Variability of the egg hatch assay to survey benzimidazole resistance in nematodes of small ruminants under field conditions

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.

Trichuris muris egg-hatching assay for anthelminthic drug discovery and characterization

Trichuriasis is a neglected tropical disease widely distributed among tropical and sub-tropical areas and associated with poverty and lack of access to safe drinking water, sanitation and hygiene. Existing drugs have limited efficacy and face a constant risk of developing resistance, necessitating the search for alternative treatments. However, drug discovery efforts are sparse and little research has been performed on anthelminthic effects on embryonated eggs, the infectious life stage of Trichuris spp. We examined bacterial species dependent egg hatching of the murine model parasite Trichuris muris and identified Escherichia coli, Pseudomonas aeruginosa and Enterobacter hormaechei effective as hatching inducers, resulting in hatching yields of 50-70%. Streptococcus salivarius, reported to be associated with reduced drug efficacy of ivermectin-albendazole coadministration in Trichuris trichiura infected patients, did not promote egg hatching in vitro. We optimized hatching conditions using E. coli grown in luria broth or brain-heart infusion media to reach consistently high hatching yields to provide a sensitive, robust and simple egg-hatching assay. Oxantel pamoate demonstrated the strongest potency in preventing hatching, with an EC50 value of 2-4 μM after 24 h, while pyrantel pamoate, levamisole and tribendimidine exhibited only moderate to weak inhibitory effects. Conversely, all tested benzimidazoles and macrolide anthelminthics as well as emodepside failed to prevent hatching (EC50 > 100 μM). Our study demonstrates that egg-hatching assays complement larval and adult stage drug sensitivity assays, to expand knowledge about effects of current anthelminthics on Trichuris spp. Further, the developed T. muris egg-hatching assay provides a simple and cheap screening tool that could potentially lead to the discovery of novel anthelminthic compounds.

Seasonal Prevalence of Helminthic Infections in the Gastrointestinal Tract of Sheep in Mazandaran Province, Northern Iran

Helminthic infection is the major cause of the sheep's reduced productivity. In this study, a total number of 240 fecal samples of sheep from stationary flocks of four different zones of Mazandaran province (Amol, Babol, Sari, and Nowshahr cities) were examined each season, out of which 53.33% of animals were affected by the helminthic infections. The most prevalent infecting parasites were the Trichostrongylidae (46.61%), followed by the Fasciola (9.96%). In addition, the Strongyloides had the lowest proportion with only 2.39%. The other detected parasites included Chabertia (5.98%), Cooperia (3.19%), Nematodirus (3.19%), Trichuris (5.58%), Toxocaridae (4.78%), Haemonchus (4.78%), Ostertagia (5.58%), Oesophagostomum (4.78%), and Dicrocoelium (3.19%). The nematodes had the highest percentage with 86.85%, whereas the trematodes followed them with 13.15%. No significant difference was observed between the infection level in females and males, with 56.9% and 43.94% rates of infection, respectively. Significantly lower infection was observed in winter compared with the other seasons. Trichostrongylidae was the dominant genus across all seasons. It was also noted that winter had the lowest percentage of helminthic infection significantly. The eggs per gram of feces was also estimated, and it showed that a significant number of sheep are infected with a moderate number of parasites. In a conclusion, even though livestock farmers have been using antiparasitic drugs in their livestock in recent years, parasitic infection still exists in livestock. Thus, a proper implementation of helminthic infection control programs in this area should be employed as the key element for reducing the high prevalence of livestock helminthic infection.

Trichostrongyle infections in domestic ruminants from Egypt: A systematic review and meta-analysis

