Elucidating parasite and host-cell factors enabling Babesia infection in sickle red cells under hypoxic/hyperoxic conditions.

Sickle red blood cells (RBCs) represent a naturally existing host-cell resistance mechanism to hemoparasite infections. We investigate the basis of this resistance using Babesia divergens grown in sickle (SS) and sickle trait (AS) cells. We found that oxygenation and its corresponding effect on RBC sickling, frequency of fetal hemoglobin positive (HbF+) cells, cellular redox environment, and parasite proliferation dynamics, all played a role in supporting or inhibiting Babesia proliferation. To identify cellular determinants that supported infection, an image flow cytometric tool was developed that could identify sickled cells and constituent Hb. We showed that hypoxic conditions impaired parasite growth in both SS and AS cells. Furthermore, cell sickling was alleviated by oxygenation (hyperoxic conditions), which decreased inhibition of parasite proliferation in SS cells. Interestingly, our tool identified HbF+-SS as host-cells of choice under both hypoxic and hyperoxic conditions, which was confirmed using cord RBCs containing high amounts of HbF+ cells. Uninfected SS cells showed a higher reactive oxygen species-containing environment, than AA or AS cells, which was further perturbed on infection. In hostile SS cells we found that Babesia alters its subpopulation structure, with 1N dominance under hypoxic conditions yielding to equivalent ratios of all parasite forms at hyperoxic conditions, favorable for growth. Multiple factors, including oxygenation and its impact on cell shape, HbF positivity, redox status, and parasite pleiotropy allow Babesia propagation in sickle RBCs. Our studies provide a cellular and molecular basis of natural resistance to Babesia, which will aid in defining novel therapies against human babesiosis.

In vivo activity and atom pair fingerprint analysis of MMV665941 against the apicomplexan parasite Babesia microti, the causative agent of babesiosis in humans and rodents.

The effect of MMV665941 on the growth of Babesia microti (B. microti) in mice, was investigated in this study using a fluorescence-based SYBR Green I test. Using atom Pair signatures, we investigated the structural similarity between MMV665941 and the commonly used antibabesial medicines diminazene aceturate (DA), imidocarb dipropionate (ID), or atovaquone (AV). In vitro cultures of Babesia bovis (B. bovis) and, Theileria equi (T. equi) were utilized to determine the MMV665941 and AV interaction using combination ratios ranged from 0.75 IC50 MMV665941:0.75 IC50 AV to 0.50 IC50 MMV665941:0.50 IC50 AV. The used combinations were prepared depending on the IC50 of each drug against the in vitro growth of the tested parasite. Every 96 h, the hemolytic anemia in the treated mice was monitored using a Celltac MEK-6450 computerized hematology analyzer. A single dose of 5 mg/kg MMV665941 exhibited inhibition in the B. microti growth from day 4 post-inoculation (p.i.) till day 12 p.i. MMV665941 caused 62.10%, 49.88%, and 74.23% inhibitions in parasite growth at days 4, 6 and 8 p.i., respectively. Of note, 5 mg/kg MMV665941 resulted in quick recovery of hemolytic anemia caused by babesiosis. The atom pair fingerprint (APfp) analysis revealed that MMV665941 and atovaquone (AV) showed maximum structural similarity. Of note, high concentrations (0.75 IC50) of MMV665941 and AV caused synergistic inhibition on B. bovis growth. These findings suggest that MMV665941 might be a promising drug for babesiosis treatment, particularly when combined with the commonly used antibabesial drug, AV.

Identification and characterization of extracellular vesicles from red cells infected with Babesia divergens and Babesia microti.

