Molecular detection and genetic diversity of Babesia gibsoni in dogs in India

Exploring tick-borne pathogens in community dogs in Nepal

Tick-borne pathogens (TBPs) in dogs are a major global health concern, with their zoonotic importance often being neglected in developing countries due to a lack of surveillance. This study aimed to highlight the incidence of six important TBPs belonging to the genera Babesia, Theileria, Hepatozoon, Anaplasma, Ehrlichia, and Rickettsia in a total of 230 community dogs from two sites: Lumbini and the Kathmandu Valley, of Nepal. A total of 75 (32.6 %) dogs were found to be infected with at least one TBP, with 11 (4.7 %) being co-infected with more than one TBP. The detection rates of TBPs were 13.9 % (n = 32) for Ehrlichia canis, 9.1 % (n = 21) for Anaplasma platys, 8.6 % (n = 20) for Babesia vogeli, and 6.5 % (n = 15) for Babesia gibsoni. None of the samples were positive for Theileria, Hepatozoon, or Rickettsia. There was a significant association between A. platys and E. canis infections, respectively, with the locations from which the samples were collected. Infections of TBPs in community dogs might be the source of infection for pet dogs or even humans in shared habitats. Further studies are needed to determine the prevalence and diversity of TBPs in dogs in other regions of Nepal. As some of these parasites are zoonotic, concerted efforts are required to raise awareness of, and control efforts for, these tick-borne pathogens.

Babesia infection in cattle and dogs in Suizhou City, Hubei Province, China

Background

Babesiosis is a zoonotic disease caused by the intraerythrocytic parasite Babesia, which poses a serious threat to public health. Currently, the prevalence of babesiosis in domestic animals and the genetic diversity of Babesia in Central China have not been comprehensively studied.

Methods

In this study, we collected 1093 ticks, including 95.24% (1041/1093) Haemaphysalis longicornis, 4.67% (51/1093) Rhipicephalus microplus, and 0.09% (1/1093) Ixodes sinensis. Blood samples from 216 goats, 56 cattle, and 25 dogs were collected from Suizhou City, Hubei Province, China, and animal blood DNA was extracted for the detection of Babesia with PCR.

Results

PCR results showed that 50.00% (28/56) of cattle and 32.00% (8/25) of dogs were Babesia-positive, including for Babesia bovis 3.57% (2/56), B. bigemina 3.57% (2/56), and B. ovata 42.86% (24/56) in cattle and B. gibsoni 32.00% (8/25) in dogs. All goats (216) and ticks (1093) were Babesia-negative.

Conclusions

Our findings showed that Babesia infections are prevalent in cattle and dogs in Central China, indicating that babesiosis should be monitored in animals and humans in Central China.

Haemoprotozoan and haemorickettsial carrier status in pet and community owned dogs of south India

The increasing population of dogs and changes in the climatic conditions have resulted in the emergence and re-emergence of vector-borne diseases in canines. These vectors borne diseases in canines pose a diagnostic challenge to the field veterinarians because of co-infections with several pathogens. Comprehensive data on the prevalence of haemoparasites and haemorickettsiales in pet and community owned dogs from south India are scant. Hence, the present study aims to find and compare the prevalence of these infections in the pet and the community owned dogs of Kerala, a south Indian state. Two hundred and seventy-two pets and 150 community owned dogs were examined by microscopy and polymerase chain reaction (PCR) for infections with different heamoparasites and haemorickettsials from January 2018-November 2020 in the state of Kerala. A high prevalence of Babesia gibsoni infection (42.2-60.0 %) in pet and community owned dogs, followed by Babesia vogeli (5.8-39.3 %), Hepatozoon canis (0.7-28.0 %), Trypanosoma evansi (0.0-27.3 %), Ehrlichia canis (0.3-0.6 %) and Anaplasma platys (0.0-0.6 %) was observed in the present study. Eighty-eight per cent (132/150) of the community owned dogs and 49.2 % (134/272) of the pet dogs were positive for at least one pathogen. Phylogenetic analysis based on the partial nucleotide sequences of 18S rRNA and TRAP gene of B. gibsoni, 18S rRNA genes of B. vogeli and H. canis and RoTat, 1.2 virB9 and 16S rRNA genes of T. evansi, E. canis and A. platys, respectively was carried out. B. vogeli, H. canis, E. canis and A. platys revealed genetic relatedness between the Indian isolates and the isolates from other countries. However, B. gibsoni isolates from the Indian sub-continent were genetically unique compared to other Asian isolates. The clustering of T. evansi isolates from India in two clades viz., livestock origin (cattle, buffalo) and others indicated their genetic variability. The present study summarizes the prevalence of some of the haemoparasites and haemorickettsials in the dog populations of Kerala (south India) and also determined their genetic relationship with the isolates prevalent in dogs in other countries.

