babesia spp., Theileria spp., and Trypanosoma spp., are lethal to susceptible animals or reduce their productivity on a global scale. Nonetheless, efforts to diagnose the causative agents and assess the genotypic profiles as well as quantify the parasite burden of aforementioned parasites across seasons remain limited. Therefore, the present investigation sought to elucidate the genotypic composition of Anaplasma spp., Babesia spp., Theileria spp., and Trypanosoma spp. The findings revealed heightened infection rates during the summer, manifesting a correlation between Trypanosoma spp. infection and seasonal fluctuations. Among the identified pathogens, Anaplasma marginale emerged as the most dominant species, while the occurrence of Anaplasma platys in Thai cattle was confirmed via the sequencing of the groEL gene. Moreover, the study successfully identified two lineages of Trypanosoma theileri. The findings of this investigation offer valuable insights that can inform the development of preventive strategies for vector-borne diseases, such as considering the appropriate use of insect repellent, mosquito or insect nets, or eliminating breeding places for insects in each season.

Rearing of Rhipicephalus annulatus ticks on rabbits for the biological transmission of Anaplasma marginale

Background and Aim

Anaplasma marginale is an obligate intraerythrocytic rickettsial parasite that infects cattle in tropical and subtropical regions. There is no evidence that A. marginale inoculation can be used to culture Rhipicephalus annulatus in rabbits. This study aimed to determine the molting of R. annulatus larvae, nymphs, and adults on rabbits as well as nymphs and adults of R. annulatus on calves with or without A. marginale. Transstadial, horizontal, and transovarial transmissions of A. marginale in R. annulatus reared on rabbits and calves were evaluated.

Materials and Methods

Engorged female ticks were collected from field samples of A. marginale-infected and non-infected cattle. We divided the eight rabbits into two groups: A and B. Group A rabbits were infected with A. marginale through parenteral inoculation, whereas Group B rabbits were kept as a control. The "clean rabbits" in Group B were observed for tick rearing without A. marginale. Polymerase chain reaction was used to screen A. marginale in rabbits and stages of tick. The complete life cycle of R. annulatus with or without A. marginale was observed on rabbits.

Results

A 6.5-day longer life cycle was observed in ticks harboring A. marginale than in ticks without A. marginale. To observe transstadial transmission, transstadial, horizontal, and transovarial transmissions of A. marginale in R. annulatus ticks were experimentally observed in one clean calf fed separately with infected nymphs and female adult ticks.

Conclusion

We experimentally observed transovarian, transstadial, and transovarial transmission of A. marginale in R. annulatus ticks as a biological vector reared on calves and rabbits. We used rabbits as a model animal for rearing R. annulatus ticks and culture of A. marginale.

Data release: targeted systematic literature search for tick and tick-borne pathogen distributions in six countries in sub-Saharan Africa from 1901 to 2020

BACKGROUND

Surveillance data documenting tick and tick-borne disease (TBD) prevalence is needed to develop risk assessments and implement control strategies. Despite extensive research in Africa, there is no standardized, comprehensive review.

METHODS

Here we tackle this knowledge gap, by producing a comprehensive review of research articles on ticks and TBD between 1901 and 2020 in Chad, Djibouti, Ethiopia, Kenya, Tanzania, and Uganda. Over 8356 English language articles were recovered. Our search strategy included 19 related MeSH terms. Articles were reviewed, and 331 met inclusion criteria. Articles containing mappable data were compiled into a standardized data schema, georeferenced, and uploaded to VectorMap.

RESULTS

Tick and pathogen matrixes were created, providing information on vector distributions and tick-pathogen associations within the six selected African countries.

CONCLUSIONS

These results provide a digital, mappable database of current and historical tick and TBD distributions across six countries in Africa, which can inform specific risk modeling, determine surveillance gaps, and guide future surveillance priorities.

Completing the Puzzle: A Cluster of Hunting Dogs with Tick-Borne Illness from a Fishing Community in Tobago, West Indies

Eight hunting dogs were visited by a state veterinarian on the island of Tobago, Trinidad and Tobago, West Indies, as owners reported anorexia and paralysis in five of their dogs. The veterinarian observed a combination of clinical signs consistent with tick-borne illness, including fever, anorexia, anaemia, lethargy and paralysis. Blood and ticks were collected from each dog and submitted to a diagnostic laboratory for analysis. Microscopic analysis revealed a mixed infection of intracytoplasmic organisms consistent with Babesia spp. (erythrocyte) and Ehrlichia spp. (monocyte), respectively, from one dog, while a complete blood count indicated a regenerative anaemia (n = 1; 12.5%), non-regenerative anaemia (n = 4; 50%), neutrophilia (n = 3; 37.5%), lymphocytosis (n = 2; 25%), thrombocytopaenia (n = 3; 37.5%) and pancytopaenia (n = 1; 12.5%). DNA isolated from the eight blood samples and 20 ticks (16 Rhipicephalus sanguineus and 4 Amblyomma ovale) were subjected to conventional PCR and next-generation sequencing of the 16S rRNA and 18S rRNA gene for Anaplasma/Ehrlichia and Babesia/Theileria/Hepatozoon, respectively. The DNA of Ehrlichia spp., closely related to Ehrlichia canis, was detected in the blood of three dogs (37.5%), Anaplasma spp., closely related to Anaplasma marginale, in two (25%), Babesia vogeli in one dog (12.5%) and seven ticks (35%) and Hepatozoon canis and Anaplasma spp., in one tick (5%), respectively. These findings highlight the need to test both the vector and host for the presence of tick-borne pathogens when undertaking diagnostic investigations. Further studies are also warranted to elucidate the susceptibility of canids to Anaplasma marginale.

