Global food security: The impact of veterinary parasites and parasitologists

Next-generation sequencing technologies for helminth diagnostics and surveillance in ruminants: shifting diagnostic barriers

Helminth infections in grazing ruminants are a major issue for livestock farming globally, but are unavoidable in outdoor grazing systems and must be effectively managed to avoid deleterious effects to animal health, and productivity. Next-generation sequencing (NGS) technologies are transforming our understanding of the genetic basis of anthelmintic resistance (AR) and epidemiological studies of ruminant gastrointestinal parasites. They also have the potential to not only help develop and validate molecular diagnostic tests but to be directly used in routine diagnostics integrating species-specific identification and AR into a single test. Here, we review how these developments have opened the pathway for the development of multi-AR and multispecies identification in a single test, with widespread implications for sustainable livestock farming for the future.

Pulmonary and Gastrointestinal Parasitic Infections in Small Ruminant Autochthonous Breeds from Centre Region of Portugal-A Cross Sectional Study

The production of small ruminant autochthonous breeds in the Centre region of Portugal is practiced in a semi-extensive husbandry system, exposing animals to parasitic infections. The main objective of this study was to estimate the prevalence of lungworm infection and identify risk factors. Fecal samples of 203 goats and 208 sheep from 30 herds were collected per rectum and subjected to the modified Baermann test. The overall prevalence of infection was 57.7%, significantly higher in goats (95.6%) than in sheep (20.7%) (p < 0.001). According to the binary logistic regression model, sheep dewormed with albendazole, mebendazole plus closantel, or ivermectin plus clorsulon presented a risk of Protostrongylidae infection 29.702, 7.426, or 8.720 times higher, respectively, than those dewormed with eprinomectin. Additionally, the presence of gastrointestinal parasites was investigated in 307 fecal samples using Mini-FLOTAC®. The overall prevalence of infection was 86.3%, also significantly higher in goats (93.2%) than in sheep (79.9%) (p < 0.001). Strongyle-type eggs were the most frequently identified, both in sheep (69.8%) and goats (87.8%), followed by Eimeria oocysts (40.3% in sheep and 68.9% in goats). Considering the high prevalence and the burden of lungworm parasitic infection, it is urgent to determine its economic impact and the repercussions in animal health in the Centre region of Portugal to establish appropriate therapeutic guidelines.

Antagonism between co-infecting gastrointestinal nematodes: A meta-analysis of experimental infections in Sheep

Gastrointestinal nematodes (GIN) have enormous global impacts in humans, wildlife and grazing livestock. Within grazing livestock, sheep are of particular global importance and the economics and sustainability of sheep production are greatly constrained by GIN infections. Natural infections are composed of co-infections with multiple species, and while some past work suggests species can interact negatively with one another within the same host, there is wide variation in reported patterns. Here, we undertook a systematic literature search and meta-analysis of experimental GIN co-infections of sheep to determine whether these experimental studies support the hypothesis of antagonistic interactions between different co-infecting GIN, and test whether aspects of parasite biology or experimental design influence the observed effects. A systematic search of the literature yielded 4848 studies, within which, we identified 19 experimental sheep studies comparing post-mortem worm counts across two co-infecting GIN species. Meta-analysis of 67 effects obtained from these studies provides strong evidence for interactions between GIN species. There was wide variation in the strength and direction of these interactions, but the global effect was significantly antagonistic. On average, there was a decrease in the number of worms of one species when a co-infecting species was also present, relative to a mono-infection with that species alone. This effect was dependent on the infectious dose and was rapidly lost after anthelmintic treatment, suggesting that live worms are required for the effect to occur. Individual parasite species varied in the extent to which they both exerted, and were subject to, these interspecies interactions, and these differences are more complex than simply co-localisation within the gastrointestinal tract. Antagonistic interactions between co-infecting GIN may feedback into their epidemiology as well as potentially affecting the clinical impacts of infection. Furthermore, the consequences of these interactions may be heightened when clinical interventions affect only one species within the co-infecting network. Whilst it was not possible to identify the causes of variation between GIN species in the impact of co-infection, these findings point to new avenues for epidemiological, clinical and mechanistic research on GIN co-infections.

First report on detection of Hepatozoon ayorgbor in Rhipicephalus haemaphysaloides and Hepatozoon colubri in Haemaphysalis sulcata and Hyalomma anatolicum: risks of spillover of Hepatozoon spp. from wildlife to domestic animals

This study aimed to detect Hepatozoon spp. in ticks infesting asymptomatic domestic animals and to provide insight into their potential spillover from wild to domestic animals. In total, 537 tick specimens were collected in Khyber Pakhtunkhwa, Pakistan, and morphologically identified. The most prevalent tick species was Haemaphysalis cornupunctata (69; 12.8%), followed by Haemaphysalis kashmirensis (62; 11.5%), Rhipicephalus microplus (58; 10.8%), Haemaphysalis montgomeryi (51; 9.5%), Rhipicephalus sanguineus (49; 9.1%), each Haemaphysalis bispinosa and Haemaphysalis sulcata (43; 8.0%), each Hyalomma anatolicum and Rhipicephalus turanicus (37; 6.9%), Rhipicephalus haemaphysaloides (33; 6.1%) Hyalomma scupense (30; 5.6%), and Hyalomma isaaci (25; 4.7%). The extracted DNA from a subset of each tick species was subjected to PCR to amplify 18S rRNA fragments of Hepatozoon spp. By BLAST analysis, the Hepatozoon sp. detected in Hy. anatolicum infesting cows and in Ha. sulcata infesting sheep showed 99.7% maximum identity with Hepatozoon colubri. Similarly, the Hepatozoon sp. detected in R. haemaphysaloides infesting goats shared 99.49% maximum identity with Hepatozoon ayorgbor, and the Hepatozoon sp. detected in R. sanguineus infesting dogs exhibited 99.7% identity with Hepatozoon canis. Having an overall infection rate (9.3%; 16/172), the highest infection rate was recorded for each H. canis, and H. colubri (3.5%; 6/172), followed by H. ayorgbor (2.3%; 4/172). In the phylogenetic tree, H. colubri clustered with corresponding species from Iran, H. ayorgbor clustered with the same species from Croatia, Ghana, and Portugal, and H. canis clustered with the conspecifics from Iran, Israel, Romania, and Zambia. Regarding the potential spillover of Hepatozoon spp. from wildlife through ticks, free ranging animals was at higher risk compared to confined animals (RR = 3.05), animals consuming food from wildlife habitats were at higher risk compared to those consuming domestic food (RR = 3.06), and animals residing in farm buildings located in wildlife habitats were at higher risk compared to those residing in farm buildings located in villages (RR = 3.28). In addition to the first report on H. canis in R. sanguineus in Pakistan, this is the earliest data showing H. ayorgbor in R. haemaphysaloides and H. colubri in Ha. sulcata and Hy. anatolicum. These preliminary findings suggest a potential spillover of Hepatozoon spp. from wild to domestic animals via ticks under certain risk factors.

Scientometric Analysis of Gastrointestinal Parasites Prevalence in Sheep and Goats of India

PURPOSE

In the present study, gastrointestinal parasites (GIP) prevalence in sheep and goats from India was estimated by scientometrics.

METHODS

The GIP prevalence studies (86) reported during 1998-2021 was obtained from online databases, and offline literatures, meta-analysis was undertaken by using "meta" package in R-Software.

RESULTS

The pooled GIP prevalence in India was 65% (95% level CI 56-74%, PI 12-96%) in sheep, 74% (95% level CI 66-80%, PI 14-98%) in goats and 68% (95% level CI 62-73%, PI 15-96%) in sheep and goats. Period-wise analysis revealed a higher GIP prevalence during 1998-2010 than the recent periods. Among the zones, GIP prevalence was higher in the Central zone (79%) in sheep, North zone (82%) in goats, and Central zone (78%) in sheep and goats. Based on the state-wise analysis, a higher GIP prevalence was observed in Haryana for sheep, Himachal Pradesh for goats, and Uttarakhand for sheep and goats. In India, a higher prevalence was reported by nematodes than other parasite classes. Based on climatic regions, a higher GIP prevalence was observed in semi-arid Steppe type region (84%).

CONCLUSION

The high prevalence zones, states, species, sample types, parasite classes, parasite species and climate regions of GIP will be useful in decision-making and resource use efficiency by policymakers and stake holders. There is an urgent need to prevent the occurrence of GIP infections in sheep and goats by adopting scientific management practices, effective therapeutic measures, and hygienic practices on farms to augment the economic benefits to sheep and goat farmers in India.

A member of the CAP protein superfamily, Hc-CAP-15, is important for the parasitic-stage development of Haemonchus contortus

BACKGROUND

The CAP superfamily proteins are distributed widely in eukaryotes and play crucial roles in various biological processes. However, very little is known about their functions in parasitic nematodes, including Haemonchus contortus, a socioeconomically important parasitic nematode. We have therefore studied a member of the CAP protein family of H. contortus, named Hc-CAP-15, with the aim to explore its roles in regulating the parasitic developmental process.

METHODS

The conservation and phylogenetic relationships, spatial expression and temporal transcription profiles of Hc-CAP/cap-15, as well its biological function during parasite development were investigated using bioinformatics, immunofluorescence, real-time PCR and RNA interference (RNAi).

RESULTS

Hc-CAP-15 was found to be a single-domain CAP protein consisting of four conserved motifs that is localized in the cuticle, intestine and oocyte of adult worms. Hc-cap-15 was transcribed at all developmental stages of H. contortus, with the highest transcription level in parasitic fourth-stage larvae (L4s). Silencing of Hc-cap-15 resulted in a significant increase in the body length of L4s.