Genetic diversity and molecular evolution of the internal transcribed spacer regions (ITS1-5.8S-ITS2) of Babesia vogeli

Canine babesiosis, a severe haemoparasitic disease caused by Babesia species, has a significant global presence and can be fatal if left untreated. The current study was aimed to perform the population genetic characterization of B. vogeli on the basis of the internal transcribed spacer regions (ITS1-5.8S-ITS2). A maximum likelihood tree constructed with the Hasegawa-Kishino-Yano model grouped all sequences into a single major clade (BvG1), with the exception of a Taiwanese isolate (EF186914), which branched separately. This Taiwanese isolate represented a novel genotype (BvG2) identified in the present study. Nucleotide sequences (n = 62) exhibited 92.5-100 % nucleotide identity among themselves. However, the BvG1 and BvG2 genotypes shared a lower identity of 92.5-93.8 % between them. Notably, the newly generated Indian sequences (n = 21) demonstrated a high degree of homology, with 98.3-100 % identity. Alignment of the nucleotide sequences revealed 58 variations across the dataset. Additionally, 32 sites exhibited variation within the BvG1 genotype, while 56 sites differed between BvG1 and BvG2 genotypes. Within different B. vogeli populations, the nucleotide diversity (π) was low, but the haplotype diversity (Hd) was high. The haplotype diversity of the Indian population, BvG1 genotype, and the combined dataset was ∼0.8 suggesting a high haplotype diversity. The median-joining haplotype network displayed a total of 21 haplotypes, out of which six haplotypes consisted of more than one sequence (2-25 sequences). Haplotype distribution showed significant geographical structuring, with most haplotypes confined to a single country. Only two haplotypes (9.52 %; Hap_1 and Hap_4) were shared between countries, whereas 19 haplotypes (90.48 %) were country-specific. Hap_1, Hap_6, and Hap_4 were the most representative haplotypes, comprising 25, 10, and four sequences, respectively. India exhibited the highest number of haplotypes (h = 13) followed by China (h = 4), the United States of America (h = 3), Taiwan and Tunisia (h = 2), and Thailand (h = 1). Both location-wise and genotype-wise median joining haplotype networks clustered the haplotypes in two groups, representing two distinct genotypes (BvG1 and BvG2). The B. vogeli populations between Thailand and Tunisia exhibited the highest genetic differentiation (FST = 0.80) with a low gene flow (Nm = 0.125) between them. Results of AMOVA revealed a higher genetic variation within populations (69.43 %) as compared to the variation between them (30.57 %). Neutrality indices and the mismatch distributions of the Indian population and the overall dataset of B. vogeli indicated a constant population size to population expansion and population expansion, respectively, with the presence of two distinct genotypes. These data provide information about parasite population genetics and highlight the importance of starting a long-term molecular surveillance program. In conclusion, a high genetic diversity along with the presence of two distinct genotypes of B. vogeli were observed on the basis of internal transcribed spacer regions (ITS1-5.8S-ITS2).

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.

Evaluation of recombinant Babesia gibsoni thrombospondin-related adhesive protein (BgTRAP) for the sero-diagnosis of canine babesiosis

Canine babesiosis, caused by Babesia gibsoni is one of the most significant tick-borne illnesses across the world. Light microscopy as well as polymerase chain reaction may fail in the diagnosis of disease when the level of parasitaemia is very low during subclinical and chronic cases. The serological techniques using a recombinant protein will be useful for the accurate and sensitive surveillance of the disease, especially in chronic cases. The present study describes the evaluation of recombinant N-terminal B. gibsoni Thrombospondin-related adhesive protein (BgTRAP) based indirect ELISA for the sero-diagnosis of B. gibsoni infection in dogs. A partial N-terminal BgTRAP gene (870 bp) of B. gibsoni, was expressed in Escherichia coli using a pET32a (+) vector. The recombinant BgTRAP based indirect ELISA was compared with the PCR targeting the same gene. A sensitivity and a specificity of 84% and 73.33% were observed in the indirect ELISA. The accuracy, positive predictive value and negative predictive value were 78.18%, 72.30%, 84.60% respectively. The rBgTRAP antigen did not show any cross-reactivity with sera from dogs infected with common helminth parasites viz. Ancylostoma caninum, Dirofilaria immitis, D. repens, Spirometra spp., Toxocara canis and haemoparasites like Trypanosoma evansi, Babesia vogeli, Hepatozoon canis and Ehrlichia canis.

Transcriptional variation in Babesia gibsoni (Wuhan isolate) between in vivo and in vitro cultures in blood stage

BACKGROUND

Babesia gibsoni, the causative agent of canine babesiosis, belongs to the phylum Apicomplexa. The development of in vitro culture technology has driven research progress in various kinds of omics studies, including transcriptomic analysis of Plasmodium spp. between in vitro and in vivo environments, which has prompted the observation of diagnostic antigens and vaccine development. Nevertheless, no information on Babesia spp. could be obtained in this respect, which greatly hinders the further understanding of parasite growth and development in the blood stage.

