Infective Nematode Larvae Research Articles

Efeito nematicida do fungo Duddingtonia flagrans em ovinos

The health of the sheep flock depends, among other factors, on effective sanitary control, and the use of fungus-based bioproducts has been a promising alternative against sheep gastrointestinal nematodes. The control of ovine gastrointestinal diseases caused by parasites requires good management practices that minimize the exposure of animals to the infective larvae of parasites present in the environment. The fungus Duddingtonia flagrans is an efficient agent for the biological control of nematodes due to its efficiency in controlling parasites in domestic animals. The aim of this literature review is to demonstrate the predatory activity of the fungus Duddingtonia flagrans against infective larvae (L) of gastrointestinal nematodes in ruminant sheep. The fungus in the form of D. flagrans chlamydospores proved to be resistant to the digestive process of ruminants and efficient against intestinal parasites. Its use in association with anthelmintics proved to be a good alternative for biological control. This possibility of using bioproducts and anthelmintics in combination reduces the effects of parasite resistance. Various methods of delivering the fungus orally, in pellets or powder, have obtained results that prove the efficacy of D. flagrans isolates in reducing infective nematode larvae.

Animal Behaviour Packs a Punch: From Parasitism to Production, Pollution and Prevention in Grazing Livestock.

Behaviour is often the fundamental driver of disease transmission, where behaviours of individuals can be seen to scale up to epidemiological patterns seen at the population level. Here we focus on animal behaviour, and its role in parasite transmission to track its knock-on consequences for parasitism, production and pollution. Livestock face a nutrition versus parasitism trade-off in grazing environments where faeces creates both a nutritional benefit, fertilizing the surrounding sward, but also a parasite risk from infective nematode larvae contaminating the sward. The grazing decisions of ruminants depend on the perceived costs and benefits of the trade-off, which depend on the variations in both environmental (e.g., amounts of faeces) and animal factors (e.g., physiological state). Such grazing decisions determine the intake of both nutrients and parasites, affecting livestock growth rates and production efficiency. This impacts on the greenhouse gas costs of ruminant livestock production via two main mechanisms: (1) slower growth results in longer durations on-farm and (2) parasitised animals produce more methane per unit food intake. However, the sensitivity of behaviour to host parasite state offers opportunities for early detection of parasitism and control. Remote monitoring technology such as accelerometers can detect parasite-induced sickness behaviours soon after exposure, before impacts on growth, and thus may be used for targeting individuals for early treatment. We conclude that livestock host x parasite interactions are at the centre of the global challenges of food security and climate change, and that understanding livestock behaviour can contribute to solving both.

A single subcutaneous dose of eprinomectin (Eprecis®) is effective against common gastrointestinal nematodes and lungworms in experimentally infected lactating goats

BackgroundThe health and productivity of dairy goats continue to be impacted by gastrointestinal nematodes (GIN) and lungworms (LW). Eprinomectin (EPN) is frequently selected for treatment because it is generally effective and does not require a milk withdrawal period. However, some factors, such as lactation, can have an impact on EPN pharmacokinetics and potentially its efficacy. To evaluate whether this can alter the efficacy of Eprecis® 2%, an eprinomectin injectable solution, a study was performed in lactating goats using the dose currently registered in cattle, sheep and goats (0.2 mg/kg).MethodsThis study was a blinded, randomized, controlled trial performed according to the VICH guidelines. Eighteen (18) worm-free lactating goats were included and experimentally challenged on day 28 with a mixed culture of infective gastrointestinal and lung nematode larvae (Haemonchus contortus, Trichostrongylus colubriformis, Teladorsagia circumcincta, Dictyocaulus filaria). At D-1, fecal samples were collected to confirm patent infection in all animals. On D0, the goats were randomly allocated into two groups of nine goats; group 1 was treated with Eprecis® 2% at 0.2 mg/kg BW by subcutaneous injection, while group 2 remained untreated. Fecal samples for egg counts were collected from all animals on days 3, 5, 7, 9, 11 and 14. On D14, all goats were killed, and the abomasum, small intestine and lungs were removed, processed and subsampled to record the number and species of worms.ResultsThe treatment was well tolerated. After treatment, the arithmetic mean FEC decreased in the treated group and remained < 5 EPG until the end of the study, while the arithmetic mean FEC in the control group remained > 849.0 EPG. At D14, goats in the treated group had very limited or zero total worm counts, whereas all animals from the control group had a high worm burden. The measured efficacy was 100.0% against H. contortus and T. colubriformis, 99.9% against T. circumcincta and 98.0% against D. filaria.ConclusionsEprinomectin (Eprecis®, 20 mg/ml), administered at the label dose (0.2 mg/kg), is highly effective against gastrointestinal nematodes and lungworms in lactating goats.Graphical abstract

