Improving the Cost-efficiency of Preventive Chemotherapy: Impact of New Diagnostics on Stopping Decisions for Control of Schistosomiasis.

BACKGROUND: Control of schistosomiasis (SCH) relies on the regular distribution of preventive chemotherapy (PC) over many years. For the sake of sustainable SCH control, a decision must be made at some stage to scale down or stop PC. These "stopping decisions" are based on population surveys that assess whether infection levels are sufficiently low. However, the limited sensitivity of the currently used diagnostic (Kato-Katz [KK]) to detect low-intensity infections is a concern. Therefore, the use of new, more sensitive, molecular diagnostics has been proposed. METHODS: Through statistical analysis of Schistosoma mansoni egg counts collected from Burundi and a simulation study using an established transmission model for schistosomiasis, we investigated the extent to which more sensitive diagnostics can improve decision making regarding stopping or continuing PC for the control of S. mansoni. RESULTS: We found that KK-based strategies perform reasonably well for determining when to stop PC at a local scale. Use of more sensitive diagnostics leads to a marginally improved health impact (person-years lived with heavy infection) and comes at a cost of continuing PC for longer (up to around 3 years), unless the decision threshold for stopping PC is adapted upward. However, if this threshold is set too high, PC may be stopped prematurely, resulting in a rebound of infection levels and disease burden (+45% person-years of heavy infection). CONCLUSIONS: We conclude that the potential value of more sensitive diagnostics lies more in the reduction of survey-related costs than in the direct health impact of improved parasite control.

A randomized assessors-blind clinical trial to evaluate the safety and the efficacy of albendazole alone and in combination with mebendazole or pyrantel for the treatment of Trichuris trichiura infection in school-aged children in Lambaréné and surroundings.

Helminthiasis remains a public health issue in endemic areas. Various drugs have been proposed to improve efficacy against helminths. The study aimed to assess the safety and efficacy of three different anthelmintic combinations to treat Trichuris trichiura infections. We conducted a randomized assessors-blind clinical trial involving children aged 2-17 years with T. trichiura. Participants were randomly assigned to one of three treatment arms. On the first and third days, all participants got albendazole 400 mg, and on the second day, albendazole (arm A), mebendazole 500 mg (arm B), or pyrantel 125 mg/kg (arm C). We assessed treatment efficacy using the cure rate (CR) and egg reduction rate (ERR) at 3 and 6 weeks post-treatment. At 3 weeks post-treatment, ERR and CR were highest in study arm A [ERR = 94%, 95% confidence interval (CI): 92-95; CR = 71%; 95% CI: 58-81] compared to the B and C arms. Decrease in ERR was significant only for arm B versus arm A (P-value <0.001); decrease in ERR was significant for arms B and C (P-value <0.001). No statistical difference was observed in CR when comparing arms A and B (P-value =1.00) and C (P-value =0.27). At 6 weeks, a decrease in ERR was observed in three arms, significant only for arm C, 81% (95% CI: 78-83). A significant increase in egg counts was observed between 3 and 6 weeks post-treatment. All treatments were safe with mild adverse events. Albendazole 400 mg/day (arm A) showed the highest efficacy against trichuriasis. Nonetheless, this treatment regimen was able to cure half of the treated individuals highlighting concerns about controlling the transmission of T. trichiura.CLINICAL TRIALRegistered at ClinicalTrials.gov (NCT04326868).

US-wide equine strongylid egg count data demonstrate seasonal and regional trends.

Equine strongylid parasites are ubiquitous around the world and are main targets of parasite control programmes. In recent years, automated fecal egg counting systems based on image analysis have become available allowing for collection and analysis of large-scale egg count data. This study aimed to evaluate equine strongylid fecal egg count (FEC) data generated with an automated system over three years in the US with specific attention to seasonal and regional trends in egg count magnitude and sampling activity. Five US regions were defined; North East, South East, North Central, South Central and West. The data set included state, region and zip code for each FEC. The number of FECs falling in each of the following categories were recorded: (1) 0 eggs per gram (EPG), (2) 1 ⩽ 200 EPG, (3) 201 ⩽ 500 EPG and (4) >500 EPG. The data included 58 329 FECs. A fixed effects model was constructed fitting the number of samples analysed per month, year and region, and a mixed effects model was constructed to fit the number of FECs falling in each of the 4 egg count categories defined above. The overall proportion of horses responsible for 80% of the total FEC output was 18.1%, and this was consistent across years, months and all regions except West, where the proportion was closer to 12%. Statistical analyses showed significant seasonal trends and regional differences of sampling frequency and FEC category. The data demonstrated that veterinarians tended to follow a biphasic pattern when monitoring strongylid FECs in horses, regardless of location.

