A systematic review on modelling approaches for economic losses studies caused by parasites and their associated diseases in cattle

Bovine anaplasmosis in Zimbabwe: spatio-temporal distribution and environmental drivers

Understanding the spatial and temporal distribution of Bovine anaplasmosis is crucial for identifying areas of high prevalence for targeted disease control. This research was aimed at modelling and mapping the B. anaplasmosis potential distribution, and identify hotspots as well as significant variables explaining the occurrence of the disease. The Getis Ord Gi* statistic for Hotspot analysis was used as well as MaxEnt ecological niche modelling. The effects of time, land-use, and agro-ecological regions on B. anaplasmosis occurrence were tested using Analysis of Variance (ANOVA). Results showed that several districts in Zimbabwe are suitable for the occurence of the disease for example Binga, Seke, Buhera, Kwekwe, Gweru, Mhondoro, Chegutu, Sanyati, and in the North: Mbire, Muzarabani, Mt Darwin, Shamva, Bindura, Zvimba and Makonde. Morbidity and mortality hotspots were detected in Gokwe-south, Kwekwe, and Chirumhanzu districts. Binga, Gokwe-south, Gutu, Hurungwe, Mazoe, Nkayi, Shamva, and Kwekwe districts also experienced high disease incidences. Temperature seasonality, precipitation seasonality, mean diurnal range, and isothermality were the most important variables in explaining 93% of B. anaplasmosis distribution. Unlike land-use and agro-ecological regions, time (months) had a significant effect on B. anaplasmosis occurrence with July and September having significantly (p < 0.05) higher cases and deaths than the rest of the months. The results of this study provide insights into the management strategies and control of B. anaplasmosis in Zimbabwe. It is thus concluded that geo-spatial techniques, combined with ecological niche modelling can provide useful insights into disease prevalence and distribution and hence can contribute to effective management and control of B. anaplasmosis in Zimbabwe.

Ultrasonography screening of hepatic cystic echinococcosis in sheep flocks used for evaluating control progress in a remote mountain area of Hejing County, Xinjiang

BACKGROUND

Although ultrasonography (US) has been widely used in the diagnosis of human diseases to monitor the progress of cystic echinococcosis (CE) control, the screening method for hepatic CE in sheep flocks requires adjustment. In this study, we used a US scanner to screen sheep flocks and evaluated the efficacy of dosing dogs once a year with praziquantel for 7 years from 2014 to 2021.

METHODS

All sheep in the three flocks were screened using an ultrasound scanner in 2014 and compared with the prevalence of infection in 2021 in Bayinbuluke, Xinjiang, China. Sheep age was determined using incisor teeth. Cyst activity and calcification were determined using US images. The dogs were dewormed with praziquantel once a year to control echinococcosis in the community.

RESULTS

Three flocks had 968 sheep in 2014, with 13.22%, 22.62%, 18.7%, 27.27%, 11.88%, and 6.3% of sheep aged 1, 2, 3, 4, 5, and ≥ 6 years old, respectively. US scanning revealed that the overall CE prevalence was 38.43% (372/968), with active cysts and calcified cysts present in 9.40% (91/968) and 29.02% (281/968) of the sheep, respectively. For the young sheep aged 1 and 2 years, the prevalence of active and calcified cysts was: 1.56% and 0.91%, and 10.94% and 18.72%, respectively. Approximately 15.15% and 16.52% of the 4- and 5-year-old sheep, respectively, harbored active cysts. There was no significant difference in the infection rates of sheep between 2014 and 2021 (P > 0.05).

CONCLUSIONS

US is a practical tool for the field screening of CE in sheep flocks. One-third of the sheep population in the flocks was 1-2 years old, and these sheep played a very limited role in CE transmission, as most of the cysts were calcified. Old sheep, especially culled aged sheep, play a key role in the transmission of CE. Dosing dogs once a year did not affect echinococcosis control.

Theileria annulata subtelomere-encoded variable secreted protein-TA05560 interacts with bovine RNA binding motif protein 39 (RBM39)

Theileria annulata is the only eukaryotic pathogen able to transform bovine leukocytes, including B cells, macrophages and dendritic cells. T. annulata-transformed cells exhibit several cancer-like phenotypes, such as hyperproliferation, immortalization and dissemination. Although several parasite factors involved in bovine cell transformation have been explored, the roles of subtelomere-encoded variable secreted proteins (SVSPs) of the parasite in host-cell interactions are largely unknown. In the present study, the target molecule TA05560, a member of the SVSP multigene family of T. annulata, was identified at the mRNA level during different life cycles through a quantitative real-time PCR assay, and the subcellular distribution of TA05560 was examined via confocal microscopy. The results showed that the parasite molecule TA05560 was transcribed mainly in the schizont stage of T. annulata infection, and the protein was distributed in the nucleus and cytoplasm of the parasitized cells. The potential host cell proteins that interact with TA05560 were screened using the yeast two-hybrid system, and the direct interaction between TA05560 and its prey protein, Bos taurus RNA binding motif protein 39 (RBM39) was further identified in HEK293T cells by using confocal microscopy, coimmunoprecipitation and bimolecular fluorescence complementation assays. Moreover, the interaction between TA05560 and its host protein was observed in T. annulata-infected cells via confocal microscopy. Therefore, our study is the first to show that the T. annulata-secreted TA05560 protein directly binds to both the exogenous and endogenous host cell molecule RBM39, laying the foundation for exploring host-parasite interactions and understanding the transformation mechanisms induced by T. annulata and other transforming parasites.

Towards modelling tick-virus interactions using the weakly pathogenic Sindbis virus: Evidence that ticks are competent vectors

Most tick-borne viruses (TBVs) are highly pathogenic and require high biosecurity, which severely limits their study. We found that Sindbis virus (SINV), predominantly transmitted by mosquitoes, can replicate in ticks and be subsequently transmitted, with the potential to serve as a model for studying tick-virus interactions. We found that both larval and nymphal stages of Rhipicephalus haemaphysaloides can be infected with SINV-wild-type (WT) when feeding on infected mice. SINV replicated in two species of ticks (R. haemaphysaloides and Hyalomma asiaticum) after infecting them by microinjection. Injection of ticks with SINV expressing enhanced Green Fluorescent Protein (eGFP) revealed that SINV-eGFP specifically aggregated in the tick midguts for replication. During blood-feeding, SINV-eGFP migrated from the midguts to the salivary glands and was transmitted to a new host. SINV infection caused changes in expression levels of tick genes related to immune responses, substance transport and metabolism, cell growth and death. SINV mainly induced autophagy during the early stage of infection; with increasing time of infection, the level of autophagy decreased, while the level of apoptosis increased. During the early stages of infection, the transcript levels of immune-related genes were significantly upregulated, and then decreased. In addition, SINV induced changes in the transcription levels of some functional genes that play important roles in the interactions between ticks and tick-borne pathogens. These results confirm that the SINV-based transmission model between ticks, viruses, and mammals can be widely used to unravel the interactions between ticks and viruses.

Development of a qPCR Duplex Assay for simultaneous detection of Fascioloides magna and Galba truncatula in eDNA samples: Monitoring beyond boundaries

Parasites constitute a significant economic burden and highly impact environmental, public, and animal health. The emergence of many parasitic diseases is environmentally mediated and they share the same biogeography with humans and both domestic and wild animals. American liver fluke, Fascioloides magna - a trematode parasite of domestic and wild ungulates - is an example of the anthropogenic introduction of an "invasive alien species" in Italy and Europe. Multiple introductions to Europe have led to the biogeographical expansion of the parasite across the Danube region mainly provided by the presence of suitable habitats for all hosts involved in the parasite's life cycle, human-assisted transport, and drastic environmental events such as flooding. In Italy, it was introduced and established in La Mandria Regional Park (LMRP) near Turin in 1865 along with imported wapitis (Cervus elaphus canadensis) from North America (Bassi, 1875), but with no reported expansion to the surrounding areas. LMRP isolated F. magna focus, poses an important threat of possible expansion since the enclosed area is vulnerable to occasional bidirectional passage of roe deer. Additionally, tributary rivers to the Po river system, traversing the enclosed area, could further bolster the possibility of such spread. In this study, we developed a duplex qPCR assay for F. magna and its principal intermediate host Galba truncatula optimized for testing eDNA samples to meet the needs for surveillance of the parasite. Moreover, we validated the developed assay in natura by testing samples derived from filtered water and sediments collected inside and outside LMRP's fenced-off area. Our findings for the first time demonstrate the presence of F. magna's eDNA outside the park's internal fenced-off area.

Differential Effects of Two Common Antiparasitics on Microbiota Resilience

BACKGROUND

Parasitic infections challenge vertebrate health worldwide, and off-target effects of antiparasitic treatments may be an additional obstacle to recovery. However, there have been few investigations of the effects of antiparasitics on the gut microbiome in the absence of parasites.

METHODS

We investigated whether two common antiparasitics-albendazole (ALB) and metronidazole (MTZ)-significantly alter the gut microbiome of parasite-free mice. We treated mice with ALB or MTZ daily for 7 days and sampled the fecal microbiota immediately before and after treatment and again after a two-week recovery period.