Modified technique for recovery of nematode infective larvae in different grass genera

Most gastrointestinal nematodes are in the grazing environment. As an option, the study aimed to evaluate an alternative technique for recovery of infecting larvae in various grass genera: Tyfton 85 (Cynodon dactylon) Capim–Vencedor (Megathyrsus maximus) Capim–Gordura (Melinis minutiflora) Capim–Marandu (Brachiaria brizantha), Setaria (Setaria anceps) Capim-Humidicula (Brachiaria humidicula) and Andropogon (Andropogon gayanus). The collection of samples and procedures were developed at the Institute of Animal Science, Nova Odessa, Brazil. The grasses came from isolated paddocks. Three subsamples were used: 1-control sample (AC1); 2-control frozen sample (ACC2); 3-infested sample (AI). AC1, after the process of larvae recoveries, served as control, the rest was frozen. After de-freezing, it was divided into two samples (ACC2 and AI). In ACC2, no larvae were observed. AI was infested with 1600 ± 30 L3 larvae of trichostrongylids, recovered from sheep manure. The larvae recovery procedures were applied to the samples in the three periods. The overall mean of recovery (±SD) and percentage of success was estimated (SISVAR®) in 1544.63 ± 1.31 larvae, 96.54 ± 17% respectively. There were no differences between grass genera, as well as between weeks, with near recovery numbers (p&gt;0.05). The technique had satisfactory results in a short time.

Compatibility study of Duddingtonia flagrans conidia and its crude proteolytic extract

This study aimed to evaluate the concomitant use of the nematophagous fungus Duddingtonia flagrans (AC001) and its protease-rich crude extract for the in vitro control of Panagrellus sp., Haemonchus spp., and Trichostrongylus spp. The nematicidal tests were carried out on larvae of the free-living nematode Panagrellus sp. and infective larvae of the gastrointestinal parasitic nematodes of domestic ruminants (Haemonchus spp. and Trichostrongylus spp). Five experimental groups were set: (1) one control group (G1) and (4) four treated groups –G2 – active crude extract; G3 – denatured crude extract; G4 – fungus, and G5 – fungus + active extract. Plates were incubated at 28 ºC for 24 h followed by the recovery of the larvae using the Baermann technique. The results showed a lower recovery of Panagrellus sp. larvae in the experimental groups compared to the control group, as follows: 52 % (G2), 16 % (G3), 46 % (G4), and 77 % (G5). An even greater reduction (77 ± 5 %) occurred in the group (G5). In addition, the authors observed lower averages of L3 of Haemonchus spp. and Trichostrongylus spp. in the experimental groups compared to the control group, as follows: 59 % (G2), 0 % (G3), 86 % (G4), and 76 % (G5). In turn, there was a difference (p < 0.01) between (G5) and (G2). The results this study indicate a positive effect from the compatible use of the D. flagrans fungus and its enzymatic crude extract (protease), which has been demonstrated here for the first time and with potential field applications for further designs.