Trichostrongylid nematodes can cause serious loss in the livestock economy; nevertheless, infections with these ubiquitous nematodes in animals from developing countries are largely neglected. The present paper provides a systematic review and meta-analysis to evaluate the status of trichostrongyle infections in domestic ruminants from Egypt. Out of 626 collected publications, 118 were defined suitable for inclusion in this review and represented trichostrongyle infections in 5 ruminant species (sheep, goats, cattle, buffaloes and camels) from Egypt. Published surveys have mostly focused on sheep, which had the highest (44.8%) pooled prevalence of trichostrongyle infections based on 95% confidence interval (35.9-53.6%) with no significant variations among sheep in different Egyptian regions. Goats had lower infection prevalence (31.2%, 21.5-40.8%) in comparison to sheep, and no significant regional differences were also found. The management and marketing practices likely account for the wide distribution of infection among small ruminants across Egypt. Variable trichostrongyle infection rates were estimated for camels (38.8%, 28.9-48.7%), cattle (27.4%, 14.4-40.3%) and buffaloes (12.2%, 8.0-16.4%). The prevalence of infection was significantly high during winter (52.1%, 32.2-72.1%), which provide favorable conditions for development and survival of larvae on pastures. The most common trichostrongyle identified in infected animals was Haemonchus contortus. The parasite was detected in 38.8% (29.9-47.6%) of infected sheep, 35.3% (24.8-45.7%) of infected goats and in 40.6% (18.6-62.5%) of infected camels. Clinical infections have been reported in a limited number of studies. Analysis of fecal egg counts (FECs) revealed that more than half (52.7%, 30.4-75.0%) of the tested sheep had low counts (<500 eggs per gram EPG), whereas only a few sheep (6.1%, 3.5-8.7%) had high counts >2000 EPG, implying that subclinical infections are common; however, the clinical infections cannot be completely ruled out. Anthelmintic resistance does not appear to be serious in trichostrongyle populations infecting ruminants from Egypt; nonetheless there have been a few cases of albendazole resistance in trichostrongyles infecting sheep. This paper contributes to a better understanding of the epidemiology and economic implications of trichostrongyle infections in ruminants from Egypt, which is crucial for establishing effective control strategies against these ubiquitous nematodes.

Population replacement of benzimidazole-resistant Haemonchus contortus with susceptible strains: evidence of changes in the resistance status

The spread of anthelmintic resistance (AR) in nematode populations threatens the viability of sheep production systems worldwide, and warrants the adoption of sensitive, practical, and standardized tests to detect AR. The aim of this study was to characterize the replacement of an Haemonchus contortus population resistant to benzimidazoles (BZDs) by a susceptible one, by means of both phenotypic and genotypic techniques. Phenotypic methods to assess BZD resistance included in vivo tests, such as the fecal egg count reduction test (FECRT), and in vitro tests, such as the egg hatch assay (EHA). Additionally, genotypification of polymorphisms associated with BZD resistance by sequencing a fragment of the isotype 1 β-tubulin gene was carried out. The initial, BZD-resistant population (initial Balcarce population) exhibited an egg count reduction (ECR) of 59.3%. Following refugium replacement, the final population (final Balcarce population) exhibited an ECR of 95.2%. For the initial Balcarce population, the median effective dose (ED₅₀) for the EHA was 0.607 μg thiabendazole (TBZ)/mL, with a rate of eclosion at a discriminating dose (E_DD) of 0.1 μg TBZ/mL of 76.73%. For the final Balcarce population, ED₅₀ was 0.02 μg TBZ/mL, and E_DD was 1.97%. In the initial population, 93% of the analyzed individuals exhibited genotypic combinations associated with BZD resistance (53% Phe/Phe₁₆₇-Tyr/Tyr₂₀₀, 37% Phe/Tyr₁₆₇-Phe/Tyr₂₀₀, and 3% Phe/Tyr₁₆₇-Glu/Leu₁₉₈). Conversely, no combination associated with resistance was found in individuals from the final population. All of the tests were useful for detecting AR to BZDs. The results from the genetic and phenotypical studies were consistent, and the resulting information greatly aided in interpreting the outcomes of the population replacement and the potential impact of this strategy on management of AR.

In vitro nematocidal activity of Punica granatum L. against gastrointestinal helminths in goats

The objective of this study was to evaluate the in vitro ovicidal activity, phytochemistry, and toxicity of a saline extract obtained from peel of Punica granatum L fruits. The ovicidal activity was evaluated by the hatching inhibition of eggs recovered from fecal samples of naturally infected goats; the phytochemical analysis was carried out using the fruit peel; and the toxicity was tested on Artemia salina, using saline extract. The results showed that the ovicidal effect of the tested extract was 99% (25 mg mL^-1), 99% (12.5 mg mL^-1), 98% (6.25 mg mL^-1), and 95% (3.12 mg mL^-1), higher than that of the control drug, thiabendazole (83%). The phytochemical analysis showed presence of phenols, anthraquinones, and condensed and hydrolysable tannins in the fruit extract. The toxicity test of the extract of P. granatum showed an LC50 of 6.19 mg mL^-1, which indicates a safe use for a concentration of 3.12 mg mL^-1, since it was the tested concentration that was below the reliable LC50. The saline extract from peels of P. granatum has ovicidal activity, important secondary metabolites, and absence of toxicity at the lowest concentration tested. However, in vivo tests in experimental models are recommended before performing experiments in ruminants.

