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

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.

Tick-, flea- and mite-borne pathogens and associated diseases of public health importance in Bangladesh: a review

Background

This scoping review provides a baseline summary of the current records of the ticks, fleas, and mites of public health importance that are present in Bangladesh. It summarizes their geographic distributions and reports the levels of their infestation of livestock, pets, wildlife, and humans, and the clinical and epidemiological studies pertinent to these vectors and their pathogens.

Methods

Sixty-one articles were identified in a literature search, including 43 published since 2011.

Results

Twelve articles contained reliable information on ticks and their associated hosts. However, information on fleas and mites in Bangladesh is very limited. Seventeen species of ixodid ticks that commonly parasitize peridomestic animals and can bite humans are described: Rhipicephalus microplus, R. appendiculatus, R. sanguineus, Haemaphysalis bispinosa, Hyalomma anatolicum, and Amblyomma testudinarium. Thirty-eight veterinary articles describe livestock pathogens, including Babesia, Anaplasma, and Theileria, and the diseases they cause. Few of those studies used modern molecular techniques to identify these pathogens. Eleven articles reported human diseases or surveillance studies, 10 from the last 10 years. Two country-wide serosurveys of 1,209 and 720 patients, using Enzyme Linked Immunosorbent Assay (ELISA) and Indirect Immunofluorescence Assay (IFA), respectively, reported human exposure to Orientia tsutsugamushi (8.8%-23.7%), typhus and spotted-fever group rickettsiae (19.7%-66.6%), and Coxiella burnetii (3%). The seropositivity rates varied regionally. PCR-based studies confirmed that febrile patients in Bangladesh may be infected with O. tsutsugamushi, Rickettsia typhi, Rickettsia felis, or Bartonella elizabethae. Only limited molecular research has been done with dogs and cats. These studies have reported PCR-confirmed canine infections with Babesia gibsoni (30%), Anaplasma bovis (58%), or Rickettsia monacenis (14%, n=50), and feline infections with Rickettsia felis (21%, n=100). Similarly, fleas from cats tested positive for Rickettsia felis (20.6%).

Conclusions

These findings indicate that diseases borne by non-mosquito vectors in Bangladesh urgently require more attention from public health, medical, and veterinary specialists to establish their true occurrence.

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.

Molecular detection and characterization of Anaplasma marginale and Babesia canis vogeli infecting dogs in Luxor, Egypt

Tick-borne diseases in animals are increasing rapidly worldwide, but there is insufficient information about tick-borne diseases infecting dogs in southern Egypt. Thus, in the current study, we detected the presence of Anaplasma marginale (A. marginale) and Babesia canis vogeli (B. canis vogeli) in the blood of dogs. The results revealed that 4/100 (4%) were positive, and a higher infection rate was found in males (75%), than females (25%). The phylogenetic analysis for the major surface protein 4 (msp4) gene in this study was compared with amplicons separate from other reported isolates with alignment by identity 100% with cattle and camels from Egypt, and the phylogenetic analysis for the B. canis vogeli small subunit ribosomal RNA (SSU rRNA) gene in this study identified identity by 99.89% with dogs from Egypt. This report is considered the first report in southern Egypt about A. marginale in dogs based on the sequence analysis of the msp4 gene, providing new data for the classification and identification of A. marginale in dogs compared to A. marginale isolated from other animals in southern Egypt.

Molecular survey of canine tick-borne pathogens in ticks and stray dogs in Dhaka city, Bangladesh

Molecular surveillance of canine tick-borne pathogens (TBPs) in Bangladesh has constantly been undervalued. Therefore, the emergence of new pathogens often remains undetected. This study aimed to screen tick-borne pathogens in stray dogs and ticks in the Dhaka metropolitan area (DMA). Eighty-five dog blood and 53 ticks were collected in six city districts of DMA from September 2022 to January 2023. The ticks were identified by morphology. Screening of TBPs was performed by polymerase chain reaction (PCR), followed by sequencing. The PCR assays were conducted to analyze the 18S rRNA (Babesia gibsoni, B. vogeli, and Hepatozoon canis), 16S rRNA (Anaplasma phagocytophilum, A. platys, and A. bovis), gltA (Ehrlichia canis and Rickettsia spp.), flagellin B (Borrelia spp.) and 16-23S rRNA (Bartonella spp.). Three tick species, Rhipicephalus sanguineus (50/53), R. microplus (1/53), and Haemaphysalis bispinosa (2/53), were identified. Babesia gibsoni (38 out of 85) and A. platys (7 out of 85) were detected in dog blood. In contrast, four pathogens, B. gibsoni (1 out of 53), B. vogeli (1 out of 53), H. canis (22 out of 53), and A. platys (1 out of 53), were detected in the ticks. However, the detection rates of TBPs in dog blood and ticks were not correlated in this study. The phylogenetic analyses suggested that a single genotype for each of the four pathogens is circulating in DMA. This study reports the existence of B. vogeli, H. canis, and A. platys in Bangladesh for the first time.