CONCLUSIONS

The results suggested that Hc-CAP-15 is important for the development of H. contortus. Our findings provide a basis for further study of the functions of the CAP family proteins in H. contortus and related parasitic nematodes.

Exploring the transcriptomic changes underlying recombinant vaccine efficacy against Teladorsagia circumcincta in 3-month-old lambs

Teladorsagia circumcincta is an abomasal parasitic nematode that can cause serious issues in small ruminant production, which are aggravated by drug resistance. Vaccines have been suggested as a feasible, long-lasting alternative for control since adaptation to the host's immune mechanisms by helminths develops at a much slower pace than anthelmintic resistance. Recently, a T. circumcincta recombinant subunit vaccine yielded over a 60% reduction in egg excretion and worm burden and induced strong humoral and cellular anti-helminth responses in vaccinated 3-month-old Canaria Hair Breed (CHB) lambs, but Canaria Sheep (CS) of a similar age were not protected by the vaccine. Here, we compared the transcriptomic profiles in the abomasal lymph nodes of such 3-month-old CHB and CS vaccinates 40 days after infection with T. circumcincta to understand differences in responsiveness at the molecular level. In the CS, differentially expressed genes (DEG) identified were related to general immunity processes such as antigen presentation or antimicrobial proteins and down-regulation of inflammation and immune response through regulatory T cell-associated genes. However, upregulated genes in CHB vaccinates were associated with type-2 oriented immune responses, i.e., immunoglobulin production, activation of eosinophils, as well as tissue structure and wound repair-related genes and protein metabolism pathways such as DNA and RNA processing. These results highlight potentially more optimal timing and orientation of immune responses in CHB sheep compared to CS associated with vaccine-induced protection. The data obtained in this study thus deepens our understanding of variations in responsiveness to vaccination in young lamb and provides insights for vaccine refinement strategies.

Molecular Characterization of the Interplay between Fasciola hepatica Juveniles and Laminin as a Mechanism to Adhere to and Break through the Host Intestinal Wall

Fasciola hepatica is the main causative agent of fasciolosis, a zoonotic parasitic disease of growing public health concern. F. hepatica metacercariae are ingested by the host and excyst in the intestine, thereby releasing the newly excysted juveniles (FhNEJ), which traverse the gut wall and migrate towards the biliary ducts. Since blocking F. hepatica development is challenging after crossing of the intestinal wall, targeting this first step of migration might result in increased therapeutic success. The intestinal extracellular matrix (ECM) is constituted by a network of structural proteins, including laminin (LM) and fibronectin (FN), that provide mechanical support while acting as physical barrier against intestinal pathogens. Here, we employed ELISA and immunofluorescent assays to test for the presence of LM- and FN-binding proteins on a tegument-enriched antigenic fraction of FhNEJ, and further determined their identity by two-dimensional electrophoresis coupled to mass spectrometry. Additionally, we performed enzymatic assays that revealed for the first time the capability of the juvenile-specific cathepsin L3 to degrade LM, and that LM degradation by FhNEJ proteins is further potentiated in the presence of host plasminogen. Finally, a proteomic analysis showed that the interaction with LM triggers protein changes in FhNEJ that may be relevant for parasite growth and adaptation inside the mammalian host. Altogether, our study provides valuable insights into the molecular interplay between FhNEJ and the intestinal ECM, which may lead to the identification of targetable candidates for the development of more effective control strategies against fasciolosis.

Epidemiology of Gastrointestinal Parasites of Cattle in Three Districts in Central Ethiopia

Parasitic diseases are a major impediment to livestock production worldwide. However, knowledge about the epidemiology of gastrointestinal parasites in many low-income countries is still limited. An epidemiological survey on these parasites in traditionally reared cattle was performed in central Ethiopia (West Shewa Zone), from September 2019 to November 2021. Overall, 691 samples were analyzed qualitatively (flotation technique) and quantitatively (McMaster technique) to detect helminth eggs and Eimeria oocysts. Furthermore, coprocultures were conducted on pooled samples to identify the genera of gastrointestinal strongyles (GIS). The difference in prevalence according to agroecology, season, age, sex and body condition score (BCS) was investigated using univariable tests and through a multivariable logistic regression analysis, whereas abundance values were interpreted using a descriptive approach. The highest prevalence values were observed for GIS (50.2%) and Eimeria spp. (36.0%), whereas Moniezia spp. (16.3%), Strongyloides spp. (5.1%) and Schistosoma spp. (4.2%) showed lower values. Trichuris spp. and Toxocara vitulorum were sporadically found. A coproculture revealed that Haemonchus spp. (34.6%), Trichostrongylus spp. (25.9%) and Bunostomum spp. (19.1%) were the most frequent genera of GIS. A poor BCS was strongly associated with the occurrence of GIS, while seasonal variations were detected for Eimeria spp., GIS, Moniezia spp. and Schistosoma spp., with a higher prevalence and burden during the rainy season, and agroecology also strongly influenced different parasitic taxa. This present study increases the knowledge about the epidemiological features of gastrointestinal parasites in the context of a low-income country, suggesting a more tailored approach for their control. The use of a BCS as an indicator for the selective treatment of highly infested animals is supported by our findings, introducing a possible way to prevent anthelmintic resistance in areas where basic diagnostic services are rarely used by farmers.

Smallholders' knowledge about healing goat gastrointestinal parasite infections with wild plants in southern DR Congo

Gastrointestinal parasite (GIP) infections control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. This study aimed to collect indigenous knowledge and identify wild plants locally used by goat smallholders of three territories of Haut-Katanga province for treating signs of gastrointestinal parasitism. Ethnoveterinary surveys were conducted by semi-structured interviews and a bibliographic screening of the biological activities relating to cited plants was carried out. Our interviews showed that ethnosemantic diagnoses of GIP diseases are based on signs. Eighty-seven informants reported that 27 plant species from 15 families, dominated by Fabaceae (29.6%) and Lamiaceae (18.5%) were commonly used in their goats treatment. Among these plants, five species with palmately compound leaves were considerably more used. From those, we noted a substitution of Vitex congolensis De Wild. and T. Durand (Lamiaceae) by Oldfieldia dactylophylla (Welw. Ex Oliv.) J. Leonard (Picrodendraceae) and of Vitex mombassae Vatke by Vitex madiensis Oliv. Subsp. Milanjiensis (Britten) F. White. Roots (46.9%), leaves (28.0%) and seeds (12.5%) were the most frequently used plant organs, and maceration is applied for most of the medicinal preparations (62.2%). Recipes were administered by oral route, for GIP 1) prevention (33.3%), by macerating the ground plant material in drinking water for 2 weeks at the start of each season (dry and rainy); and 2) treatment (66.7%). According to the literature, some of these plants have few or no studies investigating their anthelmintic activity. The cited plants are worth investigating further as they could constitute an effective alternative strategy in maintaining animal productivity. Studies on the biological activity of these plants can also provide indications of promising leads for extracts that could be developed into commercial standardized medications.

Essential Oils as Novel Anthelmintic Drug Candidates

Helminths, with an estimated 1.5 billion annual global infections, are one of the major health challenges worldwide. The current strategy of the World Health Organization to prevent helminth infection includes increasing hygienic awareness, providing better sanitation and preventative anthelmintic drug therapy in vulnerable populations. Nowadays, anthelmintic drugs are used heavily in livestock, both in case of infection and as a preventative measure. However, this has led to the development of resistance against several of the most common drugs, such as levamisole, ivermectin and thiabendazole. As many as 70% of the livestock in developed countries now has helminths that are drug resistant, and multiple resistance is common. Because of this, novel anthelmintics are urgently needed to help combat large-scale production losses. Prior to this review, no comprehensive review of the anthelmintic effects of essential oils and their components existed. Multiple review articles have been published on the uses of a single plant and its extracts that only briefly touch upon their anthelmintic activity. This review aims to provide a detailed overview of essential oils and their components as anthelmintic treatment against a wider variety of helminths.

The effect of naturally acquired rumen fluke infection on animal health and production in dairy and beef cattle in the UK

The incidence of paramphistomosis, caused by the rumen fluke, Calicophoron daubneyi, has greatly increased within Europe in the last 15–20 years. However, the production impacts of this disease are poorly understood. This study firstly aimed to investigate the prevalence of rumen fluke in England and Northern Ireland (NI) by conducting an abattoir survey of dairy and beef cattle which also allowed the impact of rumen fluke on carcass weight, conformation and fat classification to be assessed. Secondly, an experiment aimed to assess the impact of C. daubneyi infection on diarrhea score, production loss and welfare in dairy heifers, while also evaluating the impacts of treating infected heifers with oxyclozanide. Rumen fluke prevalence was greater in NI than in England, with 53.8% (95% CI 51.9 - 55.9%) of the NI cattle carcases sampled being infected compared to 16.3% (95% CI 15.8 - 16.8%) and 17.9% (95% CI 17.4 - 18.4%) detected at the two abattoirs in England. However, there was no significant difference (P > 0.05) in the cold carcass weight between infected and non-infected cattle. Similarly, carcass conformation and fat classification were unaffected (P > 0.05) by the presence of rumen fluke. In the second experiment, daily live weight gain (DLWG), diarrhea score and welfare score were also unaffected (P > 0.05) by rumen fluke infection and by oxyclozanide treatment against rumen fluke. The farms in this experiment were managed to a high standard and animals had no intercurrent disease. Therefore, these findings suggest that on well–managed farms, production losses (growth rates) should not be compromised as a result of sub-clinical rumen fluke infection.