Anthelmintic Drug Resistance of Gastrointestinal Nematodes of Naturally Infected Goats in Haramaya, Ethiopia

Gastrointestinal parasites and their anthelmintic resistance are major constraints to goat production in Ethiopia. Experimental investigation by faecal egg count reduction test (FECRT) and larval cultures were used to assess the occurrence of anthelmintic resistance in naturally infected goats with gastrointestinal nematodes (GIN) in Haramaya, Ethiopia. One hundred goats with a minimum of 150 eggs per gram (EPG) count were selected and randomly divided into five groups, 20 goats in each group, four treated and one untreated group. The result of the faecal egg count reduction test percentage (FECRT%) and the lower 95% confidence limit showed the presence of anthelmintic resistance for all tested drugs except tetramisole. FECRT% and lower 95% confidence limit were 69.9% and 36.9 for albendazole, 84.3% and 66.1 for tetraclozan, 95.7% and 87.4 for tetramisole, and 71.1% and 38.2 for ivermectin, respectively. Trichostrongylus, Teladorsagia, and Haemonchus showed anthelmintic resistance for tested drugs. Coproculture from different treatment groups revealed Trichostrongylus (69.2% in ivermectin and 59.6% in albendazole) were the predominant nematode followed by Teladorsagia (21.9% in albendazole and 14.7% in ivermectin). In tetraclozan treatment group, Trichostrongylus (42%) and Teladorsagia (41.3%) were comparable, followed by Haemonchus (13%). In group treated with tetramisole, Teladorsagia (54.3%) were the most frequently detected nematode followed by Trichostrongylus (25.7%) and Haemonchus (11.4%). Therefore, this study demonstrated the presence of multidrug resistant nematodes that may limit the productivity of goats. Moreover, further studies covering wider areas of Ethiopia and mechanisms of nematode resistance need to be studied in the future.

Cluster analysis to explore additive-genetic patterns for the identification of sheep resistant, resilient and susceptible to gastrointestinal nematodes

Infection caused by gastrointestinal nematodes is an important issue for animal health and production. Controlling worm infections improves the sustainability of the sheep industry. Genetic selection of animals that are resistant to gastrointestinal nematodes is another strategy to render sheep production more sustainable by decreasing the use of anthelmintics. The aims of this study were (1) to explore the additive-genetic pattern of EBVs for Famacha© (FAM), packed-cell volume (PVC), and fecal egg counts (FEC) of Santa Ines sheep, (2) to propose a classification of animals that are resistant, resilient and susceptible to gastrointestinal nematodes based on their additive-genetic patterns, and (3) to identify the most suitable animals for selection based on their genetic pattern. A dataset of 2,241 records from 747 animals was used to predict the breeding values for indicator traits of resistance to gastrointestinal nematodes with THRGIBBS1F90 and to carry out cluster analyses was used R software. Three clusters of animals were found in the population using hierarchical cluster analysis of the breeding values for FAM, PCV and FEC. Each cluster was characterized by different additive-genetic patterns identified by k-means non-hierarchical cluster analysis. Among a total of 747 animals, 196 were classified as resistant, 288 as resilient, and 263 as susceptible. Cluster analysis is a valuable tool for data screening that permits to evaluate only selection candidates based on their additive-genetic pattern for gastrointestinal nematode resistance. EBVs for FEC were decisive to divide the population into resilient, resistant and susceptible animals. It is also important to include the EBVs for PCV and FAM to adequately distinguish resistant from resilient animals. Finally, the resistant cluster consisted of the most desirable animals to be used as selection candidates in order to genetically improve resistance to infection with gastrointestinal nematodes. This cluster contained animals with the most appropriate additive-genetic pattern to achieve the breeding goal, with positive breeding values for PCV and negative breeding values for FAM and FEC.

