First detection and molecular identification of Babesia gibsoni from Rhipicephalus sanguineus ticks

Analysis of Genetic Diversity of cytb gene from Babesia gibsoni Isolates from Naturally Infected Dogs in Karnataka, India

PURPOSE

The study aimed to investigate genetic diversity in Babesia gibsoni, the causative agent of canine babesiosis, and to assess the presence of atovaquone-resistant isolates in naturally infected dogs.

METHODS

A total of 24 blood samples confirmed for B. gibsoni infection was subjected to PCR amplification and sequencing based on cytb gene. Genetic characterization of B. gibsoni as well as attempts to detect the point mutation rendering atovaquone resistance was carried out based on the analysis of nucleotide sequence of cytb gene using bioinformatics software.

RESULTS

The findings indicated that the B. gibsoni isolates in the investigation exhibited a high nucleotide identity with the Asian genotype, ranging from 98.41 to 98.69%. Notably, none of the isolates carried cytb gene variants associated with atovaquone resistance. Phylogenetic analysis revealed clustering of most isolates with those from Japan and China, except for one isolate forming a distinct subclade. Haplotype network analysis indicated a high diversity with 22 distinct haplotypes among the B. gibsoni isolates, emphasizing the genetic variability within the studied population.

CONCLUSION

In conclusion, the cytb gene exhibited remarkable conservation among the twenty-four B. gibsoni isolates studied and the study represents the first genetic diversity assessment of B. gibsoni using the cytb gene in dogs from India. These findings shed light on the genetic characteristics of B. gibsoni in the region and provide valuable insight for addressing the challenges posed by this life-threatening disease in dogs.

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.

Correlation between Babesia Species Affecting Dogs in Taiwan and the Local Distribution of the Vector Ticks

The objective of our study was to survey Babesia infection rates by PCR and tick species on stray dogs to correlate the distribution of Babesia with the distribution of ticks infesting dogs in Taiwan. Three hundred eighty-eight blood samples and 3037 ticks were collected from 388 roaming, and free-ranging owned dogs at residential sites in Taiwan between January 2015 and December 2017. The prevalence of B. gibsoni and B. vogeli was 15.7% (61/388) and 9.5% (37/388), respectively. Most positive B. gibsoni dogs were found in the northern part of the country 56/61 (91.8%), whereas a few were found in the middle 5/61 (8.2%). Babesia vogeli infection rates were 10%, 3.6%, and 18.2% in the northern, central, and southern regions, respectively. Five species of ticks were found: Rhipicephalus sanguineus (throughout Taiwan), Rhipicephalus haemaphysaloides (in the north), Haemaphysalis hystricis (in the north and middle of Taiwan), and Amblyomma testidunarium and Ixodes ovatus (both in the north). None of the dogs in the south were infected with B gibsoni, which correlated with the absence of H. hystricis, a tick recently identified as the local vector for B gibsoni. Babesia vogeli was more equally distributed, coinciding with R. sanguineus, a tick that is present throughout Taiwan. Anaemia was detected in 86.9% of infected dogs; among these dogs, approximately 19.7% showed severe anaemia (HCT < 20). These findings provide useful advice for owners regarding outdoor activities with their dogs and local veterinarians with a regional differential diagnosis of babesiosis in Taiwan.

Evidence of Permethrin Resistance and Fipronil Tolerance in Rhipicephalus sanguineus s.l. (Acari: Ixodidae) Populations From Florida and California

Rhipicephalus sanguineus s.l. (Latreille), is a vector of multiple disease-causing pathogens to humans and dogs. Permethrin and fipronil are two acaricides used to manage R. sanguineus s.l. infestations. Homeowners have reported treatment failures in managing brown dog ticks using permethrin and fipronil based products. Previous studies demonstrated that high permethrin resistance in some R. sanguineus s.l. populations was due to metabolic detoxification and target site insensitivity. In this study, three R. sanguineus s.l. strains, one from a laboratory colony (NC) and two colonies originally collected from Florida (FL) and California (CA), were evaluated for resistance expression against permethrin and fipronil. Metabolic detoxification mechanisms were evaluated in the FL strain using three synergists, while a polymerase chain reaction assay was used to detect a resistance mutation in all strains. The NC strain was susceptible to both permethrin and fipronil, while both the FL and CA strains exhibited high resistance to permethrin and tolerance to fipronil. The synergist tests and PCR results indicated that the FL strain utilized both metabolic resistance and target site insensitivity against permethrin, while the CA strain was documented to have the target-site insensitivity resistant allele. This study confirmed permethrin resistance in both California and Florida populations and its persistence in Florida populations, although its susceptibility can potentially be increased by adding a synergist. Fipronil resistance was not detected suggesting this acaricide may provide suitable tick control.