METHODS

In this study, considerable changes in the morphology and infectivity of continuous in vitro cultured B. gibsoni (Wuhan isolate) were observed compared to in vivo parasites. Based on these changes, B. gibsoni (Wuhan isolate) was collected from both in vivo and in vitro cultures, followed by total RNA extraction and Illumina transcriptome sequencing. The acquired differentially expressed genes (DEGs) were validated using qRT-PCR, and then functionally annotated through several databases. The gene with the greatest upregulation after in vitro culture was cloned from the genome of B. gibsoni (Wuhan isolate) and characterized by western blotting and indirect immunofluorescence assay for detecting the native form and cellular localization.

RESULTS

Through laboratory cultivation, multiple forms of parasites were observed, and the infectivity of in vitro cultured parasites in dogs was found to be lower. Based on these changes, Illumina transcriptome sequencing was conducted, showing that 377 unigenes were upregulated and 334 unigenes were downregulated. Notably, an AP2 transcription factor family, essential for all developmental stages of parasites, was screened, and the transcriptional changes in these family members were tested. Thus, the novel AP2 transcription factor gene (BgAP2-M) with the highest upregulated expression after in vitro adaptation was selected. This gene comprises an open reading frame (ORF) of 1989 base pairs encoding a full-length protein of 662 amino acids. BgAP2-M contains one AP2 domain and one ACDC conserved domain, which may be involved in the nuclear biology of parasites. The prepared polyclonal antibodies against the BgAP2-M peptides further detected a native size of ~ 73 kDa and were localized to the nuclei of B. gibsoni.

CONCLUSION

This study presents a thorough transcriptome analysis of B. gibsoni in vivo and in vitro for the first time, contributing to a detailed understanding of the effects of environmental changes on the growth and development of parasites in the blood stage. Moreover, it also provides a deeper investigation for the different members of the ApiAP2 transcription factor family as various life stage regulators in Babesia spp.

First molecular confirmation of multiple zoonotic vector-borne diseases in pet dogs and cats of Hong Kong SAR

In recent years, the incidence of vector-borne diseases (VBDs) has increased throughout the globe. In particular, tick-borne diseases (e.g., caused by Ehrlichia canis, E. ewingii, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi sensu stricto (s.s.) and Babesia gibsoni) and mosquito-borne diseases (e.g., caused by Dirofilaria immitis) diseases pose a burden on animal health. Nevertheless, there have been no studies undertaken on the occurrence of VBDs in pet dogs and cats in Hong Kong SAR. This study fills this gap, and is the first to determine the seroprevalence of major VBDs, such as those caused by D. immitis, E. canis, E. ewingii, A. phagocytophilum, A. platys and B. burgdorferi s.s, in dogs and cats through commercially available SNAP 4Dx plus testing. Infection by all these pathogens and Babesia sp. was further assessed through PCR and DNA sequencing. A total of 224 blood samples were collected from domestic dogs (n = 159) and cats (n = 65) in Hong Kong SAR during summer 2022. Hematocrit and platelet counts were determined in each blood sample and other hematological parameters were assessed using an automatic hematology analyzer and vortex the specimen for one to two minutes at or near the highest setting to minimize the clumping. All cat sera samples were negative for tested pathogens, but antibodies against some of the pathogens were detected in dog sera samples. Here, the highest figures were recorded for seroprevalence of E. canis/E. ewingii (10.7%), followed by D. immitis (5.7%), and A. phagocytophilum/A. platys (2.5%). No B. burgdorferi s.s. antibodies were detected in any of the dogs tested. Through molecular diagnostics, we detected the presence of B. gibsoni (3.7%), E. canis (3.1%), D. immitis (5.7%), and A. phagocytophilum (1.3%). Neighbor-Joining phylogenetic trees for vector-borne pathogens (i.e., genus Anaplasma sp.) showed 100% clustering to Japan, the USA and Germany, whereas genus Ehrlichia sp. showed 100% clustering to China, Turkey, Cuba, and Greece. Similarly, genus Babesia sp. clustered 100% to India, Sri Lanka and Austria, while D. immitis clustered in Iraq, South Korea, Portugal, France, the USA and Italy. This study provides the first evidence on the occurrence of tick-borne pathogens in pet dogs in Hong Kong SAR. Based on these findings, it is recommended that appropriate screening should be undertaken in domestic dogs to evaluate the prevalence of these pathogens and promote the timely control of VBDs.

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.