Evaluation of Anaplasma spp. seroprevalence in dogs and association with incidence of human anaplasmosis

Point-of-care (POC) ELISA tests are routinely used in US veterinary practices to screen canine patients for antibodies to tick-transmitted pathogens. Results are also used to monitor spatial and temporal trends in canine seroprevalence, and these data can build awareness of the risk to humans of tick-transmitted diseases such as Lyme disease and anaplasmosis. This study utilized a second-generation test that has incorporated additional Anaplasma-specific peptides into a commercial POC ELISA test to allow detection of Anaplasma spp. antibodies earlier post-infection. A convenience population consisting of 19,894 canine samples from a US commercial diagnostic laboratory were tested using the second-generation POC ELISA test to describe regional Anaplasma spp. canine seroprevalence and assess correlation to anaplasmosis cases reported to Centers for Disease Control and Prevention by state. Antibodies to Anaplasma spp. were detected in 1646 samples (8.3%) with the Northeast and Midwest US census regions having the highest proportion of positive samples. At the state level, a significant correlation was found between canine Anaplasma spp. seroprevalence and human anaplasmosis incidence (r2 = 0.64). Although estimates of canine Anaplasma spp. seroprevalence presented here using the second-generation POC ELISA are generally increased, especially in the Northeast and Midwest, the regional distribution of canine samples testing positive for Anaplasma spp. antibodies is consistent with previous reports. The observed correlation with human anaplasmosis incidence indicates that results from the second-generation POC ELISA will continue to add value in epidemiological assessment of human anaplasmosis risk.

Morphological and molecular identification of the brown dog tick in Mexico

Ticks of the Rhipicephalus sanguineus complex are known as the brown dog ticks. This complex groups at least 12 species of ticks that are distributed worldwide. On the American continents, R. sanguineus sensu stricto (s.s.), is distributed in temperate areas, while Rhipicephalus sanguineus sensu lato (s.l.), also called "tropical lineage" is distributed in tropical regions. Previous analyses of brown dog ticks from Mexico have identified the so-called tropical lineage and the country generally has a climate more favorable for these ticks (> 20o C in average). In addition, some pathogens thought to be transmitted by this lineage (such as Ehrlichia canis, and Rickettsia rickettsii) are prevalent in Mexico. Herein we aim to contribute to the study of brown dog ticks by providing morphological identification and molecular analysis of mt 12S rDNA and 16S rDNA sequences from ticks collected from 12 states in Mexico. Our results indicate that the tropical lineage of R. sanguineus s.l., recently redescribed as R. linnaei is widely distributed in Mexico.

Transovarial Transmission of Anaplasma marginale in Rhipicephalus (Boophilus) microplus Ticks Results in a Bottleneck for Strain Diversity

Anaplasma marginale is an obligate intraerythrocytic bacterium of bovines, responsible for large economic losses worldwide. It is mainly transmitted by Rhipicephalus (Boophilus) microplus ticks and, despite mounting evidence suggesting transovarial transmission, the occurrence of this phenomenon remains controversial. We evaluated the vector competence of R. microplus larvae vertically infected with A. marginale to transmit the bacterium to a naïve bovine. A subgroup of engorged female ticks collected from an A. marginale-positive animal was dissected and the presence of the pathogen in its tissues was confirmed. A second subgroup of ticks was placed under controlled conditions for oviposition. After confirming the presence of A. marginale in the hatched larvae, an experimental infestation assay was conducted. Larvae were placed on an A. marginale-free splenectomized calf. The bacterium was detected in the experimentally infested bovine 22 days post-infestation. We analyzed the A. marginale diversity throughout the transmission cycle using the molecular marker MSP1a. Different genotypes were detected in the mammalian and arthropod hosts showing a reduction of strain diversity along the transmission process. Our results demonstrate the vertical transmission of A. marginale from R. microplus females to its larvae, their vector competence to transmit the pathogen, and a bottleneck in A. marginale strain diversity.

Pathogenic Rickettsia, Anaplasma, and Ehrlichia in Rhipicephalus microplus ticks collected from cattle and laboratory hatched tick larvae

BACKGROUND

The order Rickettsiales contains a group of vector-borne gram-negative obligate intracellular bacteria, which often cause human emerging infectious diseases and economic losses for dairy and meat industries. The purpose of this study is to investigate the distribution of the pathogens including Rickettsia spp., Anaplasma spp., and Ehrlichia spp. in the order Rickettsiales in ticks from Yueyang, a prefecture-level city of Hunan Province in Sothern China, and assess the potentiality of transovarial transmission of these rickettsial organisms.

METHODS

Ticks were collected from cattle in a farm in Yueyang City and the tick DNA was used as template to amplify the htrA, rrs, gltA, ompA and ompB genes of Rickettsia as well as rrs and groEL genes of Anaplasma and Ehrlichia.