Eficacia antiparasitaria in vitro del extracto de quebracho (Schinopsis balansae) sobre larvas infectantes de Haemonchus contortus de ovinos

El objetivo fue evaluar in vitro la eficacia del extracto de quebracho (Bioquina®), rico en taninos condensados, en el control de H. contortus de ovinos, dadas las evidencias de que los taninos condensados provenientes del extracto de quebracho (Schinopsis spp.) pueden reducir la excreción de huevos, la fecundidad de las hembras parásitas y la carga de parásitos nematodos gastrointestinales adultos en rumiantes. Se utilizó el test de inhibición de migración larval (IML) a 3 concentraciones diferentes (5 mg/ml, 15 mg/ml y 30 mg/ml) sobre larvas infectantes de H. contortus susceptibles a todos los grupos químicos. El efecto se analizó mediante un análisis de varianza y para la estimación de las diferencias entre grupos (a posteriori) se usó la prueba LSD Fisher. El test in vitro demostró que el extracto de quebracho evaluado redujo aproximadamente entre un 74% y un 80% la migración larval a las concentraciones de entre 5 mg/ml y 30 mg/ml. Del análisis de varianza surgen diferencias significativas entre tratamientos (p = 0,0494). Al realizar la prueba de comparación de medias se evidenciaron diferencias significativas (p < 0,05) entre los promedios de migración a las diluciones de 5 mg/ml y 15 mg/ml y de 5 mg/ml y 30 mg/ml, mientras que no se detectaron diferencias significativas entre la dilución de 15 mg/ml y 30 mg/ml. Estos resultados señalaron que el extracto de quebracho, a las diluciones evaluadas, presentó actividad antihelmíntica sobre larvas L3 susceptibles de H. contortus; sin embargo, se requiere ampliar los estudios in vivo en ovinos.

Teladorsagia circumcincta beta tubulin: the presence of the E198L polymorphism on its own is associated with benzimidazole resistance

BACKGROUND

Benzimidazole resistance is associated with isotype-1 β-tubulin gene F200Y, E198A and F167Y SNPs. In this study, the recently described polymorphism E198L was reported and analysed in Teladorsagia circumcincta.

METHODS

The benzimidazole phenotypic resistance was measured by the faecal egg count reduction test (FECRT) and the egg hatch test (EHT) using a discriminating dose (DD) in 39 sheep flocks. Around 1000 larvae collected before and after treatment were used for DNA extraction. The resistant species identified in all flocks was T. circumcincta. The resistance alleles frequencies were measured for F200Y and E198A. A 371-bp fragment of the isotype-1 β-tubulin gene was analysed, including the three codons of interest, and a new pyrosequencing assay was designed for testing E198L.

RESULTS

The percentage of resistant flocks was 35% by FECRT or 26% by EHT; however, F200Y and E198A SNPs were absent in T. circumcincta. The amplification of a 371-bp fragment confirmed the absence of F167Y and F200Y in 6 resistant flocks. Regarding codon 198, all samples after treatment carried a leucine (CTA). A pyrosequencing assay analysed the allele frequencies for the first two bases at codon 198 independently, G/C and A/T. The correlation between C and T frequencies was almost 1 (r = 0.929, P < 0.0001) and the mean value of both was calculated to measure the leucine frequency; this value ranged between 10.4-80.7% before treatment, and 82.3-92.8% after treatment. High and similar correlations were reported between the genotypic variables (C frequency, T frequency or mean of both frequencies) and phenotypic resistance (r > 0.720, P < 0.0001), although negatively associated with the FECRT and positively with the EHT. According to multivariate linear regression analysis, the T frequency was the most significant variable influencing the phenotypic resistance (FECRT or EHT; P < 0.0001). In the EHT, 67.1% of the phenotypic variability is associated with the T frequency but in the FECRT only 33.4%; therefore, the EHT using a DD seems to detect the genotypic resistance more accurately than the FECRT.

CONCLUSIONS

The E198L polymorphism can confer BZ resistance on its own in T. circumcincta.