Infection status of mosquitoes in Kunga Community of Jos North Local Government Area, Plateau State, Nigeria

Diseases transmitted by mosquitoes constitute serious health, economic and social problems, especially in developing countries such as Nigeria. This study aimed to examine the salivary glands of Anopheles mosquitoes for sporozoites and the culicine mosquitoes for filarial worms in Kunga community of Jos North Local Government Area, Plateau State, Nigeria. Adult mosquitoes were collected by Pyrethrum Spray Catch (PSC) and identified with morphological keys. The salivary glands of the female mosquitoes were then dissected to check for Plasmodium sporozoites and third-stage infective nematode larvae (L3i). A total of 75 mosquitoes were collected from 20 households. Out of which 18 representing 24.0% were Anopheles gambiae and 57 representing 76.0% were Culex quinquefasciatus. There was a significant difference (P &lt; 0.05) in the species composition of the mosquitoes with sex. All the 18 (100%) of An. gambiae mosquitoes collected were females, while 55 (96.49%) out of the 57 Culex quinquefasciatus were females and 2 (3.51%) were males. The population of mosquitoes in relation to house types showed no significant variation (P &gt; 0.05). Although there was a significant difference (P &lt; 0.05) in the infectivity status of the mosquitoes, the distribution of the infection status by mosquito species showed that 12 females of An. gambiae representing 66.7% were infected with Plasmodium sporozoites, while 19 females represented 34.5% of Cx. quinquefasciatus were infected with L3i. The lack of good drainage and sewage systems in the study area could be one of the factors contributing to the mosquito burden and therefore health education will go a long way in sensitizing the inhabitants on the importance of environmental and personal hygiene.

Castor bean cake for the control of parasites in pasture-finished sheep.

The purpose of this study was to evaluate castor bean cake as alternative input in the control of gastrointestinal parasites in sheep raised on irrigated pasture under continuous stocking. The treatments consisted of sheep supplemented with standard diet and pasture fertilized with urea; sheep supplemented with alternative diet and pasture fertilized with urea; sheep supplemented with standard diet and pasture fertilized with in natura castor bean cake; and sheep supplemented with alternative diet and pasture fertilized with in natura castor bean cake. A randomized complete block design (CBD) was used, with 16 replications (sheep), with repeated measures over time, the plots being the treatments, and the subplots the collection times. Infective nematode larvae in the pasture (L3.g DM−1), number of eggs per gram of feces (EPG), globular volume (GV), and total plasma protein (TPP) were evaluated. For adult gastrointestinal parasite counts, CBD was also used with six replications. Except for FAMACHA© grade, all variables had effect (P < 0.01) of the time factor. The average number of L3.g DM−1 and EPG were 126 and 841, respectively, with no effect (P > 0.05) of the treatment factor. The values observed for GV and TPP were higher than 25.9% and 6.4 g·dL−1, respectively, which were considered normal. As organic fertilizer, the fractionated application of in natura castor bean cake does not reduce the contamination of pastures by nematode larvae. The evaluated feeds improve the resilience of the sheep to infection by gastrointestinal parasites. The treatments using castor bean cake reduced the adult parasites present in the abomasum of sheep.

MINI-BAERMANN FUNNEL, A SIMPLE DEVICE FOR CLEANING NEMATODE INFECTIVE LARVAE.

The Baermann filter method is a long-standing, simple technique for recovering nematodes from soil and charcoal coprocultures. Material containing the nematodes is placed on a mesh screen lined with several layers of tissue paper or cheesecloth, and the screen is placed in the mouth of the funnel. Rubber tubing attached to the funnel stem is clamped, and water is added to submerge the material. The filtration material allows the nematodes to swim through while holding back the substrate. Over time the nematodes settle at the clamp in the tubing. After several hours, the clamp is opened and water containing the nematodes is collected. Although recovery of the nematodes is efficient, they are often contaminated with soil or charcoal debris, requiring a secondary cleaning by sedimentation or filtration. Described here is a small, simplified version of the Baermann apparatus that can be used as a secondary cleaning device. The "mini-Baermann" is constructed from materials commonly found in the laboratory. Experiments using infective larvae of 3 nematode species demonstrated that the majority of the larvae applied to the device are collected within 2 hr, and nearly all by 4 hr. Dead larvae fail to pass through the filter and do not significantly impact the passage of living larvae. In addition to removing debris from nematode suspensions, this device can rapidly and efficiently separate living, motile larvae from dead larvae.

