Critical analysis of vector-borne infections in dogs: Babesia vogeli, Babesia gibsoni, Ehrlichia canis and Hepatozoon canis in Punjab, India

Molecular Survey of Tick-Borne Haemoparasites of Dogs by Multiplex Polymerase Chain Reaction from Punjab, India

PURPOSE

Tick-transmitted parasites as Babesia gibsoni, Babesia vogeli, Ehrlichia canis, and Hepatozoon canis are major health concern for dogs. Owing to prevalence and infection severity, there is need of sensitive, specific, and affordable test for their simultaneous detection.

METHODS

Prevalence of B. gibsoni, B. vogeli, E. canis, and H. canis infections was assessed on 719 blood samples by microscopy and multiplex PCR assay targeting 18S rRNA (B. gibsoni & H. canis), ITS1 & 5.8S rRNA (B. vogeli) and VirB9 gene (E. canis). An internal control (canine-actin) was also included to increase the accuracy of assay and effect of associated risk factors with disease prevalence was also studied.

RESULTS

Microscopic prevalence of B. gibsoni, B. vogeli, E. canis and H. canis was 5.0%, 0.1%, 1.4% and 1.0%, respectively, whereas with multiplex PCR assay, the corresponding values were 8.9%, 1.1%, 2.6% and 5.1% besides concurrent infections of B. gibsoni & H. canis (0.4%), B. gibsoni & E. canis (0.4%), E. canis & H. canis (0.3%) and B. gibsoni & B. vogeli (0.1%). Analytical sensitivity of developed assay was 0.1pg (B. gibsoni & H. canis), 0.01pg (B. vogeli), and 1.0pg (E. canis). A ″fair″ (B. vogeli & H. canis) to ″substantial″ (B. gibsoni & E. canis) agreement between two tests was observed with data as statistically significant. Breed, sex and location were significantly associated with B. gibsoni infection.

CONCLUSION

The developed multiplex PCR assay offers a potential solution to detect these pathogens simultaneously, aiding in timely diagnosis and effective disease management in suspected dogs.

First report of occurrence of Babesia gibsoni in captive Indian wolves

Blood samples from fifteen captive Indian wolves (Canis lupus pallipes) maintained at Arignar Anna Zoological Park, Vandalur, Chennai were screened for the presence of Babesia spp., Ehrlichia canis and Trypnosoma evansi DNA by PCR. Out of 15 wolf samples, 3 samples were found positive for Babesia spp. The amplified 18S rRNA gene fragments from 3 wolves were sequenced and confirmed as Babesia gibsoni. A maximum likelihood tree was constructed using the three sequences along with other Babesia spp. sequences derived from GenBank adopting HKY nucleotide substitution model based on the Bayesian Information Criterion. The phylogenetic analysis confirmed that the three sequences were of Babesia gibsoni and highly divergent from Babesia canis, B. vogeli and B. vulpes. This might be a possible spill over event of B. gibsoni from community dogs through blood feeding dog ticks. This is the first report and molecular confirmation of B. gibsoni infection in captive Indian wolves.

Prevalence of haemoparasites infection in diseased bovine and canine of Bhatinda district of Punjab, India

Infections caused by tick-borne haemoparasites pose a significant global threat to both human and animal health. Within this category, various haemoparasites species belonging to genera like Anaplasma sp., Babesia sp., Ehrlichia sp., Hepatozoon sp., and Theileria sp., are particularly concerning due to their ability to cause diseases in a wide range of hosts, including mammals, birds, and reptiles. The present cross-sectional study involving 580 animals provides annual insights into the prevalence of major haemoparasites infections in the Bathinda region of Punjab. The observed trends indicate that haemoparasites infections were most common in cattle, followed by buffalo and canines. Risk factor analysis revealed that crossbreed cattle were more susceptible to infection, with a prevalence of 35.73% (95% CI 4.28-45.17). Amongst the cattle, adults exhibited a higher vulnerability to haemoparasites infections, with a prevalence of 35.89% (95% CI 5.50-33.64). Conversely, companion animals showed the opposite pattern, with a prevalence of 18.18% (95% CI 9.11-169.27). Furthermore, female dogs had a higher risk of haemoparasites infection, with a prevalence of 16.28% (95% CI 8.36-218.7). In light of these findings, it is imperative to emphasize early diagnosis, prompt antiprotozoals drug treatment, and effective control of tick vectors for the successful recovery of animals afflicted by haemoparasites infections.

