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At least 271 records · Page 15Linked to original sources
PubMed1986

On first-stage larval resistance under controlled conditions of three species of nematodes of the family Protostrongylidae Leiper, 1926.

A study was made on the survival of the first larval-stage of three species of the Family Protostrongylidae (Cystocaulus ocreatus, Muellerius capillaris and Neostrongylus linearis). At every temperature (5, 12, 20, 26 and 36 degrees C) and humidity (100, 70 and 30%) combinations, the species which needed the least time to reach the pre-established (50, 75 and 95%) mortality rates was Neostrongylus linearis. In all cases Muellerius capillaris was the species needing the longest time to reach the same mortality percentages (rates). The direct relationship between the survival capacity of each species and their relative abundance in the grazing zone of the sheep used as a source of larvae studied is also discussed. The comparison of our results with those of other authors is made on the basis of an adaptive relationship between the species of parasites studied and their definitive hosts.

Animals↗
PubMed1986

[Relation between Muellerius capillaris infestation of molluscan intermediary hosts and of goats in Touraine].

32 dairy-goat farms of Touraine were investigated for Muellerius capillaris infection. Faecal and Molluscs samples were collected in Spring and Autumn. The factors of risk for goat were the abundance of Helix aspersa in Spring and of Deroceras reticulatum in Autumn. The infestivity of pasture was related to the infection of goat in Spring but not in Autumn. The faecal larval output in goats depended on the breed of goat at both periods; environmental factors were also of importance.

Animals↗
PubMedDate not supplied

Anthelmintic resistance in nematodes of horses.

Suppressive anthelmintic treatment strategies originally designed to control Strongylus vulgaris in horses were extremely successful in reducing morbidity and mortality from parasitic disease. Unfortunately, this strategy has inadvertently resulted in the selection of drug-resistant cyathostomes (Cyathostominea), which are now considered the principal parasitic pathogens of horses. Resistance in the cyathostomes to benzimidazole drugs is highly prevalent throughout the world, and resistance to pyrantel appears to be increasingly common. However, there are still no reports of ivermectin resistance in nematode parasites of horses despite 20 years of use. It is unknown why resistance to ivermectin has not yet emerged, but considering that ivermectin is the single most commonly used anthelmintic in horses most parasitologists agree that resistance is inevitable. The fecal egg count reduction test is considered the gold standard for clinical diagnosis of anthelmintic resistance in horses, but diagnosis is complicated by lack of an accepted standard for the performance of this test or for the analysis and interpretation of data. Presently there is very little data available on the molecular mechanisms of anthelmintic resistance in cyathostomes; beta-tubulin gene is the only anthelmintic-resistance associated gene that has been cloned. The increasingly high prevalence of anthelmintic-resistant cyathostomes must be taken into account when designing worm control programs for horses. Strategies to decelerate further selection for drug resistance thereby extending the lifetime of currently effective anthelmintics should be implemented whenever possible. Considering the nature of the equine industry in which horses often graze shared pastures with horses from diverse locations, transmission and widespread dispersal of resistant parasites is virtually assured. A proactive approach to this problem centered on understanding the molecular basis of anthelmintic resistance in cyathostomes is required if we are to expect chemical control of nematodes in horses to remain a viable element of parasite control in the future.

Animals↗
PubMedDate not supplied

Recent developments in research into the Cyathostominae and Anoplocephala perfoliata.