Babesiosis is a zoonosis and an important blood-borne human parasitic infection that has gained attention because of its growing infection rate in humans by transfer from animal reservoirs. Babesia represents a potential threat to the blood supply because asymptomatic infections in man are common, and blood from such donors can cause severe disease in certain recipients. Extracellular vesicles (EVs) are vesicles released by cells that contain a complex mixture of proteins, lipids, glycans, and genetic information that have been shown to play important roles in disease pathogenesis and susceptibility, as well as cell-cell communication and immune responses. In this article, we report on the identification and characterization of EVs released from red blood cells (RBCs) infected by two major human Babesia species-Babesia divergens from in vitro culture and those from an in vivo B. microti mouse infection. Using nanoparticle tracking analysis, we show that there is a range of vesicle sizes from 30 to 1,000 nm, emanating from the Babesia-infected RBC. The study of these EVs in the context of hemoparasite infection is complicated by the fact that both the parasite and the host RBC make and release vesicles into the extracellular environment. However, the EV frequency is 2- to 10-fold higher in Babesia-infected RBCs than uninfected RBCs, depending on levels of parasitemia. Using parasite-specific markers, we were able to show that ~50%-60% of all EVs contained parasite-specific markers on their surface and thus may represent the specific proportion of EVs released by infected RBCs within the EV population. Western blot analysis on purified EVs from both in vivo and in vitro infections revealed several parasite proteins that were targets of the host immune response. In addition, microRNA analysis showed that infected RBC EVs have different microRNA signature from uninfected RBC EVs, indicating a potential role as disease biomarkers. Finally, EVs were internalized by other RBCs in culture, implicating a potential role for these vesicles in cellular communication. Overall, our study points to the multiple functional implications of EVs in Babesia-host interactions and support the potential that EVs have as agents in disease pathogenesis.

Vitellogenin-2 Accumulation in the Fat Body and Hemolymph of Babesia-Infected Haemaphysalis longicornis Ticks.

The protozoan parasite Babesia spp. invades into tick oocytes and remains in the offspring. The transovarial transmission phenomenon of Babesia in ticks has been demonstrated experimentally, but the molecular mechanisms remain unclear. Babesia invasion into oocytes occurs along with the progression of oogenesis. In the present study, to find the key tick factor(s) for Babesia transmission, we focused on molecules involved in yolk protein precursor (vitellogenin, Vg) synthesis and Vg uptake, which are crucial events in tick oogenesis. With a Haemaphysalis longicornis tick-Babesia ovata experimental model, the expression profiles of Akt, target of rapamycin, S6K, GATA, and Vg, Vg synthesis-related genes, and Vg receptor (VgR) and autophagy-related gene 6 (ATG6), Vg uptake-related genes, were analyzed using real-time PCR using tissues collected during the preovipositional period in Babesia-infected ticks. The expression levels of H. longicornis Vg-2 (HlVg-2) and HlVg-3 decreased in the fat body of Babesia-infected ticks 1 day after engorgement. In the ovary, HlVg-2 mRNA expression was significantly higher in Babesia-infected ticks than in uninfected ticks 1 and 2 days after engorgement and decreased 3 days after engorgement. HlVgR expression was significantly lower in Babesia-infected ticks than in uninfected ticks 2 and 4 days after engorgement. HlATG6 had a lower gene expression in Babesia-infected ticks compared to uninfected ticks 2 days after engorgement. Additionally, western blot analysis using protein extracts from each collected tissue revealed that H. longicornis Vg-2 (HlVg-2) accumulate in the fat body and hemolymph of Babesia-infected ticks. These results suggest that Vg uptake from the hemolymph to the ovary was suppressed in the presence of B. ovata. Moreover, HlVg-2 knockdown ticks had a lower detection rate of B. ovata DNA in the ovary and a significant reduction of B. ovata DNA in the hemolymph compared with control ticks. Taken together, our results suggest that accumulated HlVg-2 is associated with Babesia infection or transmission in the tick body. These findings, besides previous reports on VgR, provide important information to elucidate the transovarial transmission mechanisms of pathogens in tick vectors.

Seasonal differences in the intensity of acute phase response in dogs infected with Babesia canis.

The highest number of acute Babesia canis cases in dogs is recorded over the February-May (Feb-May) period, which also represents the optimal climate conditions for tick activity in Belgrade, Serbia. A possibility that the acute phase response is more intense in dogs developing the disease in the Feb-May period compared with the response in other time periods of the year was tested. A total of 63 client-owned dogs with acute B. canis infection were enrolled and the routine hematology and biochemistry parameters-serum amyloid A (SAA), IgG against B. canis, level of parasitemia, ceruloplasmin (CER), paraoxonase-1 (PON-1), and fibrinogen-were measured. Acute phase indexes (API) were calculated as (SAA×CER)/(Iron×PON-1) and (SAA×CER)/(Albumin×Iron). Statistics included Kruskal-Wallis test and logistic regression analysis. The results showed that in the Feb-May period, the following parameters were lower: creatinine, albumin, iron, and level of parasitemia. Furthermore, increased API values were more probable in the Feb-May than in the other periods. Together, higher acute phase response intensity and presumptive hemodilution in the Feb-May period indicate a more acute course of B. canis infection than in other time periods of the year.

