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At least 541 records · Page 30Linked to original sources
PubMed1997

Transmission dynamics of helminth parasites of pigs on continuous pasture: Oesophagostomum dentatum and Hyostrongylus rubidus.

An increase in alternative outdoor pig production systems is occurring in Denmark, and this study was designed to elucidate the transmission patterns of Oesophagostomum dentatum and Hyostrongylus rubidus in pigs allowed to graze continuously on a pasture. A group of pigs was turned out in May 1993 (Year 1 of the study) and subsequently inoculated with low numbers of both helminths. These pigs were followed parasitologically until October by serial necropsy and sampling of faeces, grass and soil. A non-inoculated group of pigs was similarly followed on the same pasture in Year 2 (1994). Pasture infectivity was measured using helminth-naïve tracer pigs during all seasons. The pasture vegetation was rapidly destroyed by the pigs, resulting in a dirt lot by the autumn of Year 2. The area was soon contaminated with eggs, resulting in heavy pasture infectivity and increasing worm burdens in late summer; then the numbers of larvae declined markedly. In May of Year 2, newly exposed pigs became only lightly infected (mostly O. dentatum), and no transmission was observed in July-August of Year 2, probably due to an unusually dry summer and a lack of protecting vegetation. The results indicate that both O. dentatum and H. rubidus are very sensitive to environmental factors, because significant transmission occurred only under the most favourable conditions (summer combined with protecting vegetation as in Year 1). Transmission was severely reduced during the low temperatures experienced in the winter between Years 1 and 2 and during the dry summer of Year 2, when vegetation was lacking. Continuous grazing actually reduced transmission of O. dentatum and H. rubidus because of the reduction in vegetation. This, however, is not a desirable alternative farming system, because of its adverse environmental effects. This environmental impact may be mitigated by employment of a pasture rotation system in place of continuous grazing.

Animal Husbandry↗
PubMed1994

Efficacy of moxidectin against gastrointestinal nematode infections in sheep.

The efficacy of moxidectin against gastrointestinal nematode infections was studied in 30 Fleischschaf x Rasa Aragonesa male lambs aged 3 months at the beginning of the experiment. The lambs were distributed in three groups of 10 animals each and experimentally infected with a mixture of an equal number of infective (L3) larvae from each of the following species: Haemonchus contortus (2000), Ostertagia circumcincta (2000), Trichostrongylus colubriformis (2000) and Trichostrongylus vitrinus (2000). Two groups of lambs were drenched with 0.2 mg moxidectin per kg body weight at 6 (Group B) and 21 (Group C) days post challenge while the third group of animals (Group A) remained untreated. The efficacy of the treatment based on worm counts 4 weeks post infection was of 100% against 4th stage larvae of all species and 100%, 99.98%, 100% and 100% against adults of H. contortus, O. circumcincta, T. colubriformis and T. vitrinus, respectively. Significant differences were found in daily weight gain between treated (Group B+C, 157.9 g day-1) and untreated lambs (Group A, 116 g day-1). No differences in feeding behaviour or health condition between treated and untreated lambs were observed.

Abomasum↗
PubMed2000

Parenterally administered gastrointestinal nematode infective larvae viable after more than 15 years in liquid nitrogen.

After cryopreservation for 13.3-15.8 years, the viability of the infective larvae (L3) of Trichostrongylus axei, T. colubriformis, Oesophagostomum columbianum, Haemonchus contortus, Ostertagia circumcincta, T. falculatus, Nematodirus spathiger, Chabertia ovina and Dictyocaulus filaria was assessed in sheep, by being deposited at their predilection sites. D. filaria was, however, an exception, in that the L3 were injected into the jugular vein. The mean development of all the species was 22.8%, but if three species (O. columbianum, C. ovina and D. filaria), that developed poorly are disregarded, then the mean development was 33.4%, similar to previous tests after shorter periods of cryopreservation. The L3 of some of the species appeared sluggish when examined 10-15 min after being thawed, and in the case of H. contortus practically all the larvae of the original batch tested in the previous trials of the series appeared dead when thawed for use in the present trial, and were replaced by another batch of L3 of the same species. When re-examined after about 8 h, however, a high percentage of the L3 of the original batch appeared to have become revitalised, and their viability was tested in a trial reported elsewhere. The intestinal cells of the majority of the L3 of N. spathiger, O. circumcincta and C. ovina were vesiculated when they were thawed. Nevertheless, the degree of development of the former two species was of the highest in the trial, and it can be concluded that this phenomenon does not necessarily impede the viability of larvae.

