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The El Niño La Niña Southern Oscillation (ENSO) exerts a significant influence on agroecological environments and plays a crucial role in influencing crop productivity, yet its impact on animal diseases has been largely overlooked, despite the evident impact of climate on disease transmission. This study aimed to evaluate the impact of ENSO on the transmission potential ( Q 0 ) of Haemonchus contortus (H. contortus) across agroecological zones (AEZs) in southern Africa across the region’s typical rainy season (November-April). Key results indicate that stronger El Niño events can significantly decrease H. contortus transmission potential in subtropical AEZs. Tropical AEZs exhibit lower sensitivity to El Niño generally, but stronger events can lead to significant transmission potential reductions in certain zones. Conversely, La Niña increases transmission potential in tropical AEZs by small-to-medium effect magnitudes, depending on AEZ. Importantly, the analysis found significant increases in Q 0 across direct transitions from El Niño to La Niña, with statistically significant medium effects observed in all tropical AEZs, except for the cool-subhumid AEZ. In subtropical AEZs, notable increases in Q 0 were found in the warm-humid and warm-subhumid zones, also according to medium effect sizes. The study highlights the necessity for disseminating proactive and adaptive animal management practices for small ruminants among smallholder farmers, both during ENSO events and continuing into the post-event transition period, particularly through capacity building, nutritional supplementation and targeted selective treatment. The findings underscore the importance of considering small ruminants in ENSO preparedness and response plans, allowing farmers to optimise the resilience-enhancing roles of small ruminants to mitigate the impacts of climate shocks and food insecurity.

Sheep farming is the backbone of a rural economy in developing countries, and haemonchosis is a major impediment in the way of its progress. Haemonchus contortus (H. contortus) infection persists all over the world particularly in the tropical and sub-tropical regions. Various review articles have been published to substantially cover one or more aspects of its morphology, prevalence, pathogenesis, symptoms, diagnosis, immune response, drug resistance, treatment, and control measure. The objective of this paper is to briefly review past and present information available in the aforementioned areas in one place to enable the readers to fully understand the problem from a broader perspective. H. contortus parasite harbours in abomasum of affected animal and feeds on its blood, producing mild to severe symptoms and even death in acute form. The parasite thus inflicts heavy production losses and is of economic importance. H. contortus has developed diverse characters over the years leading to limited success in the production of vaccines. Indiscriminate use of the anthelmintics has produced drug resistance against almost all conventional products. Efficacy of medicinal plants and non-conventional chemicals has been reported under controlled experiments; however, research on their adverse effects on growth and fertility is yet to be studied. Research on molecular tools for identification and introduction of resistant genes into the flock is also underway but still a long journey to find its field application. Crossbreeding may compromise the production traits of the existing flock. In given circumstances, a targeted selective treatment approach along with selective breeding, culling of more susceptible animals, and maintaining a good body condition score through the provision of a balanced diet remains a workable strategy to control haemonchosis in sheep.

The nematode Haemonchus contortus causes severe anemia in sheep and goats. Drug-resistant isolates are common, prompting a need for parasite control measures beyond chemotherapeutics. Vaccination is one promising approach for mitigation of clinical signs associated with haemonchosis. One challenge for H. contortus vaccine efforts is the need to administer repeated boosting doses at regular intervals. In this study, we evaluated a vaccine platform for extended antigen release (VPEAR) designed to initiate and maintain long-term immunity following a single immunization event in sheep. We compared a soluble vaccine depot with montanide adjuvant to the VPEAR platform with two different adjuvant combinations. Vaccination with VPEAR adjuvanted with DEAE-dextran induced antibody titers in 5 out of 6 vaccinated sheep up to 47 weeks post-vaccination. Challenge experiments revealed a 73% decrease in adult worm burden in this vaccine group compared to adjuvant alone and serum antibodies from these animals bound the luminal surface of the parasite intestine. Overall, the VPEAR platform was effective for long-term vaccination with no indication of immune tolerance to the parasite upon challenge.

Antiparasitic resistance in sheep necessitates non-chemical strategies for gastrointestinal strongylosis control. We have evaluated the potential of three predatory mite species-Macrocheles robustulus, Macrocheles muscaedomesticae and Rhabdocarpais consanguineus-to reduce transmission of the nematode Haemonchus contortus by preying on infective larvae. Under laboratory conditions, mites were exposed to mixed prey environments containing housefly Musca domestica eggs and H. contortus third-stage (L3) larvae. Predation was first monitored over 8 h. This was followed by a more detailed assessment of M. robustulus predatory capacity in sheep feces containing eggs of H. contortus and then the oviposition capacity of females was studied when fed exclusively with L3 larvae. Macrocheles robustulus demonstrated a significant preference for nematode larvae, leading to further evaluation of its predatory capacity in sheep feces containing 2250 eggs per gram of H. contortus. After 14 days at 25 ± 2 °C, the presence of M. robustulus resulted in a significant reduction of L3 larvae compared to controls (519 vs. 1067 L3 larvae; p < 0.05). Additionally, M. robustulus females oviposited when fed exclusively on nematode larvae. These findings suggest that M. robustulus could be a viable biological control agent against H. contortus in pasture settings, warranting further field studies.

