Chemotherapy against babesiosis

Exploring novel inhibitors for Babesia bigemina lactate dehydrogenase: a computational structural biology perspective

Babesia bigemina is an apicomplexan parasite responsible for causing "Texas fever" in bovines. Current treatments for bovine babesiosis are hindered by several limitations, including toxicity, insufficient efficacy in eliminating the parasite, and the potential for resistance development. A promising approach to overcome these challenges is the identification of compounds that specifically target essential metabolic pathways unique to the parasite. One such target is lactate dehydrogenase (LDH), a critical enzyme involved in the regulation of anaerobic glycolysis. Notably, Babesia bigemina LDH (BbigLDH) exhibits a five-amino acid insertion in the active site, a feature that differentiates it from the host's LDH. This structural divergence makes apicomplexan LDH an attractive and potentially selective drug target for therapeutic intervention. In this study, a structure-based drug discovery approach was implemented to find novel inhibitor candidates. Potential candidates were identified using a virtual screening workflow. The compounds with favorable docking scores were filtered using the QM-polarized ligand docking and induced fit docking methods. As a result, 20 novel compounds were identified that bind to the active site of BbigLDH but show low affinity to the host LDHs. Molecular dynamics simulations of the complexes (8.8 µs in total) were performed, and binding free energies were calculated. As a result, protein structures containing compounds C9, C16 and C18 maintained their stability throughout 1 µs simulations with low binding free energies and conserved interactions with known catalytic residues. Therefore, these three compounds deserve further investigation to better understand their mode of action and therapeutic potential for babesiosis. The results of this study elucidate the structural features of the BbigLDH enzyme and provide novel LDH binders that may pave the way for further research into the development of parasite-specific LDH inhibitors.

Molecular epidemiological survey of Babesia species infecting cattle in Paraguay

Paraguay, an agricultural country in South America, has a high prevalence of tick infestations in its cattle population due to warm temperatures, high humidity, and extensive grazing management practices. Consequently, Babesia infections, which are transmitted by ticks, might have a wide distribution in Paraguay, but the current status of these infections remains uncertain. Therefore, we aimed to assess the infection status of three clinically significant Babesia species, including Babesia bovis, Babesia bigemina, and Babesia naoakii, among cattle populations in Paraguay. Blood samples were collected from a total of 326 cattle across nine departments in Paraguay, and their DNAs were screened with species-specific PCR assays. Of the surveyed cattle, single infections of B. bovis and B. bigemina were detected in 24 (7.4 %) and 127 (39.0 %), respectively, while co-infection with both the parasite species was detected in 38 (11.7 %). In contrast, all of the surveyed cattle were negative for B. naoakii infection. The prevalence of B. bigemina-single infection was higher in the Eastern region (49.0 %) compared to the Western region (34.6 %), in cattle under extensive management (51.3 %) compared to those under semi-intensive management (34.6 %), and in Bos indicus cattle (50.3 %) compared to Bos taurus (15.8 %). Our findings demonstrated a wide distribution of B. bovis and B. bigemina infections among cattle in Paraguay, underscoring the importance of implementing effective control measures to reduce the potential economic losses associated with bovine babesiosis.

Evaluation of the inhibitory effects of sitamaquine on Babesia infections

The treatment strategies for either human or animal babesiosis have been established and used for many years. With the rising indications of drug resistance and adverse side effects, finding effective and alternative therapies is urgently needed. Sitamaquine (SQ) is an 8-aminoquinoline that was first synthesized as a part of the collaborative anti-malarial program that led to primaquine. In this study, we evaluated the inhibitory effects of SQ on Babesia spp. in vitro and in vivo. The half-maximal inhibitory concentration (IC50) on in vitro cultured Babesia gibsoni was 8.04 ± 1.34 μM. Babesia gibsoni parasites showed degenerative morphological changes following SQ treatment. The in vivo growth inhibitory effects of SQ were evaluated in BALB/c mice infected with B. microti and atovaquone (ATV)-resistant B. microti strain. Oral administration of SQ at a dose of 20 mg/kg significantly inhibited the growth of B. microti and ATV-resistant B. microti. Meanwhile, SQ also showed inhibitory effects on the growth of B. rodhaini, a lethal rodent Babesia species. All mice infected with B. rodhaini treated with SQ survived, whereas the mice in the control group succumbed to the disease. The results obtained in this study indicate that SQ has potent inhibition effects against Babesia spp., which support SQ as a prospective alternative candidate for babesiosis treatment.

A 50-year-old question: Can imidocarb chemoprophylaxis ensure seroconversion for babesiosis in cattle under field conditions?

Bovine babesiosis, caused by Babesia bovis or Babesia bigemina, is a major tick-borne disease affecting livestock. In regions with limited vaccine availability, imidocarb is widely used as a chemoprophylactic drug. Although it is assumed that chemoprophylaxis allows for the development of immunity shortly after treatment, the extent of seroconversion during the imidocarb administration protocol remains largely unexplored, with most investigations emphasizing symptom prevention. This research endeavors to verify the seroconversion rate (humoral immunity) of cattle undergoing imidocarb chemoprophylaxis while exposed to tick vectors in field conditions. Fifteen tick-naïve heifers were used, with twelve receiving imidocarb (experimental group) on day 0 of the experiment, and the remaining three serving as controls. On day one of the study, all animals were introduced into a tick-infested pasture. Subsequently, at 28-day intervals (days 28, 56, 84, 112, 140, and 168), the experimental group received imidocarb treatments (1.2 mg/Kg). The detection of antibodies against B. bovis and B. bigemina was performed using commercial ELISA kits. Throughout the study, all animals were exposed to natural infestation by Rhipicephalus microplus ticks. By the 56th day, after two imidocarb doses, 25 % of the experimental group had seroconverted for B. bovis, and 41 % for B. bigemina. By the 84th day, 66 % were seropositive for B. bovis and B. bigemina. By the 112th day, 75 % were seropositive for B. bovis. Notably, one heifer (8 %) failed to seroconvert for either species, while 41 % remained seropositive for only one Babesia species. These findings underscore certain limitations of the chemoprophylaxis protocol for bovine babesiosis. While the majority of treated cattle become seropositive for at least one Babesia species after four successive treatments, exposure to the parasite while receiving imidocarb chemoprophylaxis does not guarantee seroconversion for all treated animals.

The Combination of Buparvaquone and ELQ316 Exhibit a Stronger Effect than ELQ316 and Imidocarb Against Babesia bovis In Vitro

Background/Objectives: Bovine babesiosis is a vector-borne disease transmitted by ticks that causes important losses in livestock worldwide. Recent research performed on the drugs currently used to control bovine babesiosis reported several issues including drug resistance, toxicity impact, and residues in edible tissue, suggesting the need for developing novel effective therapies. The endochin-like quinolones ELQ-316 and buparvaquone (BPQ) act as cytochrome bc1 inhibitors and have been proven to be safe and efficacious against related apicomplexans, such as Plasmodium spp. and Babesia microti, without showing toxicity in mammals. The objectives of this study are investigating whether ELQ-316, BPQ, and their combination treatment could be effective against Babesia bovis in an in vitro culture model and comparing with imidocarb (ID), the routinely used drug. Methods: In vitro cultured parasites starting at 2% percentage of parasitemia (PPE) were treated with BPQ, ELQ-316, ID, and the combinations of BPQ + ELQ-316 and ID + ELQ-316 at drug concentrations that ranged from 25 to 1200 nM, during four consecutive days. The IC50% and IC99% were reported. Parasitemia levels were evaluated daily using microscopic examination. Data were compared using the non-parametrical Mann-Whitney and Kruskall-Wallis test. Results: All drugs tested, whether used alone or in combination, significantly decreased the survival (p < 0.05) of B. bovis in in vitro cultures. The combination of BPQ + ELQ-316 had the lowest calculated inhibitory concentration 50% (IC50%) values, 31.21 nM (IC95%: 15.06-68.48); followed by BPQ, 77.06 nM (IC95%: 70.16-86.01); ID + ELQ316, 197 nM (IC95%:129.0-311.2); ID, 635.1 nM (IC95%: 280.9-2119); and ELQ316, 654.9 nM (IC95%: 362.3-1411). Conclusions: The results reinforce the higher efficacy of BPQ at affecting B. bovis survival and the potential synergistic effects of its combination with ELQ-316, providing a promising treatment option against B. bovis.

