The corticosteroid content of cattle skin washings.

In vitro techniques have been developed to study the invasive processes of Fasciola gigantica. The conditions necessary for excystment were identical with those required by F hepatica. The ability of larvae to penetrate mouse gut in vitro was influenced by the composition of the fluid within the gut, and by the region of gut wall to which the larvae were exposed. Larvae remained viable on spleen cell monolayers for at least 60 days.     

Assessment of antibody-independent cellular cytotoxicity (AICC) of porcine neutrophilic granulocytes by quantitative flow cytometry. Lack of modulation by larval products of Oesophagostomum dentatum

After infection of pigs by the larvae of Oesophagostomum dentatum, granulomas are formed around the third-stage larvae in the submucosa of the gut which contain a considerable number of neutrophils. This has no obvious impact on the larvae, which develop to fourth-stage larvae within these granulomas. We therefore asked, whether the products of O. dentatum larvae modulate the functional capacity of porcine neutrophils. The antibody-independent cellular cytotoxicity (AICC) was chosen as a model system. This assay was developed for the pig and quantified using flow cytometry. Bovine lymphoblastoid cells (cell line Anna TA1) served as targets. The measurement of cytotoxicity was based on the determination of absolute numbers of vital target cells. This procedure proved to be reliable and required no additional labelling of target and/or effector cells. Porcine neutrophils, when stimulated with phorbol 12-myristate 13-acetate (PMA; > or = 10 nmol/l), killed target cells at effector: target ratios between 1:1 and 9:1. AICC was not demonstrable after 4 h but could be observed between 16 h and 20 h after in vitro co-culture. Killing of targets required close physical contact between effector and targets, since supernatants of PMA-stimulated polymorphonuclear cells were not able to lyse the target cells. Homogenates of third- and fourth-stage larvae of O. dentatum did not affect the vitality of porcine granulocytes or target cells in vitro, nor did they modulate the AICC capacity of porcine granulocytes.     

Transstadial and attempted transovarial transmission of Anaplasma marginale by Dermacentor variabilis

Transstadial and transovarial transmission of Anaplasma marginale by Dermacentor variabilis were attempted with with ticks exposed to the organism once by feeding as larvae or nymphs, and twice by feeding as larvae and nymphs. Typical colonies of A marginale were in gut tissues of adults that were infected as larvae, larvae and nymphs, and as nymphs; repeated exposure of ticks did not appear to result in an increase in the number of colonies in the gut of subsequently molted adults nor did it affect severity of the clinical disease that developed in cattle they fed on. In contrast, colonies of A marginale were not found in the midgut epithelium of unfed nymphs exposed as larvae, even though companion nymphs transmitted the parasite, causing severe clinical anaplasmosis in susceptible calves. The organism was not transmitted transovarially by F1 larvae or nymphs from the groups exposed as parent larvae, nymphs, larvae and nymphs, and as adults. Some of the calves fed on by F1 progeny had a few erythrocytic marginale bodies that looked suspiciously like A marginale, as well as postchallenge exposure prepatent periods that were longer than other calves in the transovarial transmission study. Sera from these calves were tested for antibody to A marginale, using a highly sensitive immunoblot technique. Antibodies were not detected in any of the sera.     

The diet of the parasitic mite Trichosurolaelaps crassipes Womersley, 1956 and its potential to act as a disease vector

The anatomy of the gaster of Trichosurolaelaps crassipes is illustrated. Protonymphs, deutonymphs and adults were all seen with a scarlet gut and gave strongly positive results to occult blood tests. Host blood cells were identified in a gut smear from a female mite. An adult female gut could hold about 7.1 x 10(-6) ml. The mite was seen frequenting small open skin lesions. Gram-negative bacteria identified in the mite's gut are most likely to be endosymbionts. Mite larvae have their gastric caeca invaded by these bacteria before birth. There is a potential for this mite to act as a weak vector of disease from one possum to another.     

