Babesia ovis, transmitted by Rhipicephalus bursa ticks, is the causative agent of ovine babesiosis, a disease characterized by fever, anemia, hemoglobinuria, and high mortality in sheep. This study investigates whether sheep that survived babesiosis without treatment can serve as a source of infection for B. ovis-free host-seeking R. bursa larvae in a later season. Three donor sheep were experimentally infected with B. ovis, and after six months, persistence of B. ovis was assessed through blood and tick transmission experiments. Blood from donor sheep was intravenously injected into three recipient sheep, while donor sheep were also infested with B. ovis-free R. bursa larvae. Engorged nymphs molted to adults, and new recipient sheep were infested with these ticks. All recipient sheep were monitored for B. ovis for 100 days using microscopic, serological, and molecular approaches. The presence of B. ovis was confirmed in the recipient sheep that received blood, leading to clinical infection in two. However, no B. ovis was detected in recipient sheep infested with ticks. These results suggest that sheep recovering from B. ovis infection do not serve as a source of infection for R. bursa larvae in subsequent seasons.

BACKGROUND: Rhipicephalus microplus poses a significant problem for livestock worldwide and is primarily controlled with synthetic acaricides. The continuous use of acaricides results in the selection of resistance and causes environmental harm. Vaccination presents an alternative solution to this problem, although searching for the suitable antigen is still a work in progress. Salivary proteins hold promise for inclusion in vaccine formulation due to their roles in modulating host responses, assisting blood feeding and pathogen transmission. Serpins are a class of proteinase inhibitors and are among the molecules found in tick saliva that modulate host blood coagulation, inflammation, and adaptive immune responses. Previous studies have demonstrated the potential of R. microplus serpin 17 (RmS-17) to interfere with the host\'s defenses, and antibodies have been shown to neutralize its effects. This makes RmS-17 an putative target for vaccine development.
METHODS: Epitope mapping of RmS-17 was achieved using in silico approach combining linear B-cell epitope and antigenicity predictor. In addition, epitope mapping using overlapping peptides in an ELISA screening was used. The serpin tridimensional structure and the epitopes spatial location within the molecule were determined. Peptides were synthetized based on the predictions and used for the production of rabbit anti-sera. Purified IgG\'s were used to assess the antibodies capacity to neutralize RmS-17.
RESULTS: Through in silico mapping, nine potential B cell epitope regions were screened, with p1RmS-17 and p2RmS-17 selected for the experiment based on antigen prediction. In the ELISA screening using overlapping peptides, eight antibody-binding regions were identified, and p3RmS-17 and p4RmS-17 were chosen. Antibodies raised against p3RmS-17 and p4RmS-17 partially neutralized RmS-17 activity.
CONCLUSIONS: It was found that antibodies against a single epitope are sufficient to partially neutralize RmS-17 activity. These findings support the possibility of using an epitope-based vaccine for immunization against R. microplus.

The management of cattle ticks, particularly Rhipicephalus microplus, poses a global challenge in subtropical regions like Ecuador due to its impact on meat and milk productivity, leading to economic losses. Misuse of acaricides has resulted in resistance and multi-resistance, diminishing their effectiveness. This study evaluated resistance to amitraz, alpha-cypermethrin, and ivermectin using the Larval Packet test, laboratory-reared tick larvae collected from cattle were tested. Data on farm management and tick control practices were gathered via a questionnaire in Northwest Pichincha and Quijos River Valley over two years. Resistance rates in the first year (2020-2021) were 67.21% for amitraz, 57.38% for ivermectin, and 67.21% for alpha-cypermethrin. One year later (2021-2022), resistance levels were 59.57% for amitraz, 57.45% for ivermectin, and 68.09% for alpha-cypermethrin, with multi-resistance rates at 67.21% and 65.96% respectively. No significant differences were found between years or locations. Analysis of larval survival data determined lethal doses for tested acaricides. The study emphasizes the association between the lack of acaricide rotation, the incorrect dosage, and the absence of non-chemical measures in tick management could be associated with the development of resistances in ticks. Likewise, this study promotes the need for collaborative efforts to improve control practices and maintain acaricide efficacy.