Tick-Borne Diseases in Sub-Saharan Africa: A Systematic Review of Pathogens, Research Focus, and Implications for Public Health

Sub-Saharan Africa, with its hot and humid climate, is a conducive zone for tick proliferation. These vectors pose a major challenge to both animal and human health in the region. However, despite the relevance of emerging diseases and evidence of tick-borne disease emergence, very few studies have been dedicated to investigating zoonotic pathogens transmitted by ticks in this area. To raise awareness of the risks of tick-borne zoonotic diseases in sub-Saharan Africa, and to define a direction for future research, this systematic review considers the trends of research on tick-borne bacteria, parasites, and viruses from 2012 to 2023, aiming to highlight the circulation of these pathogens in ticks, cattle, sheep, goats, and humans. For this purpose, three international databases were screened to select 159 papers fitting designed inclusion criteria and used for qualitative analyses. Analysis of these studies revealed a high diversity of tick-borne pathogens in sub-Saharan Africa, with a total of 37 bacterial species, 27 parasite species, and 14 viruses identified. Among these, 27% were zoonotic pathogens, yet only 11 studies investigated their presence in humans. Furthermore, there is growing interest in the investigation of bacteria and parasites in both ticks and ruminants. However, research into viruses is limited and has only received notable interest from 2021 onwards. While studies on the detection of bacteria, including those of medical interest, have focused on ticks, little consideration has been given to these vectors in studies of parasites circulation. Regarding the limited focus on zoonotic pathogens transmitted by ticks, particularly in humans, despite documented cases of emerging zoonoses and the notable 27% proportion reported, further efforts should be made to fill these gaps. Future studies should prioritize the investigation of zoonotic pathogens, especially viruses, which represent the primary emerging threats, by adopting a One Health approach. This will enhance the understanding of their circulation and impact on both human and animal health. In addition, more attention should be given to the risk factors/drivers associated to their emergence as well as the perception of the population at risk of infection from these zoonotic pathogens.

New insights in the diagnosis and treatment of equine piroplasmosis: pitfalls, idiosyncrasies, and myths

Equine piroplasmosis (EP) is a global tick-borne disease of equids caused by the intraerythrocytic apicomplexan parasites Theileria equi and Babesia caballi, and the more recently discovered Theileria haneyi. These parasites can be transmitted by several tick species, including Dermacentor, Hyalomma, and Rhipicephalus, but iatrogenic and vertical transmission are also common. Clinical signs of EP include poor performance, fever, icterus, abortions, among others, and peracute or acute forms of infection are associated with high mortality in non-endemic areas. EP is a reportable disease and represents an important barrier for the international trade of horses and other equids, causing disruption of international equine sports. Tick control measures, serological and molecular diagnostic methods, and parasiticidal drugs are currently used against EP, while vaccines remain unavailable. Since most acaricides used in equids are non-environmentally friendly and linked to drug resistances, this is considered as an unsustainable approach. Imidocarb dipropionate (ID) and buparvaquone (BPQ) are currently the main drugs used to control the disease. However, while ID has several side and toxic effects and recurrent failures of treatment have been reported, BPQ is less effective in the clearance of T. equi infection and not available in some countries. Thus, novel alternative and effective therapeutics are needed. While current trade regulations require testing equids for EP before exportation, the lack of standardized PCR tests and limitations of the currently recommended serological assays entail a risk of inaccurate diagnosis. Hereby, we propose a combination of standardized PCR-based techniques and improved serological tests to diminish the risks of exporting EP-infected animals making equid international trade safer. In addition, this review discusses, based on scientific evidence, several idiosyncrasies, pitfalls and myths associated with EP, and identifies weaknesses of current methods of control and gaps of research, as initial steps toward developing novel strategies leading to control this disease.

Antiparasitic Evaluation of Aquiluscidin, a Cathelicidin Obtained from Crotalus aquilus, and the Vcn-23 Derivative Peptide against Babesia bovis, B. bigemina and B. ovata

Babesiosis is a growing concern due to the increased prevalence of this infectious disease caused by Babesia protozoan parasites, affecting various animals and humans. With rising worries over medication side effects and emerging drug resistance, there is a notable shift towards researching babesiacidal agents. Antimicrobial peptides, specifically cathelicidins known for their broad-spectrum activity and immunomodulatory functions, have emerged as potential candidates. Aquiluscidin, a cathelicidin from Crotalus aquilus, and its derivative Vcn-23, have been of interest due to their previously observed antibacterial effects and non-hemolytic activity. This work aimed to characterize the effect of these peptides against three Babesia species. Results showed Aquiluscidin's significant antimicrobial effects on Babesia species, reducing the B. bigemina growth rate and exhibiting IC50 values of 14.48 and 20.70 μM against B. ovata and B. bovis, respectively. However, its efficacy was impacted by serum presence in culture, and it showed no inhibition against a B. bovis strain grown in serum-supplemented medium. Conversely, Vcn-23 did not demonstrate babesiacidal activity. In conclusion, Aquiluscidin shows antibabesia activity in vitro and its efficacy is affected by the presence of serum in the culture medium. Nevertheless, this peptide represents a candidate for further investigation of its antiparasitic properties and provides insights into potential alternatives for the treatment of babesiosis.

Structural variety and pharmacological potential of naphthylisoquinoline alkaloids

Naphthylisoquinoline alkaloids are a fascinating class of natural biaryl compounds. They show characteristic mono- and dimeric scaffolds, with chiral axes and stereogenic centers. Since the appearance of the last comprehensive overview on these secondary plant metabolites in this series in 1995, the number of discovered representatives has tremendously increased to more than 280 examples known today. Many novel-type compounds have meanwhile been discovered, among them naphthylisoquinoline-related follow-up products like e.g., the first seco-type (i.e., ring-opened) and ring-contracted analogues. As highlighted in this review, the knowledge on the broad structural chemodiversity of naphthylisoquinoline alkaloids has been decisively driven forward by extensive phytochemical studies on the metabolite pattern of Ancistrocladus abbreviatus from Coastal West Africa, which is a particularly "creative" plant. These investigations furnished a considerable number of more than 80-mostly new-natural products from this single species, with promising antiplasmodial activities and with pronounced cytotoxic effects against human leukemia, pancreatic, cervical, and breast cancer cells. Another unique feature of naphthylisoquinoline alkaloids is their unprecedented biosynthetic origin from polyketidic precursors and not, as usual for isoquinoline alkaloids, from aromatic amino acids-a striking example of biosynthetic convergence in nature. Furthermore, remarkable botanical results are presented on the natural producers of naphthylisoquinoline alkaloids, the paleotropical Dioncophyllaceae and Ancistrocladaceae lianas, including first investigations on the chemoecological role of these plant metabolites and their storage and accumulation in particular plant organs.

Comparative efficacy of buparvaquone and imidocarb in inhibiting the in vitro growth of Babesia bovis

Introduction

B. bovis is an apicomplexan parasite responsible for bovine babesiosis, a tick-borne disease with a worldwide impact. The disease remains inefficiently controlled, and few effective drugs, including imidocarb dipropionate (ID), are currently available in endemic areas. The objective of this study was to evaluate whether buparvaquone (BPQ), a drug currently used to treat cattle infected with the Babesia-related Theileria spp. parasites, could be active against Babesia parasites. Herein, we compared the effect of ID and BPQ on B. bovis growth in vitro erythrocyte culture.

Methods

We compared the effect of ID and BPQ on the culture-adapted Texas T2Bo strain of B. bovis. In vitro cultured parasites were incubated with ID and BPQ at two starting parasitemia levels (PPE), 0.2% and 1%. In vitro cultured parasites were treated with ID or BPQ at concentrations ranging from 10 to 300 nM, during 4 consecutive days. Parasitemia levels were daily evaluated using microscopic examination. Data was compared using the independent Student's t-test.

Results and discussion

Both ID and BPQ significantly inhibited (p < 0.05) the growth of B. bovis, regardless of the initial parasitemia used. At 1% parasitemia, BPQ had lower calculated inhibitory concentration 50 (IC50: 50.01) values than ID (IC50: 117.3). No parasites were found in wells with 0.2% starting parasitemia, treated previously with 50 nM of BPQ or ID, after 2 days of culture without drugs. At 1% parasitemia, no parasite survival was detected at 150 nM of BPQ or 300 nM of ID, suggesting that both drugs acted as babesiacidals.

Conclusion

Overall, the data suggests that BPQ is effective against B. bovis and shows a residual effect that seems superior to ID, which is currently the first-line drug for treating bovine babesiosis globally.