RESULTS

All ticks (465) collected were the cattle tick, Rhipicephalus microplus. PCR showed the minimum infection rate (MIR) was 1.5% (7/465) for Candidatus Rickettsia xinyangensis, 1.9% (9/465) for C. Anaplasma boleense, 1.3% (6/465) for Anaplasma platys, 0.6% (3/465) for A. marginale, and 1.17% (2/465) for each of A. bovis, Ehrlichia minasensis, and a non-classified Ehrlichia sp. A human pathogen, C. Rickettsia xinyangensis and A. platys were detected in 100% (3/3) and 33.3% (2/6) laboratory-hatched larval pools from infected females respectively.

CONCLUSION

Our study revealed a diversity of pathogenic rickettsial species in R. microplus ticks from Hunan Province suggesting a threat to people and animals in China. This study also provided the first molecular evidence for the potential transovarial transmission of C. Rickettsia xinyangensis and A. platys in R. microplus, indicating that R. microplus may act as the host of these two pathogens.

Dynamics of Infections in Cattle and Rhipicephalus microplus: A Preliminary Study

Tick-borne pathogens (TBPs) pose a significant threat to livestock, including bovine species. This study aimed to investigate TBPs in cattle and ticks across four sampling points, utilizing real-time microfluidic PCR. The results revealed that Rhipicephalus microplus ticks were found infesting all animals. Among the detected TBPs in cattle, Anaplasma marginale was the most frequently identified, often as a single infection, although mixed infections involving Rickettsia felis, uncharacterized Rickettsia sp., and Anaplasma sp. were also observed. In ticks, A. marginale was predominant, along with R. felis, Rickettsia sp., and Ehrlichia sp. It is noteworthy that although A. marginale consistently infected all cattle during various sampling times, this pathogen was not detected in all ticks. This suggests a complex dynamic of pathogen acquisition by ticks. A phylogenetic analysis focused on the identification of Anaplasma species using amplified 16S rDNA gene fragments revealed the presence of A. marginale and Anaplasma platys strains in bovines. These findings underscore the presence of multiple TBPs in both cattle and ticks, with A. marginale being the most prevalent. Understanding the dynamics and phylogenetics of TBPs is crucial for developing effective control strategies to mitigate tick-borne diseases in livestock.

Anaplasma species infecting questing ticks in the Iberá wetlands ecoregion, Argentina

The present study evaluated the presence of Anaplasma species in questing ticks from six sites with opposing land usage (i.e., protected natural areas or livestock establishments) within the Iberá wetlands ecoregion in Argentina. The ticks were determined as Amblyomma dubitatum (n = 15,096), Rhipicephalus microplus (n = 399), Amblyomma triste (n = 134), Haemaphysalis juxtakochi (n = 5), and Amblyomma tigrinum (n = 1). Using a real-time PCR assay targeting the 16S rRNA gene, Anaplasma sp. was detected in A. dubitatum samples (one nymph, three nymph pools and one larvae pool) and one R. microplus larvae pool. The overall minimum infection rate (MIR) for Anaplasma sp. in questing A. dubitatum nymphs was 0.169% (0.175% in protected natural areas and 0% in livestock establishments). For R. microplus, overall Anaplasma sp. MIR was 0.25% (0.52% in protected natural areas and 0% in livestock establishments). Phylogenetic analysis positioned the Anaplasma sp. from A. dubitatum in the same clade as Anaplasma odocoilei, whereas the Anaplasma sp. from R. microplus was related to Anaplasma platys. In conclusion, these results support a possible role of A. dubitatum in the ecology of the Anaplasma agent reported to infect capybaras in the region.

Geographical analysis of seroprevalence of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis, in clinics and dog shelters in different Mexican states

This study aimed to determine the seroprevalence and geographical distribution of Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis in dogs in Mexico, including owned dogs from veterinary clinics with regular medical care and shelter dogs. The Mexican territory was divided into eight geographical regions; 22 out of 32 states were included; 110 veterinary clinics and 53 dog shelters participated. SNAP® 4Dx Plus® (IDEXX® Laboratories) was used to detect antibodies against Ehrlichia spp., Anaplasma spp., Borrelia burgdorferi and Dirofilaria immitis antigens. A total of 3522 apparently healthy dogs were tested, 1648 from clinics and 1874 from shelters. The highest seroprevalence of infection/exposure was found for Ehrlichia spp. (30.9%), followed by Anaplasma spp. (14.6%), D. immitis (5.3%) and B. burgdorferi (0.1%). Significantly more positive dogs were older than 3 years. Regarding differences between facility types, there were only differences for D. immitis which was more prevalent in clinics than in shelters (OR ​= ​1.97; 95% CI: 1.45-2.69; P ​< ​0.0001). Co-infections were detected in 38.4% of the positive samples. Dogs from Mexican states located on the Atlantic and the Pacific coast were significantly more at risk for Ehrlichia spp. and Anaplasma spp. infections than dogs from interior states. Dogs in Atlantic coastal states were more at risk for Dirofilaria immitis infection.

Tick-borne pathogens detected in sheltered dogs during an epidemic of Rocky Mountain spotted fever, a One Health challenge

OBJECTIVE

To assess exposure to and infection with 3 pathogens (Rickettsia rickettsii, Anaplasma platys, and Ehrlichia canis) vectored by brown dog ticks (Rhipicephalus sanguineus) in sheltered dogs at the western US-Mexico border.

ANIMALS

239 dogs in shelters in San Diego and Imperial counties, US, and Mexicali and Tijuana, Mexico.

PROCEDURES

Each dog had blood drawn and basic demographic data collected. PCR was performed to determine active infection with Rickettsia spp, E canis, and A platys. Serology was performed to determine exposure to Rickettsia, Anaplasma, and Ehrlichia species.