Explosive networking: The role of adaptive host radiations and ecological opportunity in a species-rich host-parasite assembly

Many species-rich ecological communities emerge from adaptive radiation events. Yet the effects of adaptive radiation on community assembly remain poorly understood. Here, we explore the well-documented radiations of African cichlid fishes and their interactions with the flatworm gill parasites Cichlidogyrus spp., including 10,529 reported infections and 477 different host-parasite combinations collected through a survey of peer-reviewed literature. We assess how evolutionary, ecological, and morphological parameters determine host-parasite meta-communities affected by adaptive radiation events through network metrics, host repertoire measures, and network link prediction. The hosts' evolutionary history mostly determined host repertoires of the parasites. Ecological and evolutionary parameters predicted host-parasite interactions. Generally, ecological opportunity and fitting have shaped cichlid-Cichlidogyrus meta-communities suggesting an invasive potential for hosts used in aquaculture. Meta-communities affected by adaptive radiations are increasingly specialised with higher environmental stability. These trends should be verified across other systems to infer generalities in the evolution of species-rich host-parasite networks.

In vitro effect of three tropical plants on adult Haemonchus placei, an haematophagous nematode from cattle

Background

Vernonia amygdalina (leaf), Garcinia kola (seed), and Leucaena leucocephala (seed) are three well-known tropical plants used in African ethnomedicine to reduce parasitic worm burdens and are potential sources of alternative solution for controlling parasitic helminths infection in grazing livestock. This study investigated extracts from these plants for anthelmintic activity against adult Haemonchus placei, an haematophagous nematode from cattle abomasa. Powdered plant materials were macerated in acetone and the crude acetone extracts evaluated for anthelmintic activity using H. placei adult worm motility assay. Afterwards, fresh sample of V. amygdalina was macerated successively in chloroform and acetone and the extracts evaluated for anthelmintic activity. The chloroform extract was subjected to phytochemical and FT-IR analyses and fractionated by vacuum liquid chromatography. Anthelmintic data were fitted to a nonlinear regression equation (Log [extract or fraction] vs. lethality; variable slope) to produce best-fit sigmoidal curves and LC50 values computed with associated uncertainty.

Results

Of the three tropical plants, only V. amygdalina was active against adult H. placei with best-fit LC50 of 6.51 mg/mL (95% CI: 5.32–7.75). Evaluation of the two extracts obtained by successive maceration showed that chloroform extract (LC50, 2.46 mg/mL, 95% CI: 1.87–3.28) was 11 times as potent as acetone extract (LC50, 27.01 mg/mL, 95% CI: 21.32–48.57) (α < 0.0001). Chromatographic fractionation of the chloroform extract yielded four fractions (FA-FD) with FB (LC50, 2.38 mg/mL, 95% CI: 1.76–3.28) 2.19 times as potent as FC (LC50, 5.21 mg/mL, 95% CI: 4.40–5.79) against H. placei, while FA and FD were inactive. Phytochemical evaluation of the chloroform extract revealed the presence of saponins, steroids, terpenoids, cardiac glycosides, and the absence of tannins, flavonoids, alkaloids, and anthraquinones. FT-IR structural analysis of chloroform extract indicated the presence of key functional groups which are chemical fragments/ structural motifs known to be present in the two major classes of bioactive compounds (sesquiterpene lactones and steroid glucosides) reportedly to be found in V. amygdalina.

Conclusions

The findings showed that chloroform extract of V. amygdalina leaf possessed relatively good anthelmintic activity against adult H. placei. This could be indicative of its potential usefulness as an anthelmintic phytomedicine to control gastrointestinal nematodes infection in cattle.

Key highlights

Graphical abstract

Microbiome "Inception": an Intestinal Cestode Shapes a Hierarchy of Microbial Communities Nested within the Host

The concept of a holobiont, a host organism and its associated microbial communities, encapsulates the vital role the microbiome plays in the normal functioning of its host. Parasitic infections can disrupt this relationship, leading to dysbiosis. However, it is increasingly recognized that multicellular parasites are themselves holobionts. Intestinal parasites share space with the host gut microbiome, creating a system of nested microbiomes within the primary host. However, how the parasite, as a holobiont, interacts with the host holobiont remains unclear, as do the consequences of these interactions for host health. Here, we used 16S amplicon and shotgun metagenomics sequencing to characterize the microbiome of the intestinal cestode Eubothrium and its effect on the gut microbiome of its primary host, Atlantic salmon. Our results indicate that cestode infection is associated with salmon gut dysbiosis by acting as a selective force benefiting putative pathogens and potentially introducing novel bacterial species to the host. Our results suggest that parasitic cestodes may themselves be holobionts nested within the microbial community of their holobiont host, emphasizing the importance of also considering microbes associated with parasites when studying intestinal parasitic infections.

Phenotypic and genotypic analysis of benzimidazole resistance in reciprocal genetic crosses of Haemonchus contortus

Haemonchus contortus is arguably one of the most economically important and ubiquitous parasites of livestock globally and commonly involved in cases of anthelmintic resistance. Here, we performed reciprocal genetic crosses using susceptible (MHco3(ISE)) and multiple anthelmintic resistant (MHco18(UGA2004)) H. contortus isolates. Resultant admixed populations were designated MHco3/18 or MHco18/3, where the lead isolate reflects the origin of the females. Three independent filial generations were generated for each cross, which were subjected to bioassays, molecular approaches and population genetic analyses to investigate the phenotypic and genotypic inheritance of benzimidazole (BZ) resistance at each stage. A panel of microsatellite markers confirmed the success of the genetic cross as markers from both parents were seen in the F1 crosses. Egg hatch tests revealed a stark difference between the two F1 crosses with ED50 estimates for MHco18/3 being 9 times greater than those for MHco3/18. Resistance factors based on ED50 estimates ranged from 6 to 57 fold in the filial progeny compared to MHco3(ISE) parents. Molecular analysis of the F167Y and F200Y SNP markers associated with BZ resistance were analysed by pyrosequencing and MiSeq deep amplicon sequencing, which showed that MHco3/18.F1 and MHco18/3.F1 both had similar frequencies of the F200Y resistant allele (45.3% and 44.3%, respectively), whereas for F167Y, MHco18/3.F1 had a two-fold greater frequency of the resistant-allele compared to MHco3/18.F1 (18.2% and 8.8%, respectively). Comparison between pyrosequencing and MiSeq amplicon sequencing revealed that the allele frequencies derived from both methods were concordant at codon 200 (rc = 0.97), but were less comparable for codon 167 (rc = 0.55). The use of controlled reciprocal genetic crosses have revealed a potential difference in BZ resistance phenotype dependent on whether the resistant allele is paternally or maternally inherited. These findings provide new insight and prompt further investigation into the inheritance of BZ resistance in H. contortus.

Occurrence of GI parasites in ruminants of Kashmir and Ladakh

The study was conducted in Kashmir and Ladakh Divisions of the erstwhile state of Jammu and Kashmir to work out the occurrence of gastrointestinal parasites in ruminants. The qualitative faecal examination of 476 samples revealed an overall prevalence of GI parasites to the tune of 80.04% comprising of 80.61% in cattle, 96.70% in sheep and 66.27% in goats. In Kashmir overall prevalence of GI parasites was 88.33% comprising of 80.61% in cattle, 98.41% in sheep and 100% in goats. Highest prevalence was observed for strongyles (84.00%) followed by Eimeria spp. (31.67%), Moniezia spp. (20.00%), Ascaris spp. (5.33%) and Strongyloides spp. (1.67%). Mixed infection was observed in 37.67% samples. In cattle, the parasites observed were strongyles (68.37%) and Eimeria spp. (13.27%) with mixed infection in 1.02% samples. In sheep highest prevalence was observed for strongylid eggs (97.88%) followed by Eimeria spp. (43.38%), Moniezia spp. (31.74%), Ascaris spp. (8.47%) and Strongyloides spp. (2.64%) with mixed infection in 59.26% samples. Amongst goats, only strongylid eggs (100%) were observed. In Ladakh region overall prevalence of GI parasites was 65.91% with 82.61% in sheep and 63.40% in pashmina goats. Highest prevalence was observed for Eimeria spp. (63.64%) followed by strongyles (9.09%) Moniezia spp. (5.11%) and Thysanosoma spp. (1.14%). Mixed infection was observed in 13.07% samples. In sheep, highest prevalence was observed for Eimeria spp. (73.91%) followed by strongyles (17.39%) and Thysanosoma spp. (8.70%) with mixed infection in 17.39% samples. In pashmina goats, the prevalence of Eimeria spp. (62.09%) was observed highest followed by strongylid eggs (7.84%) and Moniezia spp. (5.88%) with mixed infection in 12.42% samples.

A High-Throughput Phenotypic Screen of the 'Pandemic Response Box' Identifies a Quinoline Derivative with Significant Anthelmintic Activity

Parasitic nematodes cause diseases in livestock animals and major economic losses to the agricultural industry worldwide. Nematodes of the order Strongylida, including Haemonchus contortus, are particularly important. The excessive use of anthelmintic compounds to treat infections and disease has led to widespread resistance to these compounds in nematodes, such that there is a need for new anthelmintics with distinctive mechanisms of action. With a focus on discovering new anthelmintic entities, we screened 400 chemically diverse compounds within the 'Pandemic Response Box' (from Medicines for Malaria Venture, MMV) for activity against H. contortus and its free-living relative, Caenorhabditis elegans-a model organism. Using established phenotypic assays, test compounds were evaluated in vitro for their ability to inhibit the motility and/or development of H. contortus and C. elegans. Dose-response evaluations identified a compound, MMV1581032, that significantly the motility of H. contortus larvae (IC₅₀ = 3.4 ± 1.1 μM) and young adults of C. elegans (IC₅₀ = 7.1 ± 4.6 μM), and the development of H. contortus larvae (IC₅₀ = 2.2 ± 0.7 μM). The favourable characteristics of MMV1581032, such as suitable physicochemical properties and an efficient, cost-effective pathway to analogue synthesis, indicates a promising candidate for further evaluation as a nematocide. Future work will focus on a structure-activity relationship investigation of this chemical scaffold, a toxicity assessment of potent analogues and a mechanism/mode of action investigation.