Anti-babesial activity of a series of 6,7-dimethoxyquinazoline-2,4-diamines (DMQDAs)

Diminazene aceturate (DA), imidocarb dipropionate (ID), atovaquone (ATO), azithromycin (AZI), clindamycin, and quinine have been used to treat animal and human babesiosis for many years, despite their negative effects and rising indications of resistance. Thus, finding anti-babesial compounds that can either treat the infection or lower the dose of drugs given has been a primary objective. Quinazolines are one of the most important nitrogen heterocycles, with a wide range of pharmacological activities including analgesic, anti-inflammatory, sedative-hypnotic, anti-histaminic, anti-cancer, and anti-protozoan properties. The present study investigated the anti-babesial activities of twenty 6,7-dimethoxyquinazoline-2,4-diamines on Babesia spp. One candidate, 6,7-dimethoxy-N4-ethylisopropyl-N2-ethyl(pyridin-4-yl)quinazoline-2,4-diamine (SHG02), showed potent inhibition on Babesia gibsoni in vitro, as well as on B. microti and B. rodhaini in mice. Our findings indicate that the candidate compound SHG02 is promising for further development of anti-babesial drugs and provides a new structure to be explored for developing anti-Babesia therapeutics.

Inhibitory effects on bovine babesial infection by iron chelator, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2-methylpyridin-4-one (CM1), and antimalarial drugs

BACKGROUND

Babesiosis is an infectious disease caused by protozoa of the apicomplexan phylum, genus Babesia. It is a malaria-like parasitic disease that can be transmitted via tick bites. The apicomplexan phylum of eukaryotic microbial parasites has had detrimental impacts on human and veterinary medicine. There are only a few drugs currently available to treat this disease; however, parasitic strains that are resistant to these commercial drugs are increasing in numbers. Plasmodium and Babesia are closely related as they share similar biological features including mechanisms for host cell invasion and metabolism. Therefore, antimalarial drugs may be useful in the treatment of Babesia infections. In addition to antimalarials, iron chelators also inhibit parasite growth. In this study, we aimed to evaluate the in vitro inhibitory efficacy of iron chelator and different antimalarials in the treatment of Babesia bovis.

METHODS

Cytotoxicity of antimalarial drugs; pyrimethamine, artefenomel, chloroquine, primaquine, dihydroarthemisinine, and the iron chelator, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2 methylpyridin-4-one (CM1), were evaluated against Madin Darby Bovine Kidney (MDBK) cells and compared to diminazene aceturate, which is the currently available drug for animal babesiosis using an MTT solution. Afterwards, an evaluation of the in vitro growth-inhibitory effects of antimalarial drug concentrations was performed and monitored using a flow cytometer. Half maximal inhibitory concentrations (IC50) of each antimalarial and iron chelator were determined and compared to the antibabesial drug, diminazine aceturate, by interpolation using a curve-fitting technique. Subsequently, the effect of the drug combination was assessed by constructing an isobologram. Values of the sum of fractional inhibitions at 50% inhibition were then estimated.

RESULTS

Results indicate that all drugs tested could safely inhibit babesia parasite growth, as high as 2500 μM were non-toxic to mammalian cells. Although no drugs inhibited B. bovis more effectively than diminazine aceturate in this experiment, in vitro growth inhibition results with IC50 values of pyrimethamine 6.25 ± 2.59 μM, artefenomel 2.56 ± 0.67 μM, chloroquine 2.14 ± 0.76 μM, primaquine 22.61 ± 6.72 μM, dihydroarthemisinine 4.65 ± 0.22 μM, 1-(N-acetyl-6-aminohexyl)- 3-hydroxy-2 methylpyridin-4-one (CM1) 9.73 ± 1.90 μM, and diminazine aceturate 0.42 ± 0.01 μM, confirm that all drugs could inhibit B. bovis and could be used as alternative treatments for bovine babesial infection. Furthermore, the efficacy of a combination of the iron chelator, CM1, in combination with artefenomel dihydroarthemisinin or chloroquine, and artefenomel in combination with the iron chelator, CM1, dihydroarthemisinin or chloroquine, exhibited synergism against B. bovis in vitro.

CONCLUSION

Our evaluation of the inhibitory efficacy of the iron chelator CM1, antimalarial drugs, and a combination of these drugs against B. bovis could be potentially useful in the development and discovery of a novel drug for the treatment of B. bovis in the future.

Antiparasitic activity of FLLL-32 against four Babesia species, B. bovis, B. bigemina, B. divergens and B. caballi, and one Theileria species, Theileria equi in vitro, and Babesia microti in mice

Introduction: FLLL-32, a synthetic analog of curcumin, is a potent inhibitor of STAT3's constitutive activation in a variety of cancer cells, and its anticancer properties have been demonstrated both in vitro and in vivo. It is also suggested that it might have other pharmacological activities including activity against different parasites. Aim: This study therefore investigated the in vitro antiparasitic activity of FLLL-32 against four pathogenic Babesia species, B. bovis, B. bigemina, B. divergens, and B. caballi, and one Theileria species, Theileria equi. In vivo anti-Babesia microti activity of FLLL-32 was also evaluated in mice. Methods: The FLLL-32, in the growth inhibition assay with a concentration range (0.005-50 μM), was tested for it's activity against these pathogens. The reverse transcription PCR (RT-PCR) assay was used to evaluate the possible effects of FLLL-32 treatment on the mRNA transcription of the target B. bovis genes including S-adenosylhomocysteine hydrolase and histone deacetylase. Results: The in vitro growth of B. bovis, B. bigemina, B. divergens, B. caballi, and T. equi was significantly inhibited in a dose-dependent manner (in all cases, p < 0.05). FLLL-32 exhibits the highest inhibitory effects on B. bovis growth in vitro, and it's IC50 value against this species was 9.57 μM. The RT-PCR results showed that FLLL-32 inhibited the transcription of the B. bovis S-adenosylhomocysteine hydrolase gene. In vivo, the FLLL-32 showed significant inhibition (p < 0.05) of B. microti parasitemia in infected mice with results comparable to that of diminazene aceturate. Parasitemia level in B. microti-infected mice treated with FLLL-32 from day 12 post infection (pi) was reduced to reach zero level at day 16 pi when compared to the infected non-treated mice. Conclusion: The present study demonstrated the antibabesial properties of FLLL-32 and suggested it's usage in the treatment of babesiosis especially when utilized in combination therapy with other antibabesial drugs.

Effect of a preventive strategic control program, with imidocarb dipropionate, against tick fever agents in dairy calves

Chemoprophylaxis with dipropionate imidocarb (IMD) is a method adopted to prevent cattle tick fever (TF). Sixty weaned dairy heifers (±60 days old), without previous exposure to Rhipicephalus microplus ticks, were housed in Tifton paddocks and were subsequently exposed to R. microplus ticks and monitored up to 315 days old. Thirty animals were kept as controls (T01) and 30 received five preventive strategic treatments with IMD at 21-day intervals (T02). The heifers were monitored weekly by means of packed cell volume (PCV) and blood smears to evaluate the presence of TF agents. Salvage treatments (ST) with diminazene and enrofloxacin were administered when animals showed PCV ≤ 24%. The A. marginale prevalence was 39.3% and 37.7%, B. bovis 6.0%, and 7.3%, and B. bigemina 16.3% and 13.7% for T01 and T02, respectively. Regarding PCV values, group T01 showed lower PCV than group T02, between 119 and 161 days of life, but when animals were 196, 210, 217, and between 252 to 301 days old, an inversion occurred. The IMD treatment protocol was effective in group T02 from day 91 to 175 while treatment was being administered, but from day 182 to 315 after the IMD treatment protocol was completed, the number of salvage treatments against TF agents performed in T02 group increased significantly. The sequential application of IMD treatments with intervals less than 21 days is not recommended.

Babesiosis: Current status and future perspectives in Pakistan and chemotherapy used in livestock and pet animals

Babesiosis is a protozoal disease affect livestock and pet animals such as cattle, buffaloes, sheep, goats, horses, donkeys, mules, dogs, and cats. It causes severe economic losses in livestock as well as in pet animals. A large number of dairy animals are imported in order to fulfill the demands of milk, milk, meat and its products. In addition, different pet animals are transported from Pakistan to various parts of the world, therefore, it is important to identify the current status and distribution of babesiosis throughout Pakistan in order to control the disease and draw attention for future research, diagnosis, treatment and control of this diseases. No work has been done on a complete review on up-to-date on blood protozoal disease burden in Pakistan. This article will provide about the complete background of babesiosis in ruminants, equines and pet animals, its current status, distribution, vectors in Pakistan and allopathic and ethnoveterinary treatments used against babesiosis. Babesiosis may be subclinical (apparently normal) and may be clinical with acute to chronic disease and sometimes fatal. Babesia is found and develops inside the erythrocytes (red blood cells). Clinically, it causes fever, fatigue, lethargy, pallor mucus membranes, malaise, cachexia, respiratory distress, jaundice, icterus, hemolytic anemia, hemoglobinuria, lymphadenopathy, chollangocytitis, hepatomegaly, and splenomegaly. Chemotherapy for babesiosis includes Imidocarb dipropionate, Diaminazine aceturate Atovaquone and Bupravaquone, Azithromycin, Quinuronium sulfate and Amicarbalidesio-thionate are most widely used. Supportive therapy includes multivitamins, fluid therapy, antipyretics intravenous fluids, and blood transfusions are used if necessary. In addition, there are certain ethnoveterinary (homeopathic) ingredients which having anti-babesial activity. As the resistance against these drugs is developing every day. New more specific long-lasting drugs should be developed for the treatment of Babesiosis. Further studies should be done on disease genome of different species of Babesia for vaccine development like malarial parasites.