Intestinal helminths are an important cause of equine disease. Of these parasites, the Cyathostominae are the commonest group that infect horses. These nematodes consist of a complex tribe of 51 species, although individual horses tend to harbour 10 or so common species, in addition to a few rarer species. The Cyathostominae can be extremely pathogenic, and high levels of infection result in clinical symptoms ranging from chronic weight loss to colic, diarrhoea and death. As part of their life cycle, immature cyathostomins penetrate the large intestinal wall, where they can enter a state of inhibited larval development. These larvae can exist in this state for months to years, after which they subsequently re-emerge. If larvae re-emerge in large numbers (i.e. several million), severe pathological consequences ensue. The inhibited larvae are also relatively refractory to several of the currently available anthelmintics, so that horses treated previously with anthelmintics can still carry life-threatening burdens of these parasitic stages. Little is known about the cyathostomin larvae during their mucosal phase, and current research efforts are focused on investigating the biology of these stages. Much of the research described here highlights this area of research and details studies aimed at investigating the host immune responses that the mucosal larvae invoke. As part of this research effort, molecular tools have been developed to facilitate the identification of larval and egg stages of cyathostomins. These molecular tools are now proving very useful in the investigation of the relative contributions that individual, common cyathostomin species make to the pathology and epidemiology of mixed helminth infections. At the more applied level, research is also in progress to develop an immunodiagnostic test that will allow numbers of mucosal larvae to be estimated. This test utilises antigen-specific IgG(T) serum antibody responses as markers of infection. As anthelmintic resistance will be the major constraint on the future control of the Cyathostominae, researchers are now actively investigating this area and studies aimed at elucidating the molecular mechanisms of drug resistance are described. Another parasite which has assumed a clinically important role in horses is the tapeworm, Anoplocephala perfoliata. This parasite is prevalent world-wide and has been shown to be a significant cause of equine colic. Because previous methods of estimating the infection intensity of tapeworm were inaccurate, recent research has been directed at developing an immunodiagnostic ELISA for these cestodes. Specific IgG(T) responses to antigens secreted by adult tapeworms have been shown to provide a reasonable indication of infection intensity. An ELISA based on these responses is now commercially available. The steps involved in the development of this ELISA are described here. In addition to these recent advances in research, this review also outlines the principle areas for future research into these important equine parasites.

Animals↗
PubMed1999

Organization of an echinoderm Hox gene cluster.

The Strongylocentrotus purpuratus genome contains a single ten-gene Hox complex >0.5 megabase in length. This complex was isolated on overlapping bacterial artificial chromosome and P1 artificial chromosome genomic recombinants by using probes for individual genes and by genomic walking. Echinoderm Hox genes of Paralog Groups (PG) 1 and 2 are reported. The cluster includes genes representing all paralog groups of vertebrate Hox clusters, except that there is a single gene of the PG4-5 types and only three genes of the PG9-12 types. The echinoderm Hox gene cluster is essentially similar to those of the bilaterally organized chordates, despite the radically altered pentameral body plans of these animals.

Amino Acid Sequence↗
PubMed2004

Prevalence of Libyostrongylus douglassii in commercially reared ostriches in the highveld region of Zimbabwe.

A total of 435 freshly dropped faecal samples were collected from 11 randomly selected ostrich farms during September and November 2002 to determine the prevalence of Libyostrongylus douglassii (ostrich wireworm) in the highveld region of Zimbabwe. Samples, which consisted of 339 samples from breeder birds and 96 samples from pre-slaughter grower birds were screened for nematode eggs using the modified McMaster technique before being individually cultured in an incubator at 28 degrees C. Cultures were examined for the presence of L. douglassii third stage larvae (L3). Using faecal egg counts, eight of 11 farms (72.7%) were positive for L. douglassii in breeders but no eggs were detected in the growers. The faecal culture method detected wireworm larvae in the breeding stock of all farms that were surveyed (100%) and five of the eight farms (62.5%) which had grower birds. Libyostrongylus douglassii was detected in all farms (100%) based on the faecal culture method. Libyostrongylus douglassii was detected for the first time in 7 of 11 farms (64%) surveyed. Data from questionnaires designed to assess farm management practices showed that four out of seven (57.1%) of the ostrich producers were unaware of the importance of wireworms in ostriches. The farms did not have a regular deworming programme for their birds and no faecal samples were sent routinely to the veterinary laboratory for screening of wireworms. Wireworm infections were not taken into consideration by farmers during buying and selling of birds.

Animals↗
PubMed2004

A dot-blot ELISA comparable to immunoblot for the specific diagnosis of human parastrongyliasis.

A dot-blot enzyme-linked immunosorbent assay (dot-blot ELISA) using an electroeluted 31-kDa glycoprotein from adult worms of Parastrongylus cantonensis as the specific antigen was evaluated for the immunological diagnosis of patients infected with P. cantonensis. The sensitivity and specificity for the detection of serum antibody to P. cantonensis in dot-blot ELISA were both 100%, as determined with serum samples of ten P. cantonensis-infected patients, 60 patients with other related parasitic infections, and 20 uninfected controls. The test was as sensitive and specific as the immunoblot test which revealed a reactive band of 31 kDa. Both the dot-blot ELISA and immunoblot detected all sera from ten P. cantonensis-infected individuals, but not with those of other heterologous parasitoses (gnathostomiasis, toxocariasis, filariasis, paragonimiasis, cysticercosis and malaria) or sera from healthy controls. The dot-blot ELISA is much simpler to perform than the immunoblot technique, and the test can be applied under field conditions where sophisticated facilities are lacking.

Animals↗