Molecular Survey and Genetic Characteristics of Vector-Borne Pathogens in Domestic Dogs from Four Regions of China

Canine vector-borne diseases are widely distributed around the world. They are transmitted by arthropods, and many seriously threaten the health of animals and humans. In China, our knowledge of Ehrlichia, Hepatozoon, and Mycoplasma species circulating in dogs is still poorly understood. Therefore, the aim of this study was to understand the prevalence and genetic characteristics of canine Ehrlichia spp., Hepatozoon spp., and Mycoplasma spp. in Chongqing (southwest), Fujian (southeast), Shandong (southeast), and Hubei (central) Provinces of China. Blood samples from healthy pet dogs were processed to detect Ehrlichia, Hepatozoon, and Mycoplasma DNA with PCR. Haplotype and phylogenetic analyses were performed on 18S rRNA sequences. Among 306 dogs, no Ehrlichia spp. or Mycoplasma spp. were detected, whereas one Hepatozoon sp. was detected in 10 (3.27%) of the animals. Only Hepatozoon canis was identified and was endemic to Chongqing (2.46%) and Hubei (8.77%). A haplotype analysis identified eight haplotypes among the H. canis isolates. A phylogenetic analysis showed that the H. canis isolates in this study clustered into four clades, together with isolates from different countries and hosts, forming a large group that was clearly separate from other Hepatozoon species. These findings provided new information on the epidemiological characteristics of canine vector-borne diseases in China and will be helpful in the development of efficient measures to safeguard the health and well-being of companion animals and their owners.

Hematological analysis of naturally infecting blood parasites in dogs

Background and Aim: Blood parasite infections such as anaplasmosis, babesiosis, and ehrlichiosis are commonly found in domestic dogs, which adversely influence their health. Many dogs are infected with multiple blood parasites that cause more severe diseases than a single infection. This study aimed to investigate the effect of multiple blood parasite infections on the hematological profiles of dogs at a shelter in Southern Thailand. Materials and Methods: The blood samples from 122 dogs were collected to assess the hematology profiles of uninfected, single-infected, and multiple blood parasite-infected dogs. The results were compared using Kruskal-Wallis test and Dwass-Steel-Critchlow-Fligner pairwise comparisons. The infections were confirmed by polymerase chain reaction. Results: The results showed that all the infected dogs had significantly lower red blood cell (RBC) count, hemoglobin (HB), hematocrit (HCT), and platelet count (PLT) than the uninfected dogs. Although the dogs with triple infection had lower RBC, HB, HCT, and PLT than those with double and single infections, the difference was not statistically significant. Conclusion: We proposed that triple blood parasite infection with Anaplasma platys, Babesia vogeli, and Ehrlichia canis caused more severe disease than double and single infections. Evaluating the hematological profiles of dogs naturally infected with single, double, and multiple blood parasite infections without clinical signs can enhance their health and welfare. Keywords: blood parasite, dogs, hematology, multiple blood parasite infection, tick-borne pathogens.

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

Background and Aim

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

Materials and Methods

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

Results

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

Conclusion

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

Prevalence of Ehrlichia-, Babesia-, and Hepatozoon-infected brown dog ticks in Khon Kaen Province, Northeast Thailand

Background and Aim:

The brown dog tick, Rhipicephalus sanguineus sensu lato, is the most common tick found on domestic dogs in Southeast Asia, including Thailand. Canine tick-borne pathogens are a public health concern worldwide. Tick-borne diseases are diagnosed by identifying pathogens based on the morphological or molecular analyses of dog blood samples. However, the collection of ticks, a non-invasive procedure, is easier than drawing blood. This study aimed to demonstrate the usefulness of collecting brown dog ticks for the diagnosis of tick-borne diseases and for estimating the prevalence of tick-borne pathogens among companion dogs in Khon Kaen, Northeast Thailand.

Materials and Methods:

Seventy brown dog ticks from 70 companion dogs in Khon Kaen Province, Thailand, were evaluated for molecular evidence of tick-borne pathogens, including Babesia spp., Ehrlichia canis, and Hepatozoon canis. Ticks were collected from dogs at a private animal hospital based on the presence of at least one of the three inclusion criteria: fever, anorexia, or lethargy. Molecular diagnosis was performed using conventional polymerase chain reaction for the detection of pathogens.

Results:

Of the 70 ticks collected from 70 sick dogs, 55 (78.57%) were positive for tick-borne pathogens. The most common infection was a single infection with H. canis (65.71%) followed by Babesia spp. (31.43%) and E. canis (30.00%). Coinfection was observed in 14 ticks (20.00%), and coinfection with Babesia spp. and E. canis was the most prevalent double infection (n = 6). The prevalence of coinfection was identical for H. canis mixed with Babesia spp. and H. canis mixed with E. canis (n = 4).

Conclusion:

The present study showed that tick-borne pathogens are highly prevalent among companion dogs in Khon Kaen Province. Therefore, we encourage an increase in tick control or the reduction and prevention of tick-borne diseases in this region. Furthermore, this study revealed that ticks are valuable samples for the molecular detection of tick-borne pathogens.