Monacrosporium sinense and Pochonia chlamydosporia for the biological control of bovine infective larvae in Brachiaria brizantha pasture

Ecologically correct solutions are necessary to minimize the use of anthelmintics in the control of cattle parasitic diseases. This study evaluated the effects of oral administration pellets containing the fungal combination Monacrosporium sinense and Pochonia chlamydosporia in the biological control of infective larvae (L3) of parasitic gastrointestinal nematodes of cattle grazed in pasture. Twelve crossbred bovines (Holstein × Zebu), seven to nine years old, after dewormed, were randomly divided into two groups (group treated with the combination of fungi and control group) and placed in separate paddocks of Brachiaria brizantha that were naturally infested with L3. Feces samples were collected from the animals to determine the parasitic load and pasture samples were collected from the soil to determine the L3 infestation. The recovery of L3 from the pasture of the treated group was 91.7% and 86.4% less than in the pasture of the control group, respectively for samples collected at 20 cm and 40 cm from the faecal pats. The values of eggs per gram of feces in the months of May 2019 and January 2020 were lower (p ≤ 0.05) in the treated group with the fungal combination. The combined administration of M. sinense and P. chlamydosporia reduced the L3 infestation on pasture and in animal parasitic load, making it a tool for controlling bovine gastrointestinal parasitic nematodes.

Predation of the fungus Duddingtonia flagrans on infective larvae of gastrointestinal nematodes from heifers in a silvopastoral system under shaded and sunny conditions.

The objective of this study was to evaluate the predatory activity of the nematophagous fungus Duddingtonia flagrans on infective larvae of gastrointestinal nematodes from dairy heifers in different conditions (shaded and sunny) of a silvopastoral system (SPS) on an agroecological farm. Ten Jersey heifers were divided into two groups: treated (received pellets containing fungus); and control (received pellets without fungus). Twelve hours after fungus administration, faeces samples were collected for in vitro efficacy tests. The animals then remained for 8 h in the experimental pasture area. At the end of this period, 20 faecal pads (10 treated and 10 control) were selected. Pasture, faecal pad and soil collections occurred at intervals of seven days (d), totalling four assessments over 28 d. To evaluate the influence of the conditions shaded and sunny, we registered the condition of the location of each faecal pad per hour. After 12 h of gastrointestinal transit in dairy heifers, a reduction of 65% was obtained through the in vitro test. The treated group presented a lower number of infective larvae (L3) in the faecal pad and upper pasture. Differences in numbers of L3 were observed between the conditions (sunny and shaded) in the faecal pad of the control group; while in the treated group there were no differences between the conditions. The predatory activity of the fungus was efficient over time in the shaded and sunny conditions of an SPS, decreasing the parasite contamination during the pasture recovery time in a subtropical climate.

Effect of growing forage legumes on the migration and survival in the pasture of gastrointestinal nematodes of sheep.