The Comparison of PCR Kits for the Detection of Erythrocytic Parasites on Filter Paper

Dried blood spot (DBS) based PCR was considered an inexpensive and feasible method for detecting pathogens in the blood. The DBS carrier filter paper and PCR kits are crucial for accurate diagnosis. We evaluated 4 types of filter papers and 20 PCR kits for DBS samples. The PCR detecting Plasmodium results showed that the minimum detection limit of the 4 filter papers was 1 × 10² parasites/μL, and the positive rates of 20 PCR kits ranged from 0% to 100%. PCR results were satisfactory for detecting Plasmodium falciparum (P. falciparum) and Plasmodium. vivax (P. vivax) in archived DBS samples and Babesia gibsoni (B. gibsoni) in fresh pet DBS samples. Our results provided a useful reference for the detection of blood pathogens with DBS samples and direct PCR, especially for screening the cost-efficacy combination of filter paper and PCR kit in resource-limited areas.

Establishment and Application of an Indirect Enzyme-Linked Immunosorbent Assay for Measuring GPI-Anchored Protein 52 (P52) Antibodies in Babesia gibsoni-Infected Dogs

Babesia gibsoni is a malaria-like protozoan that parasitizes the red blood cells of canids to cause babesiosis. Due to its high expression and essential function in the survival of parasites, the Glycosylphosphatidylinositol (GPI) anchor protein family is considered an excellent immunodiagnostic marker. Herein, we identified a novel GPI-anchored protein named as BgGPI52-WH with a size of 52 kDa; the recombinant BgGPI52-WH with high antigenicity and immunogenicity was used as a diagnostic antigen to establish a new iELISA method. The iELISA had a sensitivity of 1:400, and no cross-reaction with other apicomplexan parasites occurred. We further demonstrated that the degree of variation was less than 10% using the same samples from the same or different batches of an enzyme-labeled strip. It was found that the method was able to detect early infection (6 days after infection) in the sera of the B. gibsoni-infected experimental dogs in which antibody response to rBgGPI52-WH was evaluated. Clinical sera from pet hospitals were further tested, and the average positive rate was about 11.41% (17/149). The results indicate that BgGPI52-WH is a reliable diagnostic antigen, and the new iELISA could be used as a practical method for the early diagnosis of B. gibsoni.

Canine and Feline Parasitology: Analogies, Differences, and Relevance for Human Health

Cats and dogs are treated as family members by most pet owners. Therefore, a high quality of veterinary care and preventive medicine is imperative for animal health and welfare and for the protection of humans from zoonotic pathogens. There is a general perception of cats being treated as "small dogs," especially in the field of clinical parasitology. As a result, several important differences between the two animal species are not taken into proper consideration and are often overlooked. Dogs and cats are profoundly different under evolutionary, biological, ethological, behavioral, and immunological standpoints. These differences impact clinical features, diagnosis, and control of canine and feline parasites and transmission risk for humans. This review outlines the most common parasitoses and vector-borne diseases of dogs and cats, with a focus on major convergences and divergences, and discusses parasites that have (i) evolved based on different preys for dogs and cats, (ii) adapted due to different immunological or behavioral animal profiles, and (iii) developed more similarities than differences in canine and feline infections and associated diseases. Differences, similarities, and peculiarities of canine and feline parasitology are herein reviewed in three macrosections: (i) carnivorism, vegetarianism, anatomy, genetics, and parasites, (ii) evolutionary adaptation of nematodes, including veterinary reconsideration and zoonotic importance, and (iii) behavior and immune system driving ectoparasites and transmitted diseases. Emphasis is given to provide further steps toward a more accurate evaluation of canine and feline parasitology in a changing world in terms of public health relevance and One Health approach.

Sequence and phylogenetic analysis of the thrombospondin-related adhesive protein gene of Babesia gibsoni isolates in dogs in South India

Babesia gibsoni, the causative agent of canine piroplasmosis, is a tick-borne intraerythrocytic protozoan parasite predominantly reported in Asian countries. The present study aimed at genotypic characterization of B. gibsoni isolates prevalent in dogs in Kerala, a southern state of India. Blood samples were collected from 272 dogs in Kerala and B. gibsoni infection was detected by microscopy and polymerase chain reaction (PCR). Molecular confirmation of B. gibsoni parasites was carried out by 18S rRNA nested-PCR, followed by sequencing. Nested-PCR detected a higher percentage of dogs (40.44%) positive for B. gibsoni infection than microscopy where 15.81% dogs were detected positive for infection. Genetic characterization of B. gibsoni isolates (n = 11) prevalent in dogs in the state of Kerala was carried out by PCR amplification and sequencing of the 855 bp thrombospondin-related adhesive protein (TRAP) gene fragment. Phylogenetic analysis of the B. gibsoni TRAP (BgTRAP) gene revealed that B. gibsoni isolates from Kerala formed a distinct cluster with the isolates from north India and Bangladesh, away from other East Asian isolates. Nucleotide analysis of the tandem repeats of BgTRAP gene showed considerable genetic variation among Indian isolates that was shared by B. gibsoni isolates of Bangladesh but not by the isolates of East Asian countries. The results of the present study further confirmed that B. gibsoni parasites in a distinct genetic clade are endemic in dogs in India and Bangladesh. However, elaborate studies are required for better understanding of the genetic diversity of B. gibsoni.