Metabarcoding study to reveal the structural community of strongylid nematodes in domesticated horses in Thailand.

BACKGROUND: Mixed strongylid infections significantly impact equine health and performance. Traditional microscopy-based methods exhibit limitations in accurately identifying strongylid species. Nemabiome deep amplicon sequencing approach previously succeeded in describing the strongylid communities in livestock including equids. However, there are no available studies that describe the structural communities of strongylid parasites in horses in Thailand. Therefore, this study was undertaken encompassing the ITS-2 rDNA metabarcoding assay to characterize strongylid species within horse fecal samples collected from a cohort of yearlings at the largest domesticated stud farm in Thailand. In addition, to investigate the capability of ITS-2 rDNA in assessing the phylogenetic relationships among the identified strongylid species. RESULTS: The study identified 14 strongylid species in the examined equine populations, each with varying prevalence. Notably, Cylicocyclus nassatus and Cylicostephanus longibursatus were identified as the predominant species, with Strongylus spp. conspicuously absent. The phylogenetic analysis of 207 amplicon sequence variants (ASVs) displayed a complex relationship among the investigated cyathostomin species, with some species are positioned across multiple clades, demonstrating close associations with various species and genera. CONCLUSION: The ITS-2 nemabiome sequencing technique provided a detailed picture of horse strongylid parasite species in the studied population. This establishes a foundation for future investigations into the resistance status of these parasites and enables efforts to mitigate their impact.

Kato-Katz slide preservation technique: Extension of viability and the benefits for schistosomiasis control programs.

The World Health Organization recommends the use of the Kato-Katz method in the procedures of schistosomiasis control programs. Studies show the importance of a fast reading of the slides due to the decline of their viability, with the appearance of fungi or desiccation of the sample, which hinders diagnosis. It is necessary to establish a procedure to improve the long-term preservation of these Kato-Katz slides in order to accomplish the following: (1) preserve the slides for future quality control procedures and readings; (2) allow for the production of durable materials for training; and (3) train health professionals involved in diagnosing schistosomiasis. Therefore, this study aims to test a slide preservation methodology for these purposes. The results showed that the modifications made to the experimental slides demonstrated that egg loss was within the expected range and the limit accepted by quality control standards, as well as improved the diagnostic durability of the slides during the preservation times tested. We concluded that the application of the preservation technique to the slides promoted stabilization and permanence for long-term storage.

Effect of cattle and horse feces storage methods on Nematode egg viability and sensitivity for egg hatch test.

The aim of the present study was to validate methods of stool sample conservation for the egg hatch test (EHT). This study involved the use of a bovine naturally infected predominantly by Cooperia spp. and one equine naturally infected predominantly by cyathostomins characterized as susceptible to benzimidazoles in the EHT. Fecal samples were submitted to three treatments: aerobic methods (anaerobic storage in plastic bottles, anaerobic storage in vacuum-sealed bags or aerobic storage in plastic bags), under two temperature conditions (room temperature and refrigeration) analyzed at four different assessment times (48, 72, 96 and 120 h). As the standard test, an assay was also performed within 3 h. The tests were performed in triplicate for each drug concentration and with three experimental repetitions at one-week intervals. Two criteria were used for the storage methods: hatchability in the negative control group and sensitivity of the eggs to thiabendazole, comparing the EC50 and 95% confidence interval for each treatment to those of the standard test and the other repetitions. Bovine samples can be stored for up to 96 h and refrigerated vacuum storage can be used, ensuring hatchability of the negative control and sensitivity of the eggs to thiabendazole. For equine samples, no forms of storage were indicated due to the variation among the repetitions and the reduction in the sensitivity of the eggs to thiabendazole, which could result in a false positive detection of resistance.