The specificity of Babesia-tick vector interactions: recent advances and pitfalls in molecular and field studies.

BACKGROUND: Babesia spp. are protozoan parasites of great medical and veterinary importance, especially in the northern Hemisphere. Ticks are known vectors of Babesia spp., although some Babesia-tick interactions have not been fully elucidated. METHODS: The present review was performed to investigate the specificity of Babesia-tick species interactions that have been identified using molecular techniques in studies conducted in the last 20 years under field conditions. We aimed to indicate the main vectors of important Babesia species based on published research papers (n = 129) and molecular data derived from the GenBank database. RESULTS: Repeated observations of certain Babesia species in specific species and genera of ticks in numerous independent studies, carried out in different areas and years, have been considered epidemiological evidence of established Babesia-tick interactions. The best studied species of ticks are Ixodes ricinus, Dermacentor reticulatus and Ixodes scapularis (103 reports, i.e. 80% of total reports). Eco-epidemiological studies have confirmed a specific relationship between Babesia microti and Ixodes ricinus, Ixodes persulcatus, and Ixodes scapularis and also between Babesia canis and D. reticulatus. Additionally, four Babesia species (and one genotype), which have different deer species as reservoir hosts, displayed specificity to the I. ricinus complex. Eco-epidemiological studies do not support interactions between a high number of Babesia spp. and I. ricinus or D. reticulatus. Interestingly, pioneering studies on other species and genera of ticks have revealed the existence of likely new Babesia species, which need more scientific attention. Finally, we discuss the detection of Babesia spp. in feeding ticks and critically evaluate the data on the role of the latter as vectors. CONCLUSIONS: Epidemiological data have confirmed the specificity of certain Babesia-tick vector interactions. The massive amount of data that has been thus far collected for the most common tick species needs to be complemented by more intensive studies on Babesia infections in underrepresented tick species.

Phylogenetic analysis, genetic diversity and geographical distribution of Babesia caballi based on 18S rRNA gene.

The present investigation was aimed to study the presence of Babesia caballi clades upon phylogenetic analysis of all available V4 hypervariable 18S rRNA gene sequences in GenBank in addition to the intra- and interclade genetic diversity in B. caballi and the distribution of parasite clades in different countries. Out of altogether 155 small-subunit ribosomal RNA gene sequences of B. caballi available in the database, only 92 sequences with a complete V4 hypervariable region (>293 bp) were used in multiple sequence alignment. The phylogenetic tree placed all the sequences into two distinct clades with high bootstrap values which are designated as B. caballi clades A and B. Clade A was further divided into two subclades A1 and A2 with 98% bootstrap support. On the contrary, clade B contained multiple small subclades which either lacked bootstrap support or did not have enough bootstrap support to further group them into subclades. All the sequences of B. caballi were 91.5-100% identical with each other. Clade B manifested a comparatively higher genetic diversity (95.2-100% identity) amongst sequences as opposed to clade A (97.3-100% identity). Moreover, it indicated 91.5-93.5%, 92.9-94.6% and 91.5-94.6% nucleotide identity with B. caballi subclades A1, A2, and clade A, respectively. Significant nucleotide variations were observed in one region, between nucleotide positions 126-178, in some of the sequences. A total of 21 molecular signature residues were identified in the V4 hypervariable region. The alignment report of the V4 hypervariable region of 18S rRNA gene of clades A and B exhibited nucleotide variation at nine and 24 places, respectively. The distribution map of all the clades of B. caballi is also reported. The number of 18S rRNA gene sequences employed in the study is relatively high compared to previous studies. Therefore, a fair comparison of definite genetic variations between isolates/sequences from different countries was carried out.

Evidence for Vertical Transmission of Babesia odocoilei (Piroplasmida: Babesiidae) in Ixodes scapularis (Acari: Ixodidae).