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.

PCR detection and genetic characterization of piroplasms from dogs in Myanmar, and a possible role of dogs as reservoirs for Theileria parasites infecting cattle, water buffaloes, and goats

Canine vector-borne pathogens can act as zoonotic agents in humans; however, it poorly understood whether dogs play a role as reservoirs of vector-borne parasites in livestock animals. Here, we report the unexpected detection of 18S rRNA gene (rDNA) sequences of five ruminant Theileria species from the peripheral blood of dogs in Myanmar, in addition to those of two canine Babesia species. Using novel BTH primers capable of amplifying the 18S rDNA of Babesia, Theileria, and Hepatozoon spp., approximately 1,500 bp nested PCR products were detected in 19% (17/91) of local or imported dog breeds in different regions of Myanmar. Among the sequences of the 17 PCR products, ten were determined as Theileria 18S rDNA, including three as Theileria orientalis, three as Theileria buffeli, two as Theileria cf. velifera, one as Theileria luwenshuni, and one as Theileria sp. Most of these sequences showed higher identities with Theileria sequences determined in previous studies of cattle, water buffaloes, and goats in Myanmar. Six PCR products were identified as Babesia vogeli and one sample was determined as Babesia gibsoni. Furthermore, we obtained approximately 900 bp thrombospondin-related adhesive protein (TRAP) gene fragments from three dog blood DNA samples. Phylogenetic analysis of the TRAP gene showed that B. gibsoni parasites in Myanmar were considerably related to isolates from China, Korea, Japan, and Taiwan, but clearly separated from those from Bangladesh and India. These results provide new insights into a possible role of dogs in maintaining and spreading tick-borne pathogens among livestock and canine populations in Myanmar.

Molecular detection and genetic characteristics of Babesia gibsoni in dogs in Shaanxi Province, China

Background

Several members of genus Babesia are important pathogens causing babesiosis in dogs. In China, at least five Babesia species have been described in dogs or ticks. This study sought to determine the prevalence and molecular characteristics of various Babesia spp. in dogs in cities in Shaanxi Province in China, including Xi’an and Hanzhong.

Methods

A total of 371 blood samples were collected from pet dogs presenting to veterinary clinics in the cities of Xi’an and Hanzhong in Shaanxi, China. Babesia spp. DNA was detected via amplification of partial 18S rRNA genes by semi-nested PCR. Almost full-length 18S rRNA, ITS, partial TRAP and complete cytb genes were recovered for analysis of the genetic characteristics and relationships with known isolates.

Results

A single species, Babesia gibsoni, was identified in dogs in Xi’an and Hanzhong. Consistently, B. gibsoni was also detected in 14 ticks collected from positive dogs. Sequence similarities and phylogenetic analysis suggested that the isolates identified herein showed a closer genetic relationship with isolates from East Asian countries rather than India, Bangladesh, or the USA. Sequence analysis based on tandem repeat analysis of the TRAP gene further revealed that specific haplotypes were circulating in both Xi’an and Hanzhong, with no specific regionality. In addition, 10.9% of all isolates with atovaquone (ATV)-resistance were identified because of M121I mutation in the deduced cytb protein.

Conclusions

This study revealed a high prevalence rate of Babesia infection. Babesia gibsoni was the only Babesia species identified in cases of canine babesiosis in the cities of Xi’an and Hanzhong cities in Shaanxi, China. In addition, the TRAP gene presented high genetic diversity across isolates. Such information is useful for elucidating the epidemiological characteristics of canine babesiosis, as well as the overall genetic diversity of Babesia spp. circulating in dog populations in Shaanxi Province.

Infection with Babesia canis in dogs in the Algiers region: Parasitological and serological study

Background and Aim:

Canine babesiosis is a vector-borne disease transmitted by ticks of the Ixodidae family. The effects of infection in dogs can range from the subclinical to the severe lethal form. This study aimed to make an original contribution to the knowledge of circulating species of Babesia spp. in dogs in the region of Algiers as well as mechanisms and risk factors for their transmission.

Materials and Methods:

An epidemiological study was carried out on 189 blood samples taken from dogs from April 2015 to January 2016. The samples taken underwent parasitological by Giemsa-stained blood smear and serological analyzes by indirect fluorescent antibody test (IFAT). The ticks were looked on all the dogs taken.