Phylogenetic analysis of Babesia gibsoni isolates of south India using apical membrane antigen, 50 kDa surface antigen, and 70 kDa heat shock protein genes

The prevalence of canine babesiosis due to Babesia gibsoni has increased throughout the world including in southern India. The polymerase chain reaction (PCR) based molecular characterization of B. gibsoni in dogs of Kerala, south India, targeting three specific genes viz., apical membrane antigen (AMA1), 50 kDa surface antigen (P50), and heat shock protein (HSP70) was undertaken in this study. Out of 297 blood samples collected from clinically suspected animals, microscopy detected piroplasms of B. gibsoni in 60 (20.20 per cent), while the PCR targeting the BgP50 gene detected 85 (28.61 per cent). Polymerase chain reaction targeting the BgAMA1 and BgHSP70 detected a lesser number of samples (60 and 65 respectively) as positive. The phylogenetic analysis of BgHSP70 gene sequences did not reveal genetic heterogeneity among the B. gibsoni isolates of South India and from other countries, while the BgP50 gene differentiated the Indian isolates from Japanese isolates. When BgAMA1 was used for phylogenetic analysis, genetic variation was not observed among Indian and Taiwanese isolates, however, differentiated them from the Japanese isolates.

First detection and molecular identification of Rickettsia massiliae, a human pathogen, in Rhipicephalus sanguineus ticks collected from Southern Taiwan

The Rickettsia massiliae was firstly detected and identified in Rhipicephalus sanguineus ticks infested on dogs in Taiwan. A total of 1154 Rh. sanguineus ticks collected from 158 dogs of four districts of Tainan city were examined for Rickettsia infection by nested-PCR assay targeting the citrate synthase (gltA) and outer membrane protein B (ompB) genes of Rickettsia. The Rickettsia infection was detected with a general infection rate of 2.77%, and was detected in male, female and nymphal stage with an infection rate of 2.77%, 3.22% and 1.32%, respectively. Phylogenetic relationships were analyzed by comparing the gltA and ompB sequences obtained from 9 Taiwan strains and 16 other strains representing 13 genospecies of Rickettsia. Results revealed that all Taiwan strains were genetically affiliated to the same clades of R. massiliae (spotted fever group) and R. felis (transitional group), and can be discriminated from other genospecies of Rickettsia. This study provides the first evidence of R. massiliae, a pathogenic spotted fever Rickettsia, identified in Rh. sanguineus ticks and highlight the potential threat for the regional transmission of Rickettsia infection among humans in Taiwan.

Diversity and geographic distribution of rickettsial agents identified in brown dog ticks from across the United States

Rhipicephalus sanguineus sensu lato, or brown dog ticks, transmit a variety of pathogens of veterinary and public health importance globally. Pathogens vectored by brown dog ticks and identified in the United States include Babesia vogeli, Ehrlichia canis, and several spotted fever group Rickettsia spp. (SFGR). Due to the challenge of collecting canine blood samples nationwide to screen for exposure to these pathogens, we took an indirect approach and tested brown dog ticks for molecular evidence of infection. Brown dog ticks (616 adults and 65 nymphs) collected from dogs and cats across the nation were tested by separate PCR assays detecting Babesia spp., E. canis, and SFGR. While no Babesia sp. was found, we identified rickettsial agents in 3.5% (24/681; 95% CI 2.4-5.2%) of the ticks. Pathogens and related organisms detected in ticks included E. canis (n = 1), Rickettsia amblyommatis (n = 3), Rickettsia massiliae (n = 11), Rickettsia monacensis (n = 3), Rickettsia montanensis (n = 5), and an undefined Rickettsia species (n = 1). These data demonstrate a wider geographic distribution of R. massiliae than previously known, and to the authors' knowledge, reports R. monacensis in brown dog ticks for the first time. Due to the close association that brown dog ticks have with domestic dogs and humans, more research is needed to understand the full array of organisms, some of which are zoonotic, potentially transmitted by this widespread tick complex.

A novel promising diagnostic candidate selected by screening the transcriptome of Babesia gibsoni (Wuhan isolate) asexual stages in infected beagles

BACKGROUND

Babesia gibsoni is one of the causative agents of canine babesiosis worldwide. Some dogs infected with B. gibsoni show severe clinical signs with progressive anemia, hemoglobinuria and splenomegaly. However, most infected dogs present a state of chronic infection and thereby may be a persistent pathogen carrier, increasing the risk of pathogen spreading. To date, little is known about this pathogen, with genomic and transcriptomic data in particular generally unavailable. This lack of knowledge extensively limits the development of effective diagnostic strategies and vaccines.