Limited evidence suggests that the cervid parasite, Babesia odocoilei, is transovarially transmitted from adult female Ixodes scapularis Say to offspring. The prevalence of B. odocoilei in unfed larval I. scapularis and whether vertical transmission is crucial to pathogen maintenance are currently unknown. To investigate these questions, 275 unfed larvae from two Wisconsin counties were tested for B. odocoilei genetic material. Sixteen of 29 pools were positive for the parasite. The maximum likelihood estimation for overall larval infection prevalence was 7.8% (95% confidence interval: 4.7-12). This vertically acquired infection appears to be sustained transstadially in nymphal ticks the following year; however, our relatively small sample and replicate size warrants additional evaluation. Our study revealed further evidence of vertical transmission, a low and consistent infection prevalence in larvae, and the potential importance of vertical transmission in B. odocoilei maintenance.

Development of a novel multiplex PCR assay for the detection and differentiation of Plasmodium caprae from Theileria luwenshuni and Babesia spp. in goats.

Intraerythrocytic parasites are traditionally identified by the microscopic examination of Giemsa-stained blood smears. However, this method does not always allow for the identification of individual species in goat's RBCs. Moreover, its unreliability in detecting low levels of parasitemia makes it unsuitable for epidemiological investigations and leaves goat farms vulnerable to potential outbreaks. In the present study, a novel multiplex PCR (mPCR) targeting the cytochrome c oxidase subunit I (COI) gene was developed to detect and subsequently differentiate Plasmodium caprae, Theileria luwenshuni, and Babesia spp. The specificity of each primer set was assessed both in silico and with a panel of DNA samples from the hosts themselves and other goat hemoparasites. Amplicons generated from each pair of primers were 664, 555, and 320-bp for P. caprae, Babesia spp., and T. luwenshuni, respectively. These products were further confirmed by sequencing. Our novel mPCR reactions successfully demonstrated the accurate and simultaneous amplification of the three parasites' DNA samples. The current mPCR method showed no cross-amplification with unintended targets. The detection limit of the mPCR in this study was 108 parasites' DNA copies per reaction. The current mPCR was able to detect the minimum parasitemia of approximately 0.001%, 0.000005%, 0.00001% for P. caprae, Babesia spp. and T. luwenshuni, respectively. The diagnostic specificity in the detection of P. caprae and T. luwenshuni ranged from 94.9 to 100 %. The mPCR was further applied to a collection of field blood samples from five provinces in Thailand to validate its reliability and applicability. The results demonstrated the successful detection of P. caprae, Babesia spp. and T. luwenshuni in goat samples with the same sensitivity levels as conventional PCR methods. This study also confirmed the presence of T. luwenshuni and Babesia spp. in Thai goats. The current mPCR method offers an alternative for the diagnosis of P. caprae, T. luwenshuni, and Babesia spp., either single or under co-infection conditions, and for large-scale surveillance.

Monitoring the expansion of Dermacentor reticulatus and occurrence of canine babesiosis in Poland in 2016-2018.

BACKGROUND: The significance of tick-borne diseases has increased considerably in recent years. Because of the unique distribution of the tick species Dermacentor reticulatus in Poland, comprising two expanding populations, Eastern and Western that are separated by a Dermacentor-free zone, it is important to conduct studies on the process of tick expansion and emergence of canine babesiosis. The main aim of the current study was to monitor the expansion of D. reticulatus populations from spring 2016 to autumn 2018 to determine (1) the actual geographical range of this tick species, and (2) and the seasonal/annual shift in range limits and changes in distance between Western and Eastern populations of ticks (the size of the non-endemic area). METHODS: Ticks were collected in spring/autumn during a 3-year study. From each season and year at least three pairs of sites from the Western and Eastern populations were selected. Then the mean distance between paired sites was calculated for each season and year. We collected and analyzed data from veterinary clinics on the number of canine babesiosis cases treated in the clinic during a whole year (2018). RESULTS: Accordingly, further expansion of the two D. reticulatus populations was recorded, mainly along river basins. Marked colonization of the gap zone was observed, with a mean annual shift in the range of 2.5-10 km and a steadily decreasing distance between the two tick populations. The occurrence of babesiosis in different regions revealed low numbers of cases in Western Poland (19 cases/year) and the gap area (only 7 cases/year) and high incidence (up to 250 cases/1000 dogs) and fatality (total 3.65%) in Central and Eastern Poland. Strong associations were found geographically between tick and babesiosis occurrence and temporally in the seasonal patterns of occurrence of ticks and outbreaks of babesiosis. CONCLUSIONS: We documented the shift in range limits and continued process of colonization of the gap zone accompanied by the emergence of canine babesiosis in the Eastern expansion zone. Updated maps of the distribution of ticks and occurrence of babesiosis in different regions of Poland have allowed us to predict of the emergence of pathogens vectored by D. reticulatus. Incidence (per 1000 dogs) of canine babesiosis in veterinary clinics by current range of D. reticulatus.