Screening and phylogenetic characterization of tick-borne pathogens in a population of dogs and associated ticks in Egypt

Background

The incidence or recurrence of tick-borne diseases (TBDs) in animals and humans is increasing rapidly worldwide, but there is insufficient information about TBDs infecting dogs in Egypt. Thus, the present study was conducted to screen and genetically identify tick-borne pathogens (TBPs) in dogs and associated ticks by microscopic examination and polymerase chain reaction (PCR).

Methods

In Cairo and Giza governorates, 208 blood samples were collected from dogs of different breeds, ages, and sex. In addition, 1266 dog-associated ticks were collected (546 ticks were used to prepare hemolymph smears, and 720 ticks were kept in 70% ethanol until PCR analysis). PCR was applied to 124 dog blood samples and 144 tick pools prepared from 720 ticks.

Results

All ticks collected from dogs were Rhipicephalus sanguineus (s.l.). Microscopic examination revealed that TBP prevalence among dogs was 23.56% (49/208), including Anaplasma and Ehrlichia with 11.1% (23/208) and Babesia canis with 8.2% (17/208). Hepatozoon canis was not detected in blood smears. Co-infections with two pathogens were visible in 4.33% (9/208) of examined dogs. The prevalence of TBPs in hemolymph smears was 45.97% (251/546) including 35.89% (196/546) for H. canis, 8.1% (44/546) for B. canis, and 2.01% (11/546) for Anaplasmataceae (A. phagocytophilum, A. marginale, A. platys, and E. canis). The overall molecular prevalence rate of TBPs was 25.81% and 29.17% in the blood of examined dogs and in ticks, respectively. The molecular prevalence of Anaplasmataceae family, Babesia canis, and H. canis in dog blood samples was 19.35%, 6.45%, and 0.0%, respectively, while in ticks, it was 20.83%, 5.55%, and 2.8%, respectively. A sequential analysis identified six different species of TBPs, namely B. canis vogeli, Hepatozoon canis, A. phagocytophilum, A. marginale, A. platys, and E. canis. The obtained sequences were submitted to GenBank and assigned accession numbers.

Conclusions

The present study detected a wide range of TBPs (B. canis, H. canis, A. platys, A. phagocytophilum, A. marginale, and E. canis) that are considered a threat to domestic animals and humans in Egypt. Hepatozoon canis and A. marginale were reported in dogs and associated ticks for the first time in Egypt.

Graphical Abstract

Traditional and molecular techniques were used to screen domestic dogs and attached ticks for TBPs.

A wide range of TBPs in dogs and attached ticks was detected in Egypt.

Some accidental pathogens, such as A. marginale from other hosts, were identified in dogs.

Some canine isolates from Anaplasmataceae family have high homology to those isolated from humans.

First study on molecular detection of three major canine tick-borne pathogens in subclinically infected dogs in Chiang Mai, Thailand

Background and Aim:

Canine tick-borne pathogens (CTBPs) are an important cause of morbidity in dogs in Thailand. This study aimed to evaluate the occurrence of three CTBPs in clinically normal, owned dogs to understand the risk for the general canine population. We also examined sex, age, tick infestation, and packed cell volume (PCV) of the animals in association with active infection of the CTBPs.

Materials and Methods:

A total of 139 dogs were included in the study. Blood samples were collected for thin blood smear, PCV and nested polymerase chain reaction (PCR) assay. Statistical analyses were performed to examine the association between individual factors and CTBP infection status determined by PCR. In addition, sensitivity, specificity, and Cohen’s kappa were calculated to assess the utility of routine blood smear.

Results:

The PCR results showed that 31 dogs (22.3%) were infected with at least one of the three pathogens. The occurrence rate for Ehrlichia canis, Anaplasma platys, and Hepatozoon canis was 2.2% (3/139), 18.7% (24/139), and 2.8% (4/139), respectively. There were two cases of coinfection with A. platys and E. canis. The univariate analyses did not yield any associations between recorded variables and the active infection. Microscopic examination showed good sensitivity and agreement only for H. canis (Sn: 75%, 95% confidence interval: 24.9-98.7, k=0.85).

Conclusion:

Our findings confirmed the endemicity of the CTBPs in owned canine population in the study site. In-depth epidemiological investigation would be warranted to elucidate environmental risk factors for CTBP infection.

Duplex real-time PCR methods for molecular detection and characterization of canine tick-borne haemoparasites from Punjab state, India

Background

Microscopy is a routinely used technique for the diagnosis of canine tick-borne haemoparasitic diseases in various clinical laboratories worldwide. In an attempt to provide better diagnostic assay to the clients for effective management of these diseases duplex real-time PCR assays were applied.