METHODS

High-throughput RNA sequencing of total RNA of B. gibsoni asexual stages collected from infected beagles was performed. The unigenes were annotated in seven databases. The genes were sorted according to their fragments per kilobase per million (FPKM) value, which was used as an indicator for expression level. The gene with the highest FPKM value was cloned from the genome of B. gibsoni and further tested for immunogenicity, cellular localization and efficacy as a potential diagnostic candidate for detecting B. gibsoni in sera collected from beagles.

RESULTS

A total of 62,580,653 clean reads were screened from the 64,336,475 raw reads, and the corresponding 70,134 transcripts and 36,587 unigenes were obtained. The gene with the highest FPKM value was screened from the unigenes; its full length was 1276 bp, and it was named BgP30. The BgP30 gene comprised three exons and two introns, with a 786-bp open reading frame, and encoded 261 amino acids with a predicted molecular weight of 30 kDa. The cellular localization assay confirmed the existence of P30 protein in B. gibsoni parasites. Moreover, P30 was detected in the serum of experimentally B. gibsoni-infected beagles, from 15 days up to 422 days post-infection, suggesting its usefulness as a diagnostic candidate for both acute and chronic infections.

CONCLUSIONS

We sequenced the transcriptome of B. gibsoni asexual stages for the first time. The BgP30 gene was highly expressed in the transcriptome screening experiments, with further studies demonstrating that it could induce immune response in B. gibsoni-infected dogs. These results lead us to suggest that bgP30 may be a good diagnostic candidate marker to detect both acute and chronic B. gibsoni infections.

First detection and molecular identification of a pathogenic spotted fever group Rickettsia, R. massiliae, from Rhipicephalus haemaphysaloides ticks infesting dogs in southern Taiwan

Tick-borne Rickettsia pathogens become an emerging zoonotic infection worldwide. The prevalence and genetic identity of Rickettsia infection was determined firstly in Rhipicephalus haemaphysaloides ticks collected from dogs in southern Taiwan. A total of 141 Rh. haemaphysaloides ticks were examined for Rickettsia infection by nested-PCR assay targeting the citrate synthase (gltA) and outer membrane protein B (ompB) genes of Rickettsia. The Rickettsia infection was detected with a general infection rate of 2.84%, and was detected in male and female ticks with an infection rate of 3.13% and 2.60%, respectively. Genetic relationships were analyzed by comparing the gltA and ompB sequences obtained from 4 Taiwan strains and 15 other strains representing 13 genospecies of Rickettsia. Phylogenetic analyses reveal that all Taiwan strains were genetically affiliated with the R. massiliae (spotted fever group) and can be distinguished from other genospecies of Rickettsia. These results demonstrate the epidemiological significance of a human pathogenic Rickettsia species (R. massiliae) detected in Rh. haemaphysaloides ticks. Further study focused on the vector competence of this tick species may help to illustrate the potential threat for human infection in southern Taiwan.

The Etiology, Incidence, Pathogenesis, Diagnostics, and Treatment of Canine Babesiosis Caused by Babesia gibsoni Infection

Simple Summary

Babesia gibsoni is a parasite that causes the rupture of red blood cells in dogs. Although there is no natural, tick-borne transmission of this disease in Europe, it has become more common in European countries in recent years. Dogfighting breeds are predisposed to disease and they are a potential source of infection. Given the high popularity of these dog breeds in Europe and the participation of many dogs at sports competitions and shows, it is likely that the incidence of the disease in Europe may be higher than expected. The fact that the disease is mostly manifested as asymptomatic infection and that dogs of predisposed breeds are often imported from endemic areas, or they travel due to mating or competitions around the world, also contributes to this hypothesis.

Abstract

Babesia gibsoni is one of the small Babesia species and the infection this pathogen causes is usually asymptomatic, which complicates the capture of potential parasite carriers. In endemic areas, especially in Asia, B. gibsoni occurs quite often due to direct transmission by way of a tick vector. Due to the absence of vectors, its occurrence is described only sporadically in Europe; but, it is increasingly occurring in predisposed, so-called fighting breeds, especially the American pit bull terrier. This review describes the etiology, incidence, clinical signs, pathogenesis, diagnostics, and treatment of B. gibsoni infection, with an emphasis on the clinical and laboratory peculiarities of the disease. As the treated dogs do not eliminate the parasite from the body—only reducing parasitemia and improving clinical signs—the treatment of B. gibsoni infection is a challenge in many cases, and its study therefore deserves great attention.