RESULTS

2 of 78 (2.6%) dogs sampled in Tijuana were actively infected with R rickettsii. A single brown dog tick collected from a dog in Tijuana was PCR-positive for R rickettsii. Infection with E canis and A platys ranged across shelters from 0% to 27% and 0% to 33%, respectively. Dogs in all 4 locations demonstrated exposure to all 3 pathogens, though Rickettsia and Ehrlichia seropositivity was highest in Mexicali (81% and 49%, respectively) and Anaplasma seropositivity was highest in Tijuana (45%).

CLINICAL RELEVANCE

While infection and exposure were highest in sheltered dogs in the southern locations, dogs in all locations demonstrated exposure to all pathogens, demonstrating the potential for emergence and spread of zoonotic pathogens with significant public health consequences in southern California and northern Baja California. In addition, veterinarians and shelter staff should be aware that Ehrlichia or Anaplasma infection may co-occur with Rocky Mountain spotted fever, which is a human health risk.

Molecular detection and phylogeny of Ehrlichia canis and Anaplasma platys in naturally infected dogs in Central and Northeast Thailand

Background and Aim

Ehrlichia canis and Anaplasma platys are tick-borne, Gram-negative bacteria that cause canine monocytic ehrlichiosis and canine cyclic thrombocytopenia, respectively. These diseases are of great importance and are distributed globally. This study aimed to create new primers for the identification of E. canis and A. platys in naturally infected dogs using polymerase chain reaction (PCR), DNA sequencing, and phylogenetic analysis using the 16S rDNA and gltA genes.

Materials and Methods

In total, 120 blood samples were collected from dogs in three different locations (Saraburi, Buriram, and Nakhon Ratchasima provinces) in Central and Northeast Thailand. The molecular prevalence of E. canis and A. platys was assessed using PCR targeting the 16S rDNA and gltA genes. All positive PCR amplicons were sequenced, and phylogenetic trees were constructed based on the maximum likelihood method.

Results

Ehrlichia canis had an overall molecular prevalence of 15.8% based on the 16S rDNA gene, compared to 8.3% based on the gltA gene. In addition, the overall molecular prevalence of A. platys using the 16S rDNA gene was 10.8%, while the prevalence rate was 5.8% using the gltA gene. Coinfection was 0.8% in Saraburi province. The partial sequences of the 16S rDNA and gltA genes of E. canis and A. platys in dogs in Central and Northeast Thailand showed 96.75%-100% identity to reference sequences in GenBank. Phylogenetic analysis of the 16S rDNA and gltA genes revealed that E. canis and A. platys sequences were clearly grouped into their own clades.

Conclusion

This study demonstrated the molecular prevalence of E. canis and A. platys in Central and Northeast Thailand. The 16S rDNA and gltA genes were useful for the diagnosis of E. canis and A. platys. Based on the phylogenetic analysis, the partial sequences of the 16S rDNA and gltA genes in E. canis and A. platys were related to prior Thai strains and those from other countries.

A Vaccine for Canine Rocky Mountain Spotted Fever: An Unmet One Health Need

Outbreaks of life-threatening Rocky Mountain spotted fever in humans and dogs associated with a canine-tick maintenance cycle constitute an important One Health opportunity. The reality of the problem has been observed strikingly in Mexico, Brazil, Colombia, and Native American tribal lands in Arizona. The brown dog tick, Rhipicephalus sanguineus sensu lato, acquires the rickettsia from bacteremic dogs and can maintain the bacterium transtadially to the next tick stage. The subsequent adult tick can then transmit infection to a new host, as shown by guinea pig models. These brown dog ticks maintain spotted fever group rickettsiae transovarially through many generations, thus serving as both vector and reservoir. Vaccine containing whole-killed R. rickettsii does not stimulate sufficient immunity. Studies of Rickettsia subunit antigens have demonstrated that conformationally preserved outer-membrane autotransporter proteins A and B are the leading vaccine candidates. The possibility of a potentially safe and effective live attenuated vaccine has only begun to be explored as gene knockout methods are applied to these obligately intracellular pathogens.

Seropositivity of main vector-borne pathogens in dogs across Europe

BACKGROUND

Canine vector-borne disease (CVBD) has been an area of increasing interest in Europe over the last few decades, and there have been changes in the prevalence and distribution of many of these diseases. Monitoring CVBD infections in Europe is often done by individual countries, but aggregated data for the European countries are helpful to understand the distribution of CVBDs.

METHODS

We used an extensive retrospective database of results from point-of-care rapid enzyme-linked immunosorbent assay (ELISA) tests on dogs across Europe to identify distribution and seropositivity in animals tested for selected CVBDs (Anaplasma spp., Ehrlichia spp., Borrelia burgdorferi, Leishmania spp., and Dirofilaria immitis) from 2016 through 2020. Geographic distribution of positive tests and relative percent positive values were mapped by the Nomenclature of Territorial Units for Statistics classification for regions with sufficient test results for reporting.