In order to identify types of forage that inhibit pasture contamination, an evaluation was performed of the effect of the forage legumes Trifolium repens (white clover), Trifolium pratense (red clover) and Lotus corniculatus (bird's-foot-trefoil) on the survival and migration of infective larvae (L3) of gastrointestinal nematodes (GIN) of sheep. An experimental area of 441 m2 was divided into four blocks, subdivided into areas of 1.20 × 1.20 in which the three forage legumes were separately overseeded. After growth of the forage in each subdivision, experimental units were established that were later artificially contaminated with sheep faeces containing GIN eggs. Between October and December 2018, pasture, faecal and soil samples were collected on four occasions during weeks 1, 2, 4 and 8 after the deposition of faeces. In week 6, the forage legumes in all the experimental units were mown to simulate grazing. The number of L3 was quantified to determine their survival in the pasture, faeces and soil. In addition, the horizontal migration of L3 was measured at two distances from the faecal pellets (10 and 30 cm), as well as their vertical migration at two heights of the plant stems, that is, lower half and upper half. Larvae vertical migration was affected by the forage species (P < 0.001), in that bird's-foot-trefoil contained fewer larvae in the upper stratum. Bird's-foot-trefoil restricted the migration of L3 to the upper stratum of the plant, which could potentially decrease the risk of infection by intestinal nematodes in grazing sheep.

In vitro compatibility and nematicidal activity of Monacrosporium sinense and Pochonia chlamydosporia for biological control of bovine parasitic nematodes.

The use of nematophagous fungi is an alternative for the biological control of nematodes in ruminants. In this study, the compatibility of joint growth of the fungi Monacrosporium sinense and Pochonia chlamydosporia and the joint nematicidal activity of these fungal isolates on bovine infective larvae were evaluated. For that, tests of direct confrontation, the effect of volatile compounds and antibiosis were conducted. In order to carry out the tests, the fungi were inoculated in potato dextrose agar culture medium and, after the incubation period, the growth of the colonies, the formation of an inhibition halo and the effect of volatile metabolites were verified. The compatibility between fungi isolates M. sinense and P. chlamydosporia was confirmed and the nematicidal evaluation proved the best effectiveness was when both were used together, with a 98.90% reduction in the number of bovine nematode infective larvae under in vitro conditions. It was concluded that M. sinense and P. chlamydosporia presented synergistic action, suggesting that the joint application of the fungi increases the effectiveness of biological control of bovine infective larvae.

Prevalence and degree of gastrointestinal nematode infection of horses (Equus caballus) used as public transport in Mataram city, Indonesia

Horses of Equus caballus species which are used as public transportation in the form of Cidomo (traditional horse cart) in Mataram City need to be considered about their welfare and health. A common problem in horses is gastrointestinal nematode worms that can induce negative health effects on horses. Furthermore, the infective larvae of nematodes can survive in the environment under optimum conditions of temperature and humidity. The purpose of this study was to determine the prevalence and degree of infection of gastrointestinal nematodes in horses used as public transportation (Cidomo) in Mataram City. The cross-sectional study was conducted from July to August 2020 to collect feces of Cidomo horses at 8 traditional markets in Mataram City. A total of 131 feces of horses as Cidomo were taken directly from the rectum of Cidomo horses by the purposive method. The Morphology, prevalence of nematode egg, and Egg per gram (EPG) for a degree of infection were used examined using the floating McMaster technique. Morphological data and the prevalence of gastrointestinal nematodes in horses (Equus caballus) as Cidomo were presented descriptively, and the EPG value was analyzed by the Anova test, while the degree of infection has been categorized as low, medium, and high levels. The eggs of gastrointestinal nematodes (Trichosstrongylus spp, Strongylus spp, and Capillaria spp) have been found in feces of horses as Cidomo at 8 traditional markets in Mataram City with a prevalence of 74.04% (97/131). The EPG value of the gastrointestinal nematode of feces of horses as Cidomo between 8 traditional markets in Mataram City showed no significant difference with p > 0.05 (p-value = 0.227). Overall the degree of infection of gastrointestinal nematodes in horses (Equus caballus) as Cidomo in Mataram City was a medium level with a mean value of EPG = 547.628 ± 82.059 The results showed that the gastrointestinal nematodes have been infected horses as Cidomo in 8 traditional markets in Mataram City with a medium level of infection degree.

Predatory activity of nematophagus fungus Duddingtonia flagrans in infective larvae after gastrointestinal transit: biological control in pasture areas and in vitro.