RESULTS

ALB did not immediately change the gut microbiota, while MTZ decreased microbial richness by 8.5% and significantly changed community structure during treatment. The structural changes caused by MTZ included depletion of the beneficial family Lachnospiraceae, and predictive metagenomic analysis revealed that these losses likely depressed microbiome metabolic function. Separately, we compared the fecal microbiotas of treatment groups after recovery, and there were minor differences in community structure between the ALB, MTZ, and sham-treated control groups.

CONCLUSIONS

These results suggest that a healthy microbiome is resilient after MTZ-induced depletions of beneficial gut microbes, and ALB may cause slight, latent shifts in the microbiota but does not deplete healthy gut microbiota diversity.

First insight into strongylid nematode diversity and anthelmintic treatment effectiveness in beef cattle in the Czech Republic explored by HTS metagenomics

Parasitic diseases and mitigation of their effects play an important role in the health management of grazing livestock worldwide, with gastrointestinal strongylid nematodes being of prominent importance. These helminths typically occur in complex communities, often composed of species from numerous strongylid genera. Detecting the full diversity of strongylid species in non-invasively collected faecal samples is nearly impossible using conventional methods. In contrast, high-throughput amplicon sequencing (HTS) can effectively identify co-occurring species. During the four-year project, we collected and analysed faecal samples from beef cattle on >120 farms throughout the Czech Republic. Strongylids were the predominant nematodes, detected in 56% of the samples, but at a low level of infection. The apparent limitations in identifying strongylid taxa prompted this pilot study on a representative group of samples testing positive for strongylids using ITS-2 metabarcoding. The most widespread genera parasitizing Czech cattle were Ostertagia (O. ostertagi) and Oesophagostomum spp., followed by Trichostrongylus and Cooperia, while Bunostomum, Nematodirus and Chabertia were present only in a minority. As comparative material, 21 samples of cattle from the Danube Delta in Romania were used, which, in contrast, were dominated by Haemonchus placei. Finally, the effect of ivermectin treatment was tested at two Czech farms. After treatment with the anthelmintic, there was a shift in the strongylid communities, with a dominance of Cooperia and Ostertagia.

Antibody detection against Kunitz-type protein in Fasciola hepatica experimentally infected sheep using enzyme-linked immunosorbent assay (ELISA)

Fasciolosis is a parasitic disease considered as emerging and neglected by the WHO. Sheep are highly susceptible to this disease, and affected flocks experience decreased productivity due to increased mortality, and the reduced quality of their products, such as wool and meat. To effectively control this disease, reliable and early diagnosis is essential for making decisions regarding antiparasitic application and/or the removal of affected animals. Currently, the diagnosis of F. hepatica in sheep relies on the detection of parasite eggs in faeces, a method that becomes reliable from week 10 post-infection. Consequently, there is a need for earlier diagnostic tools based on immune response. However, obtaining antigens for antibody detection has proven to be difficult and expensive. The aim of this study was to evaluate members of the Kunitz protein family of F. hepatica expressed in the form of a fusion protein in the serological diagnosis of F. hepatica in sheep. The performance of three recombinant F. hepatica Kunitz-type inhibitors (FhKT1.1, FhKT1.3, and FhKT4) was compared with a synthetic Kunitz-type peptide (sFhKT) in sera from sheep experimentally infected with F. hepatica, using an ELISA. Of these, FhKT1.1 showed the most promising diagnostic indicators, exhibiting high precision and low cross-reactivity, and thus potential for standardized production. The results of our study demonstrated that the application of FhKT1.1 is a valuable tool for early-stage diagnosis of F. hepatica in sheep. Such an early diagnosis can aid in implementing timely interventions and effectively managing the disease in sheep populations.

Impact of Ivermectin on the Gut Microbial Ecosystem

Ivermectin is a an anti-helminthic that is critical globally for both human and veterinary care. To the best of our knowledge, information available regarding the influence of ivermectin (IVM) on the gut microbiota has only been collected from diseased donors, who were treated with IVM alone or in combination with other medicines. Results thus obtained were influenced by multiple elements beyond IVM, such as disease, and other medical treatments. The research presented here investigated the impact of IVM on the gut microbial structure established in a Triple-SHIME® (simulator of the human intestinal microbial ecosystem), using fecal material from three healthy adults. The microbial communities were grown using three different culture media: standard SHIME media and SHIME media with either soluble or insoluble fiber added (control, SF, ISF). IVM introduced minor and temporary changes to the gut microbial community in terms of composition and metabolite production, as revealed by 16S rRNA amplicon sequencing analysis, flow cytometry, and GC-MS. Thus, it was concluded that IVM is not expected to induce dysbiosis or yield adverse effects if administered to healthy adults. In addition, the donor's starting community influences the relationship between IVM and the gut microbiome, and the soluble fiber component in feed could protect the gut microbiota from IVM; an increase in short-chain fatty acid production was predicted by PICRUSt2 and detected with IVM treatment.

Function-guided selection of salivary antigens from Ornithodoros erraticus argasid ticks and assessment of their protective efficacy in rabbits

The identification of new protective antigens for the development of tick vaccines may be approached by selecting antigen candidates that have key biological functions. Bioactive proteins playing key functions for tick feeding and pathogen transmission are secreted into the host via tick saliva. Adult argasid ticks must resynthesise and replace these proteins after each feeding to be able to repeat new trophogonic cycles. Therefore, these proteins are considered interesting antigen targets for tick vaccine development. In this study, the salivary gland transcriptome and saliva proteome of Ornithodoros erraticus females were inspected to select and test new vaccine candidate antigens. For this, we focused on transcripts overexpressed after feeding that encoded secretory proteins predicted to be immunogenic and annotated with functions related to blood ingestion and modulation of the host defensive response. Completeness of the transcript sequence, as well as a high expression level and a high fold-change after feeding were also scored resulting in the selection of four candidates, an acid tail salivary protein (OeATSP), a multiple coagulation factor deficiency protein 2 homolog (OeMCFD2), a Cu/Zn-superoxide dismutase (OeSOD) and a sulfotransferase (OeSULT), which were later produced as recombinant proteins. Vaccination of rabbits with each individual recombinant antigen induced strong humoral responses that reduced blood feeding and female reproduction, providing, respectively, 46.8%, 45.7%, 54.3% and 31.9% protection against O. erraticus infestations and 0.7%, 3.9%, 3.1% and 8.7% cross-protection against infestations by the African tick, Ornithodoros moubata. The joint protective efficacy of these antigens was tested in a second vaccine trial reaching 58.3% protection against O. erraticus and 18.6% cross-protection against O. moubata. These results (i) provide four new protective salivary antigens from argasid ticks that might be included in multi-antigenic vaccines designed for the control of multiple tick species; (ii) reveal four functional protein families never tested before as a source of protective antigens in ticks; and (iii) show that multi-antigenic vaccines increase vaccine efficacy compared with individual antigens. Finally, our data add value to the salivary glands as a protective antigen source in argasids for the control of tick infestations.

In Silico Exploration and Experimental Validation of Camellia sinensis Extract against Rhipicephalus microplus and Sarcoptes scabiei: An Integrated Approach

Sarcoptes scabiei is an ectoparasite of humans and animals that causes scabies. The Rhipicephalus (Boophilus) microplus is a blood-sucking ectoparasite that transmits various pathogens. These two parasites have caused great losses to a country's dairy and agriculture sectors. The aim of this study was to determine the in vitro and in silico efficacy of Camellia sinensis plant extracts. Different concentrations of C. sinensis ethanolic plant extracts were prepared using the maceration method and were used against mites and ticks (in adult immersion test AIT and larval packet test LPT) to evaluate their in vitro acaricidal activity. Additionally, in silico molecular docking was performed to investigate the inhibitory interactions between the phytochemicals of the plant and S. scabiei and R. microplus glutathione transferase proteins (SsGST and RmGST). This study observed that the plant extract showed high efficacy in vitro against mites and different tick stages in adult immersion and larval packet tests. Additionally, the in silico study revealed a strong binding interaction between ellagic acid and SsGST protein, with a binding energy of -7.3 kcal/mol, with respect to permethrin (-6.7 kcal/mol), whereas quercetin and RmGST resulted in a docking score of -8.6 kcal/mol compared to deltamethrin (-8.2 kcal/mol). Overall, this study explored the potential of C. sinensis as a natural alternative for controlling tick and mite infestations and provided insights into the inhibitory mechanisms of its phytochemicals.