A novel time-saving multiplex PCR assay for detecting and discriminating the most common canine Babesia species in Europe

In Europe, most cases of canine babesiosis are caused by Babesia canis, Babesia vogeli (large piroplasms) and Babesia vulpes (small piroplasm). Molecular diagnosis is recommended due to its high sensitivity. Species identification after sequencing allows applying a rapid and efficient treatment, leading to a better prognosis; however, it is expensive and time-consuming. Thus, the objective of the present study was to develop a time-saving multiplex polymerase chain reaction (PCR) for simultaneously detecting and discriminating between large and small forms without sequence analysis. A new multiplex PCR was designed and tested using blood samples from 79 dogs showing clinical signs compatible with babesiosis which were previously analysed using blood smears and molecular methods. Multiplex PCR successfully discriminated between both Babesia groups showing bands of 700 and 890 bp for B. canis/B. vogeli and B. vulpes, respectively. No significant differences in the results of both PCR were detected and a substantial agreement between protocols (κ = 0.64) was found. Our multiplex PCR represents a reliable tool for detecting infections by the major Babesia spp. in dogs from Europe. Since no sequence analysis is required for identifying the species involved, this PCR allows the rapid administration of an appropriate treatment, thus improving the survival rate of the infected animals. In addition, it will represent a helpful tool for unravelling the real prevalence and distribution of B. vulpes and its implication in clinical cases.

Developing Anti-Babesia bovis Blood Stage Vaccines: A New Perspective Regarding Synthetic Vaccines

Bovine babesiosis is caused by the Apicomplexa parasites from the genus Babesia. It is one of the most important tick-borne veterinary diseases worldwide; Babesia bovis being the species associated with the most severe clinical signs of the disease and causing the greatest economic losses. Many limitations related to chemoprophylaxis and the acaricides control of transmitting vectors have led to the adoption of live attenuated vaccine immunisation against B. bovis as an alternative control strategy. However, whilst this strategy has been effective, several drawbacks related to its production have prompted research into alternative methodologies for producing vaccines. Classical approaches for developing anti-B. bovis vaccines are thus discussed in this review and are compared to a recent functional approach to highlight the latter’s advantages when designing an effective synthetic vaccine targeting this parasite.

Temporal metabolic profiling of erythrocytes in mice infected with Babesia microti

BACKGROUND

Babesiosis is an emerging zoonosis worldwide that is caused by tick-borne apicomplexans, Babesia spp., which threatens the health of domesticated and wild mammals and even humans. Although it has done serious harm to animal husbandry and public health, the study of Babesia is still progressing slowly. Until now, no effective anti-Babesia vaccines have been available, and administration of combined drugs tends to produce side effects. Therefore, non-targeted metabolomics was employed in the present study to examine the temporal dynamic changes in the metabolic profile of the infected erythrocytes. The goal was to obtain new insight into pathogenesis of Babesia and to explore vaccine candidates or novel drug targets.

METHODS

C57BL/6 mice were infected with B. microti and erythrocytes at different time points (0, 3, 6 , 9, 12, and 22-days post-infection) were subjected to parasitemia surveillance and then metabolomics analysis using liquid chromatography-mass spectrometry (LC-MS). Multivariate statistical analyses were performed to clearly separate and identify dysregulated metabolites in Babesia-infected mice. The analyses included principal components analysis (PCA) and orthogonal partial least squares-discrimination analysis (OPLS-DA). The time-series trends of the impacted molecules were analyzed using the R package Mfuzz and the fuzzy clustering principle. The temporal profiling of amino acids, lipids, and nucleotides in blood cells infected with B. microti were also investigated.

RESULTS

B. microti infection resulted in a fast increase of parasitemia and serious alteration of the mouse metabolites. Through LC-MS metabolomics analysis, 10,289 substance peaks were detected and annotated to 3,705 components during the analysis period. There were 1,166 dysregulated metabolites, which were classified into 8 clusters according to the temporal trends. Consistent with the trend of parasitemia, the numbers of differential metabolites reached a peak of 525 at 6-days post-infection (dpi). Moreover, the central carbon metabolism in cancer demonstrated the most serious change during the infection process except for that observed at 6 dpi. Sabotage occurred in components involved in the TCA cycle, amino acids, lipids, and nucleotide metabolism.

CONCLUSION

Our findings revealed a great alteration in the metabolites of Babesia-infected mice and shed new light on the pathogenesis of B. microti at the metabolic level. The results might lead to novel information about the mechanisms of pathopoiesis, babesisosis, and anti-parasite drug/vaccine development in the future.

Advanced approaches for the diagnosis and chemoprevention of canine vector-borne pathogens and parasites-Implications for the Asia-Pacific region and beyond

Vector-borne pathogens (VBPs) of canines are a diverse range of infectious agents, including viruses, bacteria, protozoa and multicellular parasites, that are pernicious and potentially lethal to their hosts. Dogs across the globe are afflicted by canine VBPs, but the range of different ectoparasites and the VBPs that they transmit predominate in tropical regions. Countries within the Asia-Pacific have had limited prior research dedicated to exploring the epidemiology of canine VBPs, whilst the few studies that have been conducted show VBP prevalence to be high, with significant impacts on dog health. Moreover, such impacts are not restricted to dogs, as some canine VBPs are zoonotic. We reviewed the status of canine VBPs in the Asia-Pacific, with particular focus on nations in the tropics, whilst also investigating the history of VBP diagnosis and examining recent progress in the field, including advanced molecular methods, such as next-generation sequencing (NGS). These tools are rapidly changing the way parasites are detected and discovered, demonstrating a sensitivity equal to, or exceeding that of, conventional molecular diagnostics. We also provide a background to the armoury of chemopreventive products available for protecting dogs from VBP. Here, field-based research within high VBP pressure environments has underscored the importance of ectoparasiticide mode of action on their overall efficacy. The future of canine VBP diagnosis and prevention at a global level is also explored, highlighting how evolving portable sequencing technologies may permit diagnosis at point-of-care, whilst further research into chemopreventives will be essential if VBP transmission is to be effectively controlled.

Efficacy of the Antimalarial MMV390048 against Babesia Infection Reveals Phosphatidylinositol 4-Kinase as a Druggable Target for Babesiosis

The present study aimed to evaluate the anti-Babesia effect of MMV390048, a drug that inhibits Plasmodium by targeting the phosphatidylinositol 4-kinase (PI4K). The half inhibitory concentration (IC₅₀) of MMV390048 against the in vitro growth of Babesia gibsoni was 6.9 ± 0.9 μM. In immunocompetent mice, oral treatment with MMV390048 at a concentration of 20 mg/kg effectively inhibited the growth of B. microti (Peabody mjr strain). The peak parasitemia in the control group was 30.5%, whereas the peak parasitemia in the MMV390048-treated group was 3.4%. Meanwhile, MMV390048 also showed inhibition on the growth of B. rodhaini (Australia strain), a highly pathogenic rodent Babesia species. All MMV390048-treated mice survived, whereas the mice in control group died within 10 days postinfection (DPI). The first 7-day administration of MMV390048 in B. microti-infected, severe combined immunodeficiency (SCID) mice delayed the rise of parasitemia by 26 days. Subsequently, a second 7-day administration was given upon recurrence. At 52 DPI, a parasite relapse (in 1 out of 5 mice) and a mutation in the B. microti PI4K L746S, a MMV390048 resistance-related gene, were detected. Although the radical cure of B. microti infection in immunocompromised host SCID mice was not achieved, results from this study showed that MMV390048 has excellent inhibitory effects on Babesia parasites, revealing a new treatment strategy for babesiosis: targeting the B. microti PI4K.