Biological control is a strategy to decrease parasitic populations, and the action takes place through natural antagonists in the environment. We studied the predatory activity of the fungus Duddingtonia flagrans in infective larvae (L3) of gastrointestinal nematodes after gastrointestinal transit. Ten heifers were divided into two groups: treated (animals received pellets containing fungus) and control (animals received pellets without fungus). Twelve hours after administration, faeces samples were collected for in vitro efficacy tests. The animals then remained for 7 h in the experimental pasture area. At the end of this period, 20 faecal pads (ten treated and ten control) were selected at random. Pasture, faecal pad and soil collections occurred with an interval of 7 days, totalling four assessments. In vitro activity demonstrated that fungi effectively preyed on L3, achieving a reduction percentage of 88%. In the faecal pad of the pasture area, there was a difference (P < 0.05) between collections 3 and 4 for both groups; in the treated group a reduction of 65% was obtained, while in the control group there was an increase of 217% in the number of L3. The recovery of L3 in the soil and in the pasture was similar in both groups. There was no influence (P = 0.87) of the passage time on the fungus predatory activity. Duddingtonia flagrans demonstrated the ability to survive gastrointestinal transit in the animals, reducing the number of L3 in the faeces, indicating that this biological control has great potential in the control of worm infections.

Arthrobotrys cladodes and Pochonia chlamydosporia: Nematicidal effects of single and combined use after passage through cattle gastrointestinal tract

Nematodiosis are responsible for financial losses in cattle production systems due to treatment costs, falling production rates and animal deaths. The incorporation of sodium alginate pellets containing nematophagous fungi in the bovine diet is a method for the control of nematodiosis. The aims of this study were to evaluate the viability of Arthrobotrys cladodes and Pochonia chlamydosporia contained in sodium alginate pellets after passage through the bovine gastrointestinal tract, as well as to evaluate the effects of single and combined use of these fungi against bovine parasitic nematodes. The reduction in parasitic nematode infective larvae of bovines by the combined use of Arthrobotrys cladodes and Pochonia chlamydosporia was more than the reduction in infective larvae by Arthrobotrys cladodes or Pochonia chlamydosporia alone in the collections 12, 24 and 36 h after giving the pellets to the animals. Arthrobotrys cladodes and Pochonia chlamydosporia combined promoted maximum reduction of infective larvae of 86.3%. Therefore, the combination of Arthrobotrys cladodes and Pochonia chlamydosporia may be an effective method to control gastrointestinal nematodiosis affecting grazing cattle.

Nematocidal Effects of a Coriander Essential Oil and Five Pure Principles on the Infective Larvae of Major Ovine Gastrointestinal Nematodes In Vitro.

The anthelmintic effects of extracted coriander oil and five pure essential oil constituents (geraniol, geranyl acetate, eugenol, methyl iso-eugenol, and linalool) were tested, using larval motility assay, on the third-stage larvae (L3s) of Haemonchus contortus, Trichostrongylus axei, Teladorsagia circumcincta, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Cooperia oncophora. Coriander oil and linalool, a major component of tested coriander oil, showed a strong inhibitory efficacy against all species, except C. oncophora with a half maximal inhibitory concentration (IC50) that ranged from 0.56 to 1.41% for the coriander oil and 0.51 to 1.76% for linalool. The coriander oil and linalool combinations conferred a synergistic anthelmintic effect (combination index [CI] <1) on larval motility comparable to positive control (20 mg/mL levamisole) within 24 h (p < 0.05), reduced IC50 values to 0.11–0.49% and induced a considerable structural damage to L3s. Results of the combined treatment were validated by quantitative fluorometric microplate-based assays using Sytox green, propidium iodide and C12-resazurin, which successfully discriminated live/dead larvae. Only Sytox green staining achieved IC50 values comparable to that of the larval motility assay. The cytotoxicity of the combined coriander oil and linalool on Madin–Darby Canine Kidney cells was evaluated using sulforhodamine-B (SRB) assay and showed no significant cytotoxic effect at concentrations < 1%. These results indicate that testing essential oils and their main components may help to find new potential anthelmintic compounds, while at the same time reducing the reliance on synthetic anthelmintics.