Molecular identification of Trypanosoma theileri (Laveran, 1902) in cattle from two slaughterhouses in Ecuador and its relation with other haemotropic agents

Trypanosoma theileri is a worldwide distributed haemoparasite that has been reported throughout the American continent in various species, including bovines, buffaloes and bats. In bovines, high incidence of T. theileri can be harmful when associated with other infections or under stress situations. There is little information on this hemoflagellate in Ecuador, which prompted the study and molecular identification of the trypanosomes collected in two slaughtering centers. Between February and April 2021, a total of 218 samples of bovine blood were collected in abattoirs located in the Andean region of Quito (n = 83) and in the coastal region, in Santo Domingo (n = 135). Quito public Slaughterhouse is the biggest in Ecuador, and for that, they receive animals from all country; on the other hand, Santo Domingo's Slaughterhouse is a small one where mainly females from the region are sacrificed and some males. The samples were evaluated using two molecular tests, the PCR cathepsin L-like (CatL) specific for T. theileri and for the positive samples, a Nested PCR that targets the ITS of the 18S gene. The corresponding PCR products were sequenced, analyzed by BLAST/NCBI and the sequences were used to build a concatenated phylogenetic tree, using the MEGA XI software. Overall, 34 out of the 218 samples, (15.6%) were positive to T. theileri by PCR CatL, resulting from 20/83 (24.1%) positives from the Quito abattoir and 14/135 (10.4%) from the Santo Domingo slaughterhouse. These prevalence rates were found to be significantly different (p = 0.006). According to the phylogenetic tree based on the CatL and ITS concatenated sequences (n = 13), the two novel Equatorial T. theileri isolates, ThI (n = 7) and ThII (n = 6) are closely related and associated to the IC, IB and IIB genotypes, present in Brazil, Venezuela and Colombia. Thirty-one out of the thirty-four T. theileri-positive bovines were co-infected with other haemotropic pathogens, Anaplasma marginale Babesia spp and T. vivax. This coinfection could be responsible for additional pathologies and harmful effects on the affected cattle. This study presents the molecular identification and genotypification of T. theileri isolated from cattle in Ecuador through the analysis of CAtL and ITS sequences, and the high frequency of coinfection of this hemoflagellate with other blood haemotropic organisms.

Evidence that ectoparasites influence the hematological parameters of the host: a systematic review

Ectoparasites are important to the one health concept because their parasitism can result in the transmission of pathogens, allergic reactions, the release of toxins, morbidity, and even death of the host. Ectoparasites can affect host physiology, as reflected in immune defenses and body condition as well as hematological and biochemical parameters. Thus, evidence that ectoparasites influence host hematological parameters was systematically reviewed, and the methodological quality of these studies was analyzed. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed, and the studies included were limited to those that evaluated changes in hematological tests in ectoparasite-infested and non-infested animals, and bias and methodological quality were evaluated using the Animal Research: Reporting of In Vivo Experiments guideline. Thirty-four studies were selected and information about the host, ectoparasite infestation, blood collection, and analysis was collected and compared whenever possible. In this review, the presence of ectoparasites influenced both the red series and the white series of hematological parameters. Among the main parameters analyzed, hematocrit, red blood cells, hemoglobin, and lymphocytes showed reductions, probably due to ectoparasite blood-feeding, while including eosinophils, neutrophils, and basophils increased in infested animals due to the host immune response. However, methodologic improvements are needed to reduce the risk of bias, enhance the reproducibility of such studies, and ensure results aligned with the mechanisms that act in the ectoparasite-host relationship.

The Economic Impact of Parasitism from Nematodes, Trematodes and Ticks on Beef Cattle Production

Global human population growth requires the consumption of more meat such as beef to meet human needs for protein intake. Cattle parasites are a constant and serious threat to the development of the beef cattle industry. Studies have shown that parasites not only reduce the performance of beef cattle, but also negatively affect the profitability of beef agriculture and have many other impacts, including contributing to the production of greenhouse gases. In addition, some zoonotic parasitic diseases may also threaten human health. Therefore, ongoing cattle parasite research is crucial for continual parasite control and the development of the beef cattle industry. Parasitism challenges profitable beef production by reducing feed efficiency, immune function, reproductive efficiency, liveweight, milk yield, calf yield and carcass weight, and leads to liver condemnations and disease transmission. Globally, beef cattle producers incur billions (US$) in losses due to parasitism annually, with gastrointestinal nematodes (GIN) and cattle ticks causing the greatest economic impact. The enormity of losses justifies parasitic control measures to protect profits and improve animal welfare. Geographical differences in production environment, management practices, climate, cattle age and genotype, parasite epidemiology and susceptibility to chemotherapies necessitate control methods customized for each farm. Appropriate use of anthelmintics, endectocides and acaricides have widely been shown to result in net positive return on investment. Implementing strategic parasite control measures, with thorough knowledge of parasite risk, prevalence, parasiticide resistance profiles and prices can result in positive economic returns for beef cattle farmers in all sectors.

Comparison of salivary gland and midgut microbiome in the soft ticks Ornithodoros erraticus and Ornithodoros moubata

Introduction

Ornithodoros erraticus and Ornithodoros moubata are the main vectors of African swine fever virus (ASFV) and the human relapsing fever spirochetes Borrelia hispanica and Borrelia crocidurae in the Mediterranean region and Borrelia duttoni in continental Africa. Manipulation of the tick microbiome has been shown to reduce vector fitness and competence in tick vectors, suggesting that the identification of key microbial players associated with tick tissues can inform interventions such as anti-microbiota vaccines to block pathogen development in the midgut and/or salivary glands.

Methods

In this study, we analyzed and compared the microbiome of the salivary glands and midgut of O. erraticus and O. moubata. For the taxonomic and functional characterization of the tissue-specific microbiome, we used 16S rRNA amplicon sequencing and prediction of metabolic profiles using PICRUSt2. Co-occurrence networks were built to characterize the community assembly and identify keystone taxa in each tick species.

Results

Our results revealed differences in the composition, diversity, and assembly of the bacterial microbiome of salivary glands and midgut within each tick species, but differences were more noticeable in O. moubata. Differences were also found in the microbiome of each tissue, salivary gland and midgut, between species. However, the 'Core Association Networks (CAN)' analysis revealed conserved patterns of interacting taxa in tissues within and between tick species. Different keystone taxa were identified in O. erraticus and O. moubata tissues, but Muribaculaceae and Alistipes were found as keystone taxa in the salivary glands of both tick species which justifies their use as anti-microbiota vaccine candidates to alter the microbiome and reduce tick fitness and/or block pathogen transmission. The high similarity of predicted metabolic pathways profiles between tissues of the two tick species suggests that taxonomic variability of the microbiome is not associated with significant changes in microbial functional profiles.

Conclusion

We conclude that the taxonomic structure of the microbiome in O. erraticus and O. moubata is tissue-specific, suggesting niche partitioning of bacterial communities associated to these soft ticks. However, shared keystone taxa and conserved patterns of interacting taxa between tissues and tick species suggest the presence of key microbial players that could be used as anti-microbiota vaccine candidates to affect tick physiology and/or pathogen colonization.

Transcriptome Profiling of Rhipicephalus annulatus Reveals Differential Gene Expression of Metabolic Detoxifying Enzymes in Response to Acaricide Treatment

Ticks are hematophagous ectoparasites of economic consequence by virtue of being carriers of infectious diseases that affect livestock and other sectors of the agricultural industry. A widely prevalent tick species, Rhipicephalus (Boophilus) annulatus, has been recognized as a prime vector of tick-borne diseases in South Indian regions. Over time, the use of chemical acaricides for tick control has promoted the evolution of resistance to these widely used compounds through metabolic detoxification. Identifying the genes related to this detoxification is extremely important, as it could help detect valid insecticide targets and develop novel strategies for effective insect control. We performed an RNA-sequencing analysis of acaricide-treated and untreated R. (B.) annulatus and mapped the detoxification genes expressed due to acaricide exposure. Our results provided high-quality RNA-sequenced data of untreated and amitraz-treated R. (B.) annulatus, and then the data were assembled into contigs and clustered into 50,591 and 71,711 uni-gene sequences, respectively. The expression levels of the detoxification genes across different developmental stages of R. (B.) annulatu identified 16,635 transcripts as upregulated and 15,539 transcripts as downregulated. The annotations of the differentially expressed genes (DEGs) revealed the significant expression of 70 detoxification genes in response to the amitraz treatment. The qRT-PCR revealed significant differences in the gene expression levels across different life stages of R. (B.) annulatus.

Weather parameters as a predictive tool potentially allowing for better monitoring of dairy cattle against gastrointestinal parasites hazard

In animal production, yield is critically related to animal health status. To ensure high productivity, innovative control strategies for herd and parasites monitoring are required. Gastrointestinal parasites have a strong influence on changing feed intake or nutrient use, limiting animal productivity. Serological control has been proposed, given that parasite development is largely dependent on environmental temperature and humidity. However, breeders and field veterinarians lack readily accessible climate characteristics that provide information to determine whether and when herds require laboratory examination. To help reduce the testing costs incurred by farmers, we investigated whether selected meteorological data could serve as conclusive predictors to increase the precision of herd selection for serological monitoring. Our results indicate that the selection of herds by farmers for testing can be guided by regular checking of meteorological data, especially various temperature and humidity indicators. In general, ranges of 24-28 °C, as well as - 0.5 to 7.5 °C for the monthly maximum and minimum temperature, respectively, and relative humidity (68-79%) and vapour pressure (10-15 hPa) correspond to a high antiparasitic response of the herd, expressed as the optical density ratio. It is recommended to introduce coproscopic and/or serological tests if the observed weather pattern (covering the prepatent period of parasite development) ranges within the estimated values.

