A Possible treatment strategy and clinical factors to estimate the treatment response in Bebesia gibsoni infection

Standardization of quantitative PCR (qPCR) method to detect the level of parasitaemia in Babesia gibsoni infected dogs

The present investigation aimed to quantitatively assess the level of parasitemia in dogs using qPCR.The dogs selected for this study were infected with the haemoprotozoan parasite Babesia gibsoni. In the study, dogs diagnosed with babesiosis were divided into two groups (n = 12) and subjected to distinct treatment strategies. The first group received clindamycin-metronidazole-doxycycline (CMD) therapy, while the second group was treated with a combination of buparvaquone-azithromycin (BPV-AZM). The level of parasitemia in the infected dogs was determined using an absolute quantification-based qPCR method. This assessment was conducted both prior to initiating the treatment and on the 10th day following the commencement of the treatment protocols. On the tenth day after the initiation of treatment, the CMD group exhibited a lower level of parasitemia in comparison to the BPV-AZM group. In the CMD treated groups, the mean parasitemia decreased from 4.9E + 06 to 3.4E + 06, indicating a reduction in parasitic load. Conversely, in the BPV-AZM treatment groups, the mean parasitemia increased from 1.62E + 06 to 2.87E + 06, suggesting an increase in parasitic load. On the 10th day, the CMD-treated group demonstrated a statistically significant decline in the level of parasitemia, with a P-value of ≤0.001. This indicates a strong and significant reduction in parasitic load following the CMD treatment. Therefore, the absolute quantification-based qPCR method could effectively assess the initial treatment response by measuring the level of parasitemia.

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

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

Babesia gibsoni Infection in Dogs—A European Perspective

Simple Summary

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

Abstract

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

Clinical Efficacy and Safety of Malarone®, Azithromycin and Artesunate Combination for Treatment of Babesia gibsoni in Naturally Infected Dogs

Babesia gibsoni is a tick-borne protozoal blood parasite that may cause hemolytic anemia, thrombocytopenia, lethargy, and/or splenomegaly in dogs. Many drugs have been used in management of canine babesiosis such as monotherapy or combined treatment, including diminazene aceturate, imidocarb dipropionate, atovaquone, and antibiotics. This report examines the effectiveness and safety of Malarone®, azithromycin (AZM) and artesunate (ART) combination for the treatment of babesiosis in dogs naturally infected with Babesia gibsoni. Twelve American Pit Bull Terriers were included in the experiment. Examined dogs underwent clinical and laboratory analysis including hematology and biochemistry profile and serum protein electrophoresis. After diagnosis, the dogs received combined therapy with Malarone® (13.5 mg/kg PO q24 h), azithromycin (10 mg/kg PO q24 h) and artesunate (12.5 mg/kg PO q24 h) for 10 days. The combined treatment improved hematology and biochemical parameters to the reference range gradually during the first 14 days already, resulting in the stable values until day 56 after treatment. No clinically apparent adverse effects were reported during treatment and monitoring. No relapses of parasitemia were detected in control days 180, 360, 540 and 720 in all dogs. Results of the study indicate that the combined treatment leads to successful elimination of parasitemia in chronically infected dogs with B. gibsoni.

Prevalence, genetic, and biochemical evaluation of immune response of police dogs infected with Babesia vogeli

Background and Aim:

Babesia species are tick-borne protozoan parasites of apicomplexan type which infect the erythrocytes of dogs it ranges from subclinical to severe cases, depending on different factors such as immune status, age, and presence of other co-infections with the Babesia species. Hence, this study aimed to identify the protozoan parasites infecting police dogs of different breeds, ages, and both sexes in Egypt. Concerning molecular detection of Babesia vogeli using conventional polymerase chain reaction sequencing and phylogenetic analysis, followed by the assessment of immunological and biochemical status of infected dogs.

Materials and Methods:

The blood of 242 police K9 dogs was collected. The age, breed, sex, and health status with clinical signs of dogs were recorded. Hematological, biochemical, and oxidative stress analyses of the blood were performed together with gene expression analysis using two genes (gamma interferon [IFN-γ] and tumor necrosis factor-alpha [TNF-α]). The identification of the causative agent was performed using molecular analysis of the 18S ribosomal RNA (rRNA). The 18S rRNA region of canine Babesia spp. was successfully amplified, and sequencing data were deposited in GenBank (accession number: MT565474.1), which resembled those of B. vogeli.