Endochin-like quinolone-300 and ELQ-316 inhibit Babesia bovis, B. bigemina, B. caballi and Theileria equi.

BACKGROUND: The most common apicomplexan parasites causing bovine babesiosis are Babesia bovis and B. bigemina, while B. caballi and Theileria equi are responsible for equine piroplasmosis. Treatment and control of these diseases are usually achieved using potentially toxic chemotherapeutics, such as imidocarb diproprionate, but drug-resistant parasites are emerging, and alternative effective and safer drugs are needed. The endochin-like quinolones (ELQ)-300 and ELQ-316 have been proven to be safe and efficacious against related apicomplexans, such as Plasmodium spp., with ELQ-316 also being effective against Babesia microti, without showing toxicity in mammals. METHODS: The inhibitory effects of ELQ-300 and ELQ-316 were assessed on the growth of cultured B. bovis, B. bigemina, B. caballi and T. equi. The percentage of parasitized erythrocytes was measured by flow cytometry, and the effect of the ELQ compounds on the viability of horse and bovine peripheral blood mononuclear cells (PBMC) was assessed by monitoring cell metabolic activity using a colorimetric assay. RESULTS: We calculated the half maximal inhibitory concentration (IC50) at 72 h, which ranged from 0.04 to 0.37 nM for ELQ-300, and from 0.002 to 0.1 nM for ELQ-316 among all cultured parasites tested at 72 h. None of the parasites tested were able to replicate in cultures in the presence of ELQ-300 and ELQ-316 at the maximal inhibitory concentration (IC100), which ranged from 1.3 to 5.7 nM for ELQ-300 and from 1.0 to 6.0 nM for ELQ-316 at 72 h. Neither ELQ-300 nor ELQ-316 altered the viability of equine and bovine PBMC at their IC100 in in vitro testing. CONCLUSIONS: The compounds ELQ-300 and ELQ-316 showed significant inhibitory activity on the main parasites responsible for bovine babesiosis and equine piroplasmosis at doses that are tolerable to host cells. These ELQ drugs may be viable candidates for developing alternative protocols for the treatment of bovine babesiosis and equine piroplasmosis.

Human babesiosis: recent advances and future challenges.

PURPOSE OF REVIEW: As human babesiosis caused by apicomplexan parasites of the Babesia genus is associated with transfusion-transmitted illness and relapsing disease in immunosuppressed populations, it is important to report novel findings relating to parasite biology that may be responsible for such pathology. Blood screening tools recently licensed by the FDA are also described to allow understanding of their impact on keeping the blood supply well tolerated. RECENT FINDINGS: Reports of tick-borne cases within new geographical regions such as the Pacific Northwest of the USA, through Eastern Europe and into China are also on the rise. Novel features of the parasite lifecycle that underlie the basis of parasite persistence have recently been characterized. These merit consideration in deployment of both detection, treatment and mitigation tools such as pathogen inactivation technology. The impact of new blood donor screening tests in reducing transfusion transmitted babesiosis is discussed. SUMMARY: New Babesia species have been identified globally, suggesting that the epidemiology of this disease is rapidly changing, making it clear that human babesiosis is a serious public health concern that requires close monitoring and effective intervention measures. Unlike other erythrocytic parasites, Babesia exploits unconventional lifecycle strategies that permit host cycles of different lengths to ensure survival in hostile environments. With the licensure of new blood screening tests, incidence of transfusion transmission babesiosis has decreased.

Complications and risk factors regarding the outcomes of canine babesiosis in Central Europe - A retrospective analysis of 240 cases.