RESULTS

A total of 404,617 samples corresponding to 1,134,648 canine results were available from dogs tested in 35 countries over the 5-year study period. Over this period the number of test results per year increased whereas test positivity decreased. Leishmania spp. had the largest increase in total test results from 25,000 results in 2016 to over 60,000 results in 2020. Test positivity for Leishmania spp. fell from 13.9% in 2016 to 9.4% in 2020. Test positivity fell for Anaplasma spp. (7.3 to 5.3%), Ehrlichia spp. (4.3 to 3.4%), and Borrelia burgdorferi (3.3 to 2.4%). Dirofilaria immitis test positivity trended down with a high of 2.7% in 2016 and low of 1.8% in 2018. Leishmania spp. test positivity was highest in endemic areas and in several non-endemic countries with low numbers of test results. Co-positivity rates were significantly higher than expected for all pathogen test positive pairs except for Ehrlichia spp. with Borrelia burgdorferi and D. immitis with Borrelia burgdorferi.

CONCLUSIONS

This study represents the largest data set on CVBD seropositivity in Europe to date. The increase in the number of test results and decreasing test positivity over the study period may reflect changes in testing behavior and increased screening of healthy animals. The Europe-wide mapping of CVBD provides expected test positivity that can help inform veterinarians' decisions on screening and improve prevention and identification of these important, sometimes zoonotic, diseases.

Illuminating the bacterial microbiome of Australian ticks with 16S and Rickettsia-specific next-generation sequencing

Next-generation sequencing (NGS) studies show that mosquito and tick microbiomes influence the transmission of pathogens, opening new avenues for vector-borne pathogen control. Recent microbiological studies of Australian ticks highlight fundamental knowledge gaps of tick-borne agents. This investigation explored the composition, diversity and prevalence of bacteria in Australian ticks (n = 655) from companion animals (dogs, cats and horses). Bacterial 16S NGS was used to identify most bacterial taxa and a Rickettsia-specific NGS assay was developed to identify Rickettsia species that were indistinguishable at the V1-2 regions of 16S. Sanger sequencing of near full-length 16S was used to confirm whether species detected by 16S NGS were novel. The haemotropic bacterial pathogens Anaplasma platys, Bartonella clarridgeiae, “Candidatus Mycoplasma haematoparvum” and Coxiella burnetii were identified in Rhipicephalus sanguineus (s.l.) from Queensland (QLD), Western Australia, the Northern Territory (NT), and South Australia, Ixodes holocyclus from QLD, Rh. sanguineus (s.l.) from the NT, and I. holocyclus from QLD, respectively. Analysis of the control data showed that cross-talk compromises the detection of rare species as filtering thresholds for less abundant sequences had to be applied to mitigate false positives. A comparison of the taxonomic assignments made with 16S sequence databases revealed inconsistencies. The Rickettsia-specific citrate synthase gene NGS assay enabled the identification of Rickettsia co-infections with potentially novel species and genotypes most similar (97.9–99.1%) to Rickettsia raoultii and Rickettsia gravesii. “Candidatus Rickettsia jingxinensis” was identified for the first time in Australia. Phylogenetic analysis of near full-length 16S sequences confirmed a novel Coxiellaceae genus and species, two novel Francisella species, and two novel Francisella genotypes. Cross-talk raises concerns for the MiSeq platform as a diagnostic tool for clinical samples. This study provides recommendations for adjustments to Illuminaʼs 16S metagenomic sequencing protocol that help track and reduce cross-talk from cross-contamination during library preparation. The inconsistencies in taxonomic assignment emphasise the need for curated and quality-checked sequence databases.

•

Bacterial pathogens identified in ticks from companion animals with 16S NGS.

•

Sanger sequencing confirmed novel Coxiellaceae gen. sp. and Francisella.

•

“Candidatus Rickettsia jingxinensis” was identified with Rickettsia-specific NGS.

•

Comparison of taxonomic assignments in 16S sequence databases revealed errors.

•

Modifications to the 16S metagenomic library protocol (Illumina) are provided.

Molecular Detection of Tick-Borne Agents in Cats from Southeastern and Northern Brazil

Even though the epidemiology of tick-borne agents (TBA) in dogs has been extensively investigated around the world, the occurrence, vectors involved, and molecular identity of these agents in cats remains elusive in many regions. Among TBA, Ehrlichia, Anaplasma, Babesia, Cytauxzoon, and Hepatozoon are responsible for diseases with non-specific clinical signs in cats, making essential the use of molecular techniques for accurate diagnosis and proper treatment. The present work aimed to investigate the occurrence and molecular identity of tick-borne agents (Ehrlichia, Anaplasma, Babesia/Theileria, Cytauxzoon, and Hepatozoon) in cats from southeastern (states of São Paulo (SP) and Minas Gerais (MG)) and northern (state of Rondônia (RO)) Brazil. For this purpose, 390 blood samples were collected from domiciled cats in MG (n = 155), SP (n = 151), and RO(n = 84) states, submitted to DNA extraction and PCR assays for Ehrlichia spp. (dsb gene), Anaplasma spp. (rrs gene), piroplasmids (18S rRNA gene), and Hepatozoon spp. (18S rRNA gene), sequencing, and phylogenetic inferences. The overall positivity for Anaplasma spp., Ehrlichia spp., Babesia/Theileria spp., Cytauxzoon spp., and Hepatozoon spp. were 7.4% (12.3% (MG) and 6.6% (SP)), 2% (4.5% (MG) and 0.6% (SP)), 0.7% (0.6% (MG), 0.6% (SP) and 1.2% (RO)), 27.2% (41.9% (MG), 24.5% (SP) and 4.8% (RO), and 0%, respectively. The phylogenetic analysis grouped the obtained sequences with 'Candidatus Anaplasma amazonensis', A. platys, B. vogeli, and Cytauxzoon sp. previously detected in wild felids from Brazil. qPCR specific for E. canis based on the dsb gene confirmed the molecular identity of the detected ehrlichial agent. The present study expanded the list and geographical distribution of hemoparasites in cats. 'Candidatus Anaplasma amazonensis', recently detected in sloths from northern Brazil, was described for the first time in cats. This is the first report of piroplasmids infecting cats in northern Brazil. Coinfection by Cytauxzoon and other TBA (Ehrlichia, Anaplasma, and B. vogeli) reported in the present study raises the need for veterinary practitioners' awareness of cats parasitized by multiple TBA.