Results:

The results of blood samples screening revealed that of the 242 blood samples, 62 were positive for B. vogeli infection. The infection rate in male dogs was higher than that in female dogs. The police dogs were classified into the following three groups of dogs: (1^st group) healthy, (2^nd infected with B. vogeli, and mixed infection of B. vogeli and Ehrlichia canis). The oxidative stress biomarkers levels in B. vogeli infected dogs were greater than that of healthy dogs. Likewise, IFN-γ and TNF-α level in B. vogeli infected dogs were elevated in infected dogs.

Conclusion:

Our findings demonstrated that B. vogeli had completely adverse effects on the health condition of the police dogs that may lead to death in some dogs.

Reduced expression levels of heat shock protein 90 in a diminazene aceturate-resistant Babesia gibsoni isolate

Heat shock protein 90 (HSP90) is a molecular chaperon and an essential component for stage differentiation and intracellular growth inside the host cells of many protozoans. HSP90 of Babesia gibsoni (BgHSP90) was suggested to function in the development of diminazene aceturate (DA)-resistance. Therefore, we examined the expression level of BgHSP90 in a DA-resistant B. gibsoni isolate. Transcription of the BgHSP90 gene in the DA-resistant isolate and wild-type B. gibsoni was assessed by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). As a result, the copy number and relative amount of BgHSP90 transcripts in the DA-resistant isolate were significantly lower than those in the wild-type. Moreover, a rabbit anti-recombinant BgHSP90 antibody was developed, and the protein synthesis of BgHSP90 in the DA-resistant isolate was compared with that in the wild-type by Western blot analysis and indirect fluorescence assay. There was significantly less BgHSP90 protein than in the wild-type. Additionally, the relative intensity of BgHSP70 in DA-resistant isolate was also lower than that in the wild-type. This suggested that the expression of BgHSP90 and BgHSP70 in the DA-resistant B. gibsoni isolate was suppressed and that the reduced amount of BgHSP90 and BgHSP70 might cause the weak proliferation of the DA-resistant isolate. Further studies are necessary to elucidate the function of BgHSP90.

An alternative combination therapy with metronidazole, clindamycin and doxycycline for Babesia gibsoni (Asian genotype) in dogs in Hong Kong

Babesia spp. are globally distributed hemoparasites that cause disease in many mammalian species. The species Babesia gibsoni (Asian genotype) is prevalent and endemic in many Asian countries but has also been reported in growing numbers in countries outside of Asia. Standard therapies for the treatment of B. gibsoni often fail to result in consistent and successful clearance of the organism. This study evaluated the use of a combination of three antibiotics: metronidazole, clindamycin and doxycycline after atovaquone and azithromycin failed to eliminate the infection on a polymerase chain reaction (PCR) test. The aim of this study was to determine whether the triple antibiotic combination was an appropriate alternative or additional treatment for the elimination of B. gibsoni. The medical records of 24 patients treated from December 2012 to July 2015 were retrospectively analyzed. The diagnosis of B. gibsoni was confirmed with a PCR test that was also used to assess treatment response. All patients were initially treated with the standard therapy, atovaquone and azithromycin with a 25% success rate clearing B. gibsoni. Dogs that remained positive on PCR using the standard therapy were then treated with the triple antibiotic protocol achieving an 87% success rate. The inclusion of an alternative and potentially effective protocol for the treatment of B. gibsoni would increase the options for the current therapeutic options, could aid in clearance of the organism and offer a more affordable option for clients.

Babesia gibsoni cytochrome b mutations in canine blood samples submitted to a US veterinary diagnostic laboratory

BACKGROUND

Babesiosis caused by Babesia gibsoni is recognized throughout the world and can be difficult to treat. Resistance to atovaquone is associated with mutations in the B. gibsoni mitochondrial genome, specifically the M128 position of cytochrome b (cytb). The prevalence of cytb mutations in North America has not been reported.

HYPOTHESIS/OBJECTIVES

The objective of our study was to describe the prevalence of cytb M128 mutations in B. gibsoni in canine blood samples submitted to a US veterinary diagnostic laboratory. A secondary objective was to determine whether or not some dogs had wild-type cytb in our initial samples then had M128 mutations detected in follow-up samples.

ANIMALS

One-Hundred seventy-four dogs that tested positive for the presence of B. gibsoni between 2012 and 2017.