Assessment of in vitro anthelmintic activity and bio-guided chemical analysis of BRS Boyrá pineapple leaf extracts

Species of the Bromeliaceae are known for their pharmacological actions, including anthelmintic effects. The aim of this study was to investigate the in vitro anthelmintic activity of extracts and fractions of BRS Boyrá pineapple leaf against the eggs and infective larvae of gastrointestinal nematodes (Trichostrongylidae) of goats and to identify the compounds involved in this activity. Crude methanol, hexane, dichloromethane, ethyl acetate and residual hydromethanol extracts were investigated by quantitative analysis of phenolic and flavonoid contents, antioxidant activity, anthelmintic activity against gastrointestinal nematodes of goats. The extracts were submitted to chromatographic methods for substance isolation and spectrometric techniques to identify their structures. The anthelmintic activity was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor goats. All extracts contained phenolic (2.22–14.12 g of gallic acid equivalent per 100 g of dry extract) and flavonoid compounds (0.13–1.45 g of quercetin equivalent per 100 g of dry extract). Bio-guided fractionation of the BRS Boyrá pineapple leaves showed high antioxidant activity (EC50 for DPPH of 2.16–21.38 mg mL−1 and inhibition of co-oxidation of β-carotene of 36.40–74.86%) and anthelmintic activity (15.69–100% inhibition of egg hatching). The ethyl acetate extract exhibited greatest activity in all assays. Through chromatographic column analysis it was possible to isolate three substances: β-sitosterol and stigmasterol mixture in dichloromethane and hexane extracts, identified by NMR and p-coumaric acid in the ethyl acetate extract, identified by HPLC-DAD. The isolated p-coumaric acid exhibited high ovicidal effect against goat gastrointestinal nematodes (IC50: 0.12 mg mL−1) and can be considered the active substance of the ethyl acetate extract. This study revealed for the first time that the pineapple BRS Boyrá possesses inhibitory activity against gastrointestinal nematodes (Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp.), and that p-coumaric acid is an important bioactive.

Factors influencing regional epidemiology of strongyle nematodes at organized sheep farms in Rajasthan

A study was conducted to observe the influence of year, season, month, breed, age and sex on epidemiology of strongyle nematodes in different sheep breeds managed at organised farms in arid and semi-arid Rajasthan by evaluating 14,030 fresh faecal samples (from April 2016 to March 2019). The overall incidence of strongyle worms was significantly higher (74.1%) in semi-arid as compared to 27.4% in arid region. Among breeds, it varied from 25.6% in Magra to 74.8% in Malpura sheep. The effect of year was significant on regional as well breed-wise incidence. Season had significant effect on regional incidence with maximum incidence during monsoon. A significant breed variation in overall and seasonal incidence was found only in arid region. Irrespective of sheep breed, significantly higher incidence of strongyle worms was observed in adult sheep in both the regions. Male had significantly higher incidence of strongyle worms in both the regions. The effect of agro-climatic region was significant on overall intensity of strongyle worms with mean FECs of 117.8±3.7 epg in arid and 1098.9±45.2 epg in semi-arid region. Breed-wise, the effect of year on intensity of strongyle nematodes was significant in arid region only. Seasonal intensity was significantly higher during monsoon season in both the agro-climatic regions and in all the breeds. Effect of age on overall intensity of infection was also significant in both the regions with higher mean FECs in adult animals as compared to young ones. In both the regions, males possessed higher FECs as compared to females. On coproculture, Haemonchus contortus, Trichostrongylus sp and Oesophagostomum sp were recovered with maximum (71.1±2.1%) mean annual proportion of H. contortus. Availability of infective larvae of GI nematodes on herbage was observed during monsoon and extended up to post-monsoon season in semi-arid region. Comparatively higher herbage infectivity was not noticed in semi-arid farm with a peak of 2,100.0±97.9 L3/kg dry matter of herbage in September. The study suggest a marked influence of agro-climatic region on epidemiology and dynamics of strongyle nematodes in sheep flocks and on pasture. The breed variation was evident only in arid conditions. Further, the magnitude of monthly intensity of strongyle infection in arid region suggested anthelmintics intervention through targeted selective approach instead of strategic en-mass drench.