Multiplex PCR for rapid differential diagnosis of co-prevalent species of Theileria (Theileria annulata and Theileria orientalis) in cattle

Theileriosis is a tick-borne disease that causes enormous losses in the dairy industry. There are several species of Theileria that can infect bovines. Generally, more than one species are prevalent in any geographical area; thus, chances of co-infections are high. Differentiation of these species may not be possible by microscopic examination or serological tests. Therefore, in this study, a multiplex PCR assay was standardized and evaluated for rapid and simultaneous differential detection of two species of Theileria viz., Theileria annulata and Theileria orientalis. Species-specific primers were designed to target the merozoite piroplasm surface antigen gene (TAMS1) of T. annulata and the major piroplasm surface protein gene of T. orientalis, yielding specific amplicon of 229 bp and 466 bp, respectively. The sensitivity of multiplex PCR was 10² and 10³ copies for T. annulata and T. orientalis, respectively. The simplex and multiplex PCRs were specific and showed no cross-reactivity with other hemoprotozoa for either primer. For comparative evaluation, blood samples from 216 cattle were tested by simplex and multiplex PCR for both species. Using multiplex PCR, 131 animals were found infected for theileriosis, of which 112 were infected with T. annulata, five were infected with T. orientalis, and 14 had mixed infections. This is the first report of T. orientalis from Haryana, India. Representative sequences of T. annulata (ON248941) and T. orientalis (ON248942) were submitted in GenBank. The standardized multiplex PCR assay used in this study was specific, sensitive, for the screening of field samples.

Cost-benefit ratio of anthelmintic treatment and its comparative efficacy in commercial dairy farms

Intestinal parasitic infection is one of the major challenges in obtaining optimal production and maintaining the health and welfare of all animals including cattle and buffaloes. Anti-parasitic treatments appear to be a reliable countermeasure. However, the effectiveness and selection of suitable anthelmintics require situational assessments in a given locality. In the current study, the efficacy and impact of benzimidazole (albendazole) were assessed in a total of 400 (100 each) on the performance of buffaloes, buffalo-heifer, cattle, and cattle-heifers at two commercial dairy farms in the Province of Punjab, Pakistan. Additionally, the cost-benefit ratio was calculated by assessing the inputs (medication, feed, and labor cost) and outputs (milk and weight gain). The qualitative and quantitative examination of helminth eggs in each type of animal indicated a prevalence of 73.3, 78.3, 76.6, and 85.0% in cattle, cattle-heifers, buffaloes, and buffaloes-heifers, respectively. Specifically, a highest rate (10.0-13.3%) of Haemonchus sp. infection was only observed in cattle and heifers, while Fasciola sp. infections (10.0-11.6%) were the most often found species in buffaloes and heifers. The highest anthelmintic impacts (egg per gram of feces, p < 0.001) were observed on day 14 post-medication. Until 60 days of post-anthelmintic treatment, an average increase of 0.8 and 0.7 L in milk production per day in cattle and buffaloes, respectively while a total of 11.45 and 9.45 kg body weight were noticed in cattle-heifer and buffaloes-heifer, respectively. Cumulative cost-benefit analysis indicated a positive correlation between treated and non-treated animals. These findings reiterate the importance of anthelmintic drugs in reducing the impacts of parasites on the productivity, health, and well-being of an animal under high infection challenges.

Excretory/secretory proteins inhibit host immune responses by downregulating the TLR4/NF-κB/MAPKs signaling pathway: A possible mechanism of immune evasion in parasitic nematode Haemonchus contortus

Haemonchus contortus is an important parasitic nematode of ruminants. Previous studies showed that H. contortus escape the immunity through complex mechanisms, including releasing excretory/secretory proteins (ESPs) to modulate the host immune response. However, the detailed mechanism through which H. contortus excretory/secretory proteins (HcESPs) promote immune evasion remains unknown. In the present study, we demonstrated that HcESPs inhibit the adaptive immune response of goats including downregulation of immune cell antigen presentation, upregulation of immune checkpoint molecules, activation of the STAT3/PD-L1 pathway, and activation of immunosuppressive regulatory T (Treg) cells. Furthermore, HcESPs reversed the LPS-induced upregulation of pro-inflammatory mediators in PBMCs by inhibiting the TLR4/NF-κB/MAPKs/NLRP3 signaling pathway. Our study provides a better understanding of the evasion mechanisms for H. contortus, which could be helpful in providing an alternative way to prevent the infection of this parasite.

Egg-laying and locomotory screens with C. elegans yield a nematode-selective small molecule stimulator of neurotransmitter release

Nematode parasites of humans, livestock and crops dramatically impact human health and welfare. Alarmingly, parasitic nematodes of animals have rapidly evolved resistance to anthelmintic drugs, and traditional nematicides that protect crops are facing increasing restrictions because of poor phylogenetic selectivity. Here, we exploit multiple motor outputs of the model nematode C. elegans towards nematicide discovery. This work yielded multiple compounds that selectively kill and/or immobilize diverse nematode parasites. We focus on one compound that induces violent convulsions and paralysis that we call nementin. We find that nementin stimulates neuronal dense core vesicle release, which in turn enhances cholinergic signaling. Consequently, nementin synergistically enhances the potency of widely-used non-selective acetylcholinesterase (AChE) inhibitors, but in a nematode-selective manner. Nementin therefore has the potential to reduce the environmental impact of toxic AChE inhibitors that are used to control nematode infections and infestations.

A C. elegans-based screening approach identifies nementin as a nematode-selective nematicide that can be used synergistically with acetylcholinesterase inhibitors

The role of IgA in gastrointestinal helminthiasis: A systematic review

Immunoglobulin-A (IgA) is an important mediator of immunity and has been associated with protection against several pathogens, although its role in gastrointestinal infections remains unclear. Then, the aim of this systematic review was to synthesize qualitative evidence in respect of IgA as mediator of protective immunity against gastrointestinal helminths. Following recommended guidelines, we searched for articles published between January 1990 and October 2019 that evaluated IgA levels and their association with gastrointestinal helminth infections. Twenty-five articles were included after screening 1,546 titles and abstracts, as well as reading in full 52 selected articles. Consistent associations between higher IgA levels and lower parasitological parameters were only found in mice, rats, and sheep. However, the role of IgA in other host species remains uncertain, making it difficult to create a consensus. Therefore, it is too soon to claim that IgA is an effective protective factor against gastrointestinal helminths, and further studies are still needed.

The association of extracts of Achyrocline satureioides and the fungus Beauveria bassiana against the tick Rhipicephalus microplus

The tick Rhipicephalus microplus (Canestrini) is a major economic hurdle to the global livestock industry. The incorrect and indiscriminate control carried out by synthetic chemical compounds has contributed to the emergence of parasite resistance present today to many products available in the veterinary market. Effective, economically viable and potentially safe alternatives need to be investigated, including herbal medicine and biological control by entomopathogenic fungi. In this study, extracts from Achyrocline satureioides (Lam.) DC. obtained by extraction with solvents of different polarities associated and not associated with the entomopathogenic fungus Beauveria bassiana (Balsamo-Crivelli) Vuillemin were evaluated on different stages of the life cycle of R. microplus. The activity of plant extracts, fungus and their associations in ticks was analyzed in vitro through the adult immersion test, larval packet test and larval immersion test. The highest efficacy on engorged females (43.3%) was reached by the hexanic partition (ASh) at 5 mg/mL + fungus, reducing larval hatchability. ASh associated with B. bassiana also caused high mortality of larvae, reaching LC₅₀ of 6.23 and 2.65 mg/mL in the packet and immersion tests, respectively. The results obtained showed that extracts, when used in combination with the fungus, have their action enhanced, reaching 100% mortality of larvae. Among the evaluated methodologies, it was observed that the larval immersion test allows better assessment, due to the time of contact with the larvae. The results obtained with A. satureioides associated with the fungus are considered promising and open new perspectives for future product development.

The economic evaluation of Cystic echinococcosis control strategies focused on zoonotic hosts: A scoping review

Background

Cystic echinococcosis (CE) is a zoonotic neglected tropical disease (zNTD) which imposes considerable financial burden to endemic countries. The 2021–2030 World Health Organization’s roadmap on NTDs has proposed that intensified control be achieved in hyperendemic areas of 17 countries by 2030. Successful interventions for disease control, and the scale-up of programmes applying such interventions, rely on understanding the associated costs and relative return for investment. We conducted a scoping review of existing peer-reviewed literature on economic evaluations of CE control strategies focused on Echinococcus granulosus zoonotic hosts.

Methodology/Principal findings

Database searches of Scopus, PubMed, Web of Science, CABI Direct and JSTOR were conducted and comprehensively reviewed in March 2022, using predefined search criteria with no date, field or language restrictions. A total of 100 papers were initially identified and assessed for eligibility against strict inclusion and exclusion criteria, following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. Bibliography review of included manuscripts was used to identify additional literature. Full review of the final manuscript selection (n = 9) was performed and cost data for control interventions were extracted.