Babesia gibsoni Infection in Dogs—A European Perspective

Simple Summary

Canine babesiosis is a tick-borne, protozoal, hemoparasitic disease caused by infection by parasites of the genus Babesia. Numerous species of Babesia exist worldwide. These protozoa are classified as either large forms (e.g., Babesia canis) or small forms (e.g., Babesia gibsoni). Reports of infections with small protozoan species are far less numerous. In most European countries where B. gibsoni has been reported, the percentage of infected dogs is around 1%. The literature review suggests that B. gibsoni should not only be considered a random and imported pathogen, but also a possible emerging parasite in Europe. The disease is much more severe than B. canis infections in most cases. Accurate molecular detection and species identification are important for selecting the correct therapy and predicting the course of the disease in dogs with babesiosis. In the future, it is expected that B. gibsoni infections may appear in other non-endemic regions in Europe, which may pose significant diagnostic and therapeutic challenges for veterinary practitioners.

Abstract

Canine babesiosis is a disease caused by infection with parasites of the genus Babesia. These protozoa are classified as either large (e.g., Babesia canis) or small (e.g., Babesia gibsoni). So far, only three small Babesia species of clinical importance, able to infect dogs, have been described: B. gibsoni, B. conradae, and B. vulpes. This review presents the current epidemiological situation of Babesia gibsoni infections in dogs in Europe. In most European countries where B. gibsoni has been reported, the percentage of infected dogs is around 1%. The higher prevalence of the B. gibsoni infection among American Pit Bull Terriers suggests breed susceptibility. An analysis of the available data makes it possible to conclude that B. gibsoni infections may appear in the future in other non-endemic regions of Europe, which may pose significant diagnostic and therapeutic challenges for veterinary practitioners.

First detection and genetic identification of Rickettsia infection in Rhipicephalus sanguineus (Acari: Ixodidae) ticks collected from Southern Taiwan

The prevalence and genetic identity of Rickettsia infection in Rhipicephalus sanguineus sensu lato (s.l.) ticks were determined in Taiwan. In total 1153 ticks were examined for Rickettsia infection by PCR assay targeting the citrate synthase gene (gltA) of Rickettsia. The prevalence of Rickettsia infection in R. sanguineus s.l. ticks with a general infection rate of 2.2%, and was detected in nymph, male and female stages of R. sanguineus s.l. ticks with an infection rate of 3.1, 2.0 and 1.1%, respectively. Phylogenetic relationships were analyzed by comparing the gltA sequences obtained from four Taiwan strains and 16 other strains representing 13 genospecies of Rickettsia. Phylogenetic analyses reveal that one Taiwan strain was genetically affiliated with the Japan isolate (GRA-1 strain) which belongs to the spotted fever group (R. parkeri/R. honei) and three Taiwan strains were genetically affiliated with the transitional group of Rickettsia (R. felis). Intra- and inter-species analysis also indicated the genetic distance (GD) of the Taiwan strains with a lower level of GD < 0.011, 0.023 and 0.003 as compared with the type strains of R. parkeri, R. honei and R. felis, respectively. Our findings reveal the first detection of Rickettsia infections (R. parkeri/R. honei and R. felis) in R. sanguineus s.l. ticks of Taiwan. These results also highlight the epidemiological significance of diverse Rickettsia species existed in R. sanguineus s.l. ticks and the potential threat for the geographical transmission of Rickettsia infection in Taiwan.

Babesia gibsoni infection in Italy: a cross sectional study of 607 blood samples belonging to dogs that needed a molecular analysis investigation (2016-2019)

Babesia gibsoni (B. gibsoni) infection was sporadically described in Europe. In Italy, in particular, it was detected by PCR analysis only in one dog with unclear source of infection, while it has never been found in molecular studies involving more subjects. The aim of this retrospective, cross-sectional study was to determine the presence and the proportion of B. gibsoni infected dogs in a convenient Italian canine population. Babesia spp PCR analysis reports of canine blood samples collected from January 2016 to December 2019 were selected from the San Marco veterinary laboratory database and evaluated. Piroplasms PCR analysis was performed on 18S rRNA gene and positive samples were sequenced. Available data about signalment, living area and season of diagnosis were evaluated and statistically analyzed. The studied canine population had a median age of 62 months (interquartile range, IQR: 72.5) and was composed of male/female purebred and mixed breed dogs. Through sequencing, B. canis (26/40, 65%), B. vogeli (7/40, 17.5%), B. gibsoni (6/40, 15%) and B. vulpes (1/40, 2.5%) infections were reported. The proportion of B. gibsoni infected dogs in the described population was of 0.99%. The infection resulted more likely in male (6/6, 100%), purebred (5/6, 83.3%) dogs with median age of 40.5 months (IQR:32.3). In one case, the clinical signs and parasitemia appeared after a dogfight with a cohabitant infected dog. No other plausible sources of infection were detected. Likely, this could be considered the first autochthonous B. gibsoni infection case documented in Italy. Our results underline the need of considering B. gibsoni not only an exotic, random and rare cause of disease for dogs in Italy, but a possible emerging pathogen to take into account during diagnostic and epidemiological investigations, in symptomatic as well as in asymptomatic patients.

