STUDIES ON SOME HELMINTH PARASITES OF SMALL MAMMALS (CARNIVORES AND RODENTS).
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Animals↗
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[THE MORPHOGENESIS OF THE CHITINOID PORTION OF THE DISTINGUISHING CHARACTERISTIC OF GYRODACTYLUS DECORUS MALMBERG, 1956 (MONOGENOIDEA) AND ITS MORPHOLOGICAL-METRICAL VARIABILITY].
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Anatomy↗
The epidemiology of helminthosis in small ruminants under the traditional husbandry system in eastern Nigeria.
The epidemiology of helminth infections in West African dwarf sheep and goats under the traditional husbandry system prevailing in the derived savanna area of eastern Nigeria was studied for 12 months. The infections observed were due to Haemonchus contortus (87.1%), Trichostrongylus spp. (63.8%), metacestodes of Taenia hydatigena (30.2%), Oesophagostomum columbianum (22.4%), Strongyloides sp. (18.8%), Cooperia spp. (17.2%), Gaigeria pachyscelis (6.0%), Moniezia expansa (6.0%), Bunostomum trigonocephalum (4.3%), Trichuris ovis (3.5%), Capillaria sp. (0.9%) and paramphistomes (0.9%). Mixed infections were most prevalent. The endemicity of parasitic gastroenteritis in the area was indicated by the high prevalence of the helminths irrespective of the season of the year. The overall trend in helminthosis in these animals was that of an escalating worm burden during the period of confinement (April - October) and a low worm burden when animals were allowed free range (November - March), these periods corresponding to the cropping and harvest seasons respectively. A strong positive correlation (r = 0.73; p less than 0.01) was obtained between the mean strongyle worm burden and the eggs per gram (EPG) of faeces. A single treatment with a broad spectrum anthelmintic followed by movement into clean sheds at the beginning of confinement is suggested to give control of helminthosis in small ruminants in this area.
Animal Husbandry↗
A survey of some drugs commonly used in the camel.
Specific recommendations for drug dosages for the camel are rare and doses for this species are usually extrapolated from those recommended for other species. The pharmacology and toxicity of drugs likely to be used in the camel needs to be further studied to ensure the efficacy and safety of these drugs in this species. Most of the reported work is on the chemotherapeutic efficacy of a few drugs long in use in other species against trypanosomiasis, mange and gastrointestinal nematodes. Areas of study most deficient are pharmacodynamics, pharmacokinetics and drug metabolism. The anatomical, physiological and biochemical peculiarities of the camel warrant more pharmacological and toxicological studies in this species. This article surveys the literature on the pharmacology, toxicity and therapeutic uses of some antiparasitic and antibacterial drugs and central nervous system depressants commonly used in the camel. It appears that camels are more susceptible to the toxic action of some trypanocidal drugs than other species. In certain cases they may metabolize some drugs differently. In general, the camel appears to be a good subject for analgesics and anaesthetics.
Analgesics↗
[Preliminary observations of two microsporidian hyperparasites of Acanthocephala in marine and lagoon fishes].
Microsporidium acanthocephali n. sp. and Microsporidium propinqui n. sp. are two microsporidian species hyperparasitic in the tegumentary syncytium of salt-water fishes. Their ultrastructural study shows that both species have diplocaryotic meronts and spores, anisofilar polar filaments; meronts and some sporogonic stages of M. acanthocephali are surrounded by a parasitic vacuole. Spores of both parasites are oviform; those of M. acanthocephali are gigantic, 12-14 micron long and 6-7 micron broad, those of M. propinqui are only 3-4 micron X 1.25-1.50 micron. A poor knowledge of some sporogonic aspects prevents us from all precise generic assigning of these two parasites which may coexist in the same Helminth.
Acanthocephala↗
Gastro-intestinal helminths of donkeys in Burkina Faso.
Thirty adult donkeys from Burkina Faso were necropsied and their gastro-intestinal worm burdens counted and determined. The strongylids were the most abundant species with a prevalence of 100% for Strongylus vulgaris. Four species of Strongylus, two of Triodontophorus and six of the Cyathostominae were recovered. All of the animals were also infested with habronematid nematodes, but oxyurid and ascaridid nematodes were found in low numbers. In addition to the nematodes, the paramphistomid trematode Gastrodiscus aegyptiacus and the anoplocephalid cestode Anoplocephala magna occurred in varying numbers. Faecal egg-counts from 131 donkeys ranged between 100 and 9,200 for strongylid eggs.
Animals↗
The helminths in the gut of perch (Perca fluviatilis L.) in a small oligotrophic lake in southern Norway.
A total of 311 perch were examined for gut parasites during the period from April 1972 to December 1973. Four different metazoan parasites were found; Proteocephalus percae (Müller, 1780), Bunodera luciopercae (Müller, 1776), Acanthocephalus lucii Müller, 1776 and Camallanus lacustris Zoega, 1776. B. luciopercae and P. percae exhibited similar seasonal cycles in appearance and abundance. They were both absent from the fish population during June/July. A. lucii and C. lacustris on the other hand had a peak in infection intensity and incidence during the summer and autumn months. From September/October one year to May/June the following year B. luciopercae was the dominating parasite species showing the highest incidence (approximately 95%) and intensity (a mean of about 25 parasites per infected fish). When 2 times 2 contingency tests were applied on the material from this period a significant negative correlation between the presence of P. percae and A. lucii could be pointed out while there was no correlation between the presence of any of the other 3 parasite species.