Animals↗
PubMed1986

Glucose absorption in vitro by the enteric stages of Trichinella spiralis.

Absorption of glucose in vitro by enteric stages of Trichinella spiralis was examined in worms isolated at different times following infection. Glucose absorption by 6-h-old worms was similar to that seen during moulting (24 h post-infection (p.i.]. As embryogenesis began (48 h p.i.) glucose absorption in vitro by the parasite rose dramatically to a peak in 72-h-old worms. Absorption of glucose in vitro remained high in 96-h-old worms but as larviposition began (120 h p.i.) glucose uptake by T. spiralis dropped significantly. Glucose absorption by worms isolated from the host during the primary immune response was unaffected. Glucose absorption in vitro remained at similar levels in worms isolated between 120 and 312 h p.i. The percentage of absorbed label incorporated into parasite tissues was greatest in 48- and 312-h-old worms. Glucose uptake in vitro by pre-adult and adult worms changed with time and these changes accompanied specific events in the biology of the parasite.

Animals↗
PubMed2002

[Strongyloidosis. Part VIII. Parasitological diagnosis].

The effectiveness and safety of the methods of detecting Strongyloides stercoralis, by passing larvae from the faeces to water, in duodenal fluid (duodenal intubation, Enterotest), in sputum and other body fluids, have been estimated. The author recommend Baermann technique for detecting S. stercoralis in individual examinations and Dancescu technique in mass field examinations. The detection of S. stercoralis larvae by the two methods ought to be checked by Fülleborn agar Petri dish technique in order to identify parasite to the species level.

Animals↗
PubMed1982

Coccidiosis in swine: dose and age response to Isospora suis.

Coccidiosis is a disease of the young piglet due to infection with Isospora suis and is characterized by diarrhea which is nonresponsive to antibacterial therapy. There is variable morbidity and mortality. Piglets develop a more severe clinical illness and enteritis when infected with I. suis at one to three days of age than when infected at two weeks of age. Microscopic lesions range from villous atrophy and mild erosion to severe fibrinonecrotic enteritis.

Age Factors↗
PubMed1987

A redescription of the life cycle of Eimeria mitis Tyzzer, 1929.

Ten-day-old broiler chickens were inoculated with oocysts of a characterized strain of Eimeria mitis, and tissues were fixed at 4, 8, or 24-h intervals after inoculation for histopathological examination. Tissue collections were initiated at the time of inoculation and extended up to 168 h postinoculation. The preferred site of development of E. mitis was found to be the ileum although more limited development of the parasite also took in the jejunum, cecal pouches, cloaca, and bursa of Fabricius. No distinctive and consistent intestinal lesions were macroscopically evident even in heavily parasitized chickens. The prepatent period was approximately 92 h postinoculation. The histopathological features of the E. mitis infections were characterized using conventional bright-field microscopy as well as both scanning and transmission electron microscopy. No extra-intestinal development of the parasite was observed.

Animals↗
PubMed1988

Ascaris suum: development of intestinal immunity to infective second-stage larvae in swine.