Evaluation of the inhibitory efficacy of quaternary ammonium compounds on in vitro growth of Theileria equi parasite in MASP culture

Equine piroplasmosis has become a global problem of the equine husbandry sector. Haemoprotozoans evolved very quickly and developed resistance against most of the current available drugs. Phospholipid membrane synthesis by choline kinase enzyme is vital for propagation of intra-erythrocytic protozoa parasites. This pathway was targeted in the present study. Quaternary ammonium salts (QAS) and their analogues act against choline and hamper the biosynthesis process for phosphatidylcholine. We analysed anti-T. equi activity of three QAS - decamethonium bromide (DMB), decyl trimethyl ammonium bromide (DTAB) and dodecyl trimethyl ammonium bromide (DDTAB). Theileria equi parasites in vitro treated with different concentrations of DMB, DDTAB and DTAB. Drug treated T. equi failed to multiply further in the viability test. The IC₅₀ value of DMB, DDTAB and DTAB for growth inhibition of T. equi was 14.0 μM, 469.51 nM and 558.40 nM, respectively. DMB, DDTAB and DTAB treated T. equi parasites were observed to be devoid of internal structures, showing pyknotic and degenerative appearances. Various concentration of DMB, DDTAB and DTAB were analysed for their cytotoxicity and haemolytic activity on horse's PBMCs and RBCs. DMB was less than 10% cytotoxic to PBMCs, while DDTAB and DTAB were 40%-50% cytotoxic at 1000 μM concentrations. The respective CC₅₀ values were 7202.96 μM, 1026.26 μM and 1263.95 μM. DMB and DTAB showed least haemolytic activity (<3%); whereas DDTAB was more haemolytic to RBCs at highest concentration of 2000 μM. The respective CC₅₀ values of these drugs were 224495.3 μM, and 39101.35 μM; 713.54 μM. Specific selective index for DMB, DDTAB and DTAB values with respect to host's PBMC and RBC cells, were 514.50, 2185.81, 2263.52 and 16035.38, 1519.75, 70023.91, respectively. These data indicated its non-toxicity to host's cells and selective potential of anti-T. equi in vitro activity.

Pharmacokinetics and bioequivalence of two imidocarb formulations in cattle after subcutaneous injection

Imidocarb (IMD) is commonly used for treatment of eperythrozoon, babesia, piroplasma and trypanosoma in animals, but there are few studies on its pharmacokinetics in cattle. The purpose of this study was to obtain pharmacokinetic parameters and assess the bioequivalence of subcutaneous injections of two IMD formulations in cattle. Forty-eight healthy cattle, 24 males and 24 females, were randomLy divided into two groups (test group and reference group) with 12 males and 12 females per group. The generic IMD was injected subcutaneously with a single dose of 3.0 mg/kg in the test group. Reference group animals were given one injection of the marketed IMD at the same dosage. The limit of detection (LOD) and limit of quantification (LOQ) for IMD in cattle plasma were 0.05 ng/mL and 0.1 ng/mL, respectively. The recoveries ranged from 88.50% to 92.42%, and the equation of this calibration curve was Y = 13672.1X+187.43. The pharmacokinetics parameters of the test group showed that the maximum concentration of 2257.5±273.62 ng/mL was obtained at 2.14±0.67 h, AUC0-t 14553.95±1946.85 ng·h/mL, AUC∞ 15077.88±1952.19 ng·h/mL, T1/2 31.77±25.75 h, CL/F 0.14±0.02 mL/h/g, and Vz/F 6.53±5.34 mL/g. There was no significant difference in AUC0-t, AUC∞ and Cmax between the test group and the reference group (P>0.05). The 90% confidence interval of AUC0-t, AUC0-∞ and Cmax in the test group was included in 80%-125% AUC0-t, AUC0-∞ and 70%-143% Cmax in the reference group, respectively. Based on these results, the two preparations were found to be bioequivalent.

Lactate Dehydrogenase as a Potential Therapeutic Drug Target to Control Babesia bigemina

Babesia bigemina is a tick-borne apicomplexan hemoprotozoan responsible for bovine babesiosis. The current drugs used for bovine babesiosis treatment have several drawbacks, including toxicity, the lack of effectiveness to clear the parasite, and potential to develop resistance. Identifying compounds that target essential and unique parasite metabolic pathways is a rational approach toward finding alternative drug treatments. Based on the genome sequence and transcriptomics analysis, it can be inferred that anaerobic glycolysis is the dominant adenosine triphosphate (ATP) supply for Babesia, and lactate dehydrogenase (LDH) is one of the essential enzymes in this pathway. Furthermore, the Babesia LDH sequence is distinct from its bovine homologue and thus a potential chemotherapeutic target that would result in decreasing the ATP supply to the parasite but not to the host. Gossypol is a known efficient specific inhibitor of LDH in the sensu stricto B. bovis and the sensu lato B. microti, among other related parasites, but no such data are currently available in the sensu stricto B. bigemina parasites. Hereby, we show that the LDH amino acid sequence is highly conserved among sensu stricto but not in sensu lato Babesia spp. A predictive structural analysis of B. bigemina LDH showed the conservation of the key amino acids involved in the binding to gossypol compared to B. bovis. Gossypol has a significant (P < 0.0001) inhibitory effect on the in vitro growth of B. bigemina, with IC₅₀ of 43.97 mM after 72 h of treatment. The maximum IC (IC₉₈) was observed at 60 mM gossypol. However, a significant effect on the viability of cattle PBMC was observed when the cells were cultured with 60 mM (IC₉₈) gossypol compared with DMSO-exposed control cells. Interestingly, B. bigemina cultured at 3% oxygen expresses significantly higher levels of LDH and is more resistant to gossypol than the parasites maintained at ambient conditions containing ~20% oxygen. Altogether, the results suggest the potential of gossypol as an effective drug against B. bigemina infection, but the risk of host toxicity at therapeutic doses should be further evaluated in in vivo studies.

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.

Inhibitory effect of naphthoquine phosphate on Babesia gibsoni in vitro and Babesia rodhaini in vivo

BACKGROUND

Drug resistance and toxic side effects are major challenges in the treatment of babesiosis. As such, new drugs are needed to combat the emergence of drug resistance in Babesia parasites and to develop alternative treatment strategies. A combination of naphthoquine (NQ) and artemisinin is an antimalarial therapy in pharmaceutical markets. The present study repurposed NQ as a drug for the treatment of babesiosis by evaluating the anti-Babesia activity of naphthoquine phosphate (NQP) alone.

METHODS

An in vitro growth inhibition assay of NQP was tested on Babesia gibsoni cultures using a SYBR Green I-based fluorescence assay. In addition, the in vivo growth inhibitory effect of NQP was evaluated using BALB/c mice infected with Babesia rodhaini. The parasitemia level and hematocrit values were monitored to determine the therapeutic efficacy of NQP and the clinical improvements in NQP-treated mice.

RESULTS

The half maximal inhibitory concentration of NQP against B. gibsoni in vitro was 3.3 ± 0.5 μM. Oral administration of NQP for 5 consecutive days at a dose of 40 mg/kg of body weight resulted in significant inhibition of B. rodhaini growth in mice as compared with that of the control group. All NQP-treated mice survived, whereas the mice in the control group died between days 6 and 9 post-infection.

CONCLUSION

This is the first study to evaluate the anti-Babesia activity of NQP in vitro and in vivo. Our findings suggest that NQP is a promising drug for treating Babesia infections, and drug repurposing may provide new treatment strategies for babesiosis.

Epidemiological investigation on canine babesiosis in Tarai region of Uttarakhand

Babesiosis is a haemoprotozoan disease caused by hemotropic protozoa of the Babesia genus. It is an emerging disease and has zoonotic importance which continues to emerge worldwide. It has significant economic impact on livestock and pet animals; especially in the tropical and subtropical regions. The present study was undertaken in different epidemiological aspect on canine babesiosis in Tarai region of Uttarakhand. The overall prevalence of canine babesiosis was recorded as 23.63% based on retrospective study; out of which 55.44% dogs were infested with ticks on hospital records. It was more prevalent in males (25.89%) as compared to female dogs (19.74%). The maximum prevalence was seen in German Shepherd (29.03%) as compared to Bull Mastiff (5.25%). Young dogs (1-3 years of age) were comparatively more affected in comparison to adult dogs. The highest prevalence was found in July (33.33%) whereas least was recorded in December (8.04%). High rise of temperature, tick infestation, anorexia, dehydration, lethargy, etc. were the characteristic clinical signs of canine babesiosis.