The purpose of this study was to investigate retrospectively the prevalence of the complicated and uncomplicated forms of babesiosis and to evaluate various laboratory and clinical parameters of dogs infected with Babesia canis in order to assess their prognostic value regarding the outcomes of the disease. Medical records, complete blood count and serum biochemical analysis from the animal hospital information system of 240 dogs were reviewed and evaluated retrospectively. Binary logistic regression analysis was used to ascertain correlations between alterations in the obtained parameters and survival probability. The results showed that creatinine levels of more than 5 mg/dL and phosphate levels of more than 3 mmol/L have a highly significant link to death (P ≤ 0.001). Albumin levels of <2.2 g/dL (P = 0.003) and a rectal body temperature below 38 °C (P ≤ 0.001) may also serve as prognostic markers for the severity of the disease. If renal involvement was present, 33.9% of the dogs died, while 40.0% of the dogs died in the presence of pancreatitis. The parameters creatinine, phosphate, albumin and rectal temperature serve as reliable predictive markers of an increased risk of death in the case of an infection with B. canis.

Genetic Diversity and Coexistence of Babesia in Ticks (Acari: Ixodidae) from Northeastern China.

Background: Human babesiosis is an emerging zoonotic disease transmitted by ticks in China. A few systematic reports on Babesia spp. was involved with ticks, especially in the human babesiosis endemic areas in Northeastern China. Materials and Methods: Ticks were collected from 30 individual waypoints along 2.0 km transects in two recreational forests. Babesia spp. infection in ticks was screened by amplifying the partial 18s rRNA gene with subsequent sequencing. Multivariate logistic regression analysis was used to determine the association between tick infection and related environmental risk factors. Cluster analyses were performed using SaTScan v6.0 software to identify any geographical cluster of infected ticks. Results: A total of 2380 Ixodes persulcatus and 461 Haemaphysalis concinna ticks were collected. Of the 0.97% of I. persulcatus ticks that tested positive, five Babesia species were identified, including B. bigemina (n = 6), B. divergens (n = 2), B. microti (n = 3), B. venatorum (n = 11), and one novel strain HLJ-8. Thirteen (2.92%) H. concinna ticks tested positive for B. bigemina (n = 1), B. divergens (n = 1), three genetic variants of Babesia represented by HLJ-874, which was closely related to Babesia sp.MA#361-1, and eight other Babesia variants represented by HLJ242, which were similar to B. crassa. Each study site had 5-6 different Babesia spp. One waypoint was more likely to yield B. venatorum (relative risk = 15.36, p = 0.045) than all other waypoints. Conclusions: There exists a high genetic diversity of Babesia spp. across a relatively small sampled region. Further study is needed to understand the risks these variants pose to human health.

Equine piroplasmosis: an insight into global exposure of equids from 1990 to 2019 by systematic review and meta-analysis.

Equine piroplasmosis (EP) is a tick-borne disease of economic importance, relevant in the international movement of equids. The causative agents are at least two apicomplexan protozoan parasites Babesia caballi and Theileria equi. To date, there is no study that estimates global and regional exposure of equids to EP. We therefore conducted a systematic review and meta-analysis to estimate the pooled prevalence and heterogeneity of EP using random-effects model. Six electronic databases were searched for publications on EP and assessed according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A total of 66 eligible studies published between 1990 and 2019 and representing 24 041 equids were included. The overall pooled prevalence estimates (PPEs) of B. caballi was 22.3% (95% CI 21.7-22.8), while the overall PPE for T. equi was 29.4% (95% CI 28.7-30.0). The overall pooled prevalence due to co-infection with both parasites was 11.8% (95% CI 11.32-12.32). Also, subgroup analysis according to sex, age, diagnostic technique, equid species, region and publication years showed a substantial degree of heterogeneity across studies computed for both B. caballi and T. equi infections in equids. Awareness of the current status of EP globally will alert the relevant authorities and stakeholders where necessary on the need for better preventive and control strategies against the disease.

Evidence of acute phase reaction in asymptomatic dogs naturally infected with Babesia canis.