Prevalence of trichostrongylids in small ruminants of Kashmir valley

The present study was undertaken to work out the population structure of trichostrongylids affecting the small ruminants of Kashmir valley. The faecal samples were collected from each zone and sector of the valley and were examined by qualitative as well as quantitative techniques for presence of trichostrongyle eggs, followed by coproculture using petridish method for harvesting of infective larvae. The overall prevalence revealed Haemonchus spp. to be the most predominant trichostrongyle worm followed by Trichostrongylus spp., Oesophagostomum spp., Teladorsagia spp., Chabertia spp. and other larvae, the difference being statistically significant. In south Kashmir, a different trend was observed for trichostrongyle worms with predominance of Trichostrongylus spp., followed by Haemonchus spp., Oesophagostomum spp. and other larvae, the difference being statistically significant (P<0.05). Teladorsagia spp. and Chabertia spp. were not recorded in the south Kashmir, while as Oesophagostomum spp. and Chabertia spp. were not recorded in the north Kashmir. In small ruminants of Kashmir valley, predominance of Haemonchus spp. was observed in private sector farms than government sector farms, whereas predominance of Trichostrongylus spp. was observed in government sector farms than private sector farms, and both the difference were statistically significant. Non-significantly Teladorsagia spp. was found more in government sector farms than private sector farms. In government sector farms Oesophagostomum spp. and Chabertia spp. were recorded, while as in private sector farms Oesophagostomum spp. and Chabertia spp. were not recorded. It is concluded that trichostrongylid worms are prevalent throughout Kashmir valley in the small ruminants and appropriate control strategies need to be adopted for their control.

Linking Behavior, Co-infection Patterns, and Viral Infection Risk With the Whole Gastrointestinal Helminth Community Structure in Mastomys natalensis

Infection probability, load, and community structure of helminths varies strongly between and within animal populations. This can be ascribed to environmental stochasticity or due to individual characteristics of the host such as their age or sex. Other, but understudied, factors are the hosts' behavior and co-infection patterns. In this study, we used the multimammate mouse (Mastomys natalensis) as a model system to investigate how the hosts' sex, age, exploration behavior, and viral infection history affects their infection risk, parasitic load, and community structure of gastrointestinal helminths. We hypothesized that the hosts' exploration behavior would play a key role in the risk for infection by different gastrointestinal helminths, whereby highly explorative individuals would have a higher infection risk leading to a wider diversity of helminths and a larger load compared to less explorative individuals. Fieldwork was performed in Morogoro, Tanzania, where we trapped a total of 214 individual mice. Their exploratory behavior was characterized using a hole-board test after which we collected the helminths inside their gastrointestinal tract. During our study, we found helminths belonging to eight different genera: Hymenolepis sp., Protospirura muricola, Syphacia sp., Trichuris mastomysi, Gongylonema sp., Pterygodermatites sp., Raillietina sp., and Inermicapsifer sp. and one family: Trichostrongylidae. Hierarchical modeling of species communities (HMSC) was used to investigate the effect of the different host-related factors on the infection probability, parasite load, and community structure of these helminths. Our results show that species richness was higher in adults and in females compared to juveniles and males, respectively. Contrary to our expectations, we found that less explorative individuals had higher infection probability with different helminths resulting in a higher diversity, which could be due to a higher exposure rate to these helminths and/or behavioral modification due to the infection.

Dairy farm-workers' knowledge of factors responsible for culling and mortality in the Eastern Cape Province, South Africa

Milk serves as a significant source of protein for many families and aids in combating food insecurity. However, the demand for milk and milk-related products far exceeds the supply. The objective of the study was to evaluate dairy farm-workers' knowledge of factors responsible for culling and mortality of dairy cows in the Eastern Cape Province. Data was collected from 106 dairy farm-workers using a questionnaire. Any correctly answered question by the majority amounted to a point and a zero for incorrectly answered questions. Correct answering by the majority to more than half the questions of a subsection amounted to a pass. A less than 50% pass rate was considered a poor level of knowledge, 51-69% pass rate was considered an average level of knowledge, and anything higher than that was considered a good level of knowledge. Most farm-workers (66.0%) relied on their colleagues for dairy health information. Most dairy farm-workers (49.1%) indicated that lameness, milk fever (56.6%), and mastitis (47.2%) do not lead to culling and mortality of dairy cows. A majority (83%) of farm-workers agreed that reproduction problems, poor milk yield (77.3%), and age (81.1%) are the main reasons for culling dairy cows. The participants had varying perceptions and limited knowledge (28.3%) about the major contributing factors of culling and mortality. The lack of training courses and minimal use of other sources of information such as the internet might contribute to this poor knowledge and perceptions.

Bio-Guided Fractionation and Molecular Networking Reveal Fatty Acids to Be Principal Anti-Parasitic Compounds in Nordic Seaweeds

Widespread use of antimicrobial drugs has led to high levels of drug-resistance in pathogen populations and a need for novel sources of anti-bacterial and anti-parasitic compounds. Macroalgae (seaweed) are potentially a rich source of bioactive compounds, and several species have traditionally been used as vermifuges. Here, we investigated the anti-parasitic properties of four common cold-water Nordic seaweeds; Palmaria palmata (Rhodophyta), Laminaria digitata, Saccharina latissima and Ascophyllum nodosum (Ochrophyta, Phaeophyceae). Screening of organic extracts against helminths of swine (Ascaris suum) and sheep (Teladorsagia circumcincta) revealed that S. latissima and L. digitata had particularly high biological activity. A combination of molecular networking and bio-guided fractionation led to the isolation of six compounds from extracts of these two species identified in both fermented and non-fermented samples. The six isolated compounds were tentatively identified by using MS-FINDER as five fatty acids and one monoglyceride: Stearidonic acid (1), Eicosapentaenoic acid (2), Alpha-Linolenic acid (3), Docosahexaenoic acid (4), Arachidonic acid (5), and Monoacylglycerol (MG 20:5) (6). Individual compounds showed only modest activity against A. suum, but a clear synergistic effect was apparent when selected compounds were tested in combination. Collectively, our data reveal that fatty acids may have a previously unappreciated role as natural anti-parasitic compounds, which suggests that seaweed products may represent a viable option for control of intestinal helminth infections.

COVID-19, Livestock Systems and Food Security in Developing Countries: A Systematic Review of an Emerging Literature

In this paper, we carried out a systematic literature review to document the emerging scientific knowledge about COVID-19 impact on livestock systems and food security in developing countries to identify gaps and possible avenues for future research undertakings. Specifically, we systematically reviewed 68 peer-reviewed articles extracted based on rigorous selection criteria from Scopus, PubMed and ISI Web of Science databases and published between December 2019 and February 2021. Our results reveal that livestock supply chains presented an important 'intermediary' pathway through which the pandemic affected various dimensions of food security in developing countries. Although the research response has been rapid in terms of both quantity and temporal succession, we find a highly suggestive disjunction in studies analyzing the interconnections between COVID-19 pandemic, livestock systems and food security in developing countries. With respect to the livestock supply chain, the bulk of the reviewed evidence focuses on production and consumption, whereas considerably less focus is given to the pandemic's impact on intermediaries within livestock chains, including traders, intermediaries and processors. The analysis of livestock supply chain resilience revolves predominantly around the 'absorbance' and 'recovery' phases of resilience, whereas only a small subset of the literature investigates actions taken by supply chain actors to 'plan' or to 'adapt' livestock systems in order to reduce their vulnerability and enhance their overall resilience. Furthermore, food security has often been narrowly defined, with the majority of articles focusing on 'availability' and 'accessibility' to food due to the pandemic, and other dimensions of food security, including utilization, stability and sustainability, have been widely neglected. Based on our findings, we recommend future research to examine the dynamics of propagation of COVID-19 impact through livestock supply chains in order to develop more targeted interventions that enhance the capacity of developing countries to cope with this and future disruptions and mitigate their food insecurity outcomes. To this end, more holistic, integrated and resilience-based approaches are much recommended to recognize the complex nature of livestock systems in developing countries and to address the multifaceted and widespread effects of COVID-19 on food security channeled through livestock chains.

Vaccination against the brown stomach worm, Teladorsagia circumcincta, followed by parasite challenge, induces inconsistent modifications in gut microbiota composition of lambs

Background

Growing evidence points towards a role of gastrointestinal (GI) helminth parasites of ruminants in modifying the composition of the host gut flora, with likely repercussions on the pathophysiology of worm infection and disease, and on animal growth and productivity. However, a thorough understanding of the mechanisms governing helminth-microbiota interactions and of their impact on host health and welfare relies on reproducibility and replicability of findings. To this aim, in this study, we analysed quantitative and qualitative fluctuations in the faecal microbiota composition of lambs vaccinated against, and experimentally infected with, the parasitic GI nematode Teladorsagia circumcincta over the course of two separate trials performed over two consecutive years.

Methods

Two trials were conducted under similar experimental conditions in 2017 and 2018, respectively. In each trial, lambs were randomly assigned to one of the following experimental groups: (i) vaccinated/infected, (ii) unvaccinated/infected and (iii) unvaccinated/uninfected. Faecal samples collected from individual animals were subjected to DNA extraction followed by high-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene and bioinformatics and biostatistical analyses of sequence data.

Results

Substantial differences in the populations of bacteria affected by immunisation against and infection by T. circumcincta were detected when comparing data from the two trials. Nevertheless, the abundance of Prevotella spp. was significantly linked to helminth infection in both trials.