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.

Analysis of genetic diversity and population structure of Babesia gibsoni

Babesia gibsoni is a tick-borne apicomplexan protozoan causing canine babesiosis. This parasite has diploid sexual reproduction in ticks, during which genetic exchanges can occur leading to increased genetic diversity, which is an important factor in adapting to environmental changes. Exploring the genetic variation of B. gibsoni population can provide a foundation for understanding the patterns of disease transmission and developing babesiosis control strategies. Partial 18S rRNA fragment sequences were obtained from 11 B. gibsoni isolates collected from different regions in China and 117 publicly available sequences were from 12 geographical areas including China. The genetic variation, demographic expansion and population structure were examined. A total of 34 haplotypes were identified among B. gibsoni populations. Analysis of molecular variance, pairwise Fst and structure analysis showed that high genetic variation within populations, low genetic differentiation and obvious mixture haplotype were apparent in a single continent, but higher genetic differentiation was detected across different continents. Neutrality tests implied that B. gibsoni populations had experienced population extension. These findings will contribute to understand the genetics and evolution of B. gibsoni and will be useful for formulating effective management strategies to prevent and control this parasite.

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.

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.

Detection and molecular characterization of Babesia sp. in wild boar (Sus scrofa) from western Japan

Wild animals often act as reservoirs of tick-borne Babesia and Theileria spp., which cause piroplasmosis. Therefore, epidemiological investigations about the distribution of these parasites in wild animals are important for evaluating the transmission risk to humans and livestock. In this study, we surveyed Babesia and Theileria spp. infecting wild boar (Sus scrofa) in Kagoshima and Yamaguchi prefectures and Tsushima island, which are all in western Japan, and performed molecular genetic analyses on the samples. DNA was extracted from either blood or liver samples of wild boar captured in Kagoshima prefecture in 2015, 2016, and 2018 and from blood samples from wild boar captured in Yamaguchi prefecture in 2013-2015 and Tsushima island in 2018. PCR screening for the partial 18S ribosomal RNA gene (18S rRNA) of both Babesia and Theileria spp. in wild boar revealed that 63.9 % (140 of 219 samples) were positive. Sequencing of all positive samples revealed that they were all the same Babesia species. Subsequent phylogenetic analyses showed that the parasite is closely related to Babesia sp. previously detected in the hard tick, Amblyomma testudinarium in Kagoshima, and further analyses suggested that this species is genetically related to Babesia gibsoni. On the other hand, no Theileria were detected in any of the samples. In summary, we observed a high prevalence of B. gibsoni-like Babesia sp. in wild boar in western regions of Japan. The host range, distribution, pathogenicity, and life cycle of this protozoan should be further evaluated.

Survey and Molecular Study of Babesia gibsoni in Dogs of Baghdad Province, Iraq

This study aimed to detect Babesia gibsoni (B. gibsoni) in dogs of different ages, sex and breeds in Baghdad province by microscopic and molecular investigations using polymerase chain reaction (PCR), sequencing, and phylogenetic analyses. The present study was investigated B. gibsoni in 310 blood samples of dogs for the period from December 2018 to September 2019 in Baghdad province, Iraq. The molecular study was carried out by using universal primers of Babesia spp. (PIRO-A and PIRO-B) and specific primers of B. gibsoni (BAGIF and BAGIR) products size of 410 bp and 488 bp fragments of 18S rRNA gene respectively. The clinical signs revealed higher percentage and specific clinical signs of B. gibsoni as depression, anorexia, fever, pale mucus membrane, and ticks infestation, however icterus, and dead were low in which only occurred in two dogs out of infected dogs. The PCR assay and microscopic diagnosis revealed the infection rate of B. gibsoni 9 out of 310 (2.9%) in dogs. The sequence data analyses of nine DNA products were 98-100% similar to sequences of 18S rRNA gene of B. gibsoni data available in Gene bank. According to breed, age, and sex, the results revealed a significantly high-risk factor of infection in Husky dogs; B. gibsoni detected in females which was increased non-significantly than males; while the highest occurrence of disease was in young dogs aged three years or less in addition to the above, the infection rate of B. gibsoni was high in spring season. In conclusion, this study was considered the first molecular record of B. gibsoni in Baghdad, Iraq documented no differences in diagnosis by blood smear and conventional PCR to amplify of 18S rRNA gene and partial sequencing of B. gibsoni with low-cost method and easily done.

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.