Methods and results

Blood samples (n = 338) aseptically collected from suspected dogs of Central Plain Zone of Punjab state, India were subjected to SYBR Green based real-time duplex PCR assays for simultaneous detection of B. vogeli & E. canis and B. gibsoni & H. canis. Results revealed an overall prevalence rate of canine tick-borne haemoparasites as 54.1%, amongst which H. canis was the predominant (25.4%), followed by B. gibsoni (16.3%), E. canis (10.7%) and B. vogeli (1.8%). Sensitivity and specificity of the duplex assays ranged from 59.04 to 100.0% and 58.12 to 92.52%, respectively and their strength of agreement was ″fair″ with kappa value statistics. A significant (p < 0.05) association between prevalence of B. gibsoni, H. canis and E. canis infection with risk factors like sex, breed, season and location was recorded. The ancestral background of the field isolates of haemoparasites was also studied by phylogenetic analysis of their nucleotide sequences.

Conclusions

SYBR Green dye based duplex real-time PCR assays proved to be highly sensitive, specific, rapid and affordable diagnostic tests for use by clinicians to save the life of pets.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11033-022-07286-4.

First report on molecular characteristics and risk factor analysis of Ehrlichia canis in dogs in Khon Kaen, Thailand

Background and Aim:

Ehrlichia canis is a well-known cause of both anemia and thrombocytopenia in dogs. There are insufficient epidemiological data on this blood parasite in Thailand and the association of infections with hematological abnormalities. This study aimed to analyze the molecular characteristics and to identify E. canis as well as the risk factors associated with E. canis infection in dogs in Khon Kaen, Thailand.

Materials and Methods:

Blood samples from 126 dogs that visited animal clinics were subjected to molecular detection using nested polymerase chain reaction for E. canis16S rRNA gene. The risk factors and hematological profiles associated with the infection were analyzed using the logistic regression test in program SPSS version 19.

Results:

Forty-one dogs were infected, indicating a 32.5% molecular infection rate of E. canis. The factors significantly associated with E. canis infection include animal housing status, low packed cell volume, low red blood cell count, and low platelets (p<0.05). Ten positive samples were amplified, sequenced, and phylogenetically analyzed. Sequence and phylogenetic analysis confirmed the current ten samples as E. canis compared with reference sequences in GenBank, using the BLAST program hosted by NCBI, which showed 99.74-100% similarity.

Conclusion:

This study provided the first data of infection rate of E. canis using nested PCR and molecular characteristics of E. canis in randomly selected domestic dogs in Khon Kaen, Thailand.

Molecular detection of tick-borne pathogens in infected dogs associated with Rhipicephalus sanguineus tick infestation in Thailand

Background and Aim:

Tick-borne pathogens (TBPs) are of great concern having the potential to threaten canine health. Dogs infected with Ehrlichia canis, Anaplasma platys, Babesia canis, and Hepatozoon canis are commonly found in Thailand; Rhipicephalus sanguineus tick is the most common vector of diseases. This study aimed to determine the prevalence of common TBPs in dogs and their ticks in Thailand using polymerase chain reaction (PCR) and DNA sequencing methods.

Materials and Methods:

Forty-four blood samples were positively diagnosed with TBPs infection by microscopy. Samples were from animal hospitals in Maha Sarakham, Amnat Charoen, Nakhon Ratchasima, and Bangkok, Thailand, during January-June 2020. Five to six ticks were also taken from infected dogs, and then, both blood and tick were analyzed using PCR and DNA sequencing.

Results:

PCR results showed that R. sanguineus was the only tick species detected in this study. The appearance of single infection with E. canis was the most common infection found in dogs and ticks (64% and 82%, respectively). Correlation of pathogen infection in hosts and their vector was performed by similarity detection of pathogens between blood and tick samples based on PCR analysis in 29 samples (66%) but there was no significant differentiation.

Conclusion:

E. canis appears as the most common canine tick-borne pathogen in Thailand, which was detected in both healthy and sick dogs as well as in R. sanguineus. The findings show the relationships among host dogs, pathogens, and ticks. Veterinarians should be proactive in educating pet owners about the risks associated with ticks and their important pathogens and plan effective control strategies.

Development and application of multiplex PCR assay for the simultaneous detection of Babesia vogeli, Ehrlichia canis and Hepatozoon canis in dogs