METHODS

Case series of consecutive samples submitted to a veterinary diagnostic laboratory. Partial B. gibsoni cytb genes were amplified by polymerase chain reaction and screened for the presence of mutations at the M128 position.

RESULTS

The overall prevalence of M128 mutants was 3.5% (6/173 dogs) in the initial samples. The incidence of new cytb mutants in dogs that tested positive for B. gibsoni, which then had follow-up testing, was 12.1% (5/41). Conclusions and Clinic Importance: Our study reaffirms that B. gibsoni infection is widespread and most commonly detected in American Staffordshire Terrier/American Pit Bull Terrier dogs (128/174, 74% of the infected dogs in our study). The prevalence of cytb mutations does not warrant pretreatment genotyping.

Rapid Diagnosis of Babesia gibsoni by Point-of-Need Testing by Insulated Isothermal PCR in Dogs at High Risk of Infection

Background

Dogs seized by law enforcement agencies during dogfighting investigations are at increased risk of Babesia gibsoni infection. A rapid and cost‐effective diagnostic test would increase the feasibility of mass screening of dogs for infection and monitoring treatment efficacy in B. gibsoni‐infected dogs.

Objective

To determine the performance of a point‐of‐need insulated isothermal PCR (iiPCR) test for diagnosis of B. gibsoni in dogs rescued in dogfighting investigations.

Animals

Two hundred and thirty‐three dogs seized in dogfighting investigations.

Methods

Cross‐sectional study. Whole blood samples were tested for B. gibsoni and Babesia spp. by iiPCR. Results were compared to a reference standard comprised of concordant results from real‐time PCR in a commercial diagnostic laboratory and antibody titers.

Results

The iiPCR system was quick to learn, portable, and had a short processing time of <2 hours. Sensitivity and specificity of the iiPCR assay for B. gibsoni were 90% (95% confidence interval [CI] 81–95%) and 99% (CI, 95–100%), respectively. Sensitivity and specificity of the iiPCR assay for Babesia spp. were 87% (CI, 78–93%) and 98% (CI, 0.94–99%), respectively.

Conclusions and Clinical Importance

The iiPCR system produced few false‐positive results, indicating that positive results are likely to represent true infections when used in high‐risk animals. The iiPCR system can fail to identify 10–15% of truly infected dogs. However, the portability, speed, and economy of the iiPCR system compared to testing through a reference laboratory can allow rescue groups to screen and identify infection in more dogs.

Canine Babesiosis: Where Do We Stand?

Canine babesiosis is a tick-borne disease caused by protozoal haemoparasites of different Babesia species. Babesiosis is one of the most important globally extended and quickly spreading tick-borne infections of dogs. This comprehensive review gives an in-depth overview of Babesia species currently identified in dogs together with relevant vector tick species and their geographical distribution, life cycle and transmission of parasite. The main mechanisms in the pathogenesis of babesiosis are described and elucidated by recent literature overview. As Babesia infection causes a disease with very variable clinical manifestations, special attention is given to clinical signs, laboratory features and clinicopathological findings. The diagnosis of canine babesiosis by microscopy, serological and molecular methods is reviewed, together with recent advances in mass spectrometry based assays. Accurate detection and species recognition are important for the selection of the appropriate therapy, monitoring and prediction of the outcome of the disease. Finally, guidelines for the treatment and prevention of canine babesiosis are given.

A review of canine babesiosis: the European perspective

Canine babesiosis is a significant tick-borne disease caused by various species of the protozoan genus Babesia. Although it occurs worldwide, data relating to European infections have now been collected for many years. These data have boosted the publication record and increased our working knowledge of these protozoan parasites. Both the large and small forms of Babesia species (B. canis, B. vogeli, B. gibsoni, and B. microti-like isolates also referred to as "B. vulpes" and "Theileria annae") infect dogs in Europe, and their geographical distribution, transmission, clinical signs, treatment, and prognosis vary widely for each species. The goal of this review is to provide veterinary practitioners with practical guidelines for the diagnosis, treatment and prevention of babesiosis in European dogs. Our hope is that these guidelines will answer the most frequently asked questions posed by veterinary practitioners.