Acanthocephala↗
Experimental transmission of Acanthocephalus anguillae (Palaeacanthocephala).
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Acanthocephala↗
Pathological changes induced by Pomphorhynchus laevis Muller (Acanthocephala) in the gut of rainbow trout, Salmo gairdneri Richardson.
The consequences of infection of rainbow trout, Salmo gairdneri Richardson, by an acanthocephalan, Pomphorhynchus laevis Muller, have been studied using light and electron microscopy. The mucosal epithelium, of the gut adjacent to the metasoma of the worm suffered compression and abrasion. The praesoma of P. laevis penetrated the mucosal epithelium, lamina propria, stratum compactum, stratum granulosum, muscularis and serosa of the gut wall, and was invested by a fibrous capsule of inflammation tissue. This was composed of four principal cell types: eosinophilic granular cells (EGCs), type A cells, type B cells and fibroblasts. Some melanocytes and lymphocytes were also present. The role of the EGCs in the inflammation response is not known, but may not be an active one. The type A cells resembled neutrophils of other fish species, and have tentatively been placed in this category. The type B cells, with large cisternae formed by the RER, resembled plasma cells and may have been involved in a humoral response to the acanthocephalan. The integument of P. laevis did not appear to be damaged by the cells of the inflammation tissue, and it seems likely that this host response was incapable of rejecting the parasite.
Acanthocephala↗
[Light and electron microscopic studies of the histopathogenicity of Macracanthorhynchus hirudinaceus (Archiacanthocephala) in experimentally infected domestic swine].
One and 12 weeks after infection the lesions in the small intestine of two domestic pigs caused by Macracanthorhynchus hirudinaceus were studied by means of light and electron microscopy. Worms of 7 d.p.i. were found to have penetrated with their presoma into the tunica propria and partly into the tunica muscularis where they had caused local mechanic destructions and heavy eosinophilic-like and hemorrhagic reactions. Most eosinophilic-like granulocytes were attracted to the proboscis hooks, at the base of which an osmiophilic substance apparently was excreted. Worms of 84 d.p.i. had penetrated with their proboscis deeply into the tunica muscularis. The presoma had become encapsulated by a solid capsule of necrotic/inflammatory tissue in its inner part and by filamentous connective tissue in its outer part. The predominant leucocytes in the inflammatory tissue now were plasma cells indicating a progressive immune reaction. No worms were found to have perforated the entire intestinal wall as was described from human patients in China.
Acanthocephala↗
Autoradiographic and morphological investigations on the uptake and incorporation of tritiated lysin by acanthocephalans.
Four palaeacanthocephalans and two eoacanthocephalans from fish were autoradiographically investigated for their in vitro uptake of tritiated lysin. All worms took up the labelled amino acid at their surface without showing a species-specific pattern. The tegument of the metasoma was more heavily labelled than the presomal tegument, suggesting that the worms predominantly absorb the nutrient from the food inside the host's gut in vivo. Within the metasomal tegument the nuclei revealed the most intense labelling. In the muscles the outer myogenic belt absorbed more radioactivity than did the enclosed cytoplasmic core. In female worms the ovarian balls and eggs that showed incomplete eggshell formation were highly labelled. In male worms the cement glands showed the most intense labelling of all organs inside the body cavity. We conclude that the investigated acanthocephalans require lysin for protein synthesis and for the coding of protein synthesis in the tegumental nuclei.
Acanthocephala↗
In vitro study on the impact of fish sera on the survival and fine structure of the eel-pathogenic acanthocephalan Paratenuisentis ambiguus.
The effects of fish sera on the growth and fine structure of infective larvae of the eel-pathogenic acanthocephalan Paratenuisentis ambiguus (Eoacanthocephala: Tenuisentidae) were studied under in vitro conditions using sera from the final host Anguilla anguilla and from two accidental fish hosts as well as fetal calf serum. As controls larvae were also kept in medium in the absence of serum and in experimentally infected eels. Sera from the accidental fish hosts carp and rainbow trout exerted toxic effects on the acanthocephalans. Worms maintained in medium containing sera from these two fish were contracted and displayed inverted probosces. Moreover, the tegument exhibited vacuolization and the formation of necrotic areas, including lysis of the mitochondria. Due to these effects, the parasites died at 21 (rainbow trout) or 21-50 days (carp) post-incubation. Eel sera had no toxic effect on the infective larvae. The growth of the larvae in medium depended on the composition of the latter, but was reduced as compared with that in the natural final host. Based on these results, we conclude that components of the hosts' blood sera play a role in the determination of the host specificity of P. ambiguus.
Acanthocephala↗
Activity of luxabendazole against liver flukes, gastrointestinal roundworms, and lungworms in naturally infected sheep.