In vitro and in vivo anthelmintic effect of essential oil obtained from Thymus capitatus flowers against Haemonchus contortus and Heligmosomoides polygyrus.

Sheep haemonchosis is a disease that causes serious losses in livestock production, particularly with the increase of cases of anthelmintic resistance around the world. This justifies the urgent need of alternative solutions. The aim of this study was to determine the chemical profile, in vitro, and, in vivo, anthelmintic properties of Thymus capitatus essential oil. To evaluate the, in vitro, anthelmintic activity of the T. capitatus EO on Haemonchus contortus, two tests were used: egg hatch assay (EHA) and adult worm motility (AWM) assay. The nematicidal effect of this oil was evaluated, in vivo, in mice infected artificially with Heligmosomoides polygyrus using faecal egg count reduction (FECR) and total worm count reduction (TWCR). Chromatographic characterization of T.capitatus composition using gas chromatography coupled to mass spectrometry (GC-MS) demonstrated the presence of carvacrol (81.16%), as the major constituents. The IC50 values obtained was 1.9 mg/mL in the EHT. In the AWM assay; T. capitatus essential oil achieved 70.8% inhibition at 1 mg/mL after 8 h incubation. The in vivo, evaluation on H. polygyrus revealed a significant nematicidal effect 7 days post-treatment by inducing 49.5% FECR and 64.5% TWCR, using the highest dose (1600 mg/kg). The results of present study, demonstrate that T.capitatus EO possess a significant anthelmintic properties. Furthermore, it could be an alternative source of anthelmintic agents against gastrointestinal infections caused by H. contortus.

Anthelmintic efficacy of an organic fraction from Guazuma ulmifolia leaves and evaluation of reactive oxidative stress on Haemonchus contortus.

This study describes the anthelmintic efficacy of an organic fraction (EtOAc-F) from Guazuma ulmifolia leaves and the evaluation of its reactive oxidative stress on Haemonchus contortus. The first step was to assess the anthelmintic effect of EtOAc-F at 0.0, 3.5, 7.0 and 14 mg kg of body weight (BW) in gerbil's (Meriones unguiculatus) artificially infected with H. contortus infective larvae (L3). The second step was to evaluate the preliminary toxicity after oral administration of the EtOAc-F in gerbils. Finally, the third step was to determine the relative expression of biomarkers such as glutathione (GPx), catalase (CAT), and superoxide dismutase (SOD) against H. contortus L3 post-exposition to EtOAc-F. Additionally, the less-polar compounds of EtOAc-F were identified by gas mass spectrophotometry (GC-MS). The highest anthelmintic efficacy (97.34%) of the organic fraction was found in the gerbils treated with the 14 mg/kg of BW. Histopathological analysis did not reveal changes in tissues. The relative expression reflects overexpression of GPx (p<0.05, fold change: 14.35) and over expression of SOD (p≤0.05, fold change: 0.18) in H. contortus L3 exposed to 97.44 mg/mL of EtOAc-F compared with negative control. The GC-MS analysis revealed the presence of 4-hydroxybenzaldehyde (1), leucoanthocyanidin derivative (2), coniferyl alcohol (3), ferulic acid methyl ester acetate (4), 2,3,4-trimethoxycinnamic acid (5) and epiyangambin (6) as major compounds. According to these results, the EtOAc-F from G. ulmifolia leaves exhibit anthelmintic effect and increased the stress biomarkers on H. contortus.

Diagnosis of Human Trematode Infections.

Digenetic trematodes form a major group of human parasites, affecting a large number of humans, especially in endemic foci. Over 100 species have been reported infecting humans, including blood, lung, liver and intestinal parasites. Traditionally, trematode infections have been diagnosed by parasitological methods based on the detection and the identification of eggs in different clinical samples. However, this is complicated due to the morphological similarity between eggs of different trematode species and other factors such as lack of sensitivity or ectopic locations of the parasites. Moreover, the problem is currently aggravated by migratory flows, international travel, international trade of foods and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In the present chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.

Innate immune receptors are differentially expressed in mice during experimental Schistosoma mansoni early infection.