Conclusions

Despite the largely conflicting findings between the two trials, our data revealed that selected gut microbial populations are consistently affected by T. circumcincta infection and/or vaccination. Nevertheless, our study calls for caution when interpreting data generated from in vivo helminth-microbiome interaction studies that may be influenced by several intrinsic and extrinsic host-, parasite- and environment-related factors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04688-4.

Bioactivity and cytotoxicity profiling of vincosamide and strictosamide, anthelmintic epimers from Sarcocephalus latifolius (Smith) Bruce leaf

ETHNOPHARMACOLOGICAL RELEVANCE

The leaf of Sarcocephalus latifolius is known to be used traditionally by the Fulanis in Nigeria to deworm animals. As helminthosis remains a major constraint to profitable livestock production worldwide, a precarious situation aggravated by the advent of resistant parasites, the discovery of new anthelmintics is a priority, necessitating exploration of medicinal plants for their anthelmintic principles.

AIM OF THE STUDY

To identify and characterise compounds with anthelmintic activity from the leaf of Sarcocephalus latifolius.

MATERIALS AND METHODS

Powdered S. latifolius leaves were extracted by successive maceration with n-hexane, chloroform and acetone. The dried extracts were evaluated for anthelmintic activity against Haemonchus placei adult worms, and the most active extract was subjected to bioassay-guided chromatographic separations. The isolated compounds were evaluated for cytotoxicity against the mammalian HeLa and MC3T3-E1 cell lines, using alamar blue and CellTitreGlo^TM to quantify cell viability. LC₅₀ values were computed from the in vitro anthelmintic activity data by fitting to a non-linear regression equation (variable slope). Isolated compounds were characterized using spectroscopic and mass spectrometric analyses.

RESULTS

Anthelmintic activity LC₅₀ values for n-hexane, chloroform and acetone extracts were 47.85, 35.76 and 5.72 (mg/mL), respectively. Chromatographic separation of acetone extract afforded two bioactive epimers, identified as vincosamide (LC₅₀ 14.7 mg/mL) and strictosamide (LC₅₀ 12.8 mg/mL). Cytotoxicity evaluation showed that, below 200 μg/mL (400 μM), neither compound was toxic to the HeLa or MC3T3-E1 cells.

CONCLUSION

Vincosamide and strictosamide could serve as novel scaffolds for the development of anthelmintic derivatives with improved potency and helminth selectivity.

Advances in the discovery and development of anthelmintics by harnessing natural product scaffolds

Widespread resistance to currently-used anthelmintics represents a major obstacle to controlling parasitic nematodes of livestock animals. Given the reliance on anthelmintics in many control regimens, there is a need for the continued discovery and development of new nematocides. Enabling such a focus are: (i) the major chemical diversity of natural products; (ii) the availability of curated, drug-like extract-, fraction- and/or compound-libraries from natural sources; (iii) the utility and practicality of well-established whole-worm bioassays for Haemonchus contortus-an important parasitic nematodes of livestock-to screen natural product libraries; and (iv) the availability of advanced chromatographic (HPLC), spectroscopic (NMR) and spectrometric (MS) techniques for bioassay-guided fractionation and structural elucidation. This context provides a sound basis for the identification and characterisation of anthelmintic candidates from natural sources. This chapter provides a background on the importance and impact of helminth infections/diseases, parasite control and aspects of drug discovery, and reviews recent work focused on (i) screening well-defined compound libraries to establish the methods needed for large-scale screening of natural extract libraries; (ii) discovering plant and marine extracts with nematocidal or nematostatic activity, and purifying bioactive compounds and assessing their potential for further development; and (iii) synthesising analogues of selected purified natural compounds for the identification of possible 'lead' candidates. The chapter describes some lessons learned from this work and proposes future areas of focus for drug discovery. Collectively, the findings from this recent work show potential for selected natural product scaffolds as candidates for future development. Developing such candidates via future chemical optimisation, efficacy and safety evaluations, broad spectrum activity assessments, and target identification represents an exciting prospect and, if successful, could pave the way to subsequent pre-clinical and clinical evaluations.

Occurrence of Gastrointestinal Parasites in Small Ruminants in the Central Part of Myanmar

Gastrointestinal parasite infection in small ruminants remains one of the major economic losses caused by reduced productivity. A total of 380 faecal samples were taken from 280 sheeps in Magway and Pwintbyu Townships and 100 goats in Natmauk Township, Myanmar. Faecal flotation and sedimentation methods were carried out to detect the presence of parasitic infections. Faecal egg and oocyst counts were carried out using the McMaster technique. The overall occurrence of gastrointestinal parasites in small ruminants was 98.4% (374/380). The occurrence of gastrointestinal parasites in sheep (99.3%) was higher than that in goats (96%). The highest occurrence was found in Eimeria spp. (96%), followed by Trichostrongyle (77.1%), Trichuris spp. (35%), and Moniezia expansa (14%). The mixed infection rate was 84.8% (317/374), while a single infection was 15.2% (57/374). The mean eggs per gram (EPG) and oocysts per gram (OPG) of faeces were ranged from 50 to 600 and 50 to 29,800, respectively. Among the 4 nucleotide sequences isolated, one sequence was 94.10-94.47% similarity with Trichostrongylus colubriformis, reported from Laos, and three sequences showed 96.64-99.46% identity with Haemonchus contortus from Laos, China, India, and Mongolia. As gastrointestinal parasite infection in small ruminants was relatively high in the study area, the development of appropriate treatment and control measures should be provided to reduce production losses.

Driving Adoption and Commercialization of Subunit Vaccines for Bovine Tuberculosis and Johne's Disease: Policy Choices and Implications for Food Security

Infectious animal diseases, such as Johne's disease (JD) caused by Mycobacterium avium paratuberculosis (MAP) and bovine tuberculosis (bTB) caused by Mycobacterium bovis, have been a challenge to the livestock industry globally, impacting negatively on animal, human and environmental health, and overall food security. Despite several industry-led and government initiatives and programs aimed at preventing and reducing losses associated with JD and bTB outbreaks, JD has remained endemic in many parts of the world while there have been incidental outbreaks of bTB. While several studies focus on sustainable intensification of food (crop) production as a critical solution to food insecurity, following the existential interconnection between animals, humans and the environment recognized by one health, we frame food security through the lens of animal disease prevention and control, given the importance of livestock products to human health and livelihood. Vaccination has been a popular strategy successfully used in controlling other infectious diseases. The paper focuses on an alternate strategy of two subunit vaccines with companion diagnostics targeted at individual pathogens to attain satisfactory immunological responses for JD and bTB. We examine gaps in vaccine policies, commercialization, and potential strategies that would strengthen animal disease prevention and enhance food security. The potential of public-private partnership in strengthening private sector participation in effective animal disease control and health delivery and the implications for global food security are discussed.

Ticks and Tick-Borne Diseases in Cuba, Half a Century of Scientific Research

Ticks and the vast array of pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. In Cuba, the major tropical island in the Caribbean, ticks are an important cause of vector-borne diseases affecting livestock production, pet animal health and, to a lesser extent, human health. The higher number of tick species in the country belong to the Argasidae family and, probably less known, is the presence of an autochthonous tick species in the island, Ixodes capromydis. Herein, we provide a comprehensive review of the ticks and tick-borne pathogens (TBPs) affecting animal and human health in Cuba. The review covers research results including ecophysiology of ticks, the epidemiology of TBPs, and the diagnostic tools used currently in the country for the surveillance of TBPs. We also introduce the programs implemented in the country for tick control and the biotechnology research applied to the development of anti-tick vaccines.

Initial assessment of the economic burden of major parasitic helminth infections to the ruminant livestock industry in Europe

We report a European wide assessment of the economic burden of gastrointestinal nematodes, Fasciola hepatica (common liver fluke) and Dictyocaulus viviparus (bovine lungworm) infections to the ruminant livestock industry. The economic impact of these parasitic helminth infections was estimated by a deterministic spreadsheet model as a function of the proportion of the ruminant population exposed to grazing, the infection frequency and intensity, the effect of the infection on animal productivity and mortality and anthelmintic treatment costs. In addition, we estimated the costs of anthelmintic resistant nematode infections and collected information on public research budgets addressing helminth infections in ruminant livestock. The epidemiologic and economic input data were collected from international databases and via expert opinion of the Working Group members of the European Co-operation in Science and Technology (COST) action COMbatting Anthelmintic Resistance in ruminants (COMBAR). In order to reflect the effects of uncertainty in the input data, low and high cost estimates were obtained by varying uncertain input data arbitrarily in both directions by 20 %. The combined annual cost [low estimate-high estimate] of the three helminth infections in 18 participating countries was estimated at € 1.8 billion [€ 1.0-2.7 billion]. Eighty-one percent of this cost was due to lost production and 19 % was attributed to treatment costs. The cost of gastrointestinal nematode infections with resistance against macrocyclic lactones was estimated to be € 38 million [€ 11-87 million] annually. The annual estimated costs of helminth infections per sector were € 941 million [€ 488 - 1442 million] in dairy cattle, € 423 million [€ 205-663 million] in beef cattle, € 151million [€ 90-213 million] in dairy sheep, € 206 million [€ 132-248 million] in meat sheep and € 86 million [€ 67-107 million] in dairy goats. Important data gaps were present in all phases of the calculations which lead to large uncertainties around the estimates. Accessibility of more granular animal population datasets at EU level, deeper knowledge of the effects of infection on production, levels of infection and livestock grazing exposure across Europe would make the largest contribution to improved burden assessments. The known current public investment in research on helminth control was 0.15 % of the estimated annual costs for the considered parasitic diseases. Our data suggest that the costs of enzootic helminth infections which usually occur at high prevalence annually in ruminants, are similar or higher than reported costs of epizootic diseases. Our data can support decision making in research and policy to mitigate the negative impacts of helminth infections and anthelmintic resistance in Europe, and provide a baseline against which to measure future changes.