The anthelmintic potential of luxabendazole was investigated in sheep harboring mixed naturally acquired helminth infections. Results were assessed by comparing worm counts of the treated groups (seven animals each) on days 7-8 posttreatment with those of the nontreated control group, except for protostrongylid lungworms, for which the changes in pre- and posttreatment group mean larval counts/g feces were assessed for intensity effect. A single oral treatment at doses of 10.0 or 12.5 mg/kg body wt removed 97.6% of the adult Fasciola hepatica and 63.2%-83.8% of the Dicrocoelium dendriticum. Luxabendazole at 7.5, 10.0, and 12.5 mg/kg proved 100% effective in removing adult worms of the genera Haemonchus, Ostertagia, Trichostrongylus, Cooperia and Nematodirus as well as tissue-associated larval stages of gastrointestinal nematodes of the abomasal mucosa. The drug showed an intensity effect of 79.7%-87.6% against Strongyloides papillosus. Luxabendazole removed all Dictyocaulus filaria and reduced the fecal excretion of larvae of protostrongylid species (Protostrongylus rufescens, Neostrongylus linearis, Cystocaulus ocreatus, Muellerius capillaris) by 97.8%-99.6%. The efficacy of luxabendazole compared favorably with that of Diplin Kombi (oxyclozanide and levamisole), which was used as a reference drug.
Abomasum↗
Comparative investigations of the morphology and chemical composition of the eggshells of Acanthocephala. II. Palaeacanthocephala.
Eggshells of the palaeacanthocephalans Acanthocephalus anguillae, Pomphorhynchus laevis and Polymorphus minutus were investigated for their fine structure as well as their chemical composition. The acanthor larvae are surrounded by four eggshells (E1-E4) separated by interstices (G1-G4). Immature eggs do not exhibit the complete set of eggshells. The chemical composition of the outermost, thin eggshell (E1) remains unknown. E2 is supplied by outer filaments of different strength; it contains keratin, which was localized electron microscopically using anti-keratin. In P. laevis and P. minutus, E3 seems to contain glycoproteins, which could not be visualized in this eggshell of A. anguillae. The innermost eggshell (E4) uniformly contains chitin. The electron-lucent interstices of the eggs of P. laevis and P. minutus are rich in polysaccharides and/or proteoglycans, whereas those of A. anguillae contain low amounts of such substances. The differences observed in the abundance of carbohydrates are discussed with respect to the life cycles of the three acanthocephalans.
Acanthocephala↗
Comparative investigations of the morphology and chemical composition of the eggshells of Acanthocephala. III. Eoacanthocephala.
Eggshells of the eoacanthocephalans Neoechinorhynchus rutili (Neoechinorhynchidae) and Paratenuisentis ambiguus (Tenuisentidae) were investigated for their fine structure and their chemical composition. The acanthor larvae of P. ambiguus are surrounded by four eggshells (E1-E4) separated by electron-lucent interstices (G1-G4). This resembles the stratification of the eggshells of archiacanthocephalans and palaeacanthocephalans. However, an additional outer envelope (E0) exists in N. rutili. In mature eggs of this species, the broad interstice between E0 and E1 is densely packed with polysaccharides, but the other interstices also showed an intense Thiéry label. In both species, E2 along with its outer protuberances contains keratin, as does E2 in archiacanthocephalans and palaecanthocephalans, whereas E4 does not contain chitin, which contrasts with findings in the eggs of the two other classes of acanthocephalans. The results are discussed with respect to the classification of the Acanthocephala and to their transmission to the intermediate hosts.
Acanthocephala↗
Loperamid, an efficacious drug against fish-pathogenic acanthocephalans.
A total of 20 drugs were tested for their efficacy in the treatment of infections involving the two major acanthocephalans infesting rainbow trout in European trout farms. In in vitro experiments, the antidiarrhoeic loperamid and the well-known anthelminthic drug niclosamide showed the best efficacy. Worms treated with loperamid contracted the posterior end of their body, in which severe necrosis of the tegument caused the death of the worms. In in vivo experiments, loperamid was the most efficacious drug: 50 mg/kg given to rainbow trout on 3 consecutive days led to a complete cure. According to preliminary tolerance tests in water baths, the toxicity of this drug is low as compared with that of niclosamide, which is very toxic. Thus, loperamid can be recommended as the drug of choice for therapy of acanthocephalan infections in fish.
Acanthocephala↗
Loperamid, an efficacious drug against the acanthocephalan Macracanthorhynchus hirudinaceus in pigs.
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Acanthocephala↗
Helminths of sheep and goats in desert areas of south-west Mauritania (Trarza).
Faecal samples were obtained from sheep and goats before, during and after the rainy season at three locations in south-west Mauritania. Several animals were also necropsied at the same time. Haemonchus contortus was the most prevalent worm. Infection by digestive-tract strongyles and Strongyloides papillosus was always very light (prevalence less than 20%). Sheep were more heavily infected than goats but animals under 1 year of age were not infected by digestive-tract strongyles. It is likely that young small ruminants became infected during the rainy season and that the parasites so acquired are inhibited in their development and/or survive nearly one year as adults.
Animals↗