Human Babesiosis in Europe

Babesiosis is attracting increasing attention as a worldwide emerging zoonosis. The first case of human babesiosis in Europe was described in the late 1950s and since then more than 60 cases have been reported in Europe. While the disease is relatively rare in Europe, it is significant because the majority of cases present as life-threatening fulminant infections, mainly in immunocompromised patients. Although appearing clinically similar to human babesiosis elsewhere, particularly in the USA, most European forms of the disease are distinct entities, especially concerning epidemiology, human susceptibility to infection and clinical management. This paper describes the history of the disease and reviews all published cases that have occurred in Europe with regard to the identity and genetic characteristics of the etiological agents, pathogenesis, aspects of epidemiology including the eco-epidemiology of the vectors, the clinical courses of infection, diagnostic tools and clinical management and treatment.

Immunochromatographic assay based on high-affine monoclonal antibody for the detection of imidocarb in milk

Imidocarb (IM) is an antiprotozoal agent, which is mainly used to treat babesiosis and piroplasmosis for animals. However, overdose or improbable utilization cause IM residues in animal origin products, which would be harmful to human health. Here, a monoclonal antibody (mAb) against IM with extremely sensitive and specific features has been successfully prepared from a novel immunogen synthesized by virtue of the active ester method. The concentration of half-maximal inhibition (IC₅₀ ) of the mAb was 0.074 ng/ml and the affinity constant was 4.58 × 10¹⁰ L/mol. On the basis of this condition, an immunochromatographic strip (ICS) is proposed that could be applied in milk samples to test IM rapidly. For the ICS, the visual detection limit (cut-off value) was 5 ng/ml, IC₅₀ was 0.4 ng/ml, the limit of detection (LOD) was 0.078 ng/ml, the linear detection scope was 0.117 to 1.37 ng/ml. The recovery rates ranged from 88.83% to 91.47% and coefficients of variation (CV) were in the spectrum of 7.31% to 9.43%. In general, the recommended test strip provided an exceedingly simple and reliable detection method for quickly testing the IM. PRACTICAL APPLICATION: In our joint efforts, an extremely sensitive monoclonal antibody against imidocarb was obtained and a test strip for the rapid detection of imidocarb in milk was developed. The developed method could be applied to the field and provided great potential for analytical of imidocarb in other matrixes.

Disorders in blood circulation as a probable cause of death in dogs infected with Babesia canis

Introduction

The purpose of the study was to investigate post-mortem changes in dogs infected with Babesia canis and to establish the probable cause of death of the affected animals.

Material and Methods

Cadavers of six dogs that did not survive babesiosis were collected. Necropsies were performed and samples of various organs were collected for histological examination.

Results

Necropsies and histological examinations revealed congestion and oedemata in various organs. Most of the dogs had ascites, hydrothorax or hydropericardium, pulmonary oedema, pulmonary, renal, hepatic, and cerebral congestion, and necrosis of cardiomyocytes.

Conclusion

These results suggested disorders in blood circulation as the most probable cause of death. However, the pulmonary inflammatory response and cerebral babesiosis observed in some of these dogs could also be considered possible causes of death. This study also showed a possible role for renal congestion in the development of renal hypoxia and azotaemia in canine babesiosis.

Establishment of Babesia bovis In Vitro Culture Using Medium Free of Animal Products

Babesia bovis, an etiological agent of bovine babesiosis, causes a significant burden to the cattle industry worldwide. The most efficient method to mitigate bovine babesiosis is a live vaccine produced by serial passage in splenectomized cattle. However, there are several concerns regarding live vaccine production, including variation between batches and the use of many animals. In this study, we report a B. bovis-SF strain continuously cultured in a medium free of components of animal origin enriched with a chemically defined lipid mixture (CD lipid mixture) and the use of a perfusion bioreactor to harvest a large amount of B. bovis. Six culture media were compared, including VP-SFM, CD-CHO, CD-Hydrolyzed, CD-CHO, SFM, and ADMEM/F12. We found that the VP-SFM medium performed the best for B. bovis growth, with a maximum percentage of parasitized erythrocytes (PPE) of 8.6%. The effect of six dilutions of a commercial mixture of CD lipids added to VP-SFM showed that the CD lipid mixture at a dilution of 1:100 had the best B. bovis growth curve, with a maximum PPE of 13.9%. Propagation of the in vitro B. bovis culture was scaled up in a perfusion bioreactor using VP-SFM with a CD lipid mixture, and the PPE reached over 32%. The continuous in vitro B. bovis culture in a medium free of animal origin components could potentially reduce and replace the use of animals to produce a reagent for diagnostics and live vaccines to control bovine babesiosis.

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.

Graphic Abstract

Anti-piroplasmic activity of novobiocin as heat shock protein 90 inhibitor against in vitro cultured Theileria equi and Babesia caballi parasites

Theileria equi and Babesia caballi are the causative agents of equine piroplasmosis (EP). Currently, imidocarb dipropionate (ID) is the only available drug for treating the clinical form of EP. Serious side effects and incomplete clearance of infection is a major drawback of ID. Heat-shock proteins (Hsp) play a vital role in the life cycle of these haemoprotozoans by preventing alteration in protein conformation. These Hsp are activated during transmission of EP sporozoites from the tick vector (poikilotherm) to the natural host (homeotherm) and facilitate parasite survival. In the present study, we targeted the heat shock protein 90 (Hsp-90) pathway of T. equi and B. caballi by using its inhibitor drug - novobiocin. Dose-dependent efficacy of novobiocin on the growth of T. equi and B. caballi was observed in in vitro culture. Additionally, we examined dose-dependent cell cytotoxicity on host peripheral mononuclear cells (PBMCs) and haemolytic activity on equine red blood cells (RBC). In vivo organ toxicity of novobiocin was also assessed in a mouse model. The IC₅₀ (50 % inhibitory concentration) value of novobiocin against T. equi and B. caballi was 165 μM and 84.85 μM, respectively. Novobiocin significantly arrested the in vitro growth of T. equi and B. caballi parasites at 100 μM and 200 μM drug concentration, respectively. In vitro treated parasites had distorted nuclear material and showed no further viability. Based on the equine PBMCs and RBC, the drug was found to be safe even at 1000 μM concentration and the CC₅₀ (50 % cytotoxicity concentration) values were 11.63 mM and 261.97 mM. Very high specific selective index (SSI) values (70.47 and 1587) were observed for equine PBMCs and RBC, respectively. Organ-specific biochemical markers and histopathological examination indicated no adverse effect of the drug at a dose rate of 50 mg kg body weight in the mouse model. The results demonstrate the growth inhibitory effect of novobiocin against T. equi and B. caballi parasites and its safety for host cell lines with very high SSI. Hence, it can be inferred that the Theileria/Babesia Hsp-90 family are potential drug targets worthy of further investigation.

Catechins as Model Bioactive Compounds for Biomedical Applications

Research regarding polyphenols has gained prominence over the years because of their potential as pharmacological nutrients. Most polyphenols are flavanols, commonly known as catechins, which are present in high amounts in green tea. Catechins are promising candidates in the field of biomedicine. The health benefits of catechins, notably their antioxidant effects, are related to their chemical structure and the total number of hydroxyl groups. In addition, catechins possess strong activities against several pathogens, including bacteria, viruses, parasites, and fungi. One major limitation of these compounds is low bioavailability. Catechins are poorly absorbed by intestinal barriers. Some protective mechanisms may be required to maintain or even increase the stability and bioavailability of these molecules within living organisms. Moreover, novel delivery systems, such as scaffolds, fibers, sponges, and capsules, have been proposed. This review focuses on the unique structures and bioactive properties of catechins and their role in inflammatory responses as well as provides a perspective on their use in future human health applications.

Elevated serum manganese concentration in dogs as a possible predisposing factor of cerebral babesiosis in dogs

The aim of this study was to demonstrate a relationship between the occurrence of clinical signs of brain involvement in dogs with babesiosis and the concentration of manganese (Mn) in their serum. The study included seven dogs with early babesiosis (Group 1), seven dogs with cerebral babesiosis (Group 2) and seven healthy dogs (Group 3). Haematological and biochemical blood tests were performed in all dogs, and the results were analysed statistically. The Mann-Whitney rank test was used to demonstrate the differences in Mn concentrations, as well as other haematological and biochemical parameters between groups. In dogs in Group 2 with cerebral babesiosis, as compared to dogs in Groups 1 and 3, a statistically significant increase in serum Mn concentration was shown (P = 0.002 and P = 0.029) that may have been associated with the development of anaemia and/or impairment of liver function. Given the well-established neurotoxic effects of Mn in humans, experimental rodents and primates, additional studies on the role of Mn in the pathogenesis of the cerebral form of canine babesiosis are warranted.