Cuminaldehyde induces oxidative stress-mediated physical damage and death of Haemonchus contortus

Cuminaldehyde (CA), a monoterpenoid, preset in many plant sources including cumin, induces reactive oxygen-related damage and death in Haemonchus contortus, a parasitic worm with an LD50, values of 127.3 ± 7.5, 184.5 ± 12.1 and 104.1 ± 7.9 μg/mL for an adult female, adult male worms (12 h) and L3 larvae, respectively (24 h). Fifty percent of inhibition of egg hatching (IC50) was obtained at 142.4 ± 11.4 μg/mL after 48 h of exposure. Scanning electron microscopy revealed physical damage to the anterior and posterior ends, intestinal, ovarian, and esophageal regions of the warms on exposure to ca. The exposure of worms to CA also led to a systemic increase in reactive oxygen species (ROS) within 3 h. The better activity was seen with CA compared to standard antihelminthic drug albendazole (Alb). 74 μg/mL CA showed 2.3 fold more increase of catalase (CAT), 0.61 fold increase of superoxide dismutase (SOD), 3.3 fold increase of glutathione peroxidase (GPx) activity and 17.5 fold increase of glutathione (GSH) activity in comparison with Alb (500 μg/mL) for the same time of exposure (3 h). A firm increase of (2.9 fold) was also observed in nitric oxide synthase (NOS) activity within 12 h of exposure with CA (74 μg/mL) in comparison with Alb. Therefore the preclinical potential of CA is much higher than widely used antihelminthic drug Alb. The results open new opportunities to explore CA as a new active antihelminthic molecule.

Nematicidal Activity of Holigarna caustica (Dennst.) Oken Fruit Is Due to Linoleic Acid

Holigarna caustica (Dennst.) Oken is used by the tribes of Northeast India for the treatment of intestinal problems. Therefore, the present study was undertaken to investigate the active principles of this plant responsible for its anthelmintic activity, using bioassay-guided fractionation. An ethanol extract of H. caustica fruit was fractionated on a silica gel column, followed by HPLC, while nematicidal activity was followed throughout on Caenorhabditis (C.) elegans as a model organism. Our study constitutes the first nematicidal report for this plant. Bioassay-guided purification led to the isolation of one compound (IC₅₀ = 0.4 µM) as the only active constituent in the most active fraction. The compound was identified as linoleic acid based on spectroscopic data (¹H and ¹³C NMR and ESI-MS). No cytotoxicity was observed in the crude extract or in linoleic acid (up to 356 µM). The results support the use of H. caustica for the treatment of intestinal problems by traditional healers in India.

A perspective on the discovery of selected compounds with anthelmintic activity against the barber's pole worm-Where to from here?

Parasitic roundworms (nematodes) cause substantial morbidity and mortality in animals worldwide. Anthelmintic treatment is central to controlling these worms, but widespread resistance to most of the commercially available anthelmintics for veterinary and agricultural use is compromising control, such that there is an urgency to discover new and effective drugs. The purpose of this article is to review information on parasitic nematodes, the treatment and control of parasitic nematode infections and aspects of discovering new anthelmintics in the context of anthelmintic resistance problems, and then to discuss some progress that our group has made in identifying selected compounds with activity against nematodes. The focus of our recent work has been on discovering new chemical entities and known drugs with anthelmintic activities against Haemonchus contortus as well as other socioeconomically important parasitic nematodes for subsequent development. Using whole worm-based phenotypic assays, we have been screening compound collections obtained via product-development-partnerships and/or collaborators, and active compounds have been assessed for their potential as anthelmintic candidates. Following the screening of 15,333 chemicals from five distinct compound collections against H. contortus, we have discovered one new chemical entity (designated SN00797439), two human kinase inhibitors (SNS-032 and AG-1295), 14 tetrahydroquinoxaline analogues, one insecticide (tolfenpyrad) and two tolfenpyrad (pyrazole-5-carboxamide) derivatives (a-15 and a-17) with anthelmintic activity in vitro. Some of these 20 'hit' compounds have selectivity against H. contortus in vitro when compared to particular human cell lines. In our opinion, some of these compounds could represent starting points for 'lead' development. Accordingly, the next research steps to be pursued include: (i) chemical optimisation of representative chemicals via structure-activity relationship (SAR) evaluations; (ii) assessment of the breadth of spectrum of anthelmintic activity on a range of other parasitic nematodes, such as strongyloids, ascaridoids, enoplids and filarioids; (iii) detailed investigations of the absorption, distribution, metabolism, excretion and toxicity (ADMET) of optimised chemicals with broad nematocidal or nematostatic activity; and (iv) establishment of the modes of action of lead candidates.

Elucidating the molecular and developmental biology of parasitic nematodes: Moving to a multiomics paradigm

In the past two decades, significant progress has been made in the sequencing, assembly, annotation and analyses of genomes and transcriptomes of parasitic worms of socioeconomic importance. This progress has somewhat improved our knowledge and understanding of these pathogens at the molecular level. However, compared with the free-living nematode Caenorhabditis elegans, the areas of functional genomics, transcriptomics, proteomics and metabolomics of parasitic nematodes are still in their infancy, and there are major gaps in our knowledge and understanding of the molecular biology of parasitic nematodes. The information on signalling molecules, molecular pathways and microRNAs (miRNAs) that are known to be involved in developmental processes in C. elegans and the availability of some molecular resources (draft genomes, transcriptomes and some proteomes) for selected parasitic nematodes provide a basis to start exploring the developmental biology of parasitic nematodes. Indeed, some studies have identified molecules and pathways that might associate with developmental processes in related, parasitic nematodes, such as Haemonchus contortus (barber's pole worm). However, detailed information is often scant and 'omics resources are limited, preventing a proper integration of 'omic data sets and comprehensive analyses. Moreover, little is known about the functional roles of pheromones, hormones, signalling pathways and post-transcriptional/post-translational regulations in the development of key parasitic nematodes throughout their entire life cycles. Although C. elegans is an excellent model to assist molecular studies of parasitic nematodes, its use is limited when it comes to explorations of processes that are specific to parasitism within host animals. A deep understanding of parasitic nematodes, such as H. contortus, requires substantially enhanced resources and the use of integrative 'omics approaches for analyses. The improved genome and well-established in vitro larval culture system for H. contortus provide unprecedented opportunities for comprehensive studies of the transcriptomes (mRNA and miRNA), proteomes (somatic, excretory/secretory and phosphorylated proteins) and lipidomes (e.g., polar and neutral lipids) of this nematode. Such resources should enable in-depth explorations of its developmental biology at a level, not previously possible. The main aims of this review are (i) to provide a background on the development of nematodes, with a particular emphasis on the molecular aspects involved in the dauer formation and exit in C. elegans; (ii) to critically appraise the current state of knowledge of the developmental biology of parasitic nematodes and identify key knowledge gaps; (iii) to cover salient aspects of H. contortus, with a focus on the recent advances in genomics, transcriptomics, proteomics and lipidomics as well as in vitro culturing systems; (iv) to review recent advances in our knowledge and understanding of the molecular and developmental biology of H. contortus using an integrative multiomics approach, and discuss the implications of this approach for detailed explorations of signalling molecules, molecular processes and pathways likely associated with nematode development, adaptation and parasitism, and for the identification of novel intervention targets against these pathogens. Clearly, the multiomics approach established recently is readily applicable to exploring a wide range of interesting and socioeconomically significant parasitic worms (including also trematodes and cestodes) at the molecular level, and to elucidate host-parasite interactions and disease processes.

Economic impact of the liver condemnation of cattle infected with Fasciola hepatica in the Peruvian Andes

Fasciolosis is a zoonotic food- and waterborne infection related to great economic losses on ruminant production. In order to determine the prevalence of bovine liver condemnations due to fasciolosis in an abattoir at the Central Andes of Peru, we evaluated the records of an authorized slaughterhouse in Huancayo, at 3300 m above sea level, over 16 months. Subsequently, the average weights of condemned viscera and carcasses were also estimated to determine the direct and indirect economic losses. Fasciolosis was the main cause of liver condemnation, with a prevalence of 55.72% (3926/7046; CI 95%: 56.88-54.56%). The livers infected were more than double the amount of livers supplied to markets in this period. Although the average price of liver in the Peruvian Andes is very cheap, approximately 16.45 tons of livers were destroyed, estimating a direct economic loss of US$ 35,080 (CI 95%: US$ 29,178-40,938). The indirect loss due to decreased body weight gain (calculated using 10% of the average weight of a healthy animal carcass) was estimated at US$ 354,570 (CI 95%: US$ 387,908-US$ 321,227). Fasciolosis is an important zoonotic disease that threatens food security in the Andean region, with major repercussions on the income of the livestock industry and the availability of cheap protein sources.

Prevalence and risk factors associated with gastrointestinal parasites in ruminant livestock in the Coastal Savannah zone of Ghana

Gastrointestinal (GIT) parasite infections result in significant economic losses to ruminant livestock production. To determine the prevalence and risk factors associated with GIT parasite infections in livestock from Ghana, a cross-sectional survey was conducted in cattle and small ruminants kept under different management systems in the Coastal Savannah zone from October 2014 to February 2015. Faecal samples were collected from 328 cattle and 502 small ruminants (sheep and goats) and examined by formal ether concentration microscopy. The management systems and environmental conditions of the farm or household were observed, and a questionnaire administered to the livestock owners. Overall, 90.8% (754/830) of livestock were infected with at least one of ten different parasites (Eimeria, Strongylid nematodes, Toxocara, Trichuris, Schistosoma, Dicrocoelium, Paramphistomum, Fasciola, Moniezia and Thysaniezia), with Eimeria the most prevalent (78.4%). Most (64.5%) livestock had coinfections with two to five parasites with parasite intensity mostly light and at least one parasite was found in 98.6% (140/142) of the herds. Binary logistic regression models were generated to assess the risk factors associated with infection. Earthen floor was positively associated with strongylid infection, multiple ruminant species with Paramphistomum infection and flock size (>25 animal) with Thysaniezia, Dicrocoelium and Fasciola infections. Separating young animals from older animals was negatively associated with Strongylid infection, feed supplementation with Thysaniezia infection and small ruminant species with Paramphistomum and Toxocara infections. The findings from this study suggests that good sanitation, proper husbandry practices and improved nutrition can improve livestock health and production in Ghana.