A multiplex PCR assay was standardized and evaluated to simultaneously detect the DNA of Babesia vogeli, Ehrlichia canis and Hepatozoon canis in dogs of selected districts of Punjab state, India. Amplicons of 602 bp, 380 bp and 306 bp corresponding to B. vogeli (18S rRNA gene), E. canis (VirB9 gene), and H. canis (18S rRNA gene) were obtained, without any non-specific amplification. The results of multiplex PCR assay were further compared with the corresponding singleplex PCR assay. The diagnostic sensitivity and specificity of multiplex PCR assay with respect to singleplex PCR assay in the detection of B. vogeli, E. canis and H. canis varied from 50% to 100% and 92.08% to 98.79%, respectively revealing "moderate" to "very good" agreement by kappa value statistics. Blood samples from 322 dogs collected from selected districts of Punjab state, India, when screened by microscopy revealed the prevalence of B. vogeli, E. canis and H. canis as 0.31%, 0.93% and 1.86%, respectively whereas with multiplex PCR assay the values were 0.93%, 10.24% and 4.65%, respectively, with concurrent infection of E. canis & H. canis (1.86%) and B. vogeli & E. canis (0.31%). The diagnostic sensitivity and specificity of multiplex PCR assay with respect to microscopy in the detection of B. vogeli, E. canis and H. canis varied from 69.15% to 100% and 85.11% to 92.33%, respectively revealing "fair" agreement by kappa value statistics and the data was statistically significant. The analytical sensitivity of multiplex PCR assay in the detection of B. vogeli, E. canis and H. canis was 100 pg, 10 pg and 0.1 pg, respectively, whereas the values for the singleplex counterpart were 0.1 pg, 0.01 pg and 0.01 pg. Furthermore, various risk factors viz. age, breed, sex, season and districts were non-significantly associated with the prevalence of these haemoparasites except for E. canis that revealed a significant association with districts by multiplex PCR assay. Therefore the multiplex PCR assay developed may be useful in identification of the aetiological agents of these diseases during their early phase, which may in turn be useful in development of better health care and appropriate treatment of suspected dogs, particularly in endemic regions.

Hematological profile of blood parasitic infected dogs in Southern Thailand

Background and Aim:

Tick-borne pathogens such as Babesia canis, Hepatozoon canis, and Ehrlichia canis can cause serious disease in canines. Each blood parasite can be associated with different hematological characteristics in infected dogs. Identification of hematological alterations during routine laboratory screening of blood samples from dogs displaying clinical signs is essential for diagnosing blood parasitic infections. This study aimed to evaluate parasitic infections and hematological alterations in blood samples of infected dogs in Southern Thailand.

Materials and Methods:

A total of 474 blood samples were collected from dogs presented at the Veterinary Teaching Hospital of the Prince of Songkla University between 2016 and 2019. An automatic hematology analyzer was used to establish hematological values; peripheral blood films were screened for blood parasites and their detection was associated with hematological alterations to determine the odds ratio (OR).

Results:

This study found that E. canis (n=127) was the most common blood parasite infecting dogs in southern Thailand, followed by H. canis (n=100) and B. canis (n=24). Hematological alterations caused by Ehrlichia infections included anemia, thrombocytopenia, monocytosis, and eosinophilia (OR=14.64, 17.63, 20.34, and 13.43, respectively; p<0.01). The blood samples of Hepatozoon-infected dogs were characterized by anemia, thrombocytopenia, leukocytosis, neutrophilia, and monocytosis (OR=6.35, 3.16, 12.80, 11.11, and 17.37, respectively; p<0.01). Anemia, thrombocytopenia, eosinopenia, and lymphopenia (OR=10.09, 33.00, 20.02, and 66.47 respectively; p<0.01) were associated with B. canis-infected dogs.

Conclusion:

These data support the fact that hematological abnormalities are a hallmark for the identification of tick-borne infections. The hematological values, hereby reported, can be used as a guideline for the clinical diagnosis of canine blood parasitic infections in Southern Thailand.

Prevalence of protozoan parasitic infections in domestic dogs in Andhra Pradesh, India

Faecal (2,250) and blood samples (1,350) of dogs received from Teaching Veterinary Clinical Complex (TVCC), Gannavaram, Veterinary Hospitals in and around Krishna district and nearby Krishna, Andhra Pradesh during last five years (January 2014 to December 2018) were examined to determine the prevalence of protozoan parasites. Faecal samples were analyzed by direct smear and floatation technique and blood samples after Giemsa's staining. The overall prevalence of protozoan parasitic infections including intestinal (15.60%) and haemoprotozoan (6.22%) infections was 12.10% (n=435). Six genera of protozoan parasites namely Cystisospora, Entamoeba, Ehrlichia, Trypanosoma, Babesia and Hepatozoon were identified. The most prevalent species was Cystoisospora (14.04%) and Hepatozoan canis (0.67%) was the least prevalent species. A significant relationship between age group, breed and prevalence of protozoan parasitism was observed. The prevalence of gastrointestinal and haemoprotozoan parasites was significant during winter and rainy seasons, respectively. Sex did not influence the overall prevalence of protozoan parasites.

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.