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.

•

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

•

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

•

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.

The bacterial biome of ticks and their wildlife hosts at the urban-wildland interface

Advances in sequencing technologies have revealed the complex and diverse microbial communities present in ticks (Ixodida). As obligate blood-feeding arthropods, ticks are responsible for a number of infectious diseases that can affect humans, livestock, domestic animals and wildlife. While cases of human tick-borne diseases continue to increase in the northern hemisphere, there has been relatively little recognition of zoonotic tick-borne pathogens in Australia. Over the past 5 years, studies using high-throughput sequencing technologies have shown that Australian ticks harbour unique and diverse bacterial communities. In the present study, free-ranging wildlife (n=203), representing ten mammal species, were sampled from urban and peri-urban areas in New South Wales (NSW), Queensland (QLD) and Western Australia (WA). Bacterial metabarcoding targeting the 16S rRNA locus was used to characterize the microbiomes of three sample types collected from wildlife: blood, ticks and tissue samples. Further sequence information was obtained for selected taxa of interest. Six tick species were identified from wildlife: Amblyomma triguttatum, Ixodes antechini, Ixodes australiensis, Ixodes holocyclus, Ixodes tasmani and Ixodes trichosuri. Bacterial 16S rRNA metabarcoding was performed on 536 samples and 65 controls, generating over 100 million sequences. Alpha diversity was significantly different between the three sample types, with tissue samples displaying the highest alpha diversity (P<0.001). Proteobacteria was the most abundant taxon identified across all sample types (37.3 %). Beta diversity analysis and ordination revealed little overlap between the three sample types (P<0.001). Taxa of interest included Anaplasmataceae, Bartonella, Borrelia, Coxiellaceae, Francisella, Midichloria, Mycoplasma and Rickettsia. Anaplasmataceae bacteria were detected in 17.7% (95/536) of samples and included Anaplasma, Ehrlichia and Neoehrlichia species. In samples from NSW, 'Ca. Neoehrlichia australis', 'Ca. Neoehrlichia arcana', Neoehrlichia sp. and Ehrlichia sp. were identified. A putative novel Ehrlichia sp. was identified from WA and Anaplasma platys was identified from QLD. Nine rodent tissue samples were positive for a novel Borrelia sp. that formed a phylogenetically distinct clade separate from the Lyme Borrelia and relapsing fever groups. This novel clade included recently identified rodent-associated Borrelia genotypes, which were described from Spain and North America. Bartonella was identified in 12.9% (69/536) of samples. Over half of these positive samples were obtained from black rats (Rattus rattus), and the dominant bacterial species identified were Bartonella coopersplainsensis and Bartonella queenslandensis. The results from the present study show the value of using unbiased high-throughput sequencing applied to samples collected from wildlife. In addition to understanding the sylvatic cycle of known vector-associated pathogens, surveillance work is important to ensure preparedness for potential zoonotic spillover events.

Epidemiology, Diagnosis, and Control of Canine Infectious Cyclic Thrombocytopenia and Granulocytic Anaplasmosis: Emerging Diseases of Veterinary and Public Health Significance

This review highlights the diagnostic methods used, the control strategies adopted, and the global epidemiological status of canine cyclic thrombocytopenia and granulocytic anaplasmosis at the animal–human interface. Canine anaplasmosis is an important worldwide disease, mainly caused by Anaplasma platys and A. phagocytophilum with zoonotic implications. A. platys chiefly infects platelets in canids, while A. phagocytophilum is the most common zoonotic pathogen infecting neutrophils of various vertebrate hosts. Diagnosis is based on the identification of clinical signs, the recognition of intracellular inclusions observed by microscopic observation of stained blood smear, and/or methods detecting antibodies or nucleic acids, although DNA sequencing is usually required to confirm the pathogenic strain. Serological cross-reactivity is the main problem in serodiagnosis. Prevalence varies from area to area depending on tick exposure. Tetracyclines are significant drugs for human and animal anaplasmosis. No universal vaccine is yet available that protects against diverse geographic strains. The control of canine anaplasmosis therefore relies on the detection of vectors/reservoirs, control of tick vectors, and prevention of iatrogenic/mechanical transmission. The control strategies for human anaplasmosis include reducing high-risk tick contact activities (such as gardening and hiking), careful blood transfusion, by passing immunosuppression, recognizing, and control of reservoirs/vectors.

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.