Prevalence of GI helminths of cattle in low lying and marshy areas of Kashmir valley

The study was conducted to find out the prevalence of gastrointestinal (GI) helminths in cattle of low lying and marshy areas of Kashmir valley over a period of one year. The qualitative faecal examination of 885 samples revealed an overall prevalence of GI helminths to the tune of 37.06% comprising 7.80% trematodes, 4.29% cestodes and 31.98% nematodes. Prevalence of paramphistomes (7.34%) was more than that of Fasciola spp (0.45%). Among cestodes, the only genus reported was Moniezia spp (4.29%). In nematodes, maximum prevalence was observed for strongyle worms (31.19%) followed by Strongyloides spp. (1.24%) and Trichuris spp (0.57%). Seasonal variation of GI helminths revealed significantly highest prevalence in autumn (50%) followed by spring (41.62%), summer (33.99%) and winter (25.50%). Overall prevalence of GI helminths was significantly higher in young cattle (64.62%) than adults (32.32%). Significantly higher prevalence of GI helminths was observed in males (50.53%) as compared to females (35.44%). Mean intensity of GI nematodes ranged from 0 to 350 with an average of 177.41±28.25 eggs per gram (EPG). Significantly highest mean intensity of GI nematodes was found in summer (173.61±46.70) followed by spring (148.88±56.70), autumn (113±11.34) and winter (95.83±33.24). Mean EPG in young cattle (192.71±27.20) was significantly higher than that of adults (162.11±29.30). Sex had non-significant influence on intensity of GI nematodes. On the basis of above study, it can be concluded that the prophylactic dosing of cattle against trematodes should be done during late autumn and late winter or early spring. Similarly prophylactic de-worming of animals in mid-autumn, mid-spring and mid-summer shall be useful in preventing production losses. However, it will be better to use broad spectrum drug which is effective against trematodes, cestodes as well as nematodes to avoid frequent dosing.

GluClR-mediated inhibitory postsynaptic currents reveal targets for ivermectin and potential mechanisms of ivermectin resistance

Glutamate-gated chloride channel receptors (GluClRs) mediate inhibitory neurotransmission at invertebrate synapses and are primary targets of parasites that impact drastically on agriculture and human health. Ivermectin (IVM) is a broad-spectrum pesticide that binds and potentiates GluClR activity. Resistance to IVM is a major economic and health concern, but the molecular and synaptic mechanisms of resistance are ill-defined. Here we focus on GluClRs of the agricultural endoparasite, Haemonchus contortus. We demonstrate that IVM potentiates inhibitory input by inducing a tonic current that plateaus over 15 minutes and by enhancing post-synaptic current peak amplitude and decay times. We further demonstrate that IVM greatly enhances the active durations of single receptors. These effects are greatly attenuated when endogenous IVM-insensitive subunits are incorporated into GluClRs, suggesting a mechanism of IVM resistance that does not affect glutamate sensitivity. We discovered functional groups of IVM that contribute to tuning its potency at different isoforms and show that the dominant mode of access of IVM is via the cell membrane to the receptor.

Glutamate-gated chloride channel receptors (GluClRs) mediate chemoelectric inhibition in invertebrate animals and are targets for broad-spectrum pesticides such as ivermectin. However, resistance to ivermectin threatens the effective control of invertebrates that cause a range of agricultural and human diseases. This study investigates different isoforms of GluClR expressed by the major agricultural endoparasite, Haemonchus contortus, on a synaptic and single receptor level. We discovered that ivermectin enhances synaptic current amplitude and decay and lengthens single receptor activity. Furthermore, ivermectin is less efficacious at GluClRs that incorporate a naturally ivermectin-resistant subunit, suggesting a potential resistance mechanism. Finally, we identify two chemical interactions between the GluClR and ivermectin that determine its potency and show that ivermectin binds to GluClRs via cell membrane interactions.

Epidemiology and economic loss of fasciolosis and dicrocoeliosis in Arak, Iran

Aim:

Fasciolosis and dicrocoeliosis are important parasitic diseases worldwide, causing significant financial losses due to decrease in production and viscera condemnation in animals. We performed the current research to assess the epidemiology of these infections and determine their significance from an economic perspective in Arak, Iran.

Materials and Methods:

In total, we evaluated 118,463 sheep, 207,652 goats, and 43,675 cattle through necropsic analysis at the slaughterhouses. The average weight of sheep, goat, and cattle liver was 1000, 900, and 5000 g, respectively. The average price of liver in the market was 8 USD/kg. Moreover, the elimination of fundamental nutrients and vitamins was evaluated in infected livers. The prevalence of fasciolosis and dicrocoeliosis was determined. Analysis of variance test was applied for the statistical analysis, and the significance level was <0.05.

Results:

In total, Fasciola hepatica and Dicrocoelium dendriticum were detected in 0.56% (confidence interval CI, 0.54-0.59) and 0.77% (CI, 0.75-0.81) of the animals, respectively (p=0.1). The annual economic loss attributed to fasciolosis and dicrocoeliosis was 26698.4 and 30479.2 USD, respectively. The total economic loss was 10,880, 9079.2, and 10,520 dollars in sheep, cattle, and goats, respectively. On the other hand, financial loss resulting from fasciolosis was 7160, 6098.4, and 13,440 dollars in sheep, goats, and cattle, respectively. In addition, economic loss due to dicroceliasis was 10,880, 9079.2, and 10,520 dollars, respectively.

Conclusion:

Overall, fasciolosis and dicrocoeliosis in Iran always remain common in sheep, goats, and cattle that afford major economic loss of all the country also exist in Arak province. The present study could provide basic information for further examination of liver fluke infections in Iran.

Antiparasitic activity of chicory (Cichorium intybus) and its natural bioactive compounds in livestock: a review

Increasing drug resistance in gastrointestinal (GI) parasites of livestock and concerns about chemical residues in animal products and the environment are driving the development of alternative control strategies that are less reliant on the use of synthetic drugs. An increasingly investigated approach is the use of bioactive forages with antiparasitic properties as part of the animal's diet (nutraceuticals) or as potential sources of novel, natural parasiticides. Chicory (Cichorium intybus) is a multi-purpose crop and one of the most promising bioactive forages in temperate regions, and numerous in vivo trials have explored its potential against parasitic nematodes in livestock. However, it is unclear whether chicory can induce a direct and broad activity against various GI parasites in different livestock species, and the levels of chicory in the diet that are required to exert an efficient antiparasitic effect. Moreover, the mechanisms leading to the reported parasiticidal activity of chicory are still largely unknown, and its bioactive phytochemicals have only recently been investigated. In this review, we summarise the progress in the study of the antiparasitic activity of chicory and its natural bioactive compounds against GI parasites in livestock, through examination of the published literature. The available evidence indicates that feeding chicory can reduce faecal egg counts and/or worm burdens of abomasal nematodes, but not infections with intestinal worms, in ruminants. Highly chicory-rich diets (≥ 70% of chicory dry matter in the diet) may be necessary to directly affect abomasal parasitism. Chicory is known to synthesise several bioactive compounds with potential antiparasitic activity, but most research has been devoted to the role of sesquiterpene lactones (SL). Recent in vitro studies have confirmed direct and potent activity of SL-rich extracts from chicory against different GI helminths of livestock. Chicory SL have also been reported to exhibit antimalarial properties and its potential antiprotozoal activity in livestock remains to be evaluated. Furthermore, the detailed identification of the main antiparasitic metabolites of chicory and their pharmacokinetics need further confirmation. Research gaps and perspectives on the potential use of chicory as a nutraceutical forage and a source of bioactive compounds for parasite control in livestock are discussed.

Herd-level seroprevalence of Fasciola hepatica and Ostertagia ostertagi infection in dairy cattle population in the central and northeastern Poland

Background

Fasciola hepatica and Ostertagia ostertagi infections are widespread in cattle population of Europe, however data on their prevalence in Poland are only fragmentary. Therefore, the cross-sectional study was carried out to determine the herd-level seroprevalence of F. hepatica and O. ostertagi infection in dairy cattle population in the central and north-eastern provinces Poland, and to identify basic local risk factors for these infections. In total, 598 herds were enrolled, 394 (65.9%) in the north-eastern province and 204 (34.1%) in the central province. In each herd the questionnaire survey was conducted and bulk-tank milk (BTM) sample was collected and screened using two indirect immunoenzymatic tests. Optical density ratio (ODR) was regarded as the quantitative proxy of exposure to either of the two parasites.

Results

Both Fasciola and Ostertagia ELISA ODR in the north-eastern province was significantly higher than ODR in the central province. At the cut-off value of ODR = 0.27 the true herd-level seroprevalence of F. hepatica was 79.6% (95% CI: 74.0%, 84.3%) in the north-eastern province and 13.0% (95% CI: 5.3%, 21.7%) in the central province. At the cut-off of ODR = 0.50151 of 188 herds (80.3%, 95% CI: 74.1%, 85.4%) were seropositive for O. ostertagi in the north-eastern province and only 70 of 136 herds (51.5%, 95% CI: 43.1%, 59.7%) were seropositive in the central province. Location of a herd in the north-eastern province, longer grazing period practiced in a herd and > 50%-share of grazing grass in roughage were all positively related to the increase in exposure to both parasites. Moreover, the use of hay or haylage as main roughage proved to be positively related to the increase in exposure to F. hepatica.