Asymptomatic outdoor dogs can be carriers of Babesia canis, but data describing the development of an acute phase response (APR) are not available. We hypothesised that these dogs have a moderate APR that could be detected by hematological and biochemical changes. Two groups of Babesia-exposed dogs were represented by nine B. canis PCR-positive and twenty B. canis PCR-negative, seroreactive dogs. The control group consisted of ten Babesia-naïve dogs. Serum amyloid A (SAA), paraoxonase-1 (PON-1), complete blood count, and biochemistry parameters were analysed by standard methodologies. Protein and lipoprotein fractions were separated using agarose gel electrophoresis (GE), and the dominant diameters of lipoproteins were assessed on gradient GE. Results were evaluated using non-parametric tests and the Receiver Operating Characteristic curve. SAA (median 39.0 µg/mL, range 2.2-48.8 µg/mL), total protein (median 74.7 g/L, range 57.1-98.3 g/L) and the dominant diameter of α-lipoproteins (median 13.31 nm, range 12.09-14.17 nm) in B. canis PCR-positive dogs were higher relative to dogs in the control group or dogs that were PCR-negative but seroreactive (p < 0.001 for both groups). Mild to moderate anemia (4/29), thrombocytopenia (7/29), and leukocyte counts that were close to the upper limit of the reference range were encountered in both Babesia-exposed groups. When compared to controls, Babesia-exposed dogs displayed decreased a PON-1 activity and protein GE pattern consistent with low-grade chronic inflammation (p < 0.001 for both groups). Dogs with detectable amounts of B. canis DNA in blood contain increased levels of SAA and total protein along with α-lipoproteins that display an increased diameter relative to those dogs with positive Babesia serology but undetectable levels of B. canis DNA in blood.

The pathology of the spleen in lethal canine babesiosis caused by Babesia rossi.

To provide useful information based on the macropathology, histopathology and immunohistochemical investigation in the spleens of dogs with Babesia rossi infection. Control spleens were collected from four healthy dogs euthanized for welfare reasons. Nine dogs that died naturally because of a mono-infection with Babesia rossi were selected for the diseased group. One haematoxylin-and-eosin-stained section of splenic tissue from each of the infected and control dogs was examined under the light microscope. Immunohistochemical markers were applied to characterize different immunocyte populations. The application of analytic software enabled semi-quantitative comparison of leucocyte subpopulations. Routine splenic histopathology revealed diffuse intermingling of white and red pulp from infected dogs with a clear loss of distinction between these zones. Immunohistochemistry revealed an increase in the proportion of tissue resident and bone marrow origin macrophages in the infected spleens. Apart from a few remnant lymphocytes within the peri-arteriolar lymphatic sheaths and follicles, the majority of the immunocytes redistributed to the red pulp, supporting the observation of white and red pulp intermingling. The majority of our findings are in agreement with histomorphological descriptions of the spleen in a variety of noncanid mammalian hosts with lethal malaria or babesiosis.

Evaluation of acute kidney injury in dogs with complicated or uncomplicated Babesia rossi infection.

Dogs with babesiosis can present with multiple complications, including acute kidney injury (AKI). The objective of this study was to characterize AKI in dogs with babesiosis caused by Babesia rossi at presentation and after treatment. Thirty-five client-owned dogs with B. rossi infection and 10 control dogs were included in this prospective observational study. Blood and urine were collected in Babesia-infected dogs at presentation (T0, n = 35), after 24 h (T24h, n = 11), and after 1 month (T1m, n = 9). The following urinary kidney injury biomarkers were assessed: urinary protein to creatinine ratio (UPC), urinary glomerular injury biomarkers (immunoglobulin G (uIgG) and C-reactive protein (uCRP)), and urinary tubular injury biomarkers (retinol-binding protein (uRBP) and neutrophil gelatinase-associated lipocalin (uNGAL)). Serum functional renal biomarkers were creatinine (sCr) and symmetric dimethylarginine (sSDMA). Post-mortem kidney biopsies were analyzed by light and transmission electron microscopy. At T0, all kidney injury biomarkers were significantly higher in Babesia-infected dogs compared to healthy controls (P < 0.001), while functional renal biomarkers were not significantly different (P > 0.05). At T24h, all urinary tubular injury biomarkers and UPC decreased significantly (P < 0.01), while glomerular injury biomarkers did not (P = 0.084). At T1m, all urinary kidney injury biomarkers decreased to values not significantly different from healthy controls (P > 0.5). Significant changes in functional renal biomarkers were not seen after treatment (P > 0.05). Dogs with complicated babesiosis had significantly higher glomerular injury biomarkers, UPC, and sSDMA compared to uncomplicated cases (P < 0.05), while all tubular injury biomarkers and sCr were not significantly different (P > 0.1). Dogs with babesiosis caused by B. rossi showed transient kidney injury, which was detected by all kidney injury biomarkers, but remained undetected by functional biomarkers. All infected dogs, irrespective of disease severity, suffered comparable kidney injury based on tubular injury biomarker concentrations, while loss of function was seen more often in dogs with complicated babesiosis based on sSDMA results.