The epidemiological survey for atovaquone resistant related gene of Babesia gibsoni in Japan

In 73 gDNA samples from Babesia gibsoni-infected dogs, the M121I variant population was measured by using allele-specific real-time PCR. Although the mechanism of atovaquone against B. gibsoni has not been clearly identified, it is reported that the mitochondria cytochrome b gene of the atovaquone-resistant B. gibsoni had a single-nucleotide substitution at nt363 (G to T), which resulted in the substitution of methionine with isoleucine (M121I). In this study, 3/73 samples showed over 5% M121I variant population. Although the M121I variant population is a low percentage, it runs the risk of spreading drug-resistant parasites. It is important to prevent the spread of drug-resistance, so we need to gather information about this at regular intervals.

Canine babesiosis: a perspective on clinical complications, biomarkers, and treatment

Canine babesiosis is a common tick transmitted disease of dogs worldwide. A number of Babesia sp. can infect dogs and the spectrum is increasing as molecular methods are developed to differentiate organisms. Clinical signs are generally attributed to hemolysis caused by the organisms in the erythrocytes but in some animals with some Babesia spp. there can be an immune mediated component to the anemia and/or a severe inflammatory reaction associated. This complicated form of canine babesiosis is associated with high morbidity and mortality. A variety of clinical markers has been investigated to enable clinicians to provide more accurate prognoses and adapt their treatments which vary according to the infecting species. In this review, we discuss the taxonomy, clinical signs, diagnostic imaging, clinical biomarkers, treatment, and prophylaxis of one of the most common and important diseases of dogs worldwide.

In vitro and in vivo safety and efficacy studies of amphotericin B on Babesia gibsoni

Babesia gibsoni is a causative pathogen of canine babesiosis, which is commonly treated with anti-babesial drugs; however, the development of novel, more effective anti-babesial drugs is necessary because the currently used drugs cannot remove the parasites from dogs. Therefore we investigated the anti-babesial effect of amphotericin B (AmB), a membrane-active polyene macrolide antibiotic. The interaction of such compounds with sterols in bilayer cell membranes can lead to cell damage and ultimately cell lysis. AmB exhibits in vitro activity against B. gibsoni in normal canine erythrocytes within 12h. We also studied liposomal AmB (L-AmB), a liposomal formulation of AmB that required a longer incubation period to reduce the number of parasites. However, L-AmB completely inhibited the invasion of free parasites into erythrocytes. These results indicated that free parasites failed to invade erythrocytes in the presence of L-AmB. Both AmB and L-AmB induced mild hemolysis of erythrocytes. Moreover, the methemoglobin level and the turbidity index of erythrocytes were significantly increased when erythrocytes were incubated with AmB, suggesting that AmB induced oxidative damage in erythrocytes. Finally, the anti-babesial activity of AmB in vivo was observed. When experimentally B. gibsoni-infected dogs were administered 0.5 and 1mg/kg AmB by the intravenous route, the number of parasites decreased; however, recurrence of parasitemia was observed, indicating that AmB did not eliminate parasites completely. Blood urea nitrogen and creatinine of dogs were abnormally elevated after the administration of 1mg/kg AmB. These results indicate that AmB has in vivo activity against B. gibsoni; however, it does not eliminate parasites from infected dogs and affects kidney function at a high dose.

Efficacy of Malarone(®) in dogs naturally infected with Babesia gibsoni

The efficacy of Malarone^® alone and in combination with doxycycline (DOXY) against Babesia gibsoni infections was examined in 8 dogs. In all dogs except one treated with Malarone^®, parasitemia decreased, and anemia improved soon after initiation of treatment. However, 3 of 4 dogs treated with Malarone^® relapsed, and relapse was inhibited in 2 of 4 dogs treated with Malarone^® and DOXY. All relapsed dogs responded well to the second treatment, but 1 dog relapsed again and did not respond to the third treatment. Malarone^® may be useful for acute stage of B. gibsoni infections, and at least second repeating treatment might be effective.

The in vitro interactions and in vivo efficacy of atovaquone and proguanil against Babesia gibsoni infection in dogs

In vitro interactions between atovaquone (ATV) and proguanil (PG) against Babesia gibsoni and the clinical efficacy of this combination therapy using Malarone(®) which is the antimalarial drug containing ATV and PG were evaluated. This combination showed synergism against uncloned wild-type and ATV-resistant B. gibsoni in vitro examinations using a modified fixed ratio method. Administration of Malarone(®) to experimentally B. gibsoni infected two dogs in chronic stage and three dogs in acute stage resulted in decrease in parasitemia, and clinical improvements were observed. However, all dogs showed relapse of parasitic infection with a single-nucleotide polymorphism in the cytchrome b gene (M121I). Some side effects were confirmed: self-limiting vomiting in two dogs and hyperphosphatasia in another dog. Mild increases in the levels of alanine aminotransferase were confirmed in two dogs. This is the first study to evaluate the interactions in vitro and the clinical efficacy of ATV and PG against canine B. gibsoni infection in dogs.