Attitudes and practices of resource-limited farmers on the control of gastrointestinal nematodes in goats foraging in grasslands and forestlands

Gastrointestinal nematode infestations remain one of the main constraints to goat productivity. A cross-sectional survey was conducted to investigate the perceptions of goat farmers on the infestation and control of gastrointestinal nematode infestation. A total of 282 goat farmers from two villages of Mbizana local municipality in Alfred Nzo district were interviewed. Higher prevalence of diseases, parasites and feed availability were among the major constraints to goat productivity. Gastrointestinal parasites were ranked as the major constraint by farmers in the grassland than those in the forestland. Ordinal logistic regression analyses revealed that farmers in the grassland were 3.2 times more likely to experience gastrointestinal nematode infestation than those in the forestland (P < 0.05). On both vegetation types, tethered goats were perceived to have higher (P < 0.05) GIN infestation compared with free browsing goats. Poor farmers were 3.1 times more (P < 0.05) likely to experience high GIN infestation compared with less poor farmers. Farmers in the grassland were 2.1 times more likely to control GI nematode infestation than to those in the forestland (P < 0.05). Intervention strategies to control gastrointestinal nematodes should mainly target farmers from the grassland vegetation since they experience higher infestation rates of gastrointestinal nematodes.

Assessment of Haemonchus contortus larval and adult somatic antigens in sero-diagnosis of haemonchosis in naturally infected sheep and goats

The current work was carried out to evaluate the potency of larval and adult somatic Haemonchus contortus (H. contortus) antigens in detection of haemonchosis among sheep and goats using ELISA. Two hundred and forty-three fecal and blood samples were randomly collected from small ruminants (107 sheep and 136 goats) in Beni-Suef Governorate, Egypt, during the period from June to August 2018. The fecal analysis exhibited that 26.33% of the small ruminants were infected with gastrointestinal nematodes. The overall prevalence of H. contortus was reached 22.22% whereas it was 27.10% and 18.38% among sheep and goats, respectively. The current study elucidated that the larval antigen has claimed more superior diagnostic results compared to the adult somatic H. contortus antigen. The apparent overall sero-prevalence among small ruminants was reached 51.85%. Separately, it was 64.48% in sheep and 41.91% in goats. The larval antigen had proved 96.55% sensitivity and 47.43% specificity, for sheep serum samples. Meanwhile, sensitivity and specificity for goats' sera were 100% and 71.17%, respectively. Diagnostic efficacy of ELISA was recorded 60.74% in sheep and 76.47% in goats. This study deduced that the larval antigen has proved the priority and the potency for diagnosis of H. contortus infection. Moreover, haemonchosis is a prevalent disease among the examined sheep and goats.

A survey of Haemonchus contortus parasite of sheep from Gharb plain, Morocco

The study was designed to determine the prevalence of Haemonchus contortus, intestinal helminthes parasite of sheep in the Gharb plain (Morocco).

A total of 1154 sheep were randomly selected from farms, pastures and abattoirs, the samples were examined using a flotation techniques for determination the eggs of Haemonchus contortus. In order to identify Haemonchus contortus among the different gastrointestinal strongyles present in mixed infections, a faecal culture was carried out for each farm and pasture. This study was carried between November 2016 and October 2017. The data were analysed with respect to sex, age, season and body condition of sheep examined. Out of (1154) samples examined, (23.92%) harbored H. contortus. Prevalence among female (30.98%) was higher than that of the males (15.63%), there was significant difference between prevalence of infection and sex (P < 0.05). Based on age group, prevalence of haemonchosis was 6.25% and 43.22% in young and aged animals respectively showing the statistical significance (P < 0.05). Seasonal variation was recorded throughout the year and was highest during spring (36.36%) and autumn (32.37%) against a low rate of 2.7% in the summer with significance difference (P < 0.05). Regarding the relationship between Haemonchosis contortus and body condition, maximum prevalence (80.83%) was recorded in animals with poor body condition, followed by those with moderate body condition (34.26%), while the lowest infestation rate (6.88%) is noted in animals with good body.

Hidden in plain sight - Multiple resistant species within a strongyle community

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PCR speciation highlighted parasite species diversity on a commercial UK sheep farm.

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Species diversity confounded interpretation of faecal egg count data and bioassays.

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These tests detected only moderate resistance to benzimidazoles and ivermectin.

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Post-treatment populations were composed almost entirely of Teladorsagia circumcincta.

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Ivermectin strongly selected for a highly dual-resistant and pathogenic species.

Ovine parasitic gastroenteritis is a complex disease routinely treated using anthelmintics. Although many different strongyle species may contribute to parasitic gastroenteritis, not all are equally pathogenic: in temperate regions, the primary pathogen is Teladorsagia circumcincta. In this study we investigated benzimidazole and ivermectin resistance on a commercial sheep farm in southeast Scotland. We assessed the impact of species diversity on the diagnosis of resistance using the faecal egg count reduction test and in vitro bioassays, and correlated the results with the frequency of benzimidazole resistance-associated genotypes measured in the T. circumcincta population by pyrosequencing of the β-tubulin isotype-1 gene.