Prevalence of Infection and Co-Infection and Presence of Rickettsial Endosymbionts in Ixodes Scapularis (Acari: Ixodidae) in Connecticut, USA.

Ixodes scapularis is currently known to transmit 7 pathogens responsible for Lyme disease, anaplasmosis, babesiosis, tick-borne relapsing fever, ehrlichiosis, and Powassan encephalitis. Ixodes scapularis can also be colonized by endosymbiotic bacteria including those in the genus of Rickettsia. We screened 459 I. scapularis ticks submitted to the Connecticut Agricultural Experiment Station Tick Testing Laboratory with the objectives to (1) examine differences in infection prevalence of Borrelia burgdorferi, Anaplasma phagocytophilum, Babesia microti, and Borrelia miyamotoi, (2) evaluate whether prevalence of co-infections occur at the same frequency that would be expected based on single infection, and (3) determine the presence of rickettsial endosymbionts in I. scapularis. The prevalence of infection in I. scapularis was highest with Bo. burgdorferi sensu lato (nymph = 45.8%; female = 47.0%), followed by A. phagocytophilum (nymph = 4.0%; female = 6.9%), Ba. microti (nymph = 5.7%; female = 4.7%), and Bo. miyamotoi (nymph = 0%; female = 7.3%). We also identified rickettsial endosymbionts in 93.3% of I. scapularis. Nymphs were significantly more likely to be infected with Bo. burgdorferi if they were infected with Ba. microti, whereas adult females were significantly more likely to be infected with Bo. burgdorferi if they were infected with A. phagocytophilum. Our study suggests that the infection prevalence of Bo. burgdorferi is not independent of other co-circulating pathogens and that there is a substantially higher infection of Bo. miyamotoi in I. scapularis females compared with nymphs in this study. High prevalence of infection and co-infection with multiple pathogens in I. scapularis highlights the public health consequences in Connecticut, a state endemic for Lyme and other tick-borne diseases.

Molecular identification of Ehrlichia, Anaplasma, Babesia and Theileria in African elephants and their ticks.

Although historical records indicate the presence of Ehrlichia and Babesia in African elephants, not much is known about their prevalence and diversity in elephants and their ticks, Amblyomma thollonii and Rhipicephalus humeralis. We amplified and sequenced the hypervariable V4 region of the 18S rRNA gene of Babesia and Theileria and the heat shock protein gene (groEL) of Ehrlichia/Anaplasma in DNA extracted from elephant blood (n = 104) and from elephant ticks (n = 52). Our results showed that the African elephants were infected with a novel Babesia spp. while A. thollonii was infected with Theileria bicornis and Theileria cf. velifera. This is the first record of T. bicornis; a protozoan that is linked to fatal infection in rhinoceros in a tick. Elephants and their ticks were all infected with a species of Ehrlichia like that identified in Japanese deer. The prevalence of Babesia spp., Theileria spp. and Ehrlichia spp. in ticks was higher than that of their elephant hosts. About 13.5% of elephants were positive for Theileria or Babesia while 51% of A. thollonii ticks and 27% of R. humeralis ticks were positive for Theileria or Babesia. Moreover, 5.8% of elephants were positive for Ehrlichia or Anaplasma compared to 19.5% in A. thollonii and 18% in R. humeralis. There was no association between the positive result in ticks and that of their elephant hosts for either Babesia spp., Theileria spp. or Ehrlichia spp. Our study reveals that the African elephants are naturally infected with Babesia spp and Ehrlichia spp and opens up an opportunity for further studies to determine the role of elephant as reservoirs of tick-borne pathogens, and to investigate their potential in spreading these pathogens as they range extensively. The presence of T. bicornis in A. thollonii also suggests a need for experiments to confirm its vector competence.