Lack of infectivity of a Brazilian Anaplasma marginale isolate for Boophilus microplus ticks

Previous studies have shown that one Brazilian Anaplasma marginale isolate presents an inclusion appendage (tail), while other isolates do not present such inclusion. Studies on tick transmission have been carried out with tailless isolates but little is known about transmission of tailed isolates by Boophilus microplus. Two splenectomized calves were experimentally inoculated with the tailed A. marginale isolate. During ascending rickettsemia, B. microplus larvae, free from hemoparasites, were fed on the calves and the resulting nymphs, adult males and engorged females were examined by optic and electronic microscopy. No A. marginale colonies were observed in the gut cells of engorged females and the larvae originated from them did not transmit A. marginale to susceptible calves. In addition, no colonies of A. marginale were seen in the gut cells or in salivary glands of adult males and nymphs. These results suggest that B. microplus is not the biological vector for this tailed isolate.     

Ultrastructural morphology of Cowdria ruminantium in midgut epithelial cells of adult Amblyomma hebraeum female ticks

Amblyomma hebraeum male and female ticks, experimentally infected as larvae with the Ball 3 stock of Cowdria ruminantium, were fed on a heartwater susceptible sheep. The initial attachment of the males was required as a pre-requisite for female attachment. Reticulate bodies were the predominant morphologic form of Cowdria observed in gut epithelial cells after 1-3 days of feeding. Single intermediate bodies and no elementary bodies were observed. Organisms were found within a membrane-bound vacuole and each organism had a double-unit membrane. Infrequently colonies contained homogeneous electron-dense inclusions. Groups of Cowdria organisms within a haemocyte suggested a possible dissemination of organisms from the gut to various other tissues by haemocytes.     

The diet of the parasitic mite Trichosurolaelaps crassipes Womersley, 1956 and its potential to act as a disease vector

Abstract

The anatomy of the gaster of Trichosurolaelaps crassipes is illustrated. Protonymphs, deutonymphs and adults were all seen with a scarlet gut and gave strongly positive results to occult blood tests. Host blood cells were identified in a gut smear from a female mite. An adult female gut could hold about 7.1 × 10^?6 ml. The mite was seen frequenting small open skin lesions. Gram-negative bacteria identified in the mite's gut are most likely to be endosymbionts. Mite larvae have their gastric caeca invaded bv these bacteria before birth. There is a notential for this mite to act as a weak vector of disease from one possum to another.     

Seasonal prevalence of Strongylus vulgaris in the anterior mesenteric artery of the donkey in Morocco

The anterior mesenteric artery and its main branches, collected regularly from donkeys throughout a year, were examined for Strongylus vulgaris larvae. The mean monthly percentage of arteries infected varied from 61.5 to 100, with an overall mean of 90.5. The mean monthly number of larvae varied from 3 in January to 104 in April, with the annual mean of 32.6. A clear seasonal pattern occured in the worm burden and the age structure of larvae. The number of larvae was least in December–January, but rose gradually thereafter to reach a peak in April–May. A steep decline in June–July was followed by a progressive diminution until January. During summer and early autumn, the proportion of fifth-stage larvae was high. These observations indicate that S. vulgaris is an annual species in Morocco, infection occurring in late autumn and winter, development being completed in spring and summer, and sexually mature adults occuring in the gut mainly in summer and autumn.     

Morphogenesis of Trichostrongylus rugatus and distribution during development in sheep

Morphogenesis of Trichostrongylus rugatus was examined in 16 sheep experimentally-infected with 120 000 third-stage larvae and killed 2, 4, 6, 8, 10, 12, 16 and 20 days later (DAI). Third stage larvae moulted between Days 4 and 6, and fourth stage larvae moulted on Day 10 after infection. Four sheep first passed eggs in the faeces between Days 16 and 18 after infection. Rate of growth of larvae was constant between 2 and 10 DAI followed by a period of rapid growth from 10 to 16 DAI. Major features of larval development are described. Nematodes were largely restricted to the first 6 m of gut with 71% of worms occurring in the first 3 m.     