Faecal egg count reduction test results showed efficacies of 65% for albendazole and 77% for ivermectin, indicating moderate resistance levels on the farm. However, PCR speciation of the same populations pre- and post-treatment revealed that removal of susceptible species had masked the presence of a highly resistant population of T. circumcincta. Less than 25% of individuals in the pre-treatment populations were T. circumcincta, the remainder consisting of Cooperia curticei, Chabertia ovina, Oesophagostomum venulosum and Trichostrongylus spp. In contrast, post-treatment with albendazole or ivermectin, the majority (88% and 100% respectively) of the populations consisted of T. circumcincta. The egg hatch test for benzimidazole resistance and the larval development test for ivermectin resistance were carried out using eggs obtained from the same populations and the results were broadly consistent with the faecal egg count reduction test. Thirty individual T. circumcincta from each sampling time point were assessed for benzimidazole resistance by pyrosequencing, revealing a high frequency and diversity of resistance-associated mutations, including within the population sampled post-ivermectin treatment.

These results highlight the potential diversity of parasite species present on UK farms, and their importance in the diagnosis of anthelmintic resistance. On this particular farm, we demonstrate the presence of a highly dual-resistant population of T. circumcincta, which was strongly selected by treatment with either benzimidazoles or ivermectin, while other potentially less pathogenic species were removed.

Assessment of anthelmintic activity and bio-guided chemical analysis of Persea americana seed extracts

The aim of this study was to characterize the extracts and fractions of Persea americana Mill. (Avocado) seeds and to determine the composition and the in vitro anthelmintic activity against third-stage larvae (L3) of Haemonchus contortus. The fresh (F) and dried (H) avocado seeds (PA) were subjected to extraction with hot water (W-PAF, W-PAH), ethanol (E-PAF, E-PAH) or methanol 70% (v/v), and partition with solvents of increasing polarity [n-hexane (H-PAF, H-PAH), chloroform (C-PAF, C-PAH), ethyl acetate (Ea-PAF, Ea-PAH), and n-butanol (B-PAF, B-PAH)], yielding a total of 14 extracts/fractions. After considering the yield, water solubility, and the preliminary results of the larval migration test (LMT), the E-PAF, E-PAH, H-PAF, and H-PAH were selected for further experiments. E-PAH presented an efficiency concentration of 50% (EC₅₀) of 36 μg/mL on the LMT. E-PAH showed the greatest efficiency when its EC₅₀ was compared to the other fractions (E-PAF = 147 μg/mL; H-PAF = 801 μg/mL; H-PAH = 77 μg/mL). After that, the E-PAH was chemically characterized, considering its quantitative polyphenolic and flavonoid contents by colorimetric and chromatographic techniques. E-PAH presented 50, 38, and 24 mg/g of dry matter of total phenol, condensed tannins (CT), and flavonoid contents, respectively. Using high performance liquid chromatography (HPLC) analysis, E-PAH had shown to have epicatechin (4.7 μg/mL), rutin (2.8 μg/mL), and chlorogenic acid (1.4 μg/mL) as its main constituents besides quercetin. These isolated compounds were evaluated using the LMT in order to relate the composition to the anthelmintic activity observed for E-PAH. Quercetin (EC₅₀ = 7.8 μg/mL) and epicatechin (EC₅₀ = 10 μg/mL) presented a higher efficiency than rutin (EC₅₀ = 30 μg/mL). Chlorogenic acid was also tested with the LMT but did not present a significant efficiency. According to the results, the phenolic composition of E-PAH and the EC₅₀ values obtained for the isolated phenols, it can be suggested that, besides the CT content, the presence of epicatechin and rutin contributed to the larvicidal activity of E-PAH. In conclusion, avocado seeds may be used as a source of polyphenols with promising anthelmintic applications.

Effects of commonly used chemical fertilizers on development of free-living stages of Haemonchus contortus in experimentally infected pasture

Aim:

The effects of N-P-K fertilizers in the form of urea, single super phosphate and muriate of potash on development of free-living stages of Haemonchus contortus were studied.

