In vitro study of ivermectin efficiency against the cattle tick, Rhipicephalus (Boophilus) annulatus, among cattle herds in El-Beheira, Egypt

Toxicity of Common Acaricides, Disinfectants, and Natural Compounds against Eggs of Rhipicephalus annulatus

Ticks pose a significant threat due to their ability to lay thousands of eggs, which can persist in the environment for extended periods. While the impact of various compounds on adult and larval ticks has been studied, research on their efficacy against tick eggs is limited. This study evaluated the ovicidal activity of commercial acaricides, disinfectants, and natural products against Rhipicephalus annulatus eggs using the egg hatch assay (EHA). Deltamethrin and cypermethrin caused a non-significant inhibition of hatching (IH%), even at concentrations higher than the recommended levels. By contrast, the acaricides chlorpyrifos, phoxim, and amitraz significantly inhibited hatching at all tested concentrations. Ivermectin also demonstrated significant IH% at various concentrations but did not fully inhibit the hatching process. Among the disinfectants tested, Virkon-S®, TH4, and Chlorox showed insignificant effects, whereas formalin achieved an IH% of only 34.1% at a high concentration of 200 mg/mL. Natural products, carvacrol and thymol, exhibited significant ovicidal activity, with a significant IH%. In a semi-field application, phoxim (0.5 mg/mL) and deltamethrin (0.05 mg/mL) were sprayed on tick eggs on pasture soil from a farm. The results indicated that phoxim-treated eggs had a 40% IH%, while deltamethrin-treated eggs showed only an 8.79% IH%. In conclusion, the acaricides amitraz, phoxim, and chlorpyrifos, as well as the natural products carvacrol and thymol, caused significant toxicity to R. annulatus eggs.

Assessment of cattle tick infestation: Molecular insights into Rhipicephalus annulatus and the efficacy of garlic oil and nanoemulsion as acaricidal agents

Ticks, particularly Rhipicephalus annulatus, pose significant threats to livestock, causing economic losses and transmitting various infectious diseases. This study aimed to evaluate the potential acaricidal properties of garlic oil and its nanoemulsion against ticks infesting cattle, Rhipicephalus annulatus through the evaluation of mortality rate and morphological changes of the treated ticks. The study also included prevalence, risk factors, and molecular confirmation of tick species. Genetic characterization confirmed the identity of R. annulatus. Our results revealed a high prevalence of R. annulatus (46.9%) with a higher risk in male cattle (50%) than females (44.9%) and a nonsignificant high infection (49.1%) in animals ≤ 1 year old. The acaricidal efficiency of garlic oil and its nanoemulsion was concentration and time-dependent. The high concentration of garlic oil (20 mg/L) induced complete mortality within 48 hours. The nanoemulsion formulation enhanced efficacy, particularly at 5 mg/L, which exhibited rapid and substantial acaricidal activity. Scanning electron microscopy revealed morphological alterations induced by garlic oil and its nanoemulsion, including changes to the anterior capitulum, dorsal, and ventral cuticles. The study contributes to the exploration of effective, safe, and eco-friendly alternatives for tick control. Further research is warranted to validate their efficacy under diverse conditions and assess practical strategies.

Effect of ivermectin, amitraz and fipronil on midgut epithelium and digestive enzyme profile in Rhipicephalus microplus ticks (Acari: Ixodidae)