Conclusions/Significance

There are very little published data pertaining to the cost and cost effectiveness of CE control interventions targeting its zoonotic hosts. Data given for costs are often incomplete, thus we were unable to perform an economic analysis and cost effectiveness study, highlighting a pressing need for this information. There is much scope for future work in this area. More detailed information and disaggregated costings need to be collected and made available. This would increase the accuracy of any cost-effective analyses to be performed and allow for a greater understanding of the opportunity cost of healthcare decisions and resource allocation by stakeholders and policy makers for effective and cost-effective CE control.

Cystic echinococcosis (CE) is a zoonotic neglected tropical disease which predominantly affects poor pastoral communities globally. The parasite cycles between farm dogs and livestock, and is associated with livestock farming and feeding of infected offal to dogs. Although no noticeable clinical signs are seen in livestock, some production losses, such as reduced milk yield and live weight gain may be observed, and offal condemnation at slaughter is common. The disease can also affect people, due to accidental ingestion of parasite eggs on contaminated food and contact with dogs. Human morbidity and mortality occur due to cyst formation in body organs, exerting a substantial health and financial burden to the health sector of affected countries. Control interventions to reduce CE transmission include sheep vaccination and dog deworming. Long-term control programmes are often expensive, and the true costs of such programmes poorly documented. This scoping review aims to examine published literature on the costs of CE control in zoonotic hosts and report detailed costs of individual elements of a control programme, thereby furthering our understanding of the true economic cost of CE control.

First Data on Ornithodoros moubata Aquaporins: Structural, Phylogenetic and Immunogenic Characterisation as Vaccine Targets

Ornithodoros moubata transmits African swine fever and human relapsing fever in Africa. The elimination of O. moubata populations from anthropic environments is expected to improve the prevention and control of these diseases. Tick vaccines have emerged as a sustainable method for tick control, and tick aquaporins (AQPs) are promising targets for tick vaccines due to their vital functions, immunogenicity and ease of access by neutralising host antibodies. This study aimed at the systematic identification of the AQPs expressed by O. moubata (OmAQPs) and their characterisation as vaccine targets. Therefore, AQP coding sequences were recovered from available transcriptomic datasets, followed by PCR amplification, cloning, sequence verification and the analysis of the AQP protein structure and epitope exposure. Seven OmAQPs were identified and characterised: six were aquaglyceroporins, and one was a water-specific aquaporin. All of these were expressed in the salivary glands and midgut and only three in the coxal glands. Epitope exposure analysis identified three extracellular domains in each AQP, which concentrate overlapping B and T cell epitopes, making them interesting vaccine targets. Based on these domain sequences, a set of ten antigenic peptides was designed, which showed adequate properties to be produced and tested in pilot vaccine trials.

Soil-Borne Nematodes: Impact in Agriculture and Livestock and Sustainable Strategies of Prevention and Control with Special Reference to the Use of Nematode Natural Enemies

Soil-borne parasitic nematodes cause severe deterioration in the health of crops and supply animals, leading to enormous economic losses in the agriculture and livestock industry worldwide. The traditional strategy to control these parasites has been based on chemically synthesised compounds with parasiticidal activity, e.g., pesticides and anthelmintic drugs, which have shown a negative impact on the environment. These compounds affect the soil’s beneficial microbiota and can also remain as toxic residues in agricultural crops, e.g., fruits and legumes, and in the case of animal products for human consumption, toxic residues can remain in milk, meat, and sub-products derived from the livestock industry. Other alternatives of control with much less negative environmental impact have been studied, and new strategies of control based on the use of natural nematode enemies have been proposed from a sustainable perspective. In this review, a general view of the problem caused by parasitic nematodes affecting the agriculture and livestock industry, traditional methods of control, and new strategies of control based on eco-friendly alternatives are briefly described, with a special focus on a group of natural nematode antagonists that have been recently explored with promising results against plagues of importance for agricultural and livestock production systems.

Potential Mechanisms of Transmission of Tick-Borne Viruses at the Virus-Tick Interface

Ticks (Acari; Ixodidae) are the second most important vector for transmission of pathogens to humans, livestock, and wildlife. Ticks as vectors for viruses have been reported many times over the last 100 years. Tick-borne viruses (TBVs) belong to two orders (Bunyavirales and Mononegavirales) containing nine families (Bunyaviridae, Rhabdoviridae, Asfarviridae, Orthomyxovirida, Reoviridae, Flaviviridae, Phenuviridae, Nyamiviridae, and Nairoviridae). Among these TBVs, some are very pathogenic, causing huge mortality, and hence, deserve to be covered under the umbrella of one health. About 38 viral species are being transmitted by <10% of the tick species of the families Ixodidae and Argasidae. All TBVs are RNA viruses except for the African swine fever virus from the family Asfarviridae. Tick-borne viral diseases have also been classified as an emerging threat to public health and animals, especially in resource-poor communities of the developing world. Tick-host interaction plays an important role in the successful transmission of pathogens. The ticks' salivary glands are the main cellular machinery involved in the uptake, settlement, and multiplication of viruses, which are required for successful transmission into the final host. Furthermore, tick saliva also participates as an augmenting tool during the physiological process of transmission. Tick saliva is an important key element in the successful transmission of pathogens and contains different antimicrobial proteins, e.g., defensin, serine, proteases, and cement protein, which are key players in tick-virus interaction. While tick-virus interaction is a crucial factor in the propagation of tick-borne viral diseases, other factors (physiological, immunological, and gut flora) are also involved. Some immunological factors, e.g., toll-like receptors, scavenger receptors, Janus-kinase (JAK-STAT) pathway, and immunodeficiency (IMD) pathway are involved in tick-virus interaction by helping in virus assembly and acting to increase transmission. Ticks also harbor some endogenous viruses as internal microbial faunas, which also play a significant role in tick-virus interaction. Studies focusing on tick saliva and its role in pathogen transmission, tick feeding, and control of ticks using functional genomics all point toward solutions to this emerging threat. Information regarding tick-virus interaction is somewhat lacking; however, this information is necessary for a complete understanding of transmission TBVs and their persistence in nature. This review encompasses insight into the ecology and vectorial capacity of tick vectors, as well as our current understanding of the predisposing, enabling, precipitating, and reinforcing factors that influence TBV epidemics. The review explores the cellular, biochemical, and immunological tools which ensure and augment successful evading of the ticks' defense systems and transmission of the viruses to the final hosts at the virus-vector interface. The role of functional genomics, proteomics, and metabolomics in profiling tick-virus interaction is also discussed. This review is an initial attempt to comprehensively elaborate on the epidemiological determinants of TBVs with a focus on intra-vector physiological processes involved in the successful execution of the docking, uptake, settlement, replication, and transmission processes of arboviruses. This adds valuable data to the existing bank of knowledge for global stakeholders, policymakers, and the scientific community working to devise appropriate strategies to control ticks and TBVs.

A proteomics informed by transcriptomics insight into the proteome of Ornithodoros erraticus adult tick saliva

BACKGROUND

The argasid tick Ornithodoros erraticus is the main vector of tick-borne human relapsing fever (TBRF) and African swine fever (ASF) in the Mediterranean Basin. The prevention and control of these diseases would greatly benefit from the elimination of O. erraticus populations, and anti-tick vaccines are envisaged as an effective and sustainable alternative to chemical acaricide usage for tick control. Ornithodoros erraticus saliva contains bioactive proteins that play essential functions in tick feeding and host defence modulation, which may contribute to host infection by tick-borne pathogens. Hence, these proteins could be candidate antigen targets for the development of vaccines aimed at the control and prevention of O. erraticus infestations and the diseases this tick transmits. The objective of the present work was to obtain and characterise the proteome of the saliva of O. erraticus adult ticks as a means to identify and select novel salivary antigen targets.

METHODS

A proteomics informed by transcriptomics (PIT) approach was applied to analyse samples of female and male saliva separately using the previously obtained O. erraticus sialotranscriptome as a reference database and two different mass spectrometry techniques, namely liquid chromatography-tandem mass spectrometry (LC-MS/MS) in data-dependent acquisition mode and sequential window acquisition of all theoretical fragment ion spectra MS (SWATH-MS).

RESULTS

Up to 264 and 263 proteins were identified by LC-MS/MS in the saliva of O. erraticus female and male ticks, respectively, totalling 387 non-redundant proteins. Of these, 224 were further quantified by SWATH-MS in the saliva of both male and female ticks. Quantified proteins were classified into 23 functional categories and their abundance compared between sexes. Heme/iron-binding proteins, protease inhibitors, proteases, lipocalins and immune-related proteins were the categories most abundantly expressed in females, while glycolytic enzymes, protease inhibitors and lipocalins were the most abundantly expressed in males. Ninety-seven proteins were differentially expressed between the sexes, of which 37 and 60 were overexpressed in females and males, respectively.