Molecular investigation of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern region of the Republic of Korea

In this study, we investigated the presence of tick-borne pathogens in ticks removed from tick-bitten humans in the southwestern provinces of the Republic of Korea (ROK). We identified 33 ticks from three tick species, namely Amblyomma testudinarium (60.6%), Haemaphysalis longicornis (27.3%), and Ixodes nipponensis (12.1%) in order of occurrence via morphology and 16S rDNA-targeting polymerase chain reaction (PCR). Tick-borne pathogens were detected in 16 ticks using pathogen-specific PCR. From the results, 12 ticks (36.4%) tested positive for spotted fever group (SFG) Rickettsia: Rickettsia monacensis (1/12), R. tamurae (8/12), and Candidatus Rickettsia jingxinensis (3/12). Three ticks (9.1%) were positive for Anaplasma phagocytophilum. In addition, three ticks (9.1%) tested positive for Babesia gibsoni (1/3) and B. microti (2/3). In conclusion, we identified three tick species; the most common species was A. testudinarium, followed by H. longicornis and I. nipponensis. SFG Rickettsia, A. phagocytophilum, and Babesia spp. were the most frequently detected pathogens in ticks removed from tick-bitten humans. To our knowledge, this is the first report of R. tamurae and Ca. R. jingxinensis detection in Korea. The present results will contribute to the understanding of tick-borne infections in animals and humans in the ROK.

Prevalence and Factors Associated with Ectoparasite Infestations in Dogs from the State of Tabasco, Mexico

This study was carried out to identify the ectoparasites that infest owned dogs in the state of Tabasco, Mexico. In total, 1,302 dogs were sampled in the 5 ecological regions of Tabasco. The dog owners were surveyed to identify the factors associated with infestations. Ectoparasites were identified using taxonomic keys. Eleven species of ectoparasites were observed. General prevalence was 26.65%. Rhipicephalus sanguineus and Ctenocephalides felis were the most prevalent and abundant ectoparasites. The most important factors associated with ectoparasite infestations in the studied dogs were living outdoors, being a non-purebred, having short hair, being dark-haired, and having a body condition <3. Ectoparasite studies such as the one presented herein generate important information to create control programs focused on decreasing infestations in companion animals and thus the likelihood of zoonotic transmission of pathogens.

Challenges in Tick-Borne Pathogen Detection: The Case for Babesia spp. Identification in the Tick Vector

The causative agents of Babesiosis are intraerythrocytic protozoa of the genus Babesia. Babesia parasites are present around the world, affecting several mammals including humans, pets and livestock, hence its medical and veterinary relevance. Babesia spp. detection in its invertebrate host is a main point in understanding the biology of the parasite to acquire more knowledge on the host–Babesia–vector interactions, as increasing knowledge of the Babesia lifecycle and babesiosis epidemiology can help prevent babesiosis outbreaks in susceptible mammals. The aim of the present review is to highlight the newest findings in this field, based on a bibliographic compilation of research studies recently carried out for the detection of the main Babesia species found in tick vectors affecting mammalian hosts, including the different tick stages such as adult ticks, larvae, nymphs and eggs, as well as the detection method implemented: microscopic tools for parasite identification and molecular tools for parasite DNA detection by conventional PCR, nested-PCR, PCR-RFLP, PCR-RLB hybridization, real time-PCR, LAMP and RAP assays. Although molecular identification of Babesia parasites has been achieved in several tick species and tissue samples, it is still necessary to carry out transmission experiments through biological models to confirm the vectorial capacity of various tick species.