Chemoprophylaxis for babesiosis and anaplasmosis in cattle: case report

Cattle tick fever (CTF) causes significant economic losses in the livestock sector. The pathogenic action of the hemoparasites is associated with anemia, weight loss, abortion and reduced productivity, which result with animal death. Programs to prevent CTF involve several procedures, including immunization, chemoprophylaxis and use of ectoparasiticides, together with the vector control in the environment. The objective of this study was to report an acute outbreak of CTF in a group of 157 Hereford cattle from a farm without presence of the vector, that were moved to a farm in the same state with a high tick infestation (Rhipicephalus microplus). On the day before the transportation, the animals received a chemoprophylaxis with imidocarb dipropionate (3 mg/kg, SC), which was repeated 21 days after the first application. After 42 days, some animals showed signs compatible with CTF, which was confirmed through clinical examination, necropsy, histopathological and hemoparasitological analyses. The morbidity rate was 37.6% and the mortality rate was 24.8%. Calves that were recently weaned were the group most affected with the tick fever, morbidity (100% and mortality (73%). Chemoprophylaxis in association with use of ectoparasiticides was not sufficient to control the outbreak of the disease.

Xanthohumol and Gossypol Are Promising Inhibitors against Babesia microti by In Vitro Culture via High-Throughput Screening of 133 Natural Products

Human babesiosis caused by Babesia microti is an emerging threat for severe illness and even death, with an increasing impact worldwide. Currently, the regimen of atovaquone and azithromycin is considered as the standard therapy for treating human babesiosis, which, however, may result in drug resistance and relapse, suggesting the necessity of developing new drugs to control B. microti. In this regard, natural products are promising candidates for drug design against B. microti due to their active therapeutic efficacy, lower toxicity, and fewer adverse reactions to host. Here, the potential inhibitors against B. microti were preliminarily screened from 133 natural products, and 47 of them were selected for further screening. Gossypol (Gp) and xanthohumol (Xn) were finally shown to effectively inhibit the growth of B. microti with IC₅₀ values of 8.47 μm and 21.40 μm, respectively. The cytotoxicity results showed that Gp and Xn were non-toxic to erythrocytes at a concentration below 100 μm. Furthermore, both of them were confirmed to be non-toxic to different types of cells in previous studies. Our findings suggest the potential of Gp and Xn as effective drugs against B. microti infection.

Protein Kinase Inhibitors Arrested the In-Vitro Growth of Theileria equi

INTRODUCTION

Theileria equi is an intra-erythrocytic apicomplexean protozoa that infect equines. Protein kinases (PK), key molecules of the apicomplexean life cycle, have been implicated as significant drug targets. The growth inhibitory efficacy of PK inhibitors against Theileria/Babesia animal parasites have not been documented so far.

METHODS

The present study aimed to carry out in-vitro growth inhibitory efficacy studies of four novel drug molecules-SB239063, PD0332991 isethionate, FR180204 and apigenin, targeting different protein kinases of T. equi. A continuous microaerophilic stationary-phase culture (MASP) system was established for propagation of T. equi parasites. This in-vitro culture technique was used to assess the growth inhibitory effect of protein kinase targeted drug molecules, whereas diminazene aceturate was taken as control drug against T. equi. The inhibitory concentration (IC₅₀) was determined for comparative analysis. The potential cytotoxicity of the drug molecule was also assessed on horse's peripheral blood mononuclear cells (PBMCs) cell line.

RESULTS

SB239063 and diminazene aceturate drugs significantly inhibited (p < 0.05) the in-vitro growth of T. equi parasite at 0.1 µM, 1 µM, 10 µM, 50 µM and 100 µM concentration at ≥ 48 h of incubation period and respective IC₅₀ values were 4.25 µM and 1.23 µM. Furthermore, SB239063 was not cytotoxic to the horse PBMCs and found safer than diminazine aceturate drug. PD0332991 isethionate and FR180204 are extracellular signal-regulated kinase (ERK) inhibitors and significantly (p < 0.05) inhibited T. equi in-vitro growth at higher concentrations (≥ 48 h of incubation period) with respective IC₅₀ value of 10.41 µM and 21.0 µM. Lower concentrations of these two drugs were not effective (p > 0.05) even after 96 h of treatment period. Apigenin (protein kinase-C inhibitor) drug molecule was unsuccessful in inhibiting the T. equi parasite growth completely. After 96 h of in-vitro treatment period, a parasite viability study was performed on drug-treated T. equi parasitized RBCs. These drugs-treated parasitized RBCs were collected and transferred to wells containing fresh culture media (without drug) and naïve host RBCs. Drug-treated RBCs collected from SB239063, PD0332991, diminazene aceturate treatment (1 µM to 100 µM concentration) were unsuccessful in growing/multiplying further. Apigenin drug-treated T. equi parasites were live after 96 h of treatment.

CONCLUSION

It may be concluded that SB239063 was the most effective drug molecule (being lowest in IC₅₀ value) out of the four different protein kinase inhibitors tested in this study. This drug molecule has insignificant cytotoxic activity against horse's PBMCs.

Alsinol, an arylamino alcohol derivative active against Plasmodium, Babesia, Trypanosoma, and Leishmania: past and new outcomes

Malaria, babesiosis, trypanosomosis, and leishmaniasis are some of the most life-threatening parasites, but the range of drugs to treat them is limited. An effective, safe, and low-cost drug with a large activity spectrum is urgently needed. For this purpose, an aryl amino alcohol derivative called Alsinol was resynthesized, screened in silico, and tested against Plasmodium, Babesia, Trypanosoma, and Leishmania. In silico Alsinol follows the Lipinski and Ghose rules. In vitro it had schizontocidal activity against Plasmodium falciparum and was able to inhibit gametocytogenesis; it was particularly active against late gametocytes. In malaria-infected mice, it showed a dose-dependent activity similar to chloroquine. It demonstrated a similar level of activity to reference compounds against Babesia divergens, and against promastigotes, and amastigotes stages of Leishmania in vitro. It inhibited the in vitro growth of two African animal strains of Trypanosoma but was ineffective in vivo in our experimental conditions. It showed moderate toxicity in J774A1 and Vero cell models. The study demonstrated that Alsinol has a large spectrum of activity and is potentially affordable to produce. Nevertheless, challenges remain in the process of scaling up synthesis, creating a suitable clinical formulation, and determining the safety margin in preclinical models.

A cysteine protease of Babesia microti and its interaction with tick cystatins

Babesiosis is a tick-borne protozoonosis caused by Babesia, which can cause fever, hemolytic anemia, hemoglobinuria, and even death. Babesia microti is a parasite found in rodents and can be pathogenic to humans. In this study, the full-length cDNA of a B. microti cysteine protease (BmCYP) was expressed and the recombinant rBmCYP protein analyzed and characterized. BmCYP is encoded by an ORF of 1.3 kb, with a predicted molecular weight of 50 kDa and a theoretical pI of 8.5. The amino acid sequence of BmCYP exhibits an identity of 32.9 to 35.2% with cysteine proteases of Babesia ovis, Babesia bovis, and Theileria, respectively. The results of the proteinase assays show that rBmCYP has cysteine protease enzymatic activity. In addition, we demonstrate that tick cystatins rRhcyst-1 and rRhcyst-2 were able to effectively inhibit the activity of rBmCYP; the inhibition rates were 57.2% and 30.9%, respectively. Tick cystatins Rhcyst-1 and Rhcyst-2 were differentially expressed in ticks that fed on Babesia-infected mice relative to non-infected control ticks. Our results suggest that BmCYP is a functional enzyme with cysteine protease enzymatic activity and may be involved in tick-B. microti interactions.

Insights into the phylogenetic relationships and drug targets of Babesia isolates infective to small ruminants from the mitochondrial genomes

Background

Babesiosis, a tick-borne disease caused by protozoans of the genus Babesia, is widespread in subtropical and tropical countries. Mitochondria are essential organelles that are responsible for energy transduction and metabolism, calcium homeostasis and cell signaling. Mitochondrial genomes could provide new insights to help elucidate and investigate the biological features, genetic evolution and classification of the protozoans. Nevertheless, there are limited data on the mitochondrial genomes of ovine Babesia spp. in China.

Methods

Herein, we sequenced, assembled and annotated the mitochondrial genomes of six ovine Babesia isolates; analyzed the genome size, gene content, genome structure and cytochrome b (cytb) amino acid sequences and performed comparative mitochondrial genomics and phylogenomic analyses among apicomplexan parasites.