Clinicopathological and molecular profiles of Babesia vogeli infection and Ehrlichia canis coinfection

BACKGROUND AND AIM

Canine babesiosis, a tick-borne parasitic disease, is caused by the hemoprotozoa, Babesia vogeli, and Babesia gibsoni. Infection with these parasites, which is endemic globally, leads to life-threatening immunosuppression in dogs. The merozoites invade the red blood cells (RBCs) of infected dogs. Ehrlichia canis, an intracellular bacterium that infects monocytes, is transmitted by the same tick species (Rhipicephalus sanguineus) during blood consumption and coinfection with B. vogeli and E. canis has been reported. Although the hematology and biochemistry of canine babesiosis have been studied, more studies are needed to develop a better understanding of the hematobiochemical and molecular profiles associated with cases of single infection and coinfection of canine babesiosis in Thailand. This study aimed to investigate the hematological, biochemical, and molecular profiles of B. vogeli infection and E. canis coinfection.

MATERIALS AND METHODS

The study included 33 B. vogeli-positive blood samples and 11 E. canis-coinfected blood samples. To exclude coinfection with Hepatozoon canis and Anaplasma platys, only dogs with B. vogeli infection and B. vogeli-E. canis coinfection were included in the study. A multiplex polymerase chain reaction (PCR) assay was conducted to detect B. vogeli, E. canis, and H. canis, and a conventional PCR assay was conducted for the detection of A. platys. Besides, the PCR assay and sequencing, comprehensive data analysis was conducted, including a microscopic blood parasite examination and hematological and biochemical data analysis.

RESULTS

The comparison of the hematobiochemical data between the B. vogeli-positive and E. canis coinfection groups identified that there were statistically significant differences in the RBC parameters, including RBC count, hemoglobin concentration, hematocrit, and RBC distribution width (p=0.001). Neither B. vogeli infection nor coinfection with E. canis was associated with the sex, breed, recorded clinical signs, geographic origin of the dog and also B. vogeli 18S rRNA gene sequencing results.

CONCLUSION

Coinfection with E. canis increased the severity of babesiosis. The pathogenic mechanisms underlying this infection, such as destruction of RBCs, require further investigation. This study may enhance diagnosis, treatment, and prevention of canine babesiosis.

Molecular detection and genetic variability of Ehrlichia canis in pet dogs in Xinjiang, China

BACKGROUND AND AIM

As a tick-borne zoonotic pathogen, Ehrlichia canis has already posed a threat to public health and safety. This study aimed to clarify the prevalence and molecular characteristics of E. canis in pet dogs in Xinjiang, China.

MATERIALS AND METHODS

A total of 297 blood samples of pet dogs and 709 skin ticks (Rhipicephalus sanguineus sensu lato) were subjected to molecular detection using PCR for E. canis 16S rRNA gene, and then, positive samples were amplified, sequenced, and phylogenetically analyzed for E. canis gp36 gene.

RESULTS

The PCR detection showed that the positive rate of PCR was 12.12% (36/297) in blood samples and 15.23% (108/709) in tick samples, respectively. Based on the phylogenetic analysis of E. canis gp36 protein, these E. canis strains in different geographical regions of the world can be divided into Genogroup I and Genogroup II. Among them, the Xinjiang epidemic strain XJ-6 and 533, 36, 1055, Kasur1, and Jake strains were clustered into subgroup 1.1 of Genogroup I, while the XJ-2, XJ-21, and XJ-35 strains and the TWN1, TWN4, CM180, and CM196 strains were closely related and belonged to subgroup 2.2 of Genogroup II, displaying high genetic diversity.

CONCLUSION

This is the first study focusing on the molecular epidemiology of E. canis infection in pet dogs, which revealed that E. canis infection had been occurred in Xinjiang, China. More importantly, this study confirmed that the substantial variability in immunoreactive protein gp36 from E. canis strains circulating in pet dogs.

Comparison of conventional polymerase chain reaction and routine blood smear for the detection of Babesia canis, Hepatozoon canis, Ehrlichia canis, and Anaplasma platys in Buriram Province, Thailand

Background and Aim:

Dog blood parasites are important tick-borne diseases causing morbidity and mortality in dogs worldwide. Four dog blood parasites species are commonly found in Thailand: Babesia canis, Hepatozoon canis, Ehrlichia canis, and Anaplasma platys. They are transmitted easily by tick species. However, there is little prevalence data available in Thailand. Diseases presentation of blood parasites infection is similar, but the treatment of each species is different. Current diagnosis mainly relies on microscopic examination of a stained blood smear, which has low sensitivity. Therefore, accurate diagnosis is important. This study aims to evaluate the efficacy of the conventional polymerase chain reaction (PCR) method and routine blood smears in the detection of four blood parasites species in dogs from Buriram Province, Thailand.

Materials and Methods:

In total, 49 EDTA-blood samples were collected from dogs in Buriram Province, Thailand. Blood parasite infection was compared using the Giemsa-stained blood smear technique to identify the parasite under a 100× oil immersion with PCR amplification of the 18S rDNA gene of B. canis and H. canis and the 16S rDNA gene of E. canis and A. platys.