This study examined the pattern of resistance to widely applied synthetic pyrethroids, i.e., cypermethrin and deltamethrin, against larvae of Rhipicephalus microplus ticks sampled from Marathwada region in Maharashtra, India. The study also examined the role of α- and β-esterases and glutathione-S-transferase (GST) in resistance development. All eight R. microplus isolates tested were resistant to deltamethrin (RL IV), having RR50 values from 6.88 to 131.26. LPT analysis exhibited the resistance level II deltamethrin resistance in Beed and Hingoli, III in Dharashiv, and IV in Sambhajinagar, Parbhani, Latur, Jalna, and Nanded isolates. The LIT analysis showed that Dharashiv field isolates had the lowest LC50 value of 229.09 ppm against cypermethrin, while Sambhajinagar field isolates had the highest at 489.78 ppm. The RR50 ranged from 1145.45 to 2448.9. Seven isolates were level I resistant to cypermethrin while the Jalna isolate was level II resistant. In larvae treated with deltamethrin and cypermethrin, the activity of α- and β-esterase enzymes increased significantly compared to control groups. The enzyme ratios in treated larvae ranged from 0.7533 to 1.7023 for α-esterase and 0.7434 to 3.2054 for β-esterase. The Hingoli isolate treated with cypermethrin exhibited the highest α-esterase activity (903.261), whereas Sambhajinagar isolate had the highest GST enzyme ratio (2.8224) after deltamethrin exposure. When exposed to cypermethrin, the Hingoli isolate showed the highest GST enzyme ratio, 2.0832. The present study provides the current resistance status in tick populations from Marathwada region indicating deltamethrin and cypermethrin to be ineffective for tick control. The results also suggest that SP compounds should be regulated in this region and alternative control strategies should be introduced.

Fort Munro is a hill station in Southern Punjab the residents of whom are heavily dependent upon livestock for their living but ticks are a big treat for the livestock. The purpose of this study was to ascertain the tick infestation among the small ruminants of Fort Munro. Ticks (N = 273) were collected from 333 animals (165 goats and 168 sheep) during August and September 2022. Two tick genera Hyalomma and Rhipicephalus were identified. Rhipicephalus was most abundant tick genera (78.02%) followed by Hyalomma (21.98%).Tick distribution significantly varied with the host: Rhipicephalus ticks were more frequently infesting goats while Hyalomma were more common on sheep. For both hosts, tick infestation varied with the sampling sites and male animals were significantly more infested than females. Five tick species were infesting goats with the following relative abundance: Rhipicephalus (R.) senegalensis (39.20%) > R. sanguineus (36.8%) > R. appendiculatus (10.40%) > R. turanicus (8%) > R. guilhoni (5.6%). Rhipicephalus senegalensis (41.22%) was also the most common tick species infesting sheep followed by Hyalomma (H.) marginatum (29.73%), R. guilhoni (18.24%), H. dromedarii (5.41%) and H. impeltatum (5.41%). Male ticks very more abundantly on both goats and sheep than female. Distribution of Hyalomma species also varied between the sampling sites. In conclusion, we are reporting the infestation of 3 Hyalomma and 5 Rhipicephalus in small ruminants of Fort Munro. The data generated through this study will help in developing appropriate tick control in the study area and will add to the existing knowledge regarding tick species that are infesting the small ruminants of Pakistan.

Ticks are ectoparasites responsible for the transmission of various pathogens to vertebrates. They represent one of the major threats to livestock production worldwide due to their impact on the health, production and welfare of livestock destined for human consumption. The development of resistance to the main families of ixodicides used for their control has led to the search for new alternatives, where microbial control is an option. The use of microbial control agents against the tick Rhipicephalus microplus is reviewed in this paper. Bacteria such as Bacillus thuringiensis, Serratia marcescens and Staphylococcus spp. the nematodes Steinernema spp. and Heterorhabditis spp. as well as the fungi Metarhizium anisopliae and Beauveria bassiana are the most studied organisms for use as biological control agents against ticks. Laboratory, stable and field trials with free-living and parasitised ticks have shown that microbial agents can control both susceptible and ixodicide-resistant tick populations. However, multidisciplinary studies using novel tools like genomics, transcriptomics and proteomics should be carried out to understand the virulence factors which microbial agents use to induce pathogenesis and virulence in ticks. In addition, applied research will be carried out with the aim of improving techniques for large-scale application, as well as the improvement of cultivation, storage, formulation and application methods.

BACKGROUND: Pyrethroid chemicals are one of the main acaricides used against ticks. Resistance to these chemicals has been reported to be associated with mutations in the voltage-gated sodium channel (VGSC) gene of the Rhipicephalus microplus. This study investigates R. microplus resistance to pyrethroids in Guangxi region of China, marking one of the first research efforts in this area. The findings are intended to provide vital baseline for the effective implementation of localized tick control strategies.
METHODS: From March to July 2021, 447 R. microplus tick samples were collected from five prefecture-level cities in Guangxi. Allele-specific polymerase chain reaction (AS-PCR) was used to amplify segments C190A and G215T of the domain II S4-5 linker and T2134A of domain III S6 in the VGSC, to detect nucleotide mutations associated with resistance to pyrethroid acaricides. Subsequent analyses were conducted to ascertain the prevalence, types of mutations, and genotypic distributions within the sampled populations.
RESULTS: Mutations within VGSC gene were identified across all five studied populations of R. microplus, although the mutation rates remained generally low. Specifically, the most prevalent mutation was C190A, observed in 4.9% of the samples (22/447), followed by G215T at 4.0% (18/447), and T2134A at 1.3% (6/447). The distribution of mutations across three critical sites of the VGSC gene revealed four distinct mutation types: C190A, G215T, C190A + G215T, and T2134A. Notably, the single mutation C190A had the highest mutation frequency, accounting for 4.3%, and the C190A + G215T combination had the lowest, at only 0.7%. The analysis further identified seven genotypic combinations, with the wild-type combination C/C + G/G + T/T predominating at a frequency of 90.4%. Subsequently, the C/A + G/G + T/T combination was observed at a frequency of 4.3%, whereas the C/C + T/T + T/T combination exhibited the lowest frequency (0.2%). Additionally, no instances of simultaneous mutations at all three sites were detected. Geographical differences in mutation types were apparent. Both samples from Hechi to Chongzuo cities exhibited the same three mutation types; however, C190A was the most prevalent in Hechi, while G215T dominated in Chongzuo. In contrast, samples from Beihai to Guilin each exhibited only one mutation type: G215T occurred in 12.5% (4/32) of Beihai samples, and C190A in 7.5% (4/53) of Guilin samples.
CONCLUSIONS: These findings underscore the relatively low frequency of VGSC gene mutations in R. microplus associated with pyrethroid resistance in the Guangxi, China. Moreover, the variation in mutation types and genotypic distributions across different locales highlights the need for regionalized strategies in monitoring and managing pyrethroid resistance in tick populations. This molecular surveillance is crucial for informing targeted control measures and mitigating the risk of widespread resistance emergence.