CONCLUSIONS

The PIT approach demonstrated its usefulness for proteomics studies of O. erraticus, a non-model organism without genomic sequences available, allowing the publication of the first comprehensive proteome of the saliva of O. erraticus reported to date. These findings confirm important quantitative differences between sexes in the O. erraticus saliva proteome, unveil novel salivary proteins and functions at the tick-host feeding interface and improve our understanding of the physiology of feeding in O. erraticus ticks. The integration of O. erraticus sialoproteomic and sialotranscriptomic data will drive a more rational selection of salivary candidates as antigen targets for the development of vaccines aimed at the control of O. erraticus infestations and the diseases it transmits.

What lies behind the curtain: Cryptic diversity in helminth parasites of human and veterinary importance

Parasite cryptic species are morphologically indistinguishable but genetically distinct organisms, leading to taxa with unclear species boundaries. Speciation mechanisms such as cospeciation, host colonization, taxon pulse, and oscillation may lead to the emergence of cryptic species, influencing host-parasite interactions, parasite ecology, distribution, and biodiversity. The study of cryptic species diversity in helminth parasites of human and veterinary importance has gained relevance, since their distribution may affect clinical and epidemiological features such as pathogenicity, virulence, drug resistance and susceptibility, mortality, and morbidity, ultimately affecting patient management, course, and outcome of treatment. At the same time, the need for recognition of cryptic species diversity has implied a transition from morphological to molecular diagnostic methods, which are becoming more available and accessible in parasitology. Here, we discuss the general approaches for cryptic species delineation and summarize some examples found in nematodes, trematodes and cestodes of medical and veterinary importance, along with the clinical implications of their taxonomic status. Lastly, we highlight the need for the correct interpretation of molecular information, and the correct use of definitions when reporting or describing new cryptic species in parasitology, since molecular and morphological data should be integrated whenever possible.

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Cryptic diversity has been described in helminths of human and animal importance.

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Cryptic species are morphologically indistinguishable but genetically distinct organisms.

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These entities emerge by different evolutionary and speciation mechanisms.

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Analysis of molecular and morphological data is needed for cryptic species delimitation.

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Cryptic diversity may affect pathogenicity, virulence and drug resistance of helminths.

Detection of Babesia spp. in High Altitude Cattle in Ecuador, Possible Evidence of the Adaptation of Vectors and Diseases to New Climatic Conditions

Background: Babesia species are intraerythrocytic protozoa, distributed in tropical and subtropical areas of the world, causing anemic diseases in many animals, including cattle. This disease, called babesisosis, is transmitted from one animal to another through ticks (Tick Borne-Disease or TBD). On the other hand, Ecuador has a tropical climate that allows the development of the vector Rhipicephalus microplus, and therefore favors the transmission of Babesia spp. in cattle. Methods and principal findings: We determined the presence of Babesia spp. by PCR using 18s ribosomal gene as target (18s PCR) in 20 farms in the area of El Carmen (zone below 300 m above sea level) and 1 farm in Quito (2469 m.a.s.l.). In addition, we analyzed parameters such as age, sex, and packed cell volume (PCV) as explanatory variable associated with the disease. Results: The 18s PCR test showed that 18.94% (14.77% Babesia bovis and 4.17% Babesia bigemina) and 20.28% (14.69% B. bovis and 5.59% B. bigemina) of the cattle were positive for Babesia spp in farms sampled in El Carmen and in Quito, respectively. Age influenced the presence of animals positive for Babesia spp., but sex and PCV did not. The phylogenetic analysis of sequences showed 4 isolates of B. bovis and 3 isolates of B. bigemina in the 2 study zones, with similarities between 99.73 and 100% with other sequences. One B. bovis isolate was similar in the zone of El Carmen and Quito. Conclusion and significance: This work is the first molecular characterization of B. bigemina and B. bovis in Ecuador, and it is also the first evidence of Babesia spp. in cattle in the area of Quito at an altitude of 2469 m.a.s.l., being the highest altitude reported for animals with babesiosis and for the tick R. microplus. Climatic factors as well as mobility of tick-carrying animals without any control allow the presence of Babesiosis outbreaks in new geographical areas.

Sexual Development in Non-Human Parasitic Apicomplexa: Just Biology or Targets for Control?

Simple Summary

Cellular reproduction is a key part of the apicomplexan life cycle, and both mitotic (asexual) and meiotic (sexual) cell divisions produce new individual cells. Sexual reproduction in most eukaryotic taxa indicates that it has had considerable success during evolution, and it must confer profound benefits, considering its significant costs. The phylum Apicomplexa consists of almost exclusively parasitic single-celled eukaryotic organisms that can affect a wide host range of animals from invertebrates to mammals. Their development is characterized by complex steps in which asexual and sexual replication alternate and the fertilization of a macrogamete by a microgamete results in the formation of a zygote that undergoes meiosis, thus forming a new generation of asexual stages. In apicomplexans, sex is assumed to be induced by the (stressful) condition of having to leave the host, and either gametes or zygotes (or stages arising from it) are transmitted to a new host. Therefore, sex and meiosis are linked to parasite transmission, and consequently dissemination, which are key to the parasitic lifestyle. We hypothesize that improved knowledge of the sexual biology of the Apicomplexa will be essential to design and implement effective transmission-blocking strategies for the control of the major parasites of this group.

Abstract

The phylum Apicomplexa is a major group of protozoan parasites including gregarines, coccidia, haemogregarines, haemosporidia and piroplasms, with more than 6000 named species. Three of these subgroups, the coccidia, hemosporidia, and piroplasms, contain parasites that cause important diseases of humans and animals worldwide. All of them have complex life cycles involving a switch between asexual and sexual reproduction, which is key to their development. Fertilization (i.e., fusion of female and male cells) results in the formation of a zygote that undergoes meiosis, forming a new generation of asexual stages. In eukaryotes, sexual reproduction is the predominant mode of recombination and segregation of DNA. Sex is well documented in many protist groups, and together with meiosis, is frequently linked with transmission to new hosts. Apicomplexan sexual stages constitute a bottleneck in the life cycle of these parasites, as they are obligatory for the development of new transmissible stages. Consequently, the sexual stages represent attractive targets for vaccination. Detailed understanding of apicomplexan sexual biology will pave the way for the design and implementation of effective transmission-blocking strategies for parasite control. This article reviews the current knowledge on the sexual development of Apicomplexa and the progress in transmission-blocking vaccines for their control, their advantages and limitations and outstanding questions for the future.

Ethnoveterinary Knowledge and Biological Evaluation of Plants Used for Mitigating Cattle Diseases: A Critical Insight Into the Trends and Patterns in South Africa

Cattle farming is a traditional agricultural system that contribute to the rural economic, social and cultural values of the communities. Cattle as common with other livestock, are affected by many diseases that cause mortality and economic losses. In many rural households, the use of plants and associated knowledge are popular for managing cattle diseases especially in areas experiencing challenges with conventional veterinary medicine. Evidence on the documentation of indigenous knowledge and biological evaluation of plants used against cattle diseases remain understudied and fragmented. The aim of the review is to collate and analyse the ethnoveterinary knowledge and biological evaluation of plants used against cattle diseases in South Africa. Different scientific databases were systematically explored to extract data from 37 eligible studies. A total of 310 medicinal plants from 81 families used to treat 10 categories of cattle diseases across seven (7) provinces in South Africa. Leguminosae (Fabaceae), Compositae (Astereceae), Asparagaceae, and Xanthorrhoeaceae were the most frequently used plant families. Common plant parts used were leaves and roots. Twenty-seven (27) combination remedies involving 2–6 plants were identified as treatment regimes against cattle diseases. Common preparation methods were infusion and decoction while the administration mode was predominantly unspecified (52%) while oral and topical contributed 26 and 22%, respectively. In terms of diseases, the most treated ones were general systems infection, reproduction disorders and gastrointestinal problems. Currently, an estimated 21% of the 310 plants have been evaluated for diverse biological activities using relevant bioassays related to cattle diseases. Antibacterial activity remained the most studied biological activity. Evidence from the review revealed the significance of ethnoveterinary medicine against cattle diseases especially in rural areas of South Africa. Nevertheless, the use of plants for cattle diseases among other ethnic groups, particularly in the Northern Cape and Western Cape, remain under-studied.