Results:

Only one dog out of 49 was positive for H. canis based on microscopic examination whereas the PCR results showed that 2.04% (1/49), 4.08% (2/49), 36.73% (18/49), and 30.61% (15/49) of dogs were positive for B. canis, H. canis, E. canis, and A. platys, respectively. Moreover, coinfection was found in 16.33% (8/49) of dogs.

Conclusion:

This study is the first report to demonstrate the molecular prevalence of blood parasites in domestic dogs in Buriram Province. The results indicated that the PCR method exhibited much higher sensitivity and reliability for blood parasites diagnosis in dogs. Therefore, our data support serious concern regarding the diagnostic technique used in routine blood testing and also provide prevalence data for the management and control of blood parasites in this area.

Canine babesiosis among working dogs of organised kennels in India: A comprehensive haematological, biochemical, clinicopathological and molecular epidemiological multiregional study

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First holistic study on canine babesiosis among working dogs from India.

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B. gibsoni babesiosis is posing a diagnostic & therapeutic challenge in this country.

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Atypical babesiosis (MODS, DIC) are being maidenly documented from this country.

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Simple PCR assay results were statistically found to be significantly false negative.

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Nested PCR assay to be relied upon as screening and for epidemiological studies.

Canine babesiosis is a serious disease among tick-borne haemoprotozoan diseases, globally. The present study was envisaged for carrying out thorough investigation of the disease among working dogs of organised kennels situated in different agro-climatic zones of India as comprehensive understanding of the disease from this country was pertinently lacking. During the study period of three years (2012–2014), 330 dogs suspected for babesiosis were examined for clinicopathology by their physical examination, haematological and biochemical parameters estimation, while the detection of apicomplexan parasites was confirmed by using various diagnostic techniques i.e. by conventional microscopy, by two different Babesia specific 18S rRNA based PCR protocols (conventional/simple PCR and nested PCR assays) followed by sequencing of obtained PCR amplicons for Babsesia spp. identification. Out of 330 clinical cases screened 5.15% (17/330), 9.09% (30/330) and 15.45% (51/330) were found to be positive in microscopic examination, simple- and nested- PCR assay, respectively. Comparative statistical analyses of these diagnostic assay results revealed that significant difference exists among the three diagnostic methodologies and thus it is recommended that the nested PCR technique be relied upon as a screening molecular assay and also for epidemiological studies of the disease in this country. Phylogenetic analysis based on 18S rRNA depicted the monophyletic nature and clonal expansion among all the B. gibsoni, under study. Sequencing results of PCR amplicons revealed that B. gibsoni has predominantly established itself over B. vogeli as former was incriminated in 47 cases while latter was confirmed in only four animals. Based on the clinical severity, these 51 affected animals were classified into three main groups’ of 17 animals each viz., apparently healthy-, simple or uncomplicated babesiosis- and atypical or complicated babesiosis- group. Haematological and biochemical profiling of these dogs confirmed the characteristics findings of infection by both the Babesia spp. It was observed that the infection by small form of Babesia (B. gibsoni) is posing a significant therapeutic challenge and chemosterilization by commonly prescribed anti-protozoal drugs was not achieved as clinical relapses were often observed. The clinical signs, sequence based confirmation and severity of the infection suggested that there is a positive selection of B. gibsoni (smaller form) over B. vogeli (larger form) in this country and raises serious concerns as prognosis in former is considered to be poor compared to latter. Thus, these findings have opened new paradigms for planning of pragmatic control strategies against this emerging canine health problem.

Molecular evidence of Ehrlichia canis and Anaplasma platys and the association of infections with hematological responses in naturally infected dogs in Kalasin, Thailand

Background

Tick-borne bacteria, Anaplasma platys and Ehrlichia canis are well recognized as the etiology of anemia and thrombocytopenia in dogs. The clinical signs of anaplasmosis and ehrlichiosis range from asymptomatic to severe symptoms . There are insufficient studies about epidemiological surveys of these blood parasites, also the association of infections with the hematological study.

Aim

This study aimed to screen A. platys and E. canis in naturally infected dogs and the effects of the infection on the levels of packed cell volume (PCV) and platelet count.

Materials and Methods

A total of 68 blood samples were collected from free-roaming dogs at Nong Kung Sri district, Kalasin Province, Thailand, and examined for A. platys and E. canis infection by polymerase chain reaction (PCR) and measured PCV levels and platelet count.

Results

Using nested PCR, 42.65% of dogs were infected with one or two pathogens. The molecular detection of anaplasmosis and ehrlichiosis in this population was 29.4% (95% confidence interval [CI]: 18.98-41.71) and 25% (95% CI: 14.4-35.3), respectively. Coinfection occurred at 11.8% (95% CI: 5.22-21.87). Infection with E. canis and coinfection showed significant association with PCV levels (p<0.05) while A. platys infection showed no statistical relationship. Infection with A. platys, E. canis, and coinfection had a non-significant correlation with platelet count (p>0.05).