Molecular detection and genetic identification of Wolbachia endosymbiont in Rhipicephalus sanguineus (Acari: Ixodidae) ticks of Taiwan

The genetic identity of Wolbachia endosymbiont in Rhipicephalus sanguineus ticks was determined for the first time in Taiwan. In total 1004 Rh. sanguineus ticks were examined for Wolbachia by polymerase chain reaction assay targeting the Wolbachia surface protein (wsp) gene. The prevalence of Wolbachia infection was detected in nymphs, females, and males with an infection rate of 55.8, 39.8, and 44%, respectively. The phylogenetic relationships were analyzed by comparing the sequences of wsp gene obtained from 60 strains of Wolbachia representing 11 strains of supergroup A and 10 strains of supergroup B. In general, seven major clades of supergroup A and six major clades of supergroup B can be easily distinguished by neighbour-joining analysis and were congruent by maximum likelihood method. All these Wolbachia strains of Taiwan were genetically affiliated to supergroups A and B with high sequence similarity of 98.3-100% and 98.6-100%, respectively. Intra- and inter-group analysis based on the genetic distance (GD) values indicated a lower level (GD < 0.017) within the group A strains of Taiwan compared with the group B (GD > 0.576) of other Wolbachia strains, as well as a lower level (GD < 0.062) within the group B strains of Taiwan compared with the group A (GD > 0.246) of other Wolbachia strains. Our results provide the first genetic identification of Wolbachia endosymbiont in Rh. sanguineus ticks collected from Taiwan, and detection of Wolbachia in male and nymphal ticks may imply the possible mechanism of transstadial transmission in Rh. sanguineus ticks.

Ticks and Associated Pathogens From Rescued Wild Animals in Rainforest Fragments of Northeastern Brazil

The Ixodidae family comprises ticks that are hematophagous ectoparasites and are considered vectors of several hemoparasites from the Anaplasmataceae family and the genus Hepatozoon, Babesia, and Rickettsia. These ectoparasites parasitize domestic and wild animals belonging to several vertebrate groups. Ticks are highly adapted to different biomes and thus possess a wide geographical distribution. In the Brazilian state of Bahia, localized in the Northeast region, there are large rainforest fragments. Studies have rarely been carried out on ticks, and their hemoparasites, that parasitize wild animals in this region. Thus, this study aimed to identify the tick species parasitizing wild animals rescued in rainforest fragments of Bahia and investigate the presence of hemoparasites in tick tissues. During a 2-year period, 238 ticks were collected from 41 wild mammalians, reptiles, and amphibians. These ectoparasites were taxonomically classified according to their morphological characteristics. The ticks identified belonged to five different species from the Ixodidae family: Amblyomma varium, Amblyomma rotundatum, Amblyomma nodosum, Ixodes loricatus, and Rhipicephalus sanguineus. For the first time, an A. rotundatum parasitizing the Mesoclemmys tuberculata turtle was described. PCR assays using DNA extracted from salivary glands or midgut of the ticks were performed to detect specific DNA fragments of hemoparasites from the genus Rickettsia, Ehrlichia, Babesia, Hepatozoon, and from the Anaplasmataceae family. The results showed positive detection of the Rickettsia genus (7.9%), Anaplasmataceae family (15.8%), and Hepatozoon genus (15.8%). Specific DNA from the Ehrlichia and Babesia genera were not detected in these samples. Specific DNA from members of the Anaplasmataceae family was detected in A. varium for the first time. The present work showed that amphibians, reptiles, and mammals from Bahia's Atlantic Forest areparasitized by different tick species, and that these ectoparasites present pathogens in their tissues that impact both humans and animals due to their zoonotic potential.

First detection and genetic identification of Hepatozoon canis in Rhipicephalus sanguineus sensu lato ticks collected from dogs of Taiwan

We determined the prevalence of infection and genetic identity of Hepatozoon spp. harbored by Rhipicephalus sanguineus sensu lato ticks in Taiwan. A total of 1082 ticks were collected from dogs and DNA extraction was performed from individual tick specimens. Hepatozoon infection was detected by performing a nested-PCR assay based on the 18S small subunit ribosomal RNA (ssrRNA) gene. The genetic identity of detected Hepatozoon was identified by gene sequencing and phylogenetic analysis. Hepatozoon infection was detected in nymphs, males and females of R. sanguineus s. l. ticks with an infection rate of 20.8%, 22.8% and 29.4%, respectively. Sequence and phylogenetic analysis revealed that these Hepatozoon spp. of Taiwan were genetically affiliated to the same clade within the genospecies of H. canis and can be discriminated from other genospecies of H. americanum and H. felis. Intraspecies analysis based on the genetic distance (GD) values indicates a lower level (GD < 0.005) genetic divergence within the same genospecies of H. canis detected in Taiwan, Brazil and Spain. Interspecies analysis also reveals a higher heterogeneity of Taiwan strains distinguished from other genospecies of H. felis (GD > 0.040) and H. americanum (GD > 0.056). This study provides the first molecular evidence of H. canis detected and identified in various stages of R. sanguineus s. l. ticks in Taiwan. Detection of H. canis in unfed male ticks may imply the possible mechanism of transstadial survival in R. sanguineus s. l. ticks. Further investigations on Hepatozoon spp. harbored by various vector ticks in Taiwan may illustrate the epidemiological significance of this parasite.

ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats

Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors.

First zootiological survey of hard ticks (Acari: Ixodidae) infesting dogs in northern Taiwan

Hard ticks infesting canine hosts were determined for the first time in northern Taiwan. Between May 2010 and April 2011, a total of 9467 ticks were collected from 2025 dogs. They were identified based on pictorial keys of their morphological characteristics. These ticks belong to three genus and six species: Rhipicephalus sanguineus, R. haemaphysaloides, Haemaphysalis hystricis, H. lagrangei, H. formosensis and Ixodes ovatus. Rhipicephalus sanguineus was the most dominant species (92.5%), followed by H. hystricis (4.6%), R. haemaphysaloides (2.3%), I. ovatus (0.54%), H. lagrangei (0.04%) and H. formosensis (0.01%). The overall density was 4.7 ticks per dog (ranging from 1.8 to 20.8) and the highest seasonal prevalence was observed in September with an average density of 8.2 ticks per dog. Our results not only provide the first survey of hard ticks infesting dogs in northern Taiwan, but also highlight the possible impact of these tick species on human health.

Molecular Evidence for a Novel Species of Babesia in Unfed Rhipicephalus sanguineus sensu lato (Acari: Ixodidae)

This study reports a novel species of Babesia in unfed Rhipicephalus sanguineus sensu lato and its phylogenetic relationship to other species. One-hundred and forty DNA samples extracted from tick pools comprising 5,403 unfed R. sanguineus s.l. ticks were screened for Babesia. Overall Babesia infection was detected in female, male, and nymph pools with an infection rate maximum likelihood estimate (MLE) of 1.98 (CI 0.65-4.74), 0.50 (CI 0.03-2.40), and 0.07 (CI 0.01-0.21), respectively. Three adult female tick pools (MLE 1.44, CI 0.38-3.88) and one adult male pool (MLE 0.50, CI 0.03-2.40) hybridized to the catchall and Babesia genus probes but did not hybridize to any species-specific probe tested, suggesting the presence of an unidentified Babesia species. Phylogenetic analysis and sequencing revealed the newly detected Babesia isolate to form a clade distinct from fully identified canine, bovine, equine, and ovine Babesia species, with a range of 88.6-92.9% nucleotide identity.

Detection of Babesia spp. in Dogs and Their Ticks From Peninsular Malaysia: Emphasis on Babesia gibsoni and Babesia vogeli Infections in Rhipicephalus sanguineus sensu lato (Acari: Ixodidae)

Canine babesiosis is an emerging tick-borne disease with a worldwide distribution, including Malaysia. While the prevalence of Babesia has been documented from dogs in Malaysia, occurrence of Babesia has been relatively little studied in their tick vectors. Accordingly, a total of 240 dogs and 140 Rhipicephalus sanguineus sensu lato (s.l.) (Acari: Ixodidae) ticks from Malaysia were molecularly screened for the presence of Babesia protozoa in the present study. Babesia gibsoni was only detected in ticks (1.4%), whereas Babesia vogeli was detected in both ticks (1.4%) and dogs (2.1%). This study highlights the detection of B. gibsoni and B. vogeli for the first time, in both adult and nymphal stages of R. sanguineus s.l. in Malaysia, suggesting the potential role of this tick species in transmitting canine babesiosis.

Molecular evidence for the transovarial passage of Babesia gibsoni in Haemaphysalis hystricis (Acari: Ixodidae) ticks from Taiwan: a novel vector for canine babesiosis

BACKGROUND

Babesia gibsoni is the predominant tick-borne protozoan blood parasite affecting dogs throughout the Oriental region. Babesia gibsoni is transmitted by Haemaphysalis longicornis, whereas a similar role has been suggested for Rhipicephalus sanguineus. Haemaphysalis longicornis does not occur in Taiwan, but R. sanguineus is widely distributed on dogs. However, clinical cases of babesiosis are mainly restricted to the northern part of the island. The discrepancy between tick distribution and clinical cases stimulated us to investigate the tick species distribution on dogs in northern Taiwan, with the aim to identify the local vector for canine babesiosis.