Eimeria spp. in naturally infected beef cattle: Dynamics of oocysts excretion, prevalence, and comparison between parasitological diagnostics

Eimeria spp. infections cause mortality, reduced well-being, and substantial economic losses implications for cattle production worldwide. The present work followed up the excretion of Eimeria spp. oocysts in two naturally infected beef herds, from two different properties, to investigate the dynamics of oocyst excretion and the prevalence of Eimeria spp. in different animal categories and seasons of the year (rainy season - October to April; dry season - May to September). Even that, the species of Eimeria were identified and the parasitological techniques of Gordon and Whitlock modified and Mini-FLOTAC were used. In both herds, animals up to 14 months had a mean total OPG counts higher than older animals (after 15-16 months of age), and the species E. zuernii and E. bovis were more frequently identified, the first species being more frequent in animals from 1 to 2 months of age, while E. bovis prevailed from three months old. On property 1, the highest mean OPG counts (P ≤ 0.05) were obtained between October 2017 and September 2018, with the highest mean OPG counts in October 2017, when the animals were aged between 4-5 months. The prevalence of the pathogen on property 1 was 59.16 % and 43.62 % in the rainy and dry season, respectively, a higher parasitic load (P ≤ 0.05) was verified in the rainy season. On property 2, the mean OPG counts of Eimeria spp. was higher (P ≤ 0.05) in animals between 8-16 months, with the highest peak in November 2019, when they were one year old. The on-site prevalence during the rainy season on property 2 was 53.09 % and 49.79 % on dry season, and no difference (P = 0.92) in the mean OPG counts of Eimeria spp. during the seasons. There was a difference (P ≤ 0.05) in the count of oocysts in females after 18 months of age than males, which was probably due to the increase in animal density. Both tested techniques can be used for quantification of the excretion of oocysts of Eimeria spp. in cattle feces showing the same OPG mean count (r = 0.9287; p = 0.0025; R² = 0.8625). Mini-FLOTAC showed higher prevalence for Eimeria spp., however, can be an obstacle depending on the number of fecal samples that need to be processed.

Models for Studying the Distribution of Ticks and Tick-Borne Diseases in Animals: A Systematic Review and a Meta-Analysis with a Focus on Africa

Ticks and tick-borne diseases (TTBD) are constraints to the development of livestock and induce potential human health problems. The worldwide distribution of ticks is not homogenous. Some places are ecologically suitable for ticks but they are not introduced in these areas yet. The absence or low density of hosts is a factor affecting the dissemination of the parasite. To understand the process of introduction and spread of TTBD in different areas, and forecast their presence, scientists developed different models (e.g., predictive models and explicative models). This study aimed to identify models developed by researchers to analyze the TTBD distribution and to assess the performance of these various models with a meta-analysis. A literature search was implemented with PRISMA protocol in two online databases (Scopus and PubMed). The selected articles were classified according to country, type of models and the objective of the modeling. Sensitivity, specificity and accuracy available data of these models were used to evaluate their performance using a meta-analysis. One hundred studies were identified in which seven tick genera were modeled, with Ixodes the most frequently modeled. Additionally, 13 genera of tick-borne pathogens were also modeled, with Borrelia the most frequently modeled. Twenty-three different models were identified and the most frequently used are the generalized linear model representing 26.67% and the maximum entropy model representing 24.17%. A focus on TTBD modeling in Africa showed that, respectively, genus Rhipicephalus and Theileria parva were the most modeled. A meta-analysis on the quality of 20 models revealed that maximum entropy, linear discriminant analysis, and the ecological niche factor analysis models had, respectively, the highest sensitivity, specificity, and area under the curve effect size among all the selected models. Modeling TTBD is highly relevant for predicting their distribution and preventing their adverse effect on animal and human health and the economy. Related results of such analyses are useful to build prevention and/or control programs by veterinary and public health authorities.

Assessing the importance of Molecular and Genetic perspectives in Prophesying the KFD transmission risk provinces in the Western Ghats, Kerala, INDIA in context with spatial distribution, Extensive genetic Diversity, and phylogeography

The deadly effects of KFD have been pointed in southern India; however, the infecting regions have been getting larger in recent epochs. People who live or work in regions where KFDV infected tick vectors are present are severely prone to procuring the infection. Being aware of tick vectors and infectious agents' geospatial location is vital to direct sustenance approaches to prevent and manage such infectious diseases as KFD. The present investigation has focussed on the spatial distribution, Extensive genetic Diversity, and phylogeography to forecast the probable KFD disease risk provinces in the Western Ghats. The statistical analysis for diversity indices and community comparison has been performed by using SPSS version 24.0.0 and R software version 3.4.2. The nucleotide sequences of the respective ticks and KFDV were retrieved from NCBI. The first strand of this investigation revealed that, around the world, the Indian province was found to exhibit a maximum range of diversity for tick vectors. The next strands prophesied the KFD transmission risk areas in the Western Ghats region, India, with computational spatial analysis and phylogeography. The final strand exposed the genetic diversity of the KFD virus and the tick vectors in terms of their spatial distribution worldwide.

Comparative analysis of Rhipicephalus tick salivary gland and cement elementome

Rhipicephalus spp. (Acari: Ixodidae) ticks are obligate hematophagous arthropods, which constitute a model for the study of vector-host interactions. The chemical composition or elementome of salivary glands (SG) and cement provides information relevant for the study of protein-based complex multifunctional tissues with a key role in tick biology. In this study, we characterized the elementome of cement cones in Rhipicephalus sanguineus collected from naturally infested dogs and in SG and cement of R. bursa collected from experimentally infested rabbits at different feeding stages. The elementome was characterized using scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The results showed the identification of up to 14 chemical elements in the cement, and suggested tick/host-driven differences in the cement elementome between tick species and between SG and cement within the same species. By still unknown mechanisms, ticks may regulate cement elementome during feeding to affect various biological processes. Although these analyses are preliminary, the results suggested that N is a key component of the cement elementome with a likely origin in SG/salivary proteins (i.e., Glycine (C2H5NO2)-rich superfamily member proteins; GRPs) and other tick/host-derived components (i.e. NAPDH). Future research should be focused on tick elementome and its functional implications to better understand cement structure and function.

RNA-seq analysis and gene expression dynamics in the salivary glands of the argasid tick Ornithodoros erraticus along the trophogonic cycle

BACKGROUND

The argasid tick Ornithodoros erraticus is the main vector of tick-borne human relapsing fever (TBRF) and African swine fever (ASF) in the Mediterranean Basin. Tick salivary proteins secreted to the host at the feeding interface play critical roles for tick feeding and may contribute to host infection by tick-borne pathogens; accordingly, these proteins represent interesting antigen targets for the development of vaccines aimed at the control and prevention of tick infestations and tick-borne diseases.

METHODS

To identify these proteins, the transcriptome of the salivary glands of O. erraticus was de novo assembled and the salivary gene expression dynamics assessed throughout the trophogonic cycle using Illumina sequencing. The genes differentially upregulated after feeding were selected and discussed as potential antigen candidates for tick vaccines.

RESULTS

Transcriptome assembly resulted in 22,007 transcripts and 18,961 annotated transcripts, which represent 86.15% of annotation success. Most salivary gene expression took place during the first 7 days after feeding (2088 upregulated transcripts), while only a few genes (122 upregulated transcripts) were differentially expressed from day 7 post-feeding onwards. The protein families more abundantly overrepresented after feeding were lipocalins, acid and basic tail proteins, proteases (particularly metalloproteases), protease inhibitors, secreted phospholipases A2, 5'-nucleotidases/apyrases and heme-binding vitellogenin-like proteins. All of them are functionally related to blood ingestion and regulation of host defensive responses, so they can be interesting candidate protective antigens for vaccines.

CONCLUSIONS

The O. erraticus sialotranscriptome contains thousands of protein coding sequences-many of them belonging to large conserved multigene protein families-and shows a complexity and functional redundancy similar to those observed in the sialomes of other argasid and ixodid tick species. This high functional redundancy emphasises the need for developing multiantigenic tick vaccines to reach full protection. This research provides a set of promising candidate antigens for the development of vaccines for the control of O. erraticus infestations and prevention of tick-borne diseases of public and veterinary health relevance, such as TBRF and ASF. Additionally, this transcriptome constitutes a valuable reference database for proteomics studies of the saliva and salivary glands of O. erraticus.

Molecular characterization of the conoid complex in Toxoplasma reveals its conservation in all apicomplexans, including Plasmodium species

The apical complex is the instrument of invasion used by apicomplexan parasites, and the conoid is a conspicuous feature of this apparatus found throughout this phylum. The conoid, however, is believed to be heavily reduced or missing from Plasmodium species and other members of the class Aconoidasida. Relatively few conoid proteins have previously been identified, making it difficult to address how conserved this feature is throughout the phylum, and whether it is genuinely missing from some major groups. Moreover, parasites such as Plasmodium species cycle through 3 invasive forms, and there is the possibility of differential presence of the conoid between these stages. We have applied spatial proteomics and high-resolution microscopy to develop a more complete molecular inventory and understanding of the organisation of conoid-associated proteins in the model apicomplexan Toxoplasma gondii. These data revealed molecular conservation of all conoid substructures throughout Apicomplexa, including Plasmodium, and even in allied Myzozoa such as Chromera and dinoflagellates. We reporter-tagged and observed the expression and location of several conoid complex proteins in the malaria model P. berghei and revealed equivalent structures in all of its zoite forms, as well as evidence of molecular differentiation between blood-stage merozoites and the ookinetes and sporozoites of the mosquito vector. Collectively, we show that the conoid is a conserved apicomplexan element at the heart of the invasion mechanisms of these highly successful and often devastating parasites.

Sialotranscriptomics of the argasid tick Ornithodoros moubata along the trophogonic cycle

The argasid tick Ornithodoros moubata is the main vector of human relapsing fever (HRF) and African swine fever (ASF) in Africa. Salivary proteins are part of the host-tick interface and play vital roles in the tick feeding process and the host infection by tick-borne pathogens; they represent interesting targets for immune interventions aimed at tick control.