The development of protective immunity to Ascaris suum was examined in pigs naturally exposed to eggs on a contaminated dirt lot. Pigs became almost totally immune to second-stage larvae migrating from the intestines because few larvae from a challenge inoculum could be found in the lungs, and liver white-spot lesions (an immunopathologic response to migrating larvae) were absent. Blood from these pigs contained lymphocytes that responded blastogenically to larval antigens in vitro, while the serum contained antibody to larval antigens. Immunity was related to parasite exposure and not to the age of the host, and was not affected by the removal of adult A. suum from the intestines. Naturally exposed pigs responded to a variety of A. suum antigens with an immediate-type skin reactivity, and their intestinal mucosa contained relatively large numbers of mast cells and eosinophils. Other pigs were maintained on a dirt lot not contaminated with A. suum eggs and the effects of common environmental conditions on development of resistance to A. suum were studied. Resistance also developed in these pigs because 72% fewer larvae were detected in their lungs following a challenge exposure than in control pigs confined indoors on concrete floors and challenged similarly. This response was not expressed at the intestinal level, however, because their livers had numerous, intense white-spot lesions. To verify that the intestinal immunity that developed in pigs after natural exposure to A. suum was a direct result of homologous infection and not related to other stimuli encountered on a dirt lot, pigs maintained indoors on concrete floors, free from inadvertent helminthic infection, were inoculated orally with A. suum eggs daily for 16 weeks. Intestinal immunity was induced because larvae from a challenge inoculum were not detected in the lungs, and few white-spot lesions appeared on the livers of these pigs. Apparently, continual exposure of the intestinal mucosa to larvae eventually elicits the appropriate effector components necessary to prevent larval migration from the intestines.

Age Factors↗
PubMed1993

Enteric coccidia (Apicomplexa) in the small intestine of the northern spotted owl (Strix occidentalis caurina).

Sporulated oocysts (mean dimensions = 13.0 x 10.8 microns) and sporocysts (11.3 x 5.5 microns) of a coccidian resembling Frenkelia sp. or Sarcocystis sp. were present in the lamina propria of the small intestine of a naturally-infected northern spotted owl (Strix occidentalis caurina) collected near Medford, Oregon (USA). Dimensions of these oocytes and sporocysts appear to be considerably smaller than those from other sarcocystid species with avian definitive hosts. Additionally, numerous developmental stages and unsporulated oocysts (mean dimensions 22.8 x 17.8 microns) of a possible species of Isospora also were observed in the intestinal epithelium. This constitutes the first report of enteric coccidia from spotted owls. Neither parasite appeared to cause the death of the bird.

Animals↗
PubMed1993

Parasite spectrum and seasonal epidemiology of gastrointestinal nematodes of small ruminants in The Gambia.

One hundred and four post mortem examinations of randomly selected sheep (52) and goats (52) were carried out weekly from March 1990 to February 1991. Gastrointestinal parasites were identified and counted. A large spectrum of 16 helminth species was found in 101 (97%) infected animals. The nematodes infecting small ruminants were, in order of predominance: Trichostrongylus colubriformis (96% of all animals), Oesophagostomum columbianum (82%), Haemonchus contortus (67%), Strongyloides papillosus (55%), Gaigeria pachyscelis (38%), Cooperia spp. (49%) and Trichuris ovis (12%). Forty-five (43%) necropsies revealed an infection with Moniezia benedeni, Avitellina centripunctata or Stilesia globulosa. Infections with Schistosoma bovis and Paramphistomum spp. were rarely seen. Goats carried significantly lower worm burdens than sheep and were less often infected by tapeworms. Nematode worm burdens followed a similar seasonal pattern in both host species. While Trichostrongylus colubriformis was also recovered in high numbers in the mid dry season, other species such as H. contortus, Strongyloides papillosus and Oesophagostomum columbianum reached distinct peaks in the rainy season (July-October). Different survival strategies for the prolonged dry season were observed. Haemonchus contortus outlived the unfavourable climatic conditions as inhibited larvae in the abomasal mucosa, while the other nematode species survived as adults with a reduced fecundity. Egg production per adult worm specimen was found to depend heavily on the season and egg counts in the dry season (November-June) did not correspond to the size of worm burdens. Unexpectedly high worm burdens were recovered from adult and old animals. Investigations of young animals indicated that no reinfection can occur during the dry season. The findings are discussed with regard to their relevance for strategic control of gastrointestinal nematodes in small ruminants.

Abomasum↗
PubMed1998

Fish as paratenic hosts of Serpinema trispinosum (Leidy, 1852) (Nematoda: Camallanidae).

Third-stage larvae of the nematode Serpinema trispinosum (Leidy, 1852) were collected from the intestine of the freshwater cichlid, Cichlasoma urophthalmus (Günther), from a small lake in Yucatan, Mexico. This is the first record of Serpinema larvae from fishes, and their presence may reflect the importance of fishes as paratenic hosts of turtle parasites in this genus.

Animals↗