Blood feeding and digestion are vital physiological activities essential for the survival and reproduction of ticks. Chemical acaricides viz., ivermectin, amitraz and fipronil, are known to act on the central nervous system, resulting in the mortality of ticks. The present study is focused on the effect of these acaricides on the midgut and gut enzymes of Rhipicephalus microplus. The ultra-thin sections of midgut of ivermectin-treated ticks showed irregular basal membrane and ruptured digestive vesicles. Amitraz treatment resulted in a notable decrease in digestive cells with pleats in the basal membrane, while fipronil-exposed ticks exhibited reduced digestive cells, loss of cellular integrity, and disintegration of the basal membrane and muscle layer. The gut tissue homogenate of ivermectin and fipronil treated ticks showed a significant reduction of cathepsin D level, 76.54 ± 3.20 μg/mL and 92.67 ± 3.72 μg/mL, respectively, as compared to the control group (150.0 ± 3.80 μg/mL). The leucine aminopeptidase level (4.27 ± 0.08 units/mL) was significantly decreased in the ivermectin treated ticks compared to other treatment groups. The acid phosphatase activity (29.16 ± 0.67 μmole/min/L) was reduced in the ivermectin treated group whereas, increased activity was observed in the fipronil and amitraz treated groups. All the treatment groups revealed increased alkaline phosphatase levels (17.47-26.72 μmole/min/L). The present finding suggests that in addition to the established mechanism of action of the tested acaricides on the nervous system, the alterations in the cellular profile of digestive cells and enzymes possibly affect the blood digestion process and thus the synthesis of vital proteins which are essential for vitellogenesis, and egg production in ticks.

Evaluation of the Immune Response of a Candidate Phage-Based Vaccine against Rhipicephalus microplus (Cattle Tick)

Cattle tick (Rhipicephalus microplus) represents a severe problem causing substantial economic losses, estimated in billions of dollars annually. Currently, chemical acaricides represent the most widely used control method. However, several problems such as resistance have been described. Phage-based vaccines represent a fast and low-cost tool for antigen delivery. In this regard, the objective of the present work was to develop a candidate phage-based vaccine displaying a cattle tick antigen (Bm86-derived Sbm7462 antigen) on the surface of bacteriophage M13. Phage ELISA and dot blotting analysis confirmed the display of the antigen. Vaccine immunogenicity was evaluated using a bovine monocyte-derived dendritic cell-based ex vivo assay and a murine in vivo assay. The ex vivo model showed the maturation of dendritic cells after being pulsed with the phage-based vaccine. The humoral response was confirmed in the in vivo assay. These results demonstrated the capacity of the phage-based vaccine to induce both humoral and cellular immune-specific responses. Importantly, this is the first report describing a control method for cattle ticks using a candidate phage-based vaccine. Further studies to evaluate the immunogenicity in a bovine model are needed. The current approach represents a promising alternative to control cattle tick infestations.

Comparative susceptibility of Rhipicephalus microplus collected from the northern state of India to coumaphos, malathion, deltamethrin, ivermectin, and fipronil

The chemical-based tick management method is gradually losing its clutch due to the establishment of resistant ticks. For development of region-specific tick management strategies, the present study was aimed to evaluate the comparative resistance profile of Rhipicephalus microplus isolates collected from seven districts of Uttar Pradesh, a northern state of India. Comparative analysis of the dose-response data using adult immersion test (AIT) against coumaphos, malathion, deltamethrin, ivermectin, and fipronil revealed that all the isolates were resistant to discriminating concentration of deltamethrin having LC₅₀ of 295.12-436.52 ppm with a resistance ratio of 22.02-32.58. An emerging low level of ivermectin resistance (resistance ratio, RR₅₀ = 1.03-2.26) with LC₅₀ in the range of 22.39-48.98 ppm was found across the isolates. The coumaphos was highly effective against all except Amethi (AMT) isolate. Similarly, malathion was efficacious against most of the isolates except Pratapgarh (PRT) and Sultanpur (SUL) isolates showing LC₅₀ of 5128.61 and 5623.41 ppm, respectively. All the isolates were responsive to fipronil. Comparative detoxifying enzymes profiles revealed a significant correlation between the increased activity of esterase and deltamethrin resistance. The GST activity was 51.2% correlated with RR₅₀ of malathion while esterase activity was significantly correlated (68.9%) with RR₅₀ of coumaphos. No correlation between the ivermectin resistance and enzyme activity was established. Multiple sequence analysis of S4-5 linker region of the sodium channel gene of all the isolates revealed a point mutation at 190th position (C190A) which is associated with deltamethrin resistance. The possible tick management strategies in this part of the country are discussed.