Rhipicephalus sanguineus Complex in the Americas: Systematic, Genetic Diversity, and Geographic Insights

The Rhipicephalus sanguineus group encompasses at least 12 validated species of Palearctic and Afrotropical hard ticks, which are relevant in veterinary medicine and public health. The taxonomy of R. sanguineus s.s., has been particularly intensely debated, due to its wide geographic distribution, morphological variants, parasite-host associations, and its capacity and vectorial competence for the transmission of several pathogens. By sequencing mitochondrial markers, it was possible to identify the existence of multiple lineages, among which the Tropical and the Temperate lineages stand out, particularly in America. However, the northern limit between these lineages is not clear due to the lack of extensive sampling across Mexico. For this reason, the aim of the present study was to determine the genetic diversity and structure of the R. sanguineus group in Mexico and to compare it with the populations reported in the Americas, in order to propose the northern limit of the R. sanguineus Tropical lineage and the potential regions of sympatry with R. sanguineus s.s. The findings of this study now confirm the presence of R. sanguineus s.s. in Mexico, showing a subtle genetic structure and high genetic diversity throughout its distribution in the Americas. In contrast, the Tropical lineage seems to be genetically less diverse in its overall distribution in the Americas. The genetic diversity of these two independent lineages could have important epidemiological implications in the transmission of tick pathogens.

Protozoan and Microbial Pathogens of House Cats in the Province of Tekirdag in Western Turkey

Domestic felines’ re-emerging infectious and neglected zoonotic diseases are a significant focus of global “One Health” efforts. This study aimed to rapidly diagnose 14 pathogens, including zoonoses by using PCR primers in 167 client-owned symptomatic cats, routinely accepted to the Veterinary Clinics of Tekirdag. The prevalence of pathogens investigated were as follows: Babesia canis canis (24%), Babesia microti (2.4%), Hepatozoon felis (10.8%), Cytauxzoon felis (6.6%), Bartonella henselae (40.1%), Anaplasma platys (30.5%), Anaplasma phagocytophilum (7.2%), Rickettsia felis (26.3%), Borrelia burgdorferi (21%), and hemotropic Mycoplasma sp. (11.4%). There was a significant difference between the prevalence of the pathogens (χ² = 152.26, df = 9, p < 0.001). There was also a statistical difference between the gender of the cats in terms of the prevalence of all pathogens considered together (χ² = 4.80, df = 1, p = 0.028), where the female cats showed a higher prevalence. This was not the case for the different age groups (χ² = 2.92, df = 1, p = 0.088). The lowest infection was observed for B. microti (p < 0.001), while the highest infection was observed for B. henselae (p < 0.01). Leishmania donovani, Plasmodium spp., Ehrlichia chaffeensis, and Neoehrlichia mikurensis PCR test results were negative in all samples. In conclusion, house cats of Tekirdag are apparently highly susceptible to some neglected zoonoses important for “One Health”, and their prevalence in the region is most probably underestimated. Hence, applying PCR tests to assist fast clinic diagnosis in routine, may be an efficient option to protect the public as well as the cats from severe diseases.

Mapping the distribution and risk factors of Anaplasmataceae in wild and domestic canines in Chile and their association with Rhipicephalus sanguineus species complex lineages

Anaplasma platys and Ehrlichia canis are members of the Anaplasmataceae family that cause disease in dogs and are mainly transmitted by Rhipicephalus sanguineus species group ticks. We performed a cross-sectional study on these pathogens across six bioclimatic regions of Chile, including 719 free-ranging rural dogs, 132 Andean foxes (Lycalopex culpaeus), and 82 South American gray foxes (Lycalopex griseus). Dog and fox blood samples were first screened for DNA of Anaplasmataceae followed by two Ehrlichia-specific protocols. Antibodies against Anaplasma sp. and E. canis were assessed by immunofluorescence in dogs. Ectoparasites were collected and identified, with the determination of the lineages of the Rhipicephalus sanguineus species group by molecular and phylogenetic analyses. Finally, potential risk factors for infection were investigated across the different bioclimatic regions and host species. All DNA amplicons obtained from the screening protocol corresponded to Anaplasma platys. The occurrence of both A. platys DNA and antibodies was confirmed in all six bioclimatic regions, except for regions at high altitude and/or without either R. sanguineus species group lineage present. Dogs infested with R. sanguineus ticks were significantly more prone to be infected and exposed to Anaplasma spp. Prevalence of DNA was significantly higher in juvenile (19%) than in adult dogs (9%), whereas the opposite was found for seroprevalence (19% versus 35%, respectively). Overall prevalence of A. platys DNA was higher in dogs (11%) than in foxes (4%), probably owing to markedly lower tick infestations in the foxes. Ehrlichia canis DNA was not detected in any sample, and antibodies against this pathogen were detected only in four dogs, in areas with both R. sanguineus lineages present. Free-ranging dogs in Chile could be favoring the maintenance of A. platys in all areas suitable for its tick vector. Although apparently infrequent, spillovers from dogs to foxes may be taking place and should be considered in management plans in Chile.

Novel High-Throughput Multiplex qPCRs for the Detection of Canine Vector-Borne Pathogens in the Asia-Pacific

The Asia-Pacific hosts a large diversity of canine vector-borne pathogens (VBPs) with some of the most common and most pathogenic, generating significant mortality as well as a spectrum of health impacts on local dog populations. The VBPs Anaplasma platys, Babesia gibsoni, Babesia vogeli, Ehrlichia canis, Hepatozoon canis and haemotropic Mycoplasma spp. are all endemic throughout the region, with many exhibiting shifting geographical distributions that warrant urgent attention. Moreover, many of these species cause similar clinical signs when parasitising canine hosts, whilst knowledge of the exact pathogen is critical to ensure treatment is effective. This is complicated by frequent coinfection that can exacerbate pathology. Here, we describe the development, optimisation and validation of two novel quadruplex Taq-Man based real-time PCRs (qPCRs) for the specific and sensitive detection of the aforementioned VBPs. To ensure accurate evaluation of diagnostic performance, results of our qPCRs were evaluated on field samples from Thai dogs and compared with both conventional PCR (cPCR) results and next-generation sequencing (NGS) metabarcoding. Our qPCRs were found to be more sensitive at detecting canine VBP than cPCR and generated results similar to those achieved by NGS. These qPCRs will provide a valuable high-throughput diagnostic tool available to epidemiologists, researchers and clinicians for the diagnosis of key canine VBPs in the Asia-Pacific and further afield.