BACKGROUND: The impact of Schistosoma mansoni infection over the immune response and the mechanisms involved in pathogenesis are not yet completely understood. OBJECTIVES: This study aimed to evaluate the expression of innate immune receptors in three distinct mouse lineages (BALB/c, C57BL/6 and Swiss) during experimental S. mansoni infection with LE strain. METHODS: The parasite burden, intestinal tissue oogram and presence of hepatic granulomas were evaluated at 7- and 12-weeks post infection (wpi). The mRNA expression for innate Toll-like receptors, Nod-like receptors, their adaptor molecules, and cytokines were determined at 2, 7 and 12 wpi in the hepatic tissue by real-time quantitative polymerase chain reaction (qPCR). FINDINGS: Swiss mice showed 100% of survival, had lower parasite burden and intestinal eggs, while infected BALB/c and C57BL/6 presented 80% and 90% of survival, respectively, higher parasite burden and intestinal eggs. The three mouse lineages displayed distinct patterns in the expression of innate immune receptors, their adaptor molecules and cytokines, at 2 and 7 wpi. MAIN CONCLUSIONS: Our results suggest that the pathogenesis of S. mansoni infection is related to a dynamic early activation of innate immunity receptors and cytokines important for the control of developing worms.

Anthelmintic efficacy of nitazoxanide in dogs naturally infected with Toxocara canis.

Toxocara canis (T. canis) is a gastrointestinal nematode in dogs, and its larvae also infect humans, causing severe larval migratory disease. Anthelmintic drugs have become the primary means to combat T. canis. In this study, the efficacy of nitazoxanide (NTZ) was tested against all the internal stages of T. canis, including L3 larval stage in vitro experiments and gastrointestinal worm in vivo experiments. In the in vitro experiment, after treatment with NTZ at 7.81 and 62.5 µg/mL for 12 h, the larval mortality efficacy reached 90.0 and 100.0%, respectively. In the in vivo experiments, 100 mg/kg NTZ possessed good anthelmintic efficacy against T. canis, with an egg per gram (EPG) reduction of 99.19%, and 90.00% of dogs cleared with residual worms. These results were comparable to those of the positive control drug. The highest anthelmintic efficacy was observed in the group treated with 150 mg/kg NTZ. Based on faecal egg counts, the number of T. canis eggs decreased by 100.00%, and the percentage of dogs cleared with residual worms achieved 90.00% after 7 days of treatment in the 150-mg/kg NTZ treatment group. In general, NTZ showed great potential to be applied as an anthelmintic against T. canis.

Biomarkers of gastrointestinal nematodes in beef cattle raised in a tropical area.

Biomarkers are specific molecular, histological, or physiological characteristics of normal or pathogenic biological processes and are promising in the diagnosis of gastrointestinal nematodes (GINs). Although some biomarkers have been validated for infection by Ostertagia sp. in cattle raised in temperate regions, there is a lack of information for tropical regions. The aim of this project was to assess potential biomarkers and validate the most promising. In the first study, 36 bovines (Nelore breed) naturally infected by GINs were distributed into two groups: infected (not treated with anthelmintic) and treated (treated with fenbendazole on days 0, 7, 14, 21, 28, 42, and 56). The variables of interest were live weight, fecal egg count, hemogram, serum biochemical markers, phosphorus, gastrin, and pepsinogen. In the second step, pepsinogen was assessed in cattle of the Nelore breed distributed among three groups: infected (not treated with anthelmintic), MOX (treated with moxidectin), and IVM + BZD (treated with ivermectin + albendazole). In the first study, no difference between groups was found for weight, albumin, hematocrit (corpuscular volume [CV]), erythrocytes, or hemoglobin. Negative correlations were found between pepsinogen and both CV and albumin, and albumin was negatively correlated with the percentage of Haemonchus sp. in the fecal culture. Among the biomarkers, only pepsinogen differentiated treated and infected (beginning with the 28th day of the study). In the second study, a reduction in pepsinogen was found after anthelmintic treatment. Therefore, pepsinogen is a promising biomarker of worms in cattle naturally infected by the genera Haemonchus and Cooperia in tropical areas.

A Comparison of Three Automated Root-Knot Nematode Egg Counting Approaches Using Machine Learning, Image Analysis, and a Hybrid Model.