Generalized alopecia with vasculitis-like changes in a dog with babesiosis

A locally bred, 12-year-old, intact female Satsuma dog presented with generalized alopecia. Erythema, crusts and desquamation were observed primarily on the truck. Papules and erosions were present in the pinnae, and there were multiple areas of skin necrosis on the right forelimb. The cutaneous lesions had not responded to treatment with systemic antibiotics and prednisolone. The dog also had progressive anemia. Babesia gibsoni was detected in the blood, and the dog was treated with antiprotozoal agents. The skin lesions and anemia improved, but relapsed after the treatment was discontinued. Histopathological examination of skin biopsies revealed findings suggestive of early leukocytoclastic vasculitis or ischemic vasculopathy.

Molecular epidemiological survey of the Babesia gibsoni cytochrome b gene in western Japan

In this study, we conducted a survey of the cytochrome b (cytb) gene of Babesia gibsoni (B. gibsoni) isolated from clinical cases to determine the prevalence of potential atovaquone (ATV)-resistant variants. Ninety-two blood samples were collected from naturally B. gibsoni infected dogs. The cytb nucleotide sequence was determined by direct sequencing. Twelve non-synonymous amino acid substitutions were identified in cytb. The principal ATV-resistant substitution, M121I, was detected in three cases. This survey determined that potentially ATV-resistant B. gibsoni strains are present in dogs in Japan.

The therapeutic efficacy of two antibabesial strategies against Babesia gibsoni

Various combination strategies for treating Babesia gibsoni have been described. However, relapses after administering some combinations of antibabesial drugs and the presence of drug-resistant B. gibsoni still pose significant challenges to veterinarians. To compare the efficacy of a combination of clindamycin, diminazene, and imidocarb (CDI) to that of a combination of atovaquone and azithromycin (AA) for the treatment of B. gibsoni and to correlate drug efficacy with B. gibsoni mutations, 30 client-owned dogs with natural B. gibsoni infections were collected in the study. 17 dogs were treated with AA, and 13 dogs were treated with CDI combination. Hematological parameters were recorded on the day that the dogs were presented for treatment and during treatment. To detect the parasitic DNA, the B. gibsoni 18S rRNA gene was amplified, and to analyze the mutations, the cytochrome b (CYTb) gene was sequenced. The therapy duration for all of the dogs that recovered was 23.3±7.8 days in the AA group and 41.7±12.4 days in the CDI group. Nine of the 17 dogs in the AA group and 11 of the 13 dogs in the CDI group completely recovered. Seven dogs in the AA group and 2 dogs in the CDI group relapsed after treatment. The M121I mutation in the B. gibsoni CYTb gene was detected in all of the samples that were collected from AA-relapsed and AA-nonremission dogs. The dogs in the CDI group exhibited higher recovery rates and lower relapse rates during treatment for B. gibsoni infection. In addition, the detected M121I mutation was associated with AA treatment. The CDI combination is a promising alternative treatment strategy for B. gibsoni.

Development of in vitro atovaquone-resistant Babesia gibsoni with a single-nucleotide polymorphism in cytb

An atovaquone (ATV)-resistant Babesia gibsoni was developed by in vitro exposure of uncloned wild type (WT) B. gibsoni to 800 nM ATV for 6 days. Sequence analysis of mitochondrial genes showed a single-nucleotide polymorphism (SNP) at cytb nt363 (G to T) that resulted in the substitution of methionine with isoleucine (M121I), which is one of the SNPs reported in a previous in vivo study. 363T or 363G allele-specific real-time polymerase chain reaction (PCR) revealed that an M121I variant was present in over 99% of the ATV-resistant population. As neither ATV resistance nor gene polymorphisms appeared in the B. gibsoni WT sibling clones, the expression of ATV resistance in this study was suspected to be because of selective multiplication of the B. gibsoni M121I variant. This ATV-resistant B. gibsoni displayed the same sensitivity as the WT B. gibsoni against 5 other drugs, including diminazene aceturate, azithromycin, doxycycline, clindamycin, and proguanil. This is the first report on the in vitro establishment of an ATV-resistant B. gibsoni with gene polymorphisms.