Results

The mitochondrial genomes range from 5767 to 5946 bp in length with a linear form and contain three protein-encoding genes, cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 3 (cox3) and cytb, six large subunit rRNA genes (LSU) and two terminal inverted repeats (TIR) on both ends. The cytb gene sequence analysis indicated the binding site of anti-Babesia drugs that targeted the cytochrome bc1 complex. Babesia microti and Babesia rodhaini have a dual flip-flop inversion of 184–1082 bp, whereas other Babesia spp. and Theileria spp. have one pair of TIRs, 25–1563 bp. Phylogenetic analysis indicated that the six ovine Babesia isolates were divided into two clades, Babesia sp. and Babesia motasi. Babesia motasi isolates were further separated into two small clades (B. motasi Hebei/Ningxian and B. motasi Tianzhu/Lintan).

Conclusions

The data provided new insights into the taxonomic relationships and drug targets of apicomplexan parasites.

Naphthylisoquinoline alkaloids and their synthetic analogs as potent novel inhibitors against Babesia canis in vitro

Babesia canis is the predominant and clinically relevant canine Babesia species in Europe. Transmitted by vector ticks, the parasite enters red blood cells and induces a severe, potentially fatal hemolytic anemia. Here, we report on the antibabesial activities of three extracts of the West African tropical plant species Triphyophyllum peltatum (Dioncophyllaceae) and Ancistrocladus abbreviatus (Ancistrocladaceae) and of 13 genuine naphthylisoquinoline alkaloids isolated thereof. Two of the extracts and eight of the alkaloids were found to display strong activities against Babesia canis in vitro. Among the most potent compounds were the C,C-coupled dioncophyllines A (1a) and C (2) and the N,C-linked alkaloids ancistrocladium A (3) and B (4), with half-maximum inhibition concentration (IC₅₀) values of 0.48 μM for 1a, 0.85 μM for 2, 1.90 μM for 3, and 1.23 μM for 4. Structure-activity relationship (SAR) studies on a small library of related genuine analogs and non-natural synthetic derivatives of 1a and 2 revealed the likewise naturally occurring alkaloid N-methyl-7-epi-dioncophylline A (6b) to be the most potent (IC₅₀, 0.14 μM) among the investigated compounds. Although none of the tested naphthylisoquinolines showed 100 % inhibition of parasite infection - as displayed by imidocarb dipropionate (IC₅₀, 0.07 μM), which was used as a positive control - the antibabesial potential of the dioncophyllines A (1a) and C (2) and related compounds such as 6b, its atropo-diastereomer 6a (IC₅₀, 1.45 μM), and 8-O-(p-nitrobenzyl)dioncophylline A (14) (IC₅₀, 0.82 μM) is to be considered as high. The SAR results showed that N-methylation and axial chirality exert a strong impact on the antibabasial activities of the naphthylisoquinolines presented here, whereas dimerization, as in jozimine A₂ (5) (IC₅₀, 140 μM), leads to a significant decrease of activity against B. canis. Alkaloids displaying good to high activities against B. canis like the dioncophyllines 1a, 2, 6a, and 6b were found to cause only a small degree of hemolysis (< 0.7 %), whereas compounds with moderate to weak antibabesial activities such as 6-O-methyl-4'-O-demethylancistrocladine (15a) (IC₅₀, 14.0 μM) and its atropo-diastereomer 6-O-methyl-4'-O-demethylhamatine (15b) (IC₅₀, 830 μM) caused a high degree of hemolysis (7.3 % for 15a and 11.2 % for 15b). In this respect, the most effective anti-Babesia naphthylisoquinolines are also the safest ones.

Management strategies for human babesiosis

INTRODUCTION

Human babesiosis is reported throughout the world and is endemic in the northeastern and northern Midwestern United States and northeastern China. Transmission is primarily through hard bodied ticks. Most cases of severe disease occur in immunocompromised individuals and may result in prolonged relapsing disease or death.

AREAS COVERED

We provide a summary of evidence supporting current treatment recommendations for immunocompetent and immunocompromised individuals experiencing babesiosis.

EXPERT OPINION

Most cases of human babesiosis are successfully treated with atovaquone and azithromycin or clindamycin and quinine. Severe disease may require prolonged treatment.

Molecular epidemiological survey of Babesia bovis, Babesia bigemina, and Babesia sp. Mymensingh infections in Mongolian cattle

Bovine babesiosis caused by Babesia species is an economically significant disease of cattle. Severe clinical babesiosis in cattle is caused by Babesia bovis, B. bigemina, and the recently discovered Babesia sp. Mymensingh. Mongolia is an agricultural country with a large cattle inventory. Although previous studies have detected active infections of B. bovis and B. bigemina in Mongolian cattle, only a few provinces were surveyed. Additionally, the endemicity of Babesia sp. Mymensingh in Mongolia remains unknown. We screened blood DNA samples from 725 cattle reared in 16 of the 21 Mongolian provinces using B. bovis-, B. bigemina-, and Babesia. sp. Mymensingh-specific PCR assays. The overall positive rates of B. bovis, B. bigemina, and Babesia sp. Mymensingh were 27.9% (n = 202), 23.6% (n = 171), and 5.4% (n = 39), respectively. B. bovis and B. bigemina were detected in cattle in all surveyed provinces; whereas Babesia sp. Mymensingh was detected in 11 of the 16 surveyed provinces. On a per province basis, the B. bovis- B. bigemina-, and Babesia sp. Mymensingh-positive rates were 5.9-52.0%, 9.1-76.3%, and 0-35.7%, respectively. In conclusion, this is the first report of Babesia sp. Mymensingh in Mongolia. In addition, we found that species of Babesia that are capable of causing bovine clinical babesiosis, including B. bovis, B. bigemina, and Babesia sp. Mymensingh, are widespread throughout the country.

Management Options for Ixodes ricinus-Associated Pathogens: A Review of Prevention Strategies

Ticks are important human and animal parasites and vectors of many infectious disease agents. Control of tick activity is an effective tool to reduce the risk of contracting tick-transmitted diseases. The castor bean tick (Ixodes ricinus) is the most common tick species in Europe. It is also a vector of the causative agents of Lyme borreliosis and tick-borne encephalitis, which are two of the most important arthropod-borne diseases in Europe. In recent years, increases in tick activity and incidence of tick-borne diseases have been observed in many European countries. These increases are linked to many ecological and anthropogenic factors such as landscape management, climate change, animal migration, and increased popularity of outdoor activities or changes in land usage. Tick activity is driven by many biotic and abiotic factors, some of which can be effectively managed to decrease risk of tick bites. In the USA, recommendations for landscape management, tick host control, and tick chemical control are well-defined for the applied purpose of reducing tick presence on private property. In Europe, where fewer studies have assessed tick management strategies, the similarity in ecological factors influencing vector presence suggests that approaches that work in USA may also be applicable. In this article we review key factors driving the tick exposure risk in Europe to select those most conducive to management for decreased tick-associated risk.

Abdel-Daim M, Mosqueda J, Igarashi I. Phytochemical Characterization and Chemotherapeutic Potential of Cinnamomum verum Extracts on the Multiplication of Protozoan Parasites In Vitro and In Vivo

Cinnamomum verum is a commonly used herbal plant that has several documented properties against various diseases. The existing study evaluated the inhibitory effect of acetonic extract of C. verum (AECV) and ethyl acetate extract of C. verum (EAECV) against piroplasm parasites in vitro and in vivo. The drug-exposure viability assay was tested on Madin-Darby bovine kidney (MDBK), mouse embryonic fibroblast (NIH/3T3) and human foreskin fibroblast (HFF) cells. Qualitative phytochemical estimation revealed that AECV and EAECV containing multiple bioactive constituents namely alkaloids, tannins, saponins, terpenoids and remarkable amounts of polyphenols and flavonoids. AECV and EAECV inhibited B. bovis, B. bigemina, B. divergens, B. caballi, and T. equi multiplication at half-maximal inhibitory concentrations (IC50) of 23.1 ± 1.4, 56.6 ± 9.1, 33.4 ± 2.1, 40.3 ± 7.5, 18.8 ± 1.6 µg/mL, and 40.1 ± 8.5, 55.6 ± 1.1, 45.7 ± 1.9, 50.2 ± 6.2, and 61.5 ± 5.2 µg/mL, respectively. In the cytotoxicity assay, AECV and EAECV affected the viability of MDBK, NIH/3T3 and HFF cells with half-maximum effective concentrations (EC50) of 440 ± 10.6, 816 ± 12.7 and 914 ± 12.2 µg/mL and 376 ± 11.2, 610 ± 7.7 and 790 ± 12.4 µg/mL, respectively. The in vivo experiment showed that AECV and EAECV were effective against B. microti in mice at 150 mg/kg. These results showed that C. verum extracts are potential antipiroplasm drugs after further studies in some clinical cases.