Meloidogyne spp. (root-knot nematodes [RKNs]) are a major threat to a wide range of agricultural crops worldwide. Breeding crops for RKN resistance is an effective management strategy, yet assaying large numbers of breeding lines requires laborious bioassays that are time-consuming and require experienced researchers. In these bioassays, quantifying nematode eggs through manual counting is considered the current standard for quantifying establishing resistance in plant genotypes. Counting RKN eggs is highly laborious, and even experienced researchers are subject to fatigue or misclassification, leading to potential errors in phenotyping. Here, we present three automated egg counting models that rely on machine learning and image analysis to quantify RKN eggs extracted from tobacco and sweet potato plants. The first method relied on convolutional neural networks trained using annotated images to identify eggs (M. enterolobii R2 = 0.899, M. incognita R2 = 0.927, M. javanica R2 = 0.886), whereas a second contour-based approach used image analysis to identify eggs from their morphological characteristics and did not rely on neural networks (M. enterolobii R2 = 0.977, M. incognita R2 = 0.990, M. javanica R2 = 0.924). A third hybrid model combined these approaches and was able to detect and count eggs nearly as well as human raters (M. enterolobii R2 = 0.985, M. incognita R2 = 0.992, M. javanica R2 = 0.983). These automated counting protocols have the potential to provide significant time and resource savings annually for breeders and nematologists and may be broadly applicable to other nematode species.

Effect of calcium soaps from garlic (Allium sativum) and willow (Salix babylonica) extracts on nematode loads, nutrient intake and digestibility, nitrogen balance and rumen fermentation kinetics in dairy goats.

The objective of this study was to determine the effect of dietary calcium soaps from garlic (Allium sativum) and willow (Salix babylonica) extracts on nematode loads, nutrient intake and digestibility, nitrogen balance and rumen fermentation kinetics in dairy goats. Nine adult non-lactating Saanen goats were grouped into a complete randomized block design with 3 treatments (n = 3) over a period of 28 d. Animals were fed a diet based on alfalfa hay and a concentrate that was supplemented (65 g/kg DM) with calcium soaps of safflower (control), garlic or willow. Intake of dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) were not affected by dietary calcium soaps. However, the highest digestibility of DM and OM were observed in willow supplemented goats. In vitro gas kinetics and fermentation profile were not affected by diets. Results from fecal egg count indicated a reduction in total count, Haemonchus spp. and Trychostrongylus spp. for both garlic and willow compared to control. Our results suggest that calcium soaps of garlic or willow extracts can be used to reduce gastrointestinal parasites in goats without compromising productive traits or rumen function.

Evaluation of Reproductive Histology Response of Adult Fasciola hepatica in Goats Vaccinated with Cathepsin L Phage-Exposed Mimotopes.

Fasciolosis, a globally re-emerging zoonotic disease, is mostly caused by the parasitic infection with Fasciola hepatica, often known as the liver fluke. This disease has a considerable impact on livestock productivity. This study aimed to evaluate the fluke burdens and faecal egg counts in goats that were administered phage clones of cathepsin L mimotopes and then infected with F. hepatica metacercariae. Additionally, the impact of vaccination on the histology of the reproductive system, specifically related to egg generation in adult parasites, was examined. A total of twenty-four goats, which were raised in sheds, were divided into four groups consisting of six animals each. These groups were randomly assigned. The goats were then subjected to two rounds of vaccination. Each vaccination involved the administration of 1 × 1013 phage particles containing specific mimotopes for cathepsin L2 (group 1: PPIRNGK), cathepsin L1 (group 2: DPWWLKQ), and cathepsin L1 (group 3: SGTFLFS). The immunisations were carried out on weeks 0 and 4, and the Quil A adjuvant was used in combination with the mimotopes. The control group was administered phosphate-buffered saline (PBS) (group 4). At week 6, all groups were orally infected with 200 metacercariae of F. hepatica. At week 22 following the initial immunisation, the subjects were euthanised, and adult F. hepatica specimens were retrieved from the bile ducts and liver tissue, and subsequently quantified. The specimens underwent whole-mount histology for the examination of the reproductive system, including the testis, ovary, vitellaria, Mehlis' gland, and uterus. The mean fluke burdens following the challenge were seen to decrease by 50.4%, 62.2%, and 75.3% (p < 0.05) in goats that received vaccinations containing cathepsin L2 PPIRNGK, cathepsin L1 DPWWLKQ, and cathepsin L1 SGTFLFS, respectively. Animals that received vaccination exhibited a significant reduction in the production of parasite eggs. The levels of IgG1 and IgG2 isotypes in vaccinated goats were significantly higher than in the control group, indicating that protection is associated with the induction of a mixed Th1/Th2 immune response. The administration of cathepsin L to goats exhibits a modest level of efficacy in inducing histological impairment in the reproductive organs of liver flukes, resulting in a reduction in egg output.