The present work describes the transcriptome profile of salivary glands of O. moubata and assesses the gene expression dynamics along the trophogonic cycle using Illumina sequencing.

De novo transcriptome assembling resulted in 71,194 transcript clusters and 41,011 annotated transcripts, which represent 57.6% of the annotation success. Most salivary gene expression takes place during the first 7 days after feeding (6,287 upregulated transcripts), while a minority of genes (203 upregulated transcripts) are differentially expressed between 7 and 14 days after feeding. The functional protein groups more abundantly overrepresented after blood feeding were lipocalins, proteases (especially metalloproteases), protease inhibitors including the Kunitz/BPTI-family, proteins with phospholipase A2 activity, acid tail proteins, basic tail proteins, vitellogenins, the 7DB family and proteins involved in tick immunity and defence. The complexity and functional redundancy observed in the sialotranscriptome of O. moubata are comparable to those of the sialomes of other argasid and ixodid ticks.

This transcriptome provides a valuable reference database for ongoing proteomics studies of the salivary glands and saliva of O. moubata aimed at confirming and expanding previous data on the O. moubata sialoproteome.

The soft tick Ornithodoros moubata constitutes an important medical and veterinary problem in Africa because, in addition to being the vector of African swine fever, it transmits human relapsing fever (HRF), a hyper-endemic and lethal, but still neglected, tick-borne disease. Effective control of HRF requires eradicating its vector tick from domestic environments. As chemical acaricide application is ineffective against this tick, development of anti-tick vaccines seems the most promising method for tick control. Salivary proteins play essential functions for tick feeding and survival, which convert them in potential antigen targets for the development of tick vaccines. To know which these proteins are, we obtained the salivary transcriptome of O. moubata females and established, for the first time in a soft tick, the salivary gene transcription dynamics along its trophogonic cycle. Thereby, we have identified numerous genes encoding bioactive proteins essential for tick feeding. This information is essential to drive the selection of candidate antigens for anti-tick vaccine development and evaluate its protective potential in animal immunization trials. These data significantly enlarge the current repertory of known protein-coding sequences from soft tick salivary glands and establish a valuable reference database to improve our knowledge of the O. moubata salivary proteome.

Clinical effectiveness of autohemotherapy as an adjuvant in the control of gastrointestinal nematodes in naturally infected sheep

Abstract This study aimed to evaluate the effects of autohemotherapy as an adjuvant in the control of gastrointestinal nematodes in sheep. Four experimental groups were formed: G1, 10 animals receiving autologous venous blood; G2, 10 animals receiving autologous venous blood and vermifuge containing levamisole; G3, 10 animals receiving only vermifuge containing levamisole; and G4, 10 animals as the control group receiving no treatment. We performed fecal egg count (eggs per gram, EPG) of strongyles, larval culture, hemogram, leukogram, and serum protein dosage prior to the start of treatment (D0), and on days 14 (D14) and 42 (D42). There was a significant decrease in the EPG of the groups receiving levamisole (G2 and G3) from D14 to the end of the experimental period. At the end of the evaluations, the mean EPG of G2 and G3 was significantly lower than that of G1 and G4. The most common nematode genus was Haemonchus (88%), and the least common was Trichostrongylus (1%). The Fecal Egg Count Reduction Test (FECRT) of G2 and G3 on D14 were 98.1% and 97.9%, respectively, however, in G1, the FECRT was zero on the two days when evaluation took place. G1 and G2 showed a significant increase in monocyte counts on D14 and D42. There was a significant increase in hematocrit and hemoglobin values in G2 and G3, however, a significant increase in the absolute value of red blood cells was observed only in G2. Two doses of autohemotherapy at 21-day intervals, administered alone or as an adjuvant to levamisole, is ineffective in controlling gastrointestinal nematodes in naturally infected sheep.

Biological methods for the control of gastrointestinal nematodes

Gastrointestinal nematodes (GIN) are a cause of significant losses in animal production worldwide. In recent years, there have been important advances in the biological control of GIN of ruminants and horses. While these measures are still relatively under-utilised in practice, interest will undoubtedly grow due to the emergence of drug resistant parasite populations, the rise in demand for organically farmed products (which does not allow prophylactic use of drugs, including anthelmintics) and legislation, which regulates and restricts the use of anthelmintics. This review provides an overview of the most promising biocontrol agents of GIN of grazing animals including nematophagous fungi, dung beetles, earthworms, predacious nematodes and nematophagous mites. Recent advancements in these fields are evaluated, and the potential reasons for the delayed development and slow uptake of biocontrol agents are discussed. It is now widely believed that no method of GIN control is sustainable alone, and a combination of strategies (i.e. integrated pest management) is required for long term, effective parasite control. This review shows that, although their efficacies are lower than those of conventional anthelmintics, biological control agents are an important adjunct to traditional GIN control.

Combating Parasitic Nematode Infections, Newly Discovered Antinematode Compounds from Marine Epiphytic Bacteria

Parasitic nematode infections cause debilitating diseases and impede economic productivity. Antinematode chemotherapies are fundamental to modern medicine and are also important for industries including agriculture, aquaculture and animal health. However, the lack of suitable treatments for some diseases and the rise of nematode resistance to many available therapies necessitates the discovery and development of new drugs. Here, marine epiphytic bacteria represent a promising repository of newly discovered antinematode compounds. Epiphytic bacteria are ubiquitous on marine surfaces where they are under constant pressure of grazing by bacterivorous predators (e.g., protozoans and nematodes). Studies have shown that these bacteria have developed defense strategies to prevent grazers by producing toxic bioactive compounds. Although several active metabolites against nematodes have been identified from marine bacteria, drug discovery from marine microorganisms remains underexplored. In this review, we aim to provide further insight into the need and potential for marine epiphytic bacteria to become a new source of antinematode drugs. We discuss current and emerging strategies, including culture-independent high throughput screening and the utilization of Caenorhabditis elegans as a model target organism, which will be required to advance antinematode drug discovery and development from marine microbial sources.

A Comprehensive Subcellular Atlas of the Toxoplasma Proteome via hyperLOPIT Provides Spatial Context for Protein Functions

Apicomplexan parasites cause major human disease and food insecurity. They owe their considerable success to highly specialized cell compartments and structures. These adaptations drive their recognition, nondestructive penetration, and elaborate reengineering of the host's cells to promote their growth, dissemination, and the countering of host defenses. The evolution of unique apicomplexan cellular compartments is concomitant with vast proteomic novelty. Consequently, half of apicomplexan proteins are unique and uncharacterized. Here, we determine the steady-state subcellular location of thousands of proteins simultaneously within the globally prevalent apicomplexan parasite Toxoplasma gondii. This provides unprecedented comprehensive molecular definition of these unicellular eukaryotes and their specialized compartments, and these data reveal the spatial organizations of protein expression and function, adaptation to hosts, and the underlying evolutionary trajectories of these pathogens.

Tick and Host Derived Compounds Detected in the Cement Complex Substance

Ticks are obligate hematophagous arthropods and vectors of pathogens affecting human and animal health worldwide. Cement is a complex protein polymerization substance secreted by ticks with antimicrobial properties and a possible role in host attachment, sealing the feeding lesion, facilitating feeding and pathogen transmission, and protection from host immune and inflammatory responses. The biochemical properties of tick cement during feeding have not been fully characterized. In this study, we characterized the proteome of Rhipicephalus microplus salivary glands (sialome) and cement (cementome) together with their physicochemical properties at different adult female parasitic stages. The results showed the combination of tick and host derived proteins and other biomolecules such as α-Gal in cement composition, which varied during the feeding process. We propose that these compounds may synergize in cement formation, solidification and maintenance to facilitate attachment, feeding, interference with host immune response and detachment. These results advanced our knowledge of the complex tick cement composition and suggested that tick and host derived compounds modulate cement properties throughout tick feeding.

Modeling tick vaccines: a key tool to improve protection efficacy

Introduction: The development of more effective vaccines for the control of tick infestations and pathogen transmission is essential for prevention and control of tick-borne diseases worldwide. Recently, the application of omics technologies has advanced the identification of tick protective antigens. However, other factors such as vaccine formulation and implementation need to be addressed, and tick vaccine modeling will contribute to improve the efficacy of vaccination strategies.Areas covered: In this review, we summarized current information on tick vaccine correlates of protection and modeling, and proposed new approaches to improve vaccine evaluation and implementation using as a proof-of-concept the Hyalomma marginatum-Crimean-Congo hemorrhagic fever virus model due to its high mortality rate and potentially growing impact on human health.Expert opinion: Vaccines are required as an effective and environmentally sound intervention for the control of tick-borne diseases affecting human and animal health worldwide. Despite recent advances in the identification of candidate tick protective antigens, research on vaccine formulation and implementation need to be addressed to improve tick vaccine control efficacy. As shown here, modeling of the vaccination strategies against ticks and transmitted pathogens will contribute to vaccine development by guiding the selection of appropriate antigen combinations, target hosts, and vaccination time schedule.