METHODS

Ticks were collected from stray dogs or free ranging pet dogs in northern Taiwan between 2015 and 2017 and, after identification, were tested for the presence of tick-borne Babesia parasites using PCR and reverse line blot (RLB) hybridisation. Moreover, engorged ticks collected from the dogs were incubated at 28 °C to allow them to oviposit. Their subsequent larval progeny was also examined by PCR/RLB.

RESULTS

A total of 1085 ticks collected from 144 stray dogs at different residential areas consisted of 5 different species: H. hystricis (n = 435), R. sanguineus (n = 582), R. haemaphysaloides (n = 43), Amblyomma testudinarium (n = 14) and Ixodes ovatus (n = 11) were identified. Babesia gibsoni DNA was detected in H. hystricis females (10.3%), males (7.0%) and in 2.6% of the nymphs. One R. sanguineus female and one A. testudinarium female tick also carried B. gibsoni DNA. DNA of B. gibsoni was demonstrated in 11 out of 68 (16.2%) batches of larval ticks derived from engorged H. hystricus ticks only. Babesia vogeli DNA was detected only in R. sanguineus females (2.6%) and males (2.4%). DNA of B. vogeli was detected in 13 out of 95 (13.7%) batches of larval ticks derived from engorged R.sanguineus females.

CONCLUSIONS

Babesia gibsoni DNA was detected in the larval progeny of H. hystricis ticks only, whereas B. vogeli was restricted to the larvae of R. sanguineus. This provides evidence for transovarial passage of B. gibsoni in H. hystricis and evidence that this tick does act as the local vector for this parasite on dogs in northern Taiwan where most cases of babesiosis are reported. The vectorial capacity of R. sanguineus for babesiosis is probably restricted to the transmission of B. vogeli only.

Deciphering Babesia-Vector Interactions

Understanding host-pathogen-tick interactions remains a vitally important issue that might be better understood by basic research focused on each of the dyad interplays. Pathogens gain access to either the vector or host during tick feeding when ticks are confronted with strong hemostatic, inflammatory and immune responses. A prominent example of this is the Babesia spp.—tick—vertebrate host relationship. Babesia spp. are intraerythrocytic apicomplexan organisms spread worldwide, with a complex life cycle. The presence of transovarial transmission in almost all the Babesia species is the main difference between their life cycle and that of other piroplasmida. With more than 100 species described so far, Babesia are the second most commonly found blood parasite of mammals after trypanosomes. The prevalence of Babesia spp. infection is increasing worldwide and is currently classified as an emerging zoonosis. Babesia microti and Babesia divergens are the most frequent etiological agents associated with human babesiosis in North America and Europe, respectively. Although the Babesia-tick system has been extensively researched, the currently available prophylactic and control methods are not efficient, and chemotherapeutic treatment is limited. Studying the molecular changes induced by the presence of Babesia in the vector will not only elucidate the strategies used by the protozoa to overcome mechanical and immune barriers, but will also contribute toward the discovery of important tick molecules that have a role in vector capacity. This review provides an overview of the identified molecules involved in Babesia-tick interactions, with an emphasis on the fundamentally important ones for pathogen acquisition and transmission.

Molecular and morphological identification of a human biting tick, Amblyomma testudinarium (Acari: Ixodidae), in Taiwan

Genetic identity and morphological features of a human biting tick, Amblyomma testudinarium, were determined for the first time in Taiwan. Morphological features of adult male and female ticks of Am. testudinarium were observed and photographed by a stereo- microscope. The genetic identity was analyzed by comparing the sequences of mitochondrial 16S ribosomal DNA gene obtained from 18 strains of ticks representing 10 species of Amblyomma, and four outgroup species of Dermacentor and Rhipicephalus ticks. Nine major clades could be easily distinguished by neighbour-joining analysis and were congruent by maximum-parsimony method. All these Am. testudinarium ticks collected from Taiwan and Japan were genetically affiliated to a monophyletic group with highly homogeneous sequence (99.8-100% similarity), and can be discriminated from other species of Amblyomma and other genera of ticks (Dermacentor and Rhipicephalus) with a sequence divergence ranging from 6.9 to 23.9%. Moreover, intra- and inter-species analysis based on the genetic distance (GD) values indicated a lower level (GD < 0.003) within the same lineage of Am. testudinarium ticks collected from Taiwan and Japan, as compared with other lineage groups (GD > 0.108) of Amblyomma ticks, as well as outgroup (GD > 0.172) species. Our results provide the first distinguished features of adult Am. testudinarium ticks and the first genetic identification of Am. testudinarium ticks collected from humans in Taiwan. Seasonal prevalence, host range, and vectorial capacity of this tick species in Taiwan need to be further clarified.