Behavioural response to gastrointestinal parasites of yearling dairy calves at pasture.

AIMS: To investigate the association between gastrointestinal parasites (GIP) and animal behaviour in dairy calves under New Zealand pastoral conditions, using animal-mounted, accelerometer-based sensors. METHODS: Thirty-six, 5-6-month-old, Friesian-Jersey, heifer calves fitted with animal activity sensors to track behaviour were randomly allocated to one of two treatment groups. Half the animals were challenged with an oral dose of 20,000 larvae of Ostertagia ostertagi and Cooperia oncophera once a week for 3 weeks and half were unchallenged. Five weeks after the last dose, seven infected and nine uninfected animals were treated with an oral anthelmintic (AHC) and data collected for a further week. Accelerometer data were classified into minutes per day eating, ruminating, in moderate-high activity or in low activity. Live weight and faecal egg counts (FEC) were recorded weekly over the study period. All animals co-grazed a newly sown pasture not previously grazed by ruminants and were moved every week to fresh grazing. Treatment status was blinded to those managing the animals which were otherwise treated identically. RESULTS: Complete behavioural records were available from 30/36 calves, (13 challenged and 17 unchallenged). Before treatment with AHC, FEC increased in infected and un-treated calves over the study, while uninfected animals maintained a near zero FEC. There was no difference in live weight gain between the two groups over the study period. Bayesian, multinomial regression predicted differences in animal behaviour between infected and uninfected animals that were not treated with AHC over the 7 weeks following initial infection. Parasitised calves not treated with AHC were less active and spent up to 6 (95% highest density interval (HDI) = 1-11) minutes/day less in low level activity and up to 15 (95% HDI = 7-20) minutes/day less in moderate to high level activity. They ruminated up to 9 (95% HDI = 2-15) minutes/day more and ate up to 10 (95% HDI = 2-19) minutes/day more than control calves that were not treated with AHC. The effect of AHC on time spent in each behaviour differed between infected and uninfected calves and increased the coefficient of dispersion of the behavioural data. CONCLUSIONS AND CLINICAL RELEVANCE: Small differences in animal behaviour can be measured in calves with GIP. However, to use this to target treatment, further validation studies are required to confirm the accuracy of behavioural classification and understand the complex drivers of animal behaviour in a dynamic and variable pasture-parasite-host environment.

An automated faecal egg count system for detection of Ascaridia galli ova in chickens.

Chicken production has increased over the past decade, resulting in a concomitant rise in the demand for more humane options for poultry products including cage-free, free-range, and organic meat and eggs. These husbandry changes, however, have come hand-in-hand with increased prevalence of Ascaridia galli infection, which can cause clinical disease in chickens as well as the occasional appearance of worms in eggs. Additionally, development of anthelmintic resistance in closely related helminths of turkeys highlights the need for closely monitored anthelmintic treatment programs. Manual faecal egg counts (FECs) can be time-consuming and require specialist training. As such, this study sought to validate an automated FEC system for use in detection and quantification of A. galli eggs in chicken faeces. Automated counts using the Parasight System (PS) were compared to traditional manual McMaster counting for both precision and correlation between methods. Overall, ten repeated counts were performed on twenty individual samples for a total of 200 counts performed for each method. A strong, statistically significant correlation was found between methods (R2 = 0.7879, P < 0.0001), and PS counted more eggs and performed with statistically significant higher precision (P = 0.0391) than manual McMaster counting. This study suggests that PS is a good alternative method for performing A. galli FECs and provides a new tool for use in helminth treatment and control programs in chicken operations.

Supplementation of Acacia dealbata versus Acacia mearnsii leaf-meal has potential to maintain growth performance of lambs grazing low-quality communal rangelands in South Africa.