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.

Molecular detection and characterization of Anaplasma platys and Ehrlichia canis in dogs from the Caribbean

Anaplasma platys is a tick-transmitted rickettsial pathogen, which is known to be the etiologic agent for cyclic thrombocytopenia in its primary canine host. Infections with this pathogen are also reported in cats, cattle and people. Similarly, Ehrlichia canis is another tick-borne rickettsial pathogen responsible for canine monocytic ehrlichiosis and is also reported to cause infections in people. We describe infections in dogs with these two pathogens on the Caribbean island of Grenada, West Indies by detection using molecular methods. We utilized a 16S rRNA gene-based PCR assay to detect both Ehrlichia and Anaplasma species by screening 155 canine blood samples from asymptomatic dogs. We found 18.7 % of the dogs to be positive for A. platys and 16.8 % for E. canis. Samples that tested positive for A. platys were further assessed by sequence analysis targeting 16S rRNA, 23S rRNA, citrate synthase (gltA) and heat shock protein (groEL) genes. Phylogenetic analysis revealed high correlation of A. platys 16S rRNA and gltA gene sequences with the geographic origins, while 23S rRNA and groEL gene sequences clustered independent of the geographic origins. This study represents an important step in defining the widespread distribution of active rickettsial infections in Caribbean dogs with no apparent clinical signs, thus posing a high risk for canine health and to a lesser extent to humans, as most dogs in the Caribbean are free-roaming.

Tick-borne zoonoses and commonly used diagnostic methods in human and veterinary medicine

Around the world, human health and animal health are closely linked in terms of the One Health concept by ticks acting as vectors for zoonotic pathogens. Animals do not only maintain tick cycles but can either be clinically affected by the same tick-borne pathogens as humans and/or play a role as reservoirs or sentinel pathogen hosts. However, the relevance of different tick-borne diseases (TBDs) may vary in human vs. veterinary medicine, which is consequently reflected by the availability of human vs. veterinary diagnostic tests. Yet, as TBDs gain importance in both fields and rare zoonotic pathogens, such as Babesia spp., are increasingly identified as causes of human disease, a One Health approach regarding development of new diagnostic tools may lead to synergistic benefits. This review gives an overview on zoonotic protozoan, bacterial and viral tick-borne pathogens worldwide, discusses commonly used diagnostic techniques for TBDs, and compares commercial availability of diagnostic tests for humans vs. domestic animals, using Germany as an example, with the aim of highlighting existing gaps and opportunities for collaboration in a One Health framework.

Molecular screening for rickettsial bacteria and piroplasms in ixodid ticks surveyed from white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) in southern Texas

A survey of ixodid ticks parasitizing white-tailed deer (Odocoileus virginianus) and nilgai antelope (Boselaphus tragocamelus) was completed during the 2018–2019 public hunt season on the Laguna Atascosa National Wildlife Refuge (Cameron County, Texas) and the East Foundation's El Sauz Ranch in nearby Willacy County (Texas). Anocenter nitens was the predominant tick species identified with 5% of these ticks collected from nilgai. All life stages were encountered in high numbers on white-tailed deer, indicating that deer may be a primary host in this region. Amblyomma maculatum and Amblyomma inornatum were identified from both hosts, while Ixodes scapularis was encountered only on white-tailed deer. This is the first published record of A. inornatum on nilgai. A subset of ticks was used in PCR assays to detect Rickettsia spp., family Anaplasmataceae, Borrelia spp., and Theileria-Babesia spp. Borrelia spp. were not detected in any of the ticks analyzed. Rickettsia parkeri was detected in three A. maculatum adult ticks from deer, Rickettsia sp. endosymbiont sequences were present in all I. scapularis ticks, and Rickettsia amblyommatis was detected in three A. inornatum adult ticks from deer. Sequence analysis of Anaplasmataceae-positive amplicons from A. nitens and A. maculatum had low percent identity to published Anaplasma spp. sequences, suggesting a unique Anaplasma sp. may be circulating in the population. Anaplasma platys was detected from A. nitens larvae and an Ehrlichia sp. Delta strain was present in A. maculatum, both of unknown pathogenicity towards deer. Theileria cervi was detected in all stages of A. nitens ticks, and positive ticks originated from 27 of 31 deer and a single nilgai sampled from throughout the survey site. The primary vector for T. cervi is absent from this region, suggesting T. cervi is possibly maintained by a different tick species.

•

Anocenter nitens predominates on white-tailed deer and nilgai in southern Texas.

•

Theileria cervi was detected in Anocenter nitens ticks from deer and a single nilgai.

•

Three Theileria cervi genotypes were detected in this region of southern Texas.

•

Unique Anaplasma sp. detected in A. nitens; low identity to known Anaplasma sp.

•

Amblyomma inornatum ticks were identified on nilgai; a first record on this host.