Effects of full replacement of dietary fishmeal with insect meal from Tenebrio molitor on rainbow trout gut and skin microbiota

Background: Aquaculture must continue to reduce dependence on fishmeal(FM) and fishoil in feeds to ensure sustainable sector growth. Therefore, the use of novel aquaculture feed ingredients is growing. In this regard,insects can represent a new world of sustainable and protein-rich ingredients for farmed fish feeds. Accordingly, we investigated the effects of full replacement of FM with Tenebrio molitor(TM) larvae meal in the diet of rainbow trout(Oncorhynchus mykiss) on fish gut and skin microbiota.Methods: A feeding trial was conducted with 126 trout of about 80 g mean initial weight that were fed for 22 weeks with two isonitrogenous, isolipidic, and isoenergetic extruded experimental diets. Partially defatted TM meal was included in one of the diets to replace 100%(TM 100) of FM, whereas the other diet(TM 0) was without TM.To analyse the microbial communities, the Illumina MiSeq platform for sequencing of 16 S r RNA gene and Qiime pipeline were used to identify bacteria in the gut and skin mucosa, and in the diets.Results: The data showed no major effects of full FM substitution with TM meal on bacterial species richness and diversity in both, gut mucosa-and skin mucus-associated microbiome. Skin microbiome was dominated by phylum Proteobacteria and especially by Gammaproteobacteria class that constituted approximately half of the bacterial taxa found. The two dietary fish groups did not display distinctive features, except for a decrease in the relative abundance of Deefgea genus(family Neisseriaceae) in trout fed with insect meal. The metagenomic analysis of the gut mucosa indicated that Tenericutes was the most abundant phylum, regardless of the diet. Specifically, within this phylum, the Mollicutes, mainly represented by Mycoplasmataceae family, were the dominant class. However,we observed only a weak dietary modulation of intestinal bacterial communities. The only changes due to full FM replacement with TM meal were a decreased number of Proteobacteria and a reduced number of taxa assigned to Ruminococcaceae and Neisseriaceae families.Conclusions: The data demonstrated that TM larvae meal is a valid alternative animal protein to replace FM in the aquafeeds. Only slight gut and skin microbiota changes occurred in rainbow trout after total FM replacement with insect meal. The mapping of the trout skin microbiota represents a novel contribution of the present study. Indeed,in contrast to the increasing knowledge on gut microbiota, the skin microbiota of major farmed fish species remains largely unmapped but it deserves thorough consideration.     

In vitro pre-exposure of Haemonchus contortus L3 to blood eosinophils reduces their establishment potential in sheep

Different authors have reported that eosinophils are capable of immobilising infective larvae of different species of nematodes in vitro. However, classifying larvae as mobile or immobile is so subjective that it does not always mean all apparently immobile larvae are dead or those that are mobile are capable of surviving further immune responses if administered to their natural hosts. The objective of this experimental study was therefore to substantiate the role of eosinophils in the killing of Haemonchus contortus infective larvae by comparing the infectivity in sheep of larvae that had been incubated with eosinophil-enriched cell suspensions with control larvae. Since it was not possible to isolate pure eosinophils from sheep blood, we were compelled to evaluate the effects of other blood cells contaminating our eosinophil-enriched suspensions. Although eosinophils and neutrophils were the only cells found adherent to H. contortus infective larvae in vitro, induced eosinophils in the presence of immune serum were primarily responsible for the drastic reduction in larval motility compared to the minor effects of neutrophils and mononuclear cells. Corresponding reductions in faecal egg count and worm numbers were observed when the incubated larvae were transferred intra-abomasally to sheep. Interestingly, the proportion of larvae that failed to establish was much higher following incubation with induced eosinophils compared with other cells or with immune serum alone. Although this study did not address the in vivo role of eosinophils in sheep, the results strongly indicate that sheep blood eosinophils have a larval killing potential in vitro, and a larval mobility test alone may not fully explain the level of damage inflicted on the larvae.     