Rhipicephalus microplus poses a significant economic threat due to its role in transmitting Babesia bigemina, B. bovis and Anaplasma marginale. Chemical control methods, commonly employed, encounter challenges like resistance, high costs, and environmental concerns. Emerging as an alternative, entomopathogenic fungi, particularly Beauveria bassiana, present a promising avenue for biological control. Molecular identification using the internal transcribed spacer (ITS1-5.8-ITS4) region ensures accurate species identification. This study investigated two B. bassiana strains, assessing their molecular characterization, impact on R. microplus mortality, and reproductive effects on adult females. The Reproductive Aptitude Index (RAI) is employed to evaluate tick egg viability post-treatment, providing insights into the potential of these fungi for tick control. Results indicate the BbLn2021-1 strain causes 96% mortality, and BbSf2021-1 induces 100% mortality. The commercial strain exhibited 28% mortality, while the control treatment showed 12%. Statistical analysis reveals a significant difference between treatments (p < 0.01). The Reproductive Efficiency Index (REI) underscores BbSf2021-1is superiority, yielding lower egg weights than other treatments. Regarding the RAI, BbLn2021-1 and BbSf2021-1 show no significant differences but differ significantly from the commercial and control (p < 0.01). These findings suggest that strains isolated and characterized from the natural environment could have potential applications in field trials, serving as a biocontrol alternative for R. microplus ticks.

Equine piroplasmosis is not fully understood regarding pathogenicity, prophylaxis, host immune response expression, and specific vectors. Accurately identifying the parasite vector is crucial for developing an effective control plan for a particular infection. This study focused on morphologically identifying two Hyalomma species (H. anatolicum and H. marginatum) and one Rhipicephalus annulatus (R. annulatus) at the species level. The identification process was followed by phylogenetic analysis using the neighbor-joining method based on the cytochrome oxidase subunit 1 (COXI) gene as a specific vector for Theileria equi (T. equi) in horses. T. equi was diagnosed morphologically and molecularly from infected blood samples and crushed tick species using conventional PCR. Subsequently, phylogenetic analysis based on the amplification of the 18 S rRNA gene was conducted. The obtained sequence data were evaluated and registered in GenBank under accession numbers OR064161, OR067911, OR187727, and OR068139, representing the three tick species and the isolated T. equi, respectively. The study demonstrated that T. equi infection leads to immune system suppression by significantly increasing the levels of oxidative stress markers (CAT, GPx, MDA, and SOD) (P ≤ 0.0001), with this elevation being directly proportional to parasitemia levels in infected blood cells. Furthermore, a correlation was observed between parasitemia levels and the expression of immune response infection genes (IFN-gamma, TGF-β1, and IL-1β cytokines) in infected horses compared to non-infected equine. Common macroscopic symptoms indicating T. equi infection in horses include intermittent fever, enlarged lymph nodes (LN), and tick infestation.

Colpodella species are close relatives of Apicomplexan protozoa. Although most species of this genus are free-living organisms that feed on other protists and algae, reports indicate their occurence in ticks and human patients, including an individual with a history of tick bite manifesting neurological symptoms. During an investigation of tick-borne pathogens (TBPs) in blood samples of cattle, goats, and in ticks collected on them, Colpodella sp. DNA was detected in a Rhipicephalus bursa tick collected from cattle, while of Theileria sergenti/buffeli/orientalis, Babesia bigemina, Sarcocystis cruzi, Babesia spp., and Rickettsia spp. were molecularly detected in cattle, goats, and ticks in southern Italy. Data herein reported highlight the unprecedented presence of Colpodella sp. in ticks in Italy, raising concern due to the potential pathogenic role of this less known protozoan. This finding advocates for performing routine epidemiological surveys to monitor potential emerging vector-borne pathogens.