Effects and mechanisms of action of polyene macrolide antibiotic nystatin on Babesia gibsoni in vitro

Nystatin is a membrane-active polyene macrolide antibiotic and a channel-forming ionophore. Nystatin exhibits in vitro activity against Babesia gibsoni infecting normal canine erythrocytes containing low potassium (LK) and high sodium concentrations, i.e., LK erythrocytes. The calculated IC(50) value of nystatin against B. gibsoni infecting LK erythrocytes was 31.96 µg/ml. The anti-babesial activity of nystatin disappeared when B. gibsoni in LK erythrocytes were incubated in culture media containing high potassium concentrations (HK). Moreover, when the parasites were harbored in canine HK erythrocytes, which contained high potassium and low sodium concentrations as a result of high Na-K-ATPase activity, the in vitro anti-babesial activities of nystatin also disappeared, apparently due to protection by HK erythrocytes. This suggested that nystatin could show in vitro anti-babesial activity against B. gibsoni by its ionophorous activity, the same as other ionophores such as valinomycin. Subsequently, the effects of nystatin on the host cells were observed. Nystatin could not modify the intracellular concentrations of potassium, sodium, adenosine triphosphate, or glucose in either LK or HK erythrocytes, although it caused weak hemolysis in HK erythrocytes. In addition, nystatin did not affect the survival of canine peripheral polymorphonuclear leukocytes. In conclusion, nystatin destroyed B. gibsoni by ionophorous activity but did not affect either canine erythrocytes or leukocytes in vitro.

Evaluation of three automated human immunoturbidimetric assays for the detection of C-reactive protein in dogs

C-reactive protein (CRP) is a major, acute-phase protein in dogs; however, there is a need for automated assays to ensure in-time patient monitoring. Three automated immunoturbidimetric assays (Randox, Thermo, and Wako) developed for human beings were evaluated for their ability to detect canine CRP, including method validation, evaluation of diagnostic use, and establishment of exploratory reference intervals. Sera from 36 healthy dogs and 82 diseased dogs were included for method comparison with the enzyme-linked immunosorbent assay (ELISA; Tridelta) serving as the reference method. A nonparametric estimate of the 1-sided 95% reference interval was established (n = 36). Precision study revealed good intra-assay coefficients of variation (CVs) of 1-10%, 0-9%, and 2-13% for the Randox, Thermo, and Wako assays, respectively. Interassay CVs were 18%, 24%, and 19% respectively. Because of a low linear range, the Thermo test was considered unsuitable for use with canine specimens. No significant differences were present between the results obtained with the Randox and Wako assays with CRP concentrations less than 15 mg/l; however, median CRP results differed significantly between the Thermo test and the ELISA (P = 0.03). Bland-Altman analysis detected a proportional bias of 0.28, -0.59, and 0.61 mg/l for the Randox, Thermo, and Wako assays, respectively. For all tests, median CRP values were significantly different between healthy dogs and dogs with neoplasia. The upper limit of the reference intervals were 8.2 and 9.9 mg/l for the Randox and Wako assays, respectively. In contrast to the Thermo test, the Randox and Wako assays were suitable for detection of abnormally high canine CRP concentrations; however, improvement of assay precision and evaluation of accuracy are warranted before their clinical use with canine specimens.

Clinical management of canine babesiosis

OBJECTIVE

To review and summarize current information regarding epidemiology, pathogenesis, and pathophysiology leading to the various clinical syndromes associated with canine babesiosis. Diagnosis, treatment, preventative strategies, and zoonotic implications are discussed.

ETIOLOGY

Babesiosis is caused by hemoprotozoa of the genus Babesia. Numerous species of Babesia exist worldwide. An increased incidence of babesiosis is described, especially in North America. The babesial organism spends the majority of its life cycle within the erythrocyte of the definitive host, resulting in hemolysis, with or without systemic complications.

DIAGNOSIS

Definitive diagnosis depends on direct visualization of the organism on blood smear or polymerase chain reaction. A positive serologic antibody test indicates exposure with or without active infection.