Results:

Giemsa-stained blood smears revealed the presence of two groups of parasites of the genus Babesia: Large Babesia (3/25, 12%) and small Babesia (22/25, 88%). The IFAT at a dilution of 1/32 showed an overall seroprevalence with Babesia canis of 17.98% (95% confidence interval 11.53-22.46). The distribution of the antibody titers for the positive samples showed that of the 34 positive sera with a titer ≥1/32, 28 sera remained positive at a dilution of 1/64 (14.81%), 22 at a dilution of 1/128 (11.64%) and 15 sera remained positive at a dilution of 1/256 (7.93%). Although seroprevalence varied according to canine population (20% and 19.49% in pet dogs and canine pound dogs, respectively, and 6.66-0% in farm dogs and hunting dogs, respectively), statistical analysis showed no significant differences between populations. The antibody titers obtained after several dilutions showed that 22 canine pound dog sera remained positive at a dilution of 1/128 compared to pet dogs and farm dogs which ceased to be positive at the dilution of 1/64. The comparison between the two diagnostic methods showed a strong agreement between the parasitological examination by blood smear and the serological method by IFAT. However, IFAT was much more sensitive. The analysis of risk factors, which may influence B. canis seroprevalence, has shown the influence of age, tick presence, and season. Finally, of the 242 ticks collected from a total of 59 dogs, only one tick species was identified , Rhipicephalus sanguineus.

Conclusion:

This study indicates a frequent circulation of species of Babesia in the dog in the Algiers region and R. sanguineus was the only tick identified.

Annotation and characterization of Babesia gibsoni apicoplast genome

Background

Babesia gibsoni is an apicomplexan parasite transmitted by ticks, which can infect canine species and cause babesiosis. The apicoplast is an organelle associated with isoprenoids metabolism, is widely present in apicomplexan parasites, except for Cryptosporidium. Available data indicate that the apicoplast is essential for the survival of apicomplexan parasites.

Methods

Here, the apicoplast genome of B. gibsoni was investigated by high-throughput genome sequencing, bioinformatics analysis, and conventional PCR.

Results

The apicoplast genome of B. gibsoni-Wuhan strain (B. gibsoni-WH) consists of a 28.4 kb circular molecule, with A + T content of 86.33%, similar to that of B. microti. Specifically, this genome encodes genes involved in maintenance of the apicoplast DNA, transcription, translation and maturation of organellar proteins, which contains 2 subunits of ribosomal RNAs, 17 ribosomal proteins, 1 EF-Tu elongation factor (tufA), 5 DNA-dependent RNA polymerase beta subunits, 2 Clp protease chaperones, 23 tRNA genes and 5 unknown open reading frames (hypothetical proteins). Phylogenetic analysis revealed high similarity of B. gibsoni apicoplast genome to that of B. orientalis and B. bovis.

Conclusions

To our knowledge, this is the first report of annotation and characterization of B. gibsoni-WH apicoplast genome. The results will facilitate the development of new anti-Babesia drug targets.

Canine vector-borne pathogens from dogs and ticks from Tamil Nadu, India

Canine vector-borne diseases (CVBDs) pose a major health problem in dogs globally, with the potential to cause zoonoses, in particular in developing countries where scientific knowledge on the topic is minimal. Blood samples and ticks were collected from stray dogs in Tamil Nadu, South India to assess the prevalence of CVBD-causing pathogens (Anaplasma spp., Babesia spp., Ehrlichia spp., Hepatozoon spp., filarioids and Leishmania spp.). Of the 230 dogs examined, 229 (99.6%) were infested by ticks (mean intensity, 5.65) with Rhipicephalus sanguineus sensu lato and Rhipicephalus haemaphysaloides being morphologically identified in the 98.3% and 1.7% of the infested dogs, respectively. Overall, the 67.8% (n = 156) of dogs was positive for at least one pathogen with Hepatozoon canis being the most prevalent (37.8%) followed by Anaplasma platys (22.6%), Ehrlichia canis (16.1%) Babesia vogeli (10%), Anaplasma phagocytophilum (0.4%) and Babesia gibsoni (0.4%). Two filarioids (Dirofilaria sp. "hongkongensis" and Brugia malayi, 0.4%) were diagnosed in sampled animals. Co-infection with H. canis and A. platys was the most prevalent (8.3%, P = 0.00001), whilst all animals scored negative for Leishmania spp.. Out of 295 ticks analysed, 215 R. sanguineus s.l. (75.4%) and 8 R. haemaphysaloides (88.9%) were positive for at least one pathogen with H. canis as the predominant species (42.5%), followed by A. platys (33.8%), E. canis (16.9%), B. vogeli (3.8%) and A. phagocytophilum (0.3%). Fifty-six dogs (35.9%) harboured the same pathogen as the respective tick specimens, while 29 dogs (18.6%) had a different pathogen. Thirteen sequence types (STs) were identified for H. canis, with ST2 (49.4%) as the most representative in dogs and ST1 (73.5%) in ticks. Similarly, seven STs were found for Anaplasma spp. (i.e., five for A. platys, one for A. phagocytophilum and one for Anaplasma sp.), with ST2 as the most representative in dogs (70.6%) and ST3 (52.5%) in ticks for A. platys. Only one ST was identified for B. vogeli, B. gibsoni, E. canis, D. sp. "hongkongensis" and B. malayi. Regular surveillance and adoption of adequate treatment and control measures are needed to reduce the risk of disease-causing pathogens in stray dogs and of pathogens with zoonotic potential.