Th17 cells play important roles in anti-infective responses. The 15 kDa excretory/secretory protein of Haemonchus contortus (HcES-15) has been identified as a promising immune-protective antigen against H. contortus infection capable of up-regulating IL-17, IL-4 and IL-10 production. To obtain the peptides that primarily induce the Th17 immune response, we amplified and expressed the peptides ES15-1, ES15-2 and ES15-3 from HcES-15. In vitro studies demonstrated that ES15-1 stimulated transcriptional activation of the STAT3/RORγt signaling pathway and induced IL-17 production in goat peripheral blood mononuclear cells (PBMCs). In vivo studies, flow cytometric analysis revealed that subcutaneous injection of PLGA-encapsulated ES15-1 peptide (PLGA-ES15-1, 50 μg) significantly enhanced Th17 cell differentiation in the spleens of BALB/c mouse. Consistent with these findings, ELISA quantification demonstrated that ES15-1 treatment significantly increased serum levels of pro-inflammatory cytokine (IL-17, IL-1, IL-6, and TNF-α). In goat immune protection studies, goats ( n  = 6) were subcutaneously immunized with 500 μg of PLGA-ES15-1 on days 0 and 14, followed by infection with H. contortus infective third-stage larvae (iL3s) 1 week post-second immunization. ES15-1 significantly enhanced serum levels of pro-inflammatory cytokines (IL-17, IL-1, IL-6, TNF-α). At autopsy, vaccinated goats exhibited 69.0% ( p  < 0.001) reduction of fecal egg counts (FEC) and 50.54% ( p  < 0.05) reduction of worm burdens versus controls. Our findings suggested that peptide ES15-1 enhanced Th17 responses through regulation of the STAT3/RORγt pathway, conferring a certain immune protection against H. contortus infection.

Barbervax is the first and only available vaccine to protect animals against Haemonchus contortus - one of the most pathogenic parasites of small ruminants. This vaccine contains a kind of native antigen called H11, a glycoprotein complex derived from integral gut of this parasite. Native H11 has been shown to induce high levels (72-95%) of protection, but single or two recombinant molecules of H11 are consistently unsuccessful. An increasing number of aminopeptidases related to H11 have been characterized in the past three decades, but little is known about which ones are the key contributors to protective immunity. Our recent work has revealed that the immunoprotective effect of H11 is primarily associated with its N-glycan moieties. To identify key immunoprotective glycoproteins derived from H11 antigen, we employed glycan-related protective IgG antibodies combined with LC-MS/MS analysis and identified five glycosylated H11 proteins: H11, H11-1, H11-2, H11-4, and H11-5. Subsequently, we utilized the baculovirus-insect cell expression system and successfully expressed four H11 recombinant proteins including rH11, rH11-1, rH11-2 and rH11-4, which demonstrated similar aminopeptidase activity and comparable high-mannose and di-fucosylated N-glycan structures to those found on native H11. Immunization of goats with a cocktail of four rH11s induced a 66.29% reduction ( p > 0.05) in total worm burden and cumulative fecal egg counts. High level of anti-rH11s IgG which could inhibit H. contortus intestinal aminopeptidase activity and larval development. Collectively, our study identified glycoprotein antigens from H11 and assessed their protective efficacy of a recombinant cocktail expressed in insect cells. This work will provide valuable insights into further development of recombinant vaccines against parasitic nematodes.

BACKGROUND: On two farms it was noted that after routine treatment with monepantel, fecal egg counts failed to drop. This was accompanied by lambs mortality due to Haemonchus contortus infection. The aim of this work was to evaluate the efficacy of monepantel to control gastrointestinal nematodes (GIN) in two sheep farms, in Uruguay. FINDINGS: A Fecal Egg Count Reduction Test (FECRT) was subsequently performed at the Experimental Stations Glencoe of INIA Tacuarembó (Farm 1) and Sheep Unit of INIA La Estanzuela (Farm 2) using the World Association for the Advancement of Veterinary Parasitology guidelines. On Farm 1 the FECRT was performed using 6–8 month old Corriedale or Merino Dohne x Corriedale male lambs naturally infected with GIN. On day 0 pre-treatment, three groups of 15 lambs each were selected, blocked by fecal egg count level (FEC) and randomly assigned to one of the following: Group 0 = untreated control, Group 1 = treated with monepantel (Zolvix®, Novartis Animal Health Inc.) from stock previously purchased; Group 2 = treated with monepantel from stock provided by the supplier, at the recommended dose of 2.5 mg/kg of body weight. Fecal samples were collected directly from the rectum from each lamb on day 0 and on day 9 post-treatment. On Farm 2, the FECRT was conducted on a group of 8 month old male lambs Milchschaff x Finn. At this farm, 10 lambs were randomly allocated to be treated with monepantel (Group 1) and 10 lambs were randomly allocated to remain as untreated control (Group 0) using the same protocols as Farm 1. On farm 1 the FECR was 0.0% (95% CI = 0.0 – 49.0) and 42.0% (95% CI = 0.0 – 75.0) for Group 1 and Group 2 respectively. For Farm 2, the FECR was 82.1% (95% CI = 36.0 – 99.0). Haemonchus spp was the resistant genus. CONCLUSIONS: Poor effcicacy of monepantel in treating GIN parasites was demonstrated on both farms.