Conclusion

This study provides data of anaplasmosis and ehrlichiosis in free-roaming dogs which indicated that these zoonotic diseases are widespread and require for disease frequency determination, especially in Kalasin Province of Thailand where data of tick-borne infections in dogs have not been reported.

Development of loop-mediated isothermal amplification (LAMP) assay for detection of Hepatozoon canis infection in dogs

The laboratory diagnosis of canine hepatozoonosis, caused by Hepatozoon canis is tedious, especially in chronic and latent infections. In the present investigation, a loop mediated isothermal amplification (LAMP) assay was developed and standardized targeting the partial 18S rRNA gene (GenBank accession no. KU096058). The LAMP primers specifically amplified H. canis DNA, whereas no amplification was detected in DNA samples from dogs infected with Babesia vogeli, B. gibsoni, Ehrlichia canis and Trypanosoma evansi, and no amplification was observed in DNA samples from H. canis-free dogs. The threshold sensitivity level of the assay was determined to be 15 fg of genomic DNA of H. canis. Furthermore, evaluation of blood samples collected from 250 dogs presented at Small Animal Clinics, Teaching Veterinary Clinical Complex, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab (India) was carried out for the presence of H. canis by microscopy, 18S PCR assay and LAMP assay. Of the total samples subjected to these tests, LAMP detected H. canis in 75 samples, while 18S PCR and microscopy detected H. canis in 28 and 9 samples, respectively. The present investigation has developed, for the first time, a highly sensitive, specific and rapid LAMP assay for the detection of H. canis, which has practical applications for the screening of field samples.

Molecular characterization of Hepatozoon canis from farm dogs in Pakistan

Hepatozoon canis is a tick-borne pathogen of canids, which is distributed worldwide. However, very little is known about this protozoan parasite in Pakistan. This study provides the first molecular evidence of H. canis from farm dogs from three agro-ecological zones of Punjab, Pakistan. A conventional PCR targeting the 18S rRNA gene was used to characterize H. canis from farm dogs from three districts, namely Kasur, Rawalpindi, and Muzaffargarh, in Punjab. Of 341 blood samples tested, 155 (45.5%) were positive for H. canis, 73 (61.3%) from Kasur, 46 (42.5%) from Rawalpindi, and 36 (31.5%) from Muzaffargarh. Phylogenetic analyses revealed that 18S rRNA sequences of H. canis from this study clustered in three clades with those of H. canis from previously published studies to the exclusion of all other Hepatozoon spp. included in the analysis. This study provides the first insight into H. canis from farm dogs in Pakistan. Furthermore, it lays a foundation for future studies of the parasite to assess the impact of canine hepatozoonosis in dogs from various agro-ecological zones in Pakistan where pet ownership of dogs is increasing.

Canine Monocytic Ehrlichiosis among working dogs of organised kennels in India: A comprehensive analyses of clinico-pathology, serological and molecular epidemiological approach

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Significant difference was observed between molecular and sero-prevalence of E. canis.

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Phylogenetic analysis revealed divergence in isolates from Brazil & USA.

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Prevalence studies for CME should also involve screening of apparently healthy dogs.

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Concurrent infection of CME and Babesia gibsoni in working dogs was found to be fatal.

Canine Monocytic Ehrlichiosis (CME) is a serious tick-borne rickettsial disease affecting canine populations globally. Besides few reports from stray and pet dogs from localised geographical regions (cities/towns/small states), a comprehensive study on prevalence of Ehrlichia canis (E. canis) among working dogs from different geo-climatic zones of India was pertinently lacking. Study of CME among these dog populations was thus carried out, encompassing clinical aspects and different diagnostic methodologies viz., microscopy, serology and molecular biology. During the two-year study period, clinical specimens from 225 cases suspected of canine ehrlichiosis were examined for clinical pathology and presence of the haemoparasites. Overall prevalence of ehrlichiosis by microscopic examination, commercial dot-ELISA kit and nested PCR assay was estimated to be 1.3%, 19.1% and 5.8%, respectively, which were found to be statistically significant by McNemar Chi squared test (p < 0.05). It was also observed that possibly due to widespread use of doxycycline therapy in field, CME presently does not remain a potential threat which it uses to pose earlier. However, concurrent infections of E. canis and Babesia gibsoni were found to be mostly fatal. Keeping in view of high number of apparently healthy dogs (24) out of total positive cases (46) observed during the study, it is recommended that prevalence studies on CME should also involve screening of apparently healthy dogs. Phylogenetic analysis carried on partial sequencing of 16S rRNA of E. canis strains revealed that all of the Indian strains clustered in a single clade with other E. canis species from India and rest of the world. Molecular divergence was observed among the sequences of Brazilian and American isolates which were also included in the present study. These findings have thus opened a new paradigm for planning of pragmatic control strategies against CME.