Effect of polyphenols extracted from Punica granatum and Acacia saligna plants on glutathione S-transferase of the cattle tick Rhipicephalus (Boophilus) annulatus (Acari: Ixodidae)

Ticks are hematophageal ectoparasites that transport major pathogens around the world. Glutathione S-transferases (GST) are involved in resistance to acaricide and redox balancing during the life cycle of the tick. The inhibition of tick GST enzymes by certain phenolic compounds, such as phenolic acids and tannins, can be a promising approach to tick control. The objective of this study was to evaluate the effects of Punica granatum red peel and Acacia saligna leaf extracts on Rhipicephalus (Boophilus) annulatus GST activity in order to reduce the resistance of cattle to acaricide. The results showed that P. granatum ethanol extract (70%) contained the highest total phenol content (350 ± 1.2 μM GAE g^-1), the highest condensed tannin content (270 ± 1.3 μM CE g^-1) and the highest hydrolysable tannin content (70 ± 5.0 μM TAE g^-1). Adult immersion test with a dosage of 100 mg ml^-1 of A. saligna ethanol extracts had a significant mortality of 50% and 75% after 24 h and 96 h, respectively (p < 0.01). A simple and reproducible procedure was established to purify the whole R. annulatus GST (wRaGST) while a full-length cDNA of GST was cloned from a cDNA library of the local Egyptian cattle tick R. (B.) annulatus (rRaGST). Aqueous extracts of P. granatum inhibited both wRaGST and rRaGST with values of IC₅₀ = 0.114 and 0.07 µg ml^-1, respectively, compared to A. saligna extracts (IC₅₀ values = 2.08 and 1.35 µg ml, respectively). These inhibitory effects were attributed to the presence of a high tannin concentration (≥ 80%). HPLC analysis indicated the presence of gallic acid and catechin in both extracts, in addition to the rutin, which was only observed in A. saligna extracts. The addition of a tannin inhibitor, polyethylene glycol, suggested the existence of other phenolic compounds in combination with catechins responsible for inhibiting the activity of these extracts. Non-competitive behaviour of catechins may be helpful in preventing, or at least delaying, the development of chemical acaricide resistance in R. annulatus.

Assessing the Immunochromatographic Test Strip for Serological Detection of Bovine Babesiosis in Uganda

In Uganda, bovine babesiosis continues to cause losses to the livestock industry because of shortages of cheap, quick, and reliable diagnostic tools to guide prescription measures. In this study, the presence of antibodies to Babesia bigemina and Babesia bovis in 401 bovine blood samples obtained from eastern and central areas of Uganda were detected using enzyme-linked immunosorbent assays (ELISAs) and immunochromatographic test strips (ICTs). The ELISA and ICT test used targeted the B. bigemina C-terminal rhoptry-associated protein (RAP-1/CT17) and B. bovis spherical body protein-4 (SPB-4). Using ELISA, single-ICT and dual-ICT, positive samples for B. bovis were detected in 25 (6.2%), 17 (4.3%), and 14 (3.7%) samples respectively, and positive samples for B. bigemina were detected in 34 (8.4%), 27 (6.7%), and 25 (6.2%), respectively. Additionally, a total of 13 animals (3.2%) had a mixed infection. The correlation between ELISA and single-ICT strips results revealed slight agreement with kappa values ranging from 0.088 to 0.191 between both methods, while the comparison between dual-ICT and single-ICT results showed very good agreement with kappa values >0.80. This study documented the seroprevalence of bovine babesiosis in central and eastern Uganda, and showed that ICT could, after further optimization, be a useful rapid diagnostic test for the diagnosis of bovine babesiosis in field settings.