A novel PCR-based point-of-care method enables rapid, sensitive and reliable diagnosis of Babesia gibsoni infection in dogs

BACKGROUND

Babesia gibsoni (B. gibsoni) is an intraerythrocytic protozoan parasite of dogs that causes fever and hemolytic illness. A timely diagnosis is essential for the disease management.

RESULTS

Here, we report a QubeMDx PCR system which enables a rapid, sensitive and reliable diagnosis of B. gibsoni near the dog patient. Within 30 min, this diagnostic assay was able to detect as low as 0.002% parasitemia of the dog blood. Using clinical samples, this new assay was validated to demonstrate 100% agreement with real-time PCR.

CONCLUSIONS

This novel diagnostic method provides a reliable point-of-care test to assist in the identification of B. gibsoni.

Mitochondrial cytochrome oxidase C subunit III (cox3) gene as a sensitive and specific target for molecular detection of Babesia gibsoni infection in dogs

A PCR targeting mitochondrial cytochrome oxidase subunit III (cox3) for molecular detection of Babesia gibsoni infection in dogs has been developed in this study. Fifty blood samples from suspected clinical cases from dogs, brought to the veterinary college clinics, were examined for presence of B. gibsoni using conventional diagnosis by microscopic examination of Giemsa stained thin blood smears. In addition, species specific PCRs targeting ITS-1 region (BgITS-1 PCR) and nested PCR targeting 18S ribosomal RNA gene (Bg18SnPCR) were carried out. A 634 bp PCR fragment of B. gibsoni cox3 gene was amplified in positive samples from three geographical locations of Satara, Wai and Pune in Maharashtra state of India. From analysis of the sequence of the B. gibsoni cox3 gene, we found that the Indian isolate had 96-98% similarity to the isolate from Japan and China. Post sequencing, de-novo diagnostic primer pair for species specific amplification of 164 bp fragment of B. gibsonicox3 was designed and the PCR was standardized. The diagnostic results of de-novo Bgcox3 PCR were compared with BgITS-1 PCR and Bg18S nPCR. Thin blood smears detected 22% (11/50) samples positive for small form of Babesia species. The BgITS-1 PCR detected 25% samples (15/50) as positive and Bg18S nPCR detected 80% (40/50) B. gibsoni positive samples. The de-novo Bgcox3 PCR detected 66% (33/50) samples positive for B. gibsoni (at 95% CI). The analytical sensitivity of cox3 PCR was evaluated as 0.000003% parasitaemia or 09 parasites in 100  μl of blood. The de-novo diagnostic cox3 PCR did not cross react with control positive DNA from other haemoprotozoa and rickettsia like B. vogeli, Hepatozoon canis, Trypanosoma evansi, Ehrlichia canis and Anaplasma platys. Statistically, cox3 PCR had better diagnostic efficiency than ITS-1 PCR in terms of sensitivity (p = 0.0006). No statistically significant difference between results of cox3 PCR and 18S nPCR was observed (p = 0.1760). Kappa values estimated for each test pair showed fair to moderate agreement between the observations. Specificity of Bgcox3 PCR was 100% when compared with microscopy or BgITS-1 PCR. Sensitivity of Bgcox3 PCR was 100% when compared with that of Bg18S nPCR.

Detection of Babesia gibsoni in dogs by combining recombinase polymerase amplification (RPA) with lateral flow (LF) dipstick

Babesia gibsoni is a protozoan parasite responsible for the majority of reported cases of canine babesiosis in China. Currently, microscopic examination of the Giemsa-stained thin blood smears is the main diagnosis method in clinic. Here, we report the recombinase polymerase amplification-lateral flow (LF-RPA) dipstick detection method for targeting B. gibsoni cytochrome c oxidase subunit I (cox I) gene. The reaction takes only 20-30 min under isothermal temperatures between 30 and 45 °C. Specificity was evaluated using DNA from related apicomplexan parasites and their host, while the sensitivity was calculated based on the DNA from the experimental B. gibsoni-infected dogs. Results indicated that the LF-RPA method is 20 times more sensitive than the conventional PCR based on 18S rRNA and has no cross reaction with any other test DNAs. The applicability of the LF-RPA method was further evaluated using 15 samples collected from clinic. Thirteen of the 15 samples (86.67%) were detected as positive by LF-RPA, while 10 of them (66.67%) were found positive by conventional PCR. Overall, the novel LF-RPA assay is effective for the detection of B. gobsini and has considerable advantages over the conventional PCR in sensitivity, specificity, simplicity in operation, less time consumption, and visual detection. The LF-RPA method may facilitate the surveillance and early detection of B. gibsoni infection in dogs.