Molecular detection of tick-borne pathogens in caracals (Caracal caracal) living in human-modified landscapes of South Africa

Background

Wild carnivores living alongside humans and domestic animals are vulnerable to changes in the infectious disease dynamics in their populations. The aims of this study were to determine the prevalence and diversity of selected tick-borne pathogens (TBPs) of veterinary and/or zoonotic concern in wild populations of caracals (Caracal caracal) occurring in human-modified landscapes in South Africa. Using molecular techniques, we screened 57 caracal blood samples for infection by rickettsial bacteria and piroplasms in three regions of South Africa: rangeland in the Central Karoo (n = 27) and Namaqualand (n = 14) as well as the urban edge of the Cape Peninsula (n = 16) of South Africa. To characterise pathogen identity, we sequenced the 18S rRNA and 16S rRNA genes from positive samples and analysed sequences within a phylogenetic framework. We also examine the diversity of potential tick vectors.

Results

All individuals tested were infected with at least one tick-borne pathogen. Pathogens included Hepatozoon felis, Babesia felis, Babesia leo and a potentially novel Babesia species. An Anaplasma species previously described in South African domestic dogs was also found in 88% of urban edge caracals. Higher rates of co-infection characterised urban edge caracals (81% vs 15% and 0% in the two rangeland populations), as well as a greater incidence of mixed infections. Host attached tick species include Haemaphysalis elliptica, an important pathogen vector among carnivore hosts.

Conclusions

This study confirms the occurrence of previously undocumented tick-borne pathogens infecting free-ranging caracals in human-modified landscapes. We identify clear differences in the pathogen profiles among our study populations and discuss the likely health costs to caracals living adjacent to urban areas.

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.

Potential of cell-free DNA as a screening marker for parasite infections in dog

Parasitic infections are common in stray dogs and accurate knowledge of parasite communities in dogs would provide insight into the epidemiology of parasitic diseases. In this study, we used Illumina sequencing technology to evaluate cell-free DNA (cfDNA) as a marker for screening of parasitic infections in dogs. Plasma samples from 14 stray dogs captured in Bangladesh were used in the experiments. An average of 2.3 million reads was obtained for each sample. BLASTn analysis identified 150 reads with high similarity with parasites from 19 different genera. In particular, we detected sequences of Babesia spp. in five dogs; consistent with this, a previous study using conventional PCR showed that four of these dogs were positive for B. gibsoni. Several reads with similarity to Leishmania and filarial nematodes were also identified. These findings indicate that cfDNA in blood can be a potential screening marker for identifying parasite diversity in dogs.

Babesia gibsoni internal transcribed spacer 1 region is highly conserved amongst isolates from dogs across Japan

Babesia gibsoni is a tick-borne apicomplexan parasite of dogs that often causes fever and hemolytic anemia with highly variable clinical outcome. In this study, we sequenced the 254bp Internal Transcribed Spacer 1 region (ITS1) of 54 B. gibsoni isolates from 14 different geographical regions of Japan. The 54 isolates shared high sequence identity with each other and with B. gibsoni isolates reported in GenBank database (97.2–100%). Consistent with previous reports, phylogenetic analysis showed that B. gibsoni isolates from Japan formed the same clade with those from U.S.A., Australia, India and Taiwan. Our finding indicates that B. gibsoni ITS1 region is highly conserved among isolates from dogs in Japan, making it a useful genetic marker for molecular epidemiology of the parasite.

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

Babesia gibsoni is a tick borne intraerythrocytic protozoan parasite causing piroplasmosis in dogs and has been predominantly reported in Asian countries, including Japan, Korea, Taiwan, Malaysia, Bangladesh and India. The present communication is the first evidence on the genetic diversity of B. gibsoni of dogs in India. Blood samples were collected from 164 dogs in north and northeast states of India and 13 dogs (7.9%) were found positive for B. gibsoni infection by microscopic examination of blood smears. Molecular confirmation of these microscopic positive cases for B. gibsoni was carried out by 18S rRNA nested-PCR, followed by sequencing. Nested-PCR for the 18S rRNA gene was also carried out on microscopically B. gibsoni negative samples that detected a higher percentage of dogs (28.6%) infected with B. gibsoni. Genetic diversity in B. gibsoni in India was determined by studying B. gibsoni thrombospondin-related adhesive protein (BgTRAP) gene fragments (855bp) in 19 isolates from four north and northeast states of India. Phylogenetic analysis of the BgTRAP gene revealed that B. gibsoni parasite in India and Bangladesh formed a distinct cluster away from other Asian B. gibsoni isolates available from Japan, Taiwan and Korea. In addition, tandem repeat analysis of the BgTRAP gene clearly showed considerable genetic variation among Indian isolates that was shared by B. gibsoni isolates of Bangladesh. These results suggested that B. gibsoni parasites in a different genetic clade are endemic in dogs in India and Bangladesh. Further studies are required for better understanding of the genetic diversity of B. gibsoni prevalent in India and in its neighbouring countries.