Inhibitory effects of novel ciprofloxacin derivatives on the growth of four Babesia species and Theileria equi

The problems of parasite resistance, as well as the toxic residues to most of the commercially available antipiroplasmic drugs severely weaken their effective, curative, and environmental safe employment. Therefore, it is clear that the development of treatment options for piroplasmosis is vital for improving disease treatment and control. Ciprofloxacin is a broad-spectrum antibiotic that targets mainly the DNA replication machinery by inhibiting DNA gyrase and topoisomerase enzymes. As a result, ciprofloxacin is used for treating several bacterial and parasitic infections. In this study, the efficacy of 15 novel ciprofloxacin derivatives (NCD) that had been developed against drug-resistant Mycobacterium tuberculosis was evaluated against piroplasm parasite multiplication in vitro. The half-maximal inhibitory concentration (IC₅₀) values of the most effective five compounds of NCD (No. 3, 5, 10, 14, 15) on Babesia bovis, Babesia bigemina, Babesia caballi, and Theileria equi were 32.9, 13.7, 14.9, and 30.9; 14.9, 25.8, 13.6, and 27.5; 34.9, 33.9, 21.1, and 22.3; 26.7, 28.3, 34.5, and 29.1; and 4.7, 26.6, 33.9, and 29.1 μM, respectively. Possible detrimental effects of tested NCD on host cells were assessed using mouse embryonic fibroblast (NIH/3T3) and Madin-Darby bovine kidney (MDBK) cell lines. Tested NCD did not suppress NIH/3T3 and MDBK cell viability, even at the highest concentration used (500 μM). Combination treatments of the identified most effective compounds of NCD/diminazene aceturate (DA), /atovaquone (AQ), and /clofazimine (CF) showed mainly synergistic and additive effects. The IC₅₀ values of NCD showed that they are promising future candidates against piroplasmosis. Further in vivo trials are required to evaluate the therapeutic potential of NCD.

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.

Phytochemical Screening and Antiprotozoal Effects of the Methanolic Berberis vulgaris and Acetonic Rhus coriaria Extracts

Berberis vulgaris (B. vulgaris) and Rhus coriaria (R. coriaria) have been documented to have various pharmacologic activities. The current study assessed the in vitro as well as in vivo inhibitory efficacy of a methanolic extract of B. vulgaris (MEBV) and an acetone extract of R. coriaria (AERC) on six species of piroplasm parasites. The drug-exposure viability assay was tested on three different cell lines, namely mouse embryonic fibroblast (NIH/3T3), Madin-Darby bovine kidney (MDBK) and human foreskin fibroblast (HFF) cells. Qualitative phytochemical estimation revealed that both extracts containing alkaloid, tannin, saponins and terpenoids and significant amounts of flavonoids and polyphenols. The GC-MS analysis of MEBV and AERC revealed the existence of 27 and 20 phytochemical compounds, respectively. MEBV and AERC restricted the multiplication of Babesia (B.) bovis, B. bigemina, B. divergens, B. caballi, and Theileria (T.) equi at the half-maximal inhibitory concentration (IC50) of 0.84 ± 0.2, 0.81 ± 0.3, 4.1 ± 0.9, 0.35 ± 0.1 and 0.68 ± 0.1 µg/mL and 85.7 ± 3.1, 60 ± 8.5, 90 ± 3.7, 85.7 ± 2.1 and 78 ± 2.1 µg/mL, respectively. In the cytotoxicity assay, MEBV and AERC inhibited MDBK, NIH/3T3 and HFF cells with half-maximal effective concentrations (EC50) of 695.7 ± 24.9, 931 ± 44.9, ˃1500 µg/mL and 737.7 ± 17.4, ˃1500 and ˃1500 µg/mL, respectively. The experiments in mice showed that MEBV and AERC prohibited B. microti multiplication at 150 mg/kg by 66.7% and 70%, respectively. These results indicate the prospects of these extracts as drug candidates for piroplasmosis treatment following additional studies in some clinical cases.