High prevalence of small Babesia species in canines of Kerala, South India

Aim

Canine babesiosis is an important vector-borne hemoparasitic disease caused by Babesia canis vogeli and Babesia gibsoni, in India. The communication places on record the salient findings of the study directed to detect and characterize the pathogenic B. gibsoni isolates of Kerala state.

Materials and Methods

A total of 150 dogs were examined for the presence of hemoparasites by light microscopy as well as by PCR targeting the 18S rRNA gene of B. gibsoni. Hematological parameters were also analysed. Phylogenetic tree was constructed based on Tamura kei model adopting ML method.

Results

A sensitive and specific polymerase chain reaction assay was developed with newly designed primer pair BAGI-F/BAGI-R for the amplification of 488 bp fragment of 18S rRNA gene of B. gibsoni. Out of the 150 dogs examined, molecular evidence of B. gibsoni was recorded in 47.3% animals, while light microscopy detected the infection in 26.67% cases. The phylogenetic analyses revealed that B. gibsoni, Kerala, isolate was closest and occurred together with Bareilly isolate. Anemia and thrombocytopenia were the significant hematological alterations in chronic B. gibsoni infection.

Conclusion

A high prevalence of natural infection of B. gibsoni was detected among the study population. The affected animals showed anaemia and thrombocytopenia. Phylogenetic analysis of this pathogenic isolate from south India revealed the closest similarity with Bareilly isolates.

First molecular detection of tick-borne pathogens in dogs from Jiangxi, China

In this study, blood samples obtained from 162 dogs in Jiangxi, China, were employed in molecular screening of canine tick-borne pathogens by PCR and sequencing. Babesia spp. gene fragment was detected in 12 (7.41%) dogs. All samples were negative for Hepatozoon spp., Ehrlichia canis, Coxiella spp., Borrelia spp., Rickettsia spp. and Anaplasma platys. Species-specific PCR analysis further confirmed that 8 (4.94%) and 4 (2.47%) dogs were infected by Babesia canis vogeli and Babesia gibsoni, respectively. Based on our analyses, Babesia spp. infection in Jiangxi appeared not related to age, gender, breed, usage, activity and health status or tick infestation history of the dogs. This is the first molecular report of Babesia canis vogeli and Babesia gibsoni in dogs from Jiangxi, China.

DNA Microarray Detection of 18 Important Human Blood Protozoan Species

Background

Accurate detection of blood protozoa from clinical samples is important for diagnosis, treatment and control of related diseases. In this preliminary study, a novel DNA microarray system was assessed for the detection of Plasmodium, Leishmania, Trypanosoma, Toxoplasma gondii and Babesia in humans, animals, and vectors, in comparison with microscopy and PCR data. Developing a rapid, simple, and convenient detection method for protozoan detection is an urgent need.

Methodology/Principal Findings

The microarray assay simultaneously identified 18 species of common blood protozoa based on the differences in respective target genes. A total of 20 specific primer pairs and 107 microarray probes were selected according to conserved regions which were designed to identify 18 species in 5 blood protozoan genera. The positive detection rate of the microarray assay was 91.78% (402/438). Sensitivity and specificity for blood protozoan detection ranged from 82.4% (95%CI: 65.9% ~ 98.8%) to 100.0% and 95.1% (95%CI: 93.2% ~ 97.0%) to 100.0%, respectively. Positive predictive value (PPV) and negative predictive value (NPV) ranged from 20.0% (95%CI: 2.5% ~ 37.5%) to 100.0% and 96.8% (95%CI: 95.0% ~ 98.6%) to 100.0%, respectively. Youden index varied from 0.82 to 0.98. The detection limit of the DNA microarrays ranged from 200 to 500 copies/reaction, similar to PCR findings. The concordance rate between microarray data and DNA sequencing results was 100%.

Conclusions/Significance

Overall, the newly developed microarray platform provides a convenient, highly accurate, and reliable clinical assay for the determination of blood protozoan species.

More than 1 billion people are infected with blood protozoan diseases worldwide. The most common blood protozoa in humans, animals, and vectors include Plasmodium, Leishmania, Trypanosoma, Toxoplasma gondii and Babesia. Due to similar morphology among different blood protozoan species, misdiagnosis always occurs. Most molecular techniques are only carried out in laboratories, with a small number of samples detected simultaneously. Meanwhile, common detection methods may not be convenient for field investigation of large amounts of samples. In order to better manage blood protozoan infection, proper tools are required for the monitoring of these pathogens. Here, a comprehensive and sensitive DNA microarray was developed and tested, which allowed the parallel detection of 18 blood protozoan species.