THERAPY

Antiprotozoal drugs, antimicrobials, and supportive care are the mainstays of babesiosis therapy.

PROGNOSIS

Prognosis depends on the severity of disease, which in turn depends on both organism and host factors. Clinical syndromes associated with a poorer prognosis include red biliary syndrome, acute renal failure, acute respiratory distress syndrome, neurologic dysfunction, acute pancreatitis, cardiac dysfunction, and hypoglycemia.

Feline babesiosis

OBJECTIVE

To review and summarize current information regarding the etiology, clinical presentation, diagnosis, treatment, and prognosis of feline babesiosis, especially with regard to features distinct from canine babesiosis.

ETIOLOGY

Babesiosis is caused by hemoprotozoa of the genus Babesia. Numerous species of Babesia exist worldwide. The babesial organism spends the majority of its life cycle within the erythrocyte of the definitive host, resulting in hemolysis, with or without systemic complications.

DIAGNOSIS

Definitive diagnosis depends on direct visualization of the organism on blood smear or a positive polymerase chain reaction. Positive serologic tests indicate only exposure, with or without active infection.

THERAPY

Antiprotozoal drugs and supportive care are the mainstays of therapy. Primaquine phosphate is considered the treatment of choice in cats.

PROGNOSIS

Prognosis depends on the severity of disease, which in turn depends on both organism and host factors. Mortality rates of 15-20% are reported.

Use of a doxycycline-enrofloxacin-metronidazole combination with/without diminazene diaceturate to treat naturally occurring canine babesiosis caused by Babesia gibsoni

Canine babesiosis is an important worldwide, tick-borne disease caused by hemoprotozoan parasites of the genus Babesia. Babesia gibsoni is the predominant species that causes canine babesiosis in Taipei, Taiwan. It is a small pleomorphic intraerythrocytic parasite that can cause erythrocyte destruction and hemolytic anemia. Efficacy of oral administration of a doxycycline-enrofloxacin-metronidazole combination with and without injections of diminazene diaceturate in the management of naturally occurring canine babesiosis caused by B. gibsoni was evaluated retrospectively. The overall efficacy of this combination of doxycycline-enrofloxacin-metronidazole in conjunction with and without administration of diminazene diaceturate was 85.7% and 83.3%, respectively; with a mean recovery time of 24.2 and 23.5 days, respectively. Concomitant use of intramuscular diminazene diaceturate may not improve the efficacy of a doxycycline-enrofloxacin-metronidazole combination in management of canine babesiosis caused by B. gibsoni.

Canine babesiosis: from molecular taxonomy to control

Canine babesiosis is a clinically significant emerging vector-borne disease caused by protozoan haemoparasites. This review article considers recent literature pertaining to the taxonomic classification of Babesia and Theileria species affecting dogs and the geographical distribution of these parasites. The diagnosis of canine babesiosis by traditional, molecular and serological methods is reviewed, together with recent advances in our understanding of the pathophysiology of piroplasmosis, and of the treatment and prevention of this disease.

Evaluation of efficacy of bruceine A, a natural quassinoid compound extracted from a medicinal plant, Brucea javanica, for canine babesiosis

Bruceine A, a natural quassinoid compound extracted from the dried fruits of Brucea javanica (L.) Merr., was evaluated for its antibabesial activity in vitro and in vivo. Bruceine A inhibited the in vitro growth of Babesia gibsoni in canine erythrocytes at lower concentration compared with the standard antibabesial drug diminazene aceturate and killed the parasites within 24 hr at a concentration of 25 nM. Oral administration of bruceine A at a dosage of 6.4 mg/kg/day for 5 days resulted in no clinical findings in a dog with normal ranges of hematological and biochemical values in the blood. Three dogs were infected with B. gibsoni and two of them were treated with bruceine A at a dosage of 6.4 mg/kg/day for 6 days from day 5 post-infection. An untreated dog developed typical acute babesiosis symptoms including severe anemia, high fever, and complete loss of appetite and movement. However, the two bruceine A-treated dogs maintained their healthy conditions throughout the experimental period of 4 weeks although complete elimination of parasites from the peripheral blood was not achieved and decreases in the packed cell volume and the erythrocyte and platelet counts were observed. Since natural quassinoid compounds have been used as traditional medicines for the treatment of various ailments including cancer and malaria, the present results suggest that bruceine A or other related compounds are potential candidates for the treatment of canine babesiosis.