Conclusions

F. hepatica and O. ostertagi are widespread in cattle population in Poland, however their occurrence at a herd-level varies between different regions of Poland. This diversity can only partly be explained by different herd management, and appears linked to environmental and climate conditions typical for these regions.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1455-7) contains supplementary material, which is available to authorized users.

Metazoan Parasite Vaccines: Present Status and Future Prospects

Eukaryotic parasites and pathogens continue to cause some of the most detrimental and difficult to treat diseases (or disease states) in both humans and animals, while also continuously expanding into non-endemic countries. Combined with the ever growing number of reports on drug-resistance and the lack of effective treatment programs for many metazoan diseases, the impact that these organisms will have on quality of life remain a global challenge. Vaccination as an effective prophylactic treatment has been demonstrated for well over 200 years for bacterial and viral diseases. From the earliest variolation procedures to the cutting edge technologies employed today, many protective preparations have been successfully developed for use in both medical and veterinary applications. In spite of the successes of these applications in the discovery of subunit vaccines against prokaryotic pathogens, not many targets have been successfully developed into vaccines directed against metazoan parasites. With the current increase in -omics technologies and metadata for eukaryotic parasites, target discovery for vaccine development can be expedited. However, a good understanding of the host/vector/pathogen interface is needed to understand the underlying biological, biochemical and immunological components that will confer a protective response in the host animal. Therefore, systems biology is rapidly coming of age in the pursuit of effective parasite vaccines. Despite the difficulties, a number of approaches have been developed and applied to parasitic helminths and arthropods. This review will focus on key aspects of vaccine development that require attention in the battle against these metazoan parasites, as well as successes in the field of vaccine development for helminthiases and ectoparasites. Lastly, we propose future direction of applying successes in pursuit of next generation vaccines.

A multivariate approach to the diagnosis of gastrointestinal infection in ewes

Diagnosing the effects of helminth infections is an efficient way to manage the problem in ruminant production systems. Selection of animals in a flock that are infected with Haemonchus has traditionally involved differential packed cell volume measurements (PCV), and in recent years, the FAMACHA^© system has been used. However, few small analytical changes have been made. The objective of this study was to examine the influence of different diagnoses linked to packed cell volume (PCV) and FAMACHA^© system scores in native ewes, using a multivariate approach. Ewes were classified into three categories according to their score in the FAMACHA^© system (FS) and their packed cell volumes (PCV) as follows: Group AG (FS between 1 and 2 and PCV ≥ 30%); Group BG (FS score of 3 and PCV between 21 and 29%); Group CG (FS between 4 and 5 and PCV ≤ 20%). The animals were evaluated using performance characteristics, parasitological examinations, blood values and serum biochemistry. The data show that the use of a multivariate approach for different diagnoses using the FAMACHA^© system and PCV measurements gives similar results, although they have particular pathophysiological indicator patterns.

Factors responsible for the post-slaughter loss of carcass and offal's in abattoirs in South Africa

Global demand for food is surging upward due to the expansion of human population. Hence food production and supply need to double with little or no waste to meet this demand. Food loss at any point in the farm to fork chain inhibits the stability of food security at household and national level. A retrospective (AR) and a post mortem meat inspection (PMMI) study to identify major causes of offal and carcass condemnation was conducted in three abattoirs namely, Adeliade, Queenstown and East London abattoirs represented as AD, QT, and EL respectively. The retrospective study revealed the main causes of tongue condemnation as abscess (0.08%, 0.03% and 0.05%) and actinobacillosis (0.02%, 0% and 0.02%) respectively. The spleen was condemned due to abscess (0.35%, 0.94% and 0.17%) and splenomegaly (0.21%, 0.55% and 0.2%). The heart was condemned due to cyst (0.24%, 0.36% and 0.2%) and inflammation (0.9%, 1.85%, and 0.75%). While the kidney, was condemned due to cyst (0.08%, 0.23% and 0.16%) and nephritis (0.94%, 1.01% and 1.18%). However, a greater percentage of condemnation was recorded during the active abattoir study. During the same period, partial carcass condemnations were mainly due to bruises (63.3%, 50.4% and 41.0%), abscess (7%, 6% and 14%) and improper evisceration (19%, 31% and 27%). The combined monetary loss due to offal's and carcass condemnation during the AR and PMMI study was estimated as ZAR 255194.4 (34191.5 USD) and ZAR 25958.8 (2570.2 USD) respectively. This study identified major causes of offals and carcass condemnation as abscess, bruises, actinobacillosis, cyst, inflammatory conditions and improper evisceration. It can be used as starting point information for early warning on livestock diseases of economic loss in South Africa.

Financial loss estimation of bovine fasciolosis in slaughtered cattle in South Africa

South Africa's livestock population is rapidly evolving and consequently will require sustained epidemiological surveillance to detect and prevent diseases which contribute to a decrease in livestock productivity, public health risk and food wastage. Fasciola infection is one of the commonest diseases affecting livestock health and a significant portion of meat and offal's are declared unfit for human consumption. This study assessed the prevalence and monetary losses associated with Fasciola infection at three abattoirs in Eastern Cape Province. A retrospective data of all slaughtered cattle were obtained from Department of Rural Development and Agrarian Reform (DRDAR) from 2010–2012. A prospective abattoir survey was conducted between July 2013 and June 2014 to determine the prevalence and financial loss due to fasciolosis.

The highest prevalence was in December and January (23%) while the lowest prevalence was recorded in May and June (5%). Annual prevalence of Fasciola at abattoirs AB1, were (3.2%, 2.2% and 2.0%), AB2 (6.4%, 4.6% and 3.5%), AB3 (14.4%, 6.9% and 9.5%) for year 2010, 2011 and 2012 respectively. The total financial loss due to Fasciola infection during the active survey of the three abattoirs was ZAR 44, 930 (3456.2 USD). A breakdown of this figure shows that whole liver condemnation was ZAR 25, 230 (2, 357 USD), and partial liver condemnation was ZAR 19, 700 (1515.4 USD).

The present study reveals the economic loss due to liver condemnation from Fasciola infection and provides regional baseline information regarding the prevalence of Fasciola in cattle at three abattoirs.

Translational Rodent Models for Research on Parasitic Protozoa-A Review of Confounders and Possibilities

Rodents, in particular Mus musculus, have a long and invaluable history as models for human diseases in biomedical research, although their translational value has been challenged in a number of cases. We provide some examples in which rodents have been suboptimal as models for human biology and discuss confounders which influence experiments and may explain some of the misleading results. Infections of rodents with protozoan parasites are no exception in requiring close consideration upon model choice. We focus on the significant differences between inbred, outbred and wild animals, and the importance of factors such as microbiota, which are gaining attention as crucial variables in infection experiments. Frequently, mouse or rat models are chosen for convenience, e.g., availability in the institution rather than on an unbiased evaluation of whether they provide the answer to a given question. Apart from a general discussion on translational success or failure, we provide examples where infections with single-celled parasites in a chosen lab rodent gave contradictory or misleading results, and when possible discuss the reason for this. We present emerging alternatives to traditional rodent models, such as humanized mice and organoid primary cell cultures. So-called recombinant inbred strains such as the Collaborative Cross collection are also a potential solution for certain challenges. In addition, we emphasize the advantages of using wild rodents for certain immunological, ecological, and/or behavioral questions. The experimental challenges (e.g., availability of species-specific reagents) that come with the use of such non-model systems are also discussed. Our intention is to foster critical judgment of both traditional and newly available translational rodent models for research on parasitic protozoa that can complement the existing mouse and rat models.

Screening of the 'Open Scaffolds' collection from Compounds Australia identifies a new chemical entity with anthelmintic activities against different developmental stages of the barber's pole worm and other parasitic nematodes

The discovery and development of novel anthelmintic classes is essential to sustain the control of socioeconomically important parasitic worms of humans and animals. With the aim of offering novel, lead-like scaffolds for drug discovery, Compounds Australia released the 'Open Scaffolds' collection containing 33,999 compounds, with extensive information available on the physicochemical properties of these chemicals. In the present study, we screened 14,464 prioritised compounds from the 'Open Scaffolds' collection against the exsheathed third-stage larvae (xL3s) of Haemonchus contortus using recently developed whole-organism screening assays. We identified a hit compound, called SN00797439, which was shown to reproducibly reduce xL3 motility by ≥ 70%; this compound induced a characteristic, "coiled" xL3 phenotype (IC₅₀ = 3.46-5.93 μM), inhibited motility of fourth-stage larvae (L4s; IC₅₀ = 0.31-12.5 μM) and caused considerable cuticular damage to L4s in vitro. When tested on other parasitic nematodes in vitro, SN00797439 was shown to inhibit (IC₅₀ = 3-50 μM) adults of Ancylostoma ceylanicum (hookworm) and first-stage larvae of Trichuris muris (whipworm) and eventually kill (>90%) these stages. Furthermore, this compound completely inhibited the motility of female and male adults of Brugia malayi (50-100 μM) as well as microfilariae of both B. malayi and Dirofilaria immitis (heartworm). Overall, these results show that SN00797439 acts against genetically (evolutionarily) distant parasitic nematodes i.e. H. contortus and A. ceylanicum [strongyloids] vs. B. malayi and D. immitis [filarioids] vs. T. muris [enoplid], and, thus, might offer a novel, lead-like scaffold for the development of a relatively broad-spectrum anthelmintic. Our future work will focus on assessing the activity of SN00797439 against other pathogens that cause neglected tropical diseases, optimising analogs with improved biological activities and characterising their targets.