Immunization of swine against Trichinella spiralis

Swine were immunized with partially purified stichosome antigens derived from Trichinella spiralis muscle larvae. In 3 trials, 500 to 600 micrograms of the solubilized particle component (S3) induced moderate levels of resistance to challenge inoculation; the percent reduction in larvae per gram of muscle ranged from 43 to 55. The effect of immunization with S3 on pig intestinal expulsion of adult worms was determined in one experiment and the results indicated that S3 immunization was only weakly effective in enhancing gut expulsion. These results suggest that immunization with S3 induces a protective immune response in the pig that may be directed either against the migrating newborn larvae or against adult worm fecundity.     

The early migration of Elaphostrongylus rangiferi in goats.

The migration of nematodes of the genus Elaphostrongylus (Metastrongyloidea: Protostrongylidae) from the gut into the tissues of ruminants has not been described. Detailed histologic studies were performed on five goat kids that had received oral doses of 1,000-1,500 infective larvae of Elaphostrongylus rangiferi Mitskevich, 1960 and were subsequently autopsied at days 2, 4, 6, 10, and 14 post inoculation. The main migratory route of E. rangiferi larvae seemed to be haematogenous. The larvae penetrated the venules of the abomasum and followed the blood stream via the liver to the lungs. In the lungs, the larvae entered pulmonary venules and passed into the arterial circulation reaching the central nervous system (CNS) and other organs between days 6 and 10 post inoculation. Some of the larvae that had lodged in tissues outside the CNS probably migrated into it along the spinal nerves. A marked eosinophilia was present from day 8 post inoculation.     

Evaluation of excretory-secretory antigens for the serodiagnosis of swine trichinellosis

Groups of hog sera from endemic and non-endemic areas for swine trichinellosis in Yugoslavia were tested by ELISA using excretory-secretory (ES) antigens collected from T. spiralis muscle larvae maintained in vitro for 24, 48 or 72 h. The 24-h ES had the highest level of specificity for T. spiralis infection. Antigen preparations recovered after 48 or 72 h yielded an increasing rate of false-positive reactions. Additional antigens occurred in the 48- and 72-h ES preparations as determined by gel electrophoresis and monoclonal antibody binding. The occurrence of false-negative reactions was directly correlated with T. spiralis worm burdens. Hogs with muscle larvae densities greater than 10 larvae per gram were all positive by ELISA. Among 17 hogs with less than 10 larvae per gram, only one hog was negative by ELISA with 24-h ES antigen; the false-negative rate was higher with 48- and 72-h ES. These results show that ES antigen produced during the first 24 h of in vitro cultivation is highly specific for the immunodiagnosis of swine trichinellosis.     

全沟硬蜱围食膜初步观察研究

本工作用光镜和电镜技术对全沟硬蜱的围食膜进行了初步观察研究。结果表明，饥饿幼虫、若虫、成虫以及吸血期雄性成虫不具围食膜。吸血期幼虫、若虫及雌性成虫最晚分别于吸血开始后20、20及18小时出现了单层结构的围食膜；缓慢吸血期围食膜的厚度持续增加，而在快速吸血期其厚度却会显著减小。饱血后发育期围食膜不断增厚，愈来愈拱曲，与肠壁的距离不断扩大，并形成多层结构；至少分别于饱血后12、25及11天，仍能在幼虫、若虫及雌性成虫肠腔观察到完好状态的围食膜。全沟硬蜱是我国北方地区多种血液传播病原体的重要媒介，其围食膜的发现及围食膜形态变化的初步描述，对进一步认识这些病原体在全沟硬蜱体内迁移扩散规律、发育动态以及向宿主的传播途径，可提供有益的启示。     

Fatal strongyloidiasis in gibbons (Hylobates lar)