Supplementing livestock grazing communal rangelands with leaf-meals from Acacia trees, which are currently considered as problematic invasive alien plants globally, may be a sustainable way of exploiting their desirable nutritional and anthelmintic properties. The current study evaluated worm burdens and growth performance of lambs grazing low-quality communal rangelands supplemented with leaf-meals prepared from the invasive alien plant species; Acacia mearnsii or A. dealbata. Forty, three-month-old ewe lambs weighing an average of 18.9 ± 0.60 kg were randomly allocated to four supplementary diets: (1) rangeland hay only (control), (2) commercial protein supplement plus rangeland hay, (3) A. mearnsii leaf-meal plus rangeland hay and (4) A. dealbata leaf-meal plus rangeland hay. All the supplementary diets were formulated to meet the lambs' minimum maintenance requirements for protein. All the lambs were grazed on communal rangelands daily from 0800 to 1400 after which they were penned to allow them access to their respective supplementary diets until 08:00 the following morning. The respective supplementary diets were offered at the rate of 400 g ewe- 1 day- 1 for 60 days. Lambs fed the commercial protein supplement had the highest dry matter intake followed by those fed the Acacia leaf-meals and the control diet, respectively (P ≤ 0.05). Relative to the other supplementary diets, lambs fed the commercial protein supplement and A. dealbata leaf-meal had higher (P ≤ 0.05) final body weight and average daily gains. Dietary supplementation did not affect lamb faecal worm egg counts over the study period (P > 0.05). There was no association between supplementary diets and lamb FAMACHA© scores (P > 0.05). It was concluded that supplementation of Acacia dealbata versus Acacia mearnsii has the potential to emulate commercial protein in maintaining growth performance of lambs grazing communal rangelands in the dry season.

Diagnosis of helminths depends on worm fecundity and the distribution of parasites within hosts.

Helminth transmission and morbidity are dependent on the number of mature parasites within a host; however, observing adult worms is impossible for many natural infections. An outstanding challenge is therefore relating routine diagnostics, such as faecal egg counts, to the underlying worm burden. This relationship is complicated by density-dependent fecundity (egg output per worm reduces due to crowding at high burdens) and the skewed distribution of parasites (majority of helminths aggregated in a small fraction of hosts). We address these questions for the carcinogenic liver fluke Opisthorchis viverrini, which infects approximately 10 million people across Southeast Asia, by analysing five epidemiological surveys (n = 641) where adult flukes were recovered. Using a mechanistic model, we show that parasite fecundity varies between populations, with surveys from Thailand and Laos demonstrating distinct patterns of egg output and density-dependence. As the probability of observing faecal eggs increases with the number of mature parasites within a host, we quantify diagnostic sensitivity as a function of the worm burden and find that greater than 50% of cases are misdiagnosed as false negative in communities close to elimination. Finally, we demonstrate that the relationship between observed prevalence from routine diagnostics and true prevalence is nonlinear and strongly influenced by parasite aggregation.

Enhanced mucosal response in sheep harbouring ßA beta-globin against haemonchosis.

Association between ovine ß-globin polymorphisms and resistance against haemonchosis was described and related to the mechanism of high oxygen affinity ßA ➔ ßC switch during anaemia, but there are no studies regarding the involved local host responses. Phenotypic parameters and local responses were evaluated in sheep from two ß-globin haplotypes naturally infected with Haemonchus contortus. Morada Nova lambs were monitored at 63, 84 and 105 days of age for faecal egg counts and packed cell volume (PCV) under natural infection with H. contortus. At 210 days of age, lambs of Hb-AA and Hb-BB ß-globin haplotypes were euthanised, and the fundic region of abomasum was sampled for evaluation of microscopic lesions and relative expression of genes related to immune, mucin and lectin activities. Lambs harbouring the ßA allele presented an improved resistance/resilience against clinical haemonchosis, showing higher PCV during infection. Hb-AA animals presented increased eosinophilia in the abomasum compared to Hb-BB animals, accompanied by higher Th2 profile, mucin and lectin activity transcripts, while the inflammatory response was increased in Hb-BB animals. This is the first report to demonstrate an enhanced local response in the primary site of H. contortus infection related to ßA allele of ß-globin haplotype.