Predatory effects of the fungus Arthrobotrys cladodes on sheep gastrointestinal nematodes

ABSTRACT The biological control of gastrointestinal nematodes of animals using nematophagous fungi is considered a promising approach. The objective of this study was to evaluate the effectiveness of Arthrobotrys cladodes (CG 719) isolates in vitro and after passage through the gastrointestinal tract of sheep. In experiment 1, the in vitro predatory capacity of A. cladodes against gastrointestinal nematodes in sheep was evaluated. Petri dishes containing fungi cultured on water agar medium were inoculated with 2,000 infective larvae of sheep gastrointestinal nematodes. Experiment 2 involved treatment and control groups comprising six sheep each. The animals in the treatment group received single 10 g doses of pellets containing fungal formulations, and fecal samples were collected after 12, 24, 36, 48, 60, and 72 h. In experiment 1, a larval reduction of 72.3% was observed at 7 days after the larval inoculation. In both assays of experiment 2, larval reductions were significant (p < 0.01). In assay A, this fungus was able to pass throught the gastrointestinal tract of sheep, with a larval reduction of 83.5%. In assay B, proportion of larvae recovered from coprocultures was reduced by 72.4%. Thus, we concluded that pelleted formulations of A. cladodes were effective against gastrointestinal nematodes in vitro and after passage through the gastrointestinal tract of sheep.

S100A8/S100A9 deficiency increases neutrophil activation and protective immune responses against invading infective L3 larvae of the filarial nematode Litomosoides sigmodontis.

Neutrophils are essentially involved in protective immune responses against invading infective larvae of filarial nematodes. The present study investigated the impact of S100A8/S100A9 on protective immune responses against the rodent filarial nematode Litomosoides sigmodontis. S100A9 forms with S100A8 the heterodimer calprotectin, which is expressed by circulating neutrophils and monocytes and mitigates or amplifies tissue damage as well as inflammation depending on the immune environment. Mice deficient for S100A8/A9 had a significantly reduced worm burden in comparison to wildtype (WT) animals 12 days after infection (dpi) with infective L3 larvae, either by the vector or subcutaneous inoculation, the latter suggesting that circumventing natural immune responses within the epidermis and dermis do not alter the phenotype. Nevertheless, upon intradermal injection of L3 larvae, increased total numbers of neutrophils, eosinophils and macrophages were observed within the skin of S100A8/A9-/- mice. Furthermore, upon infection the bronchoalveolar and thoracic cavity lavage of S100A8/A9-/- mice showed increased concentrations of CXCL-1, CXCL-2, CXCL-5, as well as elastase in comparison to the WT controls. Neutrophils from S100A8/A9-/- mice exhibited an increased in vitro activation and reduced L3 larval motility more effectively in vitro compared to WT neutrophils. The depletion of neutrophils from S100A8/A9-/- mice prior to L. sigmodontis infection until 5dpi abrogated the protective effect and led to an increased worm burden, indicating that neutrophils mediate enhanced protective immune responses against invading L3 larvae in S100A8/A9-/- mice. Interestingly, complete circumvention of protective immune responses in the skin and the lymphatics by intravenous injection of L3 larvae reversed the phenotype and resulted in an increased worm burden in S100A8/A9-/- mice. In summary, our results reveal that lack of S100A8/S100A9 triggers L3-induced inflammatory responses, increasing chemokine levels, granulocyte recruitment as well as neutrophil activation and therefore impairs larval migration and susceptibility for filarial infection.