A 6-year retrospective study of necropsy material from a colony of 200 gibbons showed strongyloidiasis to be the most frequent cause of death (24 cases). Clinical signs included diarrhea, constipation, weight loss, paralytic ileus and dyspnea. Lesions were most frequent in the gastrointestinal tract and lungs. In the gut there were erosive and ulcerative enteritis associated with adult female parasites and rhabditiform larvae and acute and granulomatous enterocolitis associated with invading filariform larvae. There was severe multifocal or diffuse hemorrhage associated with migrating larvae in the lungs of 23 gibbons. Filariform larvae and the lesions they caused also occurred in various tissues; this was commensurate with the wide distribution of these larvae when hyperinfection occurred.     

In vitro effects of four tropical plants on three life-cycle stages of the parasitic nematode, Haemonchus contortus

Alcoholic extracts of four tropical plants (Zanthoxylum zanthoxyloides, Newbouldia laevis, Morinda lucida and Carica papaya) were screened in vitro for potential anti-parasitic effects against eggs, infective larvae and adult Haemonchus contortus. Significant effects were obtained with all four plants but differences were observed depending on the parasitic stage. The effects of the four plant extracts were similar on egg hatching and were dose dependent. In contrast, no dose-response relationship was found for infective larvae and adult worms, although more potent effects were usually observed with the highest concentrations. Using a larval inhibition migration test, extracts of fagara (Z. zanthoxyloides) were found to be less active against Haemonchus infective larvae than were the other plants. N. laevis was found to be highly and rapidly effective against adult worms. Overall, these in vitro results suggest that these four plants, traditionally used by small farmers in Western Africa, do possess anti-parasitic properties. These effects remain to be confirmed through in vivo studies.     

In vitro activity of various anthelmintic compounds against Haemonchus contortus larvae

Twenty-five known anthelmintic compounds were evaluated in vitro against the highly motile exsheathed non-feeding third-stage of Haemonchus contortus larvae. Activity was based on lack of motility or death of larvae after 24 h of chemical exposure. Six compounds (avermectins, closantel, levamisole, morantel, phenylhydrazone and ticarbodine) were active at a concentration of 100 μg cm^?3 or less. The most active compounds were avermectins and levamisole. When higher in vitro concentrations were used, ten compounds (bephenium, coumaphos, dichlorovos, disophenol, hygromycin b, methyridine, parbendazole, phenothiazine, pyrantel and thiabendazole) exhibited activity. Nine compounds were found to be inactive; among these were the new benzimidazoles, i.e., albendazole, fenbendazole, mebendazole and oxibendazole. Because of the inactivity of the new benzimidazoles, this in vitro system is unsuitable as a routine screening tool. Also, the system appears to favor drugs that act quickly through percuticular entry. In an initial group of 5280 untested compounds, 254 (4.8%) exhibited in vitro activity at 100 μg cm^?3 against the non-feeding larvae stage. The exogenous and in vitro cultivation techniques required for collecting, cleaning and exsheating the larvae are described.     

Green tea flavan-3-ols and oligomeric proanthocyanidins inhibit the motility of infective larvae of Teladorsagia circumcincta and Trichostrongylus colubriformis in vitro

The effects of a hot water infusion and an aqueous acetone extract of green tea (Camellia sinensis) on the motility of infective larvae of the sheep nematodes Teladorsagia circumcincta and Trichostrongylus colubriformis were investigated under in vitro conditions. The infusion and extract dose-dependently inactivated the infective larvae as assessed by the larval migration inhibition (LMI) assay. To determine the components responsible for the inhibitory activity, the hot water infusion and aqueous acetone extract of green tea were fractionated on Sephadex LH-20 and the green tea extract fractions (GTE-I-VIII) characterised by mass spectrometry. The larvae were exposed to increasing concentrations of these GTE fractions. Fractions containing epigallocatechin gallate (EGCG) and proanthocyanidin oligomers were most effective. GTE fractions were more effective against T. circumcincta than T. colubriformis larvae as assessed by the LMI assay.