Materials and Methods:

Five parasite free experimental plots of 1 m×1 m area, each of paddy leaves (15-day-old) and an equal number of Cynodon dactylon grass were infested with about 10×10⁴ eggs/ml phosphate buffer saline along with the application of the calculated amount of fertilizers solution. On the 10^th day of posttreatment, the pasture was cut, processed, larvae recovered by Baermann method and counted, which was expressed as number of L₃ per kg dry matter (DM) of pasture.

Results:

The average recovered population of L₃ of H. contortus per kg DM varied significantly (p<0.05) between the paddy leaves (5933.57±22.718) and Cynodon grass (4861.00±22.718). When different doses of chemical fertilizer and their impact on different pasture were analyzed for control (T-1, 0-0-0 kg/ha N-P-K), the mean L₃ recovery per kg DM of paddy (19512.7±50.80) was more than that of Cynodon grass (16540.9±50.80). Larvae recovery per kg DM for different pastures under treatment were in decreasing order as follows: T-2 of paddy (6981.33±50.80, 35.77%), T-2 of Cynodon (5545.38±50.80, 33.52%), T-3 of paddy (317378±50.80, 16.26%), and T-3 of Cynodon (2218.72±50.80, 13.41%) which showed significant difference (p<0.05) among the treatments. In T-4 (paddy) and T-5 (Cynodon), the average number of recovery of larvae was nil implying no significant variation (p>0.05).

Conclusion:

This study shown that when N-P-K fertilizers administered at recommended level, significantly reduced larval translation of H. contortus minimizing pasture infectivity for the free range grazing animals.

Management and control of gastrointestinal nematodes in communal goat farms in Zimbabwe

Goats are an important source of livelihood especially in smallholder communities. Infections with gastrointestinal nematodes (GIN) remain the most prevalent parasitic diseases affecting small ruminants. The study was conducted to assess management, the level of knowledge and control of gastrointestinal nematodes. Surveys were conducted in Chipinge, Shurugwi, Binga, Tsholotsho and Matobo districts, representing the five natural/agro-ecological regions (NR) in Zimbabwe. Data was collected in 135 households using a pre-tested semi-structured questionnaire. Results indicated that goats were ranked the most important livestock species, with high flock sizes in NR IV and V. Partitioning of roles was such that the adult males were involved in decision-making while females and children were involved in day-to-day management of animals. Farmers showed low levels of input use, with natural pasture (98.4%) being the main feed source and indigenous breeds (73.2%) being kept. Farmers ranked food and financial benefits as the main reasons for keeping goats. Gastrointestinal nematodes ranked the highest as the most common disease, with majority of farmers (57%) not controlling or treating animals and 63% of farmers not having knowledge on the spread of GIN. Access to veterinary services, anthelmintic class used and breeds used by the farmers had the highest effects on parasitic infections in households. Farmer education is required for capacitation of farmer in terms of disease prevention and control so as to improve goat production.

Prevalence and risk factors of gastrointestinal parasitic infections in goats in low-input low-output farming systems in Zimbabwe

A longitudinal study was conducted in low-input low-output farming systems to determine the prevalence of gastrointestinal parasitic infections in different age groups, sex and associated risk factors in goats. A total of 580 indigenous goats were randomly selected in areas representing the five agro-ecological regions of Zimbabwe in the dry and wet seasons. Blood and faecal samples were collected from each animal and egg/oocyst per gram of faeces (epg/opg), larval culture, and packed cell volumes (PCV) were determined. Factors affecting parasitic infections were evaluated. Highest prevalence was determined for Eimeria oocysts (43%), strongyles (31%) and lower levels in trematodes and cestodes. Parasites identified were Haemonchus, Strongyloides and Oesophagostomum. Area, season, sex and age significantly influenced patterns of gastrointestinal infections (P < 0.05). Cannonical correlations indicated that parasite species composition varied by area and impacts of risk factors also differed. Risk of infection was very high for goats sampled in Natural regions (NR) I, II, III (OR = 6.6-8.2; P < 0.05) as compared to those in NR IV and V. Highest helminths and Eimeria infections were observed in the wet vs. dry season (P < 0.05). Young animals were more susceptible to parasitic infections (P < 0.05). Prevalence was higher in males than females, with odds of infection for males being almost three times to that for females (P < 0.0001). Knowledge concerning gastrointestinal helminth biology and epidemiological infection patterns caused by these parasites is essential in the development of appropriate control strategies and this has a potential to reduce production losses.