Pathogen interactions arising during coinfection can exacerbate disease severity, for example when the immune response mounted against one pathogen negatively affects defense of another. It is also possible that host immune responses to a pathogen, shaped by historical evolutionary interactions between host and pathogen, may modify host immune defenses in ways that have repercussions for other pathogens. In this case, negative interactions between two pathogens could emerge even in the absence of concurrent infection. Parasitic worms and tuberculosis (TB) are involved in one of the most geographically extensive of pathogen interactions, and during coinfection worms can exacerbate TB disease outcomes. Here, we show that in a wild mammal natural resistance to worms affects bovine tuberculosis (BTB) severity independently of active worm infection. We found that worm-resistant individuals were more likely to die of BTB than were nonresistant individuals, and their disease progressed more quickly. Anthelmintic treatment moderated, but did not eliminate, the resistance effect, and the effects of resistance and treatment were opposite and additive, with untreated, resistant individuals experiencing the highest mortality. Furthermore, resistance and anthelmintic treatment had nonoverlapping effects on BTB pathology. The effects of resistance manifested in the lungs (the primary site of BTB infection), while the effects of treatment manifested almost entirely in the lymph nodes (the site of disseminated disease), suggesting that resistance and active worm infection affect BTB progression via distinct mechanisms. Our findings reveal that interactions between pathogens can occur as a consequence of processes arising on very different timescales.

This study examined the effects of levels of artificial Haemonchus contortus infection on lamb behaviour and physiology. Forty 6-month-old Romney-cross wethers were assigned to one of four treatments (n = 10/treatment): 8000 L3 larvae (High; H), 4000 L3 larvae (Medium; M), 1000 L3 larvae (Low; L), or water (Control; C). Lambs were monitored 1 week pre- and 6 weeks post-treatment. Weekly measurements included faecal egg counts, liveweight, blood counts, and cytokine concentrations (e.g., IL-6). Behaviour was continuously monitored using cameras and accelerometers. Faecal egg counts increased in H, M, and L lambs from week 3 post-treatment, exceeding 830 epg in H and M lambs by week 6 (P ≤ 0.05). No behavioural differences were observed (P > 0.19). At week 3, H lambs had lower red blood cells, haemoglobin, and haematocrit, and higher mean corpuscular volume (P < 0.02). IL-6 concentrations tended to be higher in H lambs from weeks 4-6 (P = 0.06). Liveweight gains were lower in challenged lambs by trial end, differing significantly from controls 2 weeks post-trial (P = 0.04). These results suggest that while H. contortus infection may not affect lamb behaviour, higher doses (4000-8000 larvae) cause dose-dependent physiological changes indicative of anaemia, immune activation, and reduced weight-gain, negatively impacting lamb welfare and productivity.

Background Haemonchosis, due to infection with Haemonchus contributes to livestock morbidity globally, resulting in economic losses. Hybrids between Haemonchus contortus and H. placei have been evidenced, where sharing of hosts, geographical sympatry, and farming practices allow opportunities for hybridization. In Thailand, high prevelances of H. contortus infecting goats have been documented, and high levels of drug resistance are strongly suspected, due to unregulated and widespread use of anthelmintics (e.g. benzimidazoles and imidazothiazoles). Moreover, the exchange of genetic material facilitates the spread of anthelmintic resistance. Here, we aim to identify the Haemonchus species infecting goats, investigate their population genetic structure, and assess anthelmintic resistance to albendazole and levamisole. Results Using 188 Haemonchus adults obtained from goats across six provinces in Thailand, molecular identification was performed using the nuclear ITS2 region. The population genetic structure was investigated by amplifying the mitochondrial COI gene of representative H. contortus specimens. Genotypic resistance to albendazole and levamisole resistance status were assessed via the single-nucleotide polymorphisms in the β -tubulin and hco-acr-8 gene, respectively. Of the specimens, 97.3% were molecularly identified as H. contortus , while 2.7% were potential hybrids between H. contortus and H. placei. Hybrids were identified in Nakhon Pathom, Kanchanaburi, Ratchaburi, and Suphanburi provinces. The population genetic structure of H. contortus revealed high genetic diversity, high gene flow, and low genetic differentiation between populations. High levels of albendazole resistance were detected, with an overall frequency of 0.56 and 0.44 for the susceptible and resistant alleles, respectively. Compared to albendazole, lower levels of levamisole resistance were obtained, with an overall frequency of 0.87 and 0.13 for the susceptible and resistant alleles, respectively. Conclusions This study revealed the hybrid form of H. contortus and H. placei in goats, high genetic diversity of H. contortus populations, and the presence of albendazole and levamisole resistance. The growing challenge of drug resistance and hybridization in Haemonchus populations demonstrates the urgent need for regulated drug use and the implementation of sustainable management practices.