Biomedical subjects

J Cabaret

Publications and source records attributed to J Cabaret.

At least 73 records · Page 4Linked to original sources

PubMed1997

Species diversity in gastrointestinal nematode communities of dairy goats: species-area and species-climate relationships.

Gastrointestinal nematode communities (12 species) of dairy goats were studied in four regions located in the centre of the western part of France. These regions had very similar annual mean temperatures (11 to 12.5 degrees C) but had rainfall accumulations ranging from 600 to 1330 mm per year. Breeding management (area of pastures, number of goats in the flock, the age of the farm, and the size of the initial goat population) was investigated only in the driest region. The number of helminth species and Shannon diversity index were positively correlated to the permanent pasture area and negatively to the age of the farm. Evenness was negatively correlated to the age of the farm and increased with the increasing levels of rainfall. The results are interpreted in the following terms: i) large areas of permanent pasture include a large array of environments favourable to the development of the free-living stages of various species of nematodes; ii) age of the farm is unfavourable to the maintenance of all introduced species as the farms are helminth-isolated and infestation can only occur during the grazing season thus imposing the necessity of successive annual recolonization of the pastures; and iii) free-living stages are very susceptible to dryness and survive better in areas with heavy rainfall.

Analysis of Variance↗

PubMed1997

Sheep and goat lines of Teladorsagia circumcincta (Nematoda): from allozyme to morphological identification.

Previous allozyme analyses demonstrated the existence of Teladorsagia circumcincta sheep and goat lines, based on the presence (goat line) or absence (sheep line) of an allele at the cathodic loci of malate dehydrogenase (MDH), with rapid migration (coded sR or super rapid) when starch gel electrophoresis was used. Simultaneous allozyme and morphometric characterization of individual worms from 3 natural populations harbored by goats were assessed. The nematodes with sR allele could be identified by a combination of measures of the dorsal ray of the bursa. Simple and fast morphological differentiation of worms with sR allele constitute an attractive tool for thorough studies on the frequency of these 2 types of worms and finally to assess the prevalence of goat and sheep lines.

Alleles↗

PubMed1996

Relationship between genetic diversity in the nematode Trichostrongylus colubriformis and breeding management in ten dairy-goat farms.

Ten dairy-goat farms were investigated in center-west of France for genetic variability of Trichostrongylus colubriformis in relation to breeding management. Farm management data were obtained from a questionnaire. Genetic variability was based on two polymorphic enzymes, malate dehydrogenase (MDH) and glucose-phosphate isomerase (GPI). After their establishment, the farms were subsequently isolated from introduction of strongyle worms as shown in the questionnaire; this was also suggested by the absence of a relationship between genetic variability and distance between farm locations. The genetic variability which was recorded could then be ascribed in part to the influence of management. The breeding management estimates combined the fact that animal breeding was the main economic resource; that goats were or were not the only animal bred; and that there was or was not free access to exercise yards in winter. The farms that were similar on the basis of breeding management, were also similar in the frequency of allozymes, indicating that the chosen allozymes were not neutral in respect to environment. Genetic variability was not related to the frequency of T. colubriformis in the strongyle community, this being possibly due to the fact that our farm samples predominantly harboured T. colubriformis. Between-farm genetic variability was positively correlated to the size of herd (P < 0.01), probably due to the fact that larger herds were originally constituted from several different herds.

Animal Husbandry↗

PubMed1996

Adaptation to arid environment: Haemonchus longistipes in dromedaries of Saharo-Sahelian areas of Mauritania.

The adaptations of the trichostrongylid nematode Haemonchus longistipes of dromedaries (Camelus dromedarius) to the harsh environment of Saharo-Sahelian climate were assessed by means of (i) an epidemiological survey of dromedary infection in the south-west of Mauritania, (ii) an estimate over a 3 year period of parasite distribution within the host population and of prolificacy of H. longistipes females recovered from natural populations of infected dromedaries sampled at Nouakchott's slaughterhouse, and (iii) experimental infections of young dromedaries during three different periods of the year (end of the rainy season, middle and end of the dry season). Egg excretions (estimated by faecal egg counts), infective larvae derived from eggs as well as female prolificacy showed a marked seasonal pattern: high values in the rainy season and very low values in the dry season (especially March and April). Female prolificacy differed slightly between morphotypes: the knobbed type excreting over a longer period than the linguiform and smooth types. Following experimental infections in young dromedaries, arrest of larval development took place irrespective of the period. The survival strategy of H. longistipes in the dry season was based only on arrested larval development. Patent infections occurred from July to October, i.e. during the rainy season and was facilitated by the conjunction of high prevalence and intensity of adult worm burdens associated with high female prolificacy.

Adaptation, Physiological↗

PubMed1996

The Effect of Parasitism by Fasciola hepatica and Muellerius capillaris on the Nerve Ganglia of Lymnaea truncatula

Morphometric and histopathological studies were performed in Lymnaea truncatula experimentally infected by Fasciola hepatica or Muellerius capillaris between Days 30 and 60 postinfection. In the pedal ganglia, snail parasitism had a significant influence on the decrease in length and the increase in width in the M. capillaris group. In the dorsal lobes of cerebral ganglia, snail parasitism had a significant influence on the decrease in lobe width in the F. hepatica group and the increase in width in the M. capillaris group. In the two groups of infected snails, snail parasitism had a significant influence on the decrease in the number of neurons in the pedal ganglia and the dorsal lobes of the cerebral ganglia. The other ganglia and lobes did not demonstrate any significant differences in the size or number of neurons. Infected snails of both groups had multifocal nerve lesions, i.e. (a) dyskariosis with occasionally eccentric nuclei and (b) cell lysis with only cell remnants present.

Journal Article↗

PubMed1996

Evidence for the existence of a sheep and a goat line of Teladorsagia circumcincta (Nematoda).

Populations of Teladorsagia circumcincta harbored by sheep and goats were investigated by means of isoenzyme electrophoresis. Genetic characterization of 16 natural goat populations was based on 5 polymorphic enzymes. Malate dehydrogenase (MDH-1) was the most informative; it had three alleles, the electrophoretically fast migrating one being named sR. We distinguished three groups with presence to over 20%, low frequency, and absence of sR, respectively. In four sheep flocks, only the third group was found. Neither of two laboratory-reared lamb populations originating from two geographic origins presented this third allele. When populations of worms with high sR frequency were passaged into lambs, a steep decrease in the sR-allele frequency was recorded, which was no longer demonstrated in lambs after the third passage. We suggest that the worms lacking the third allele belong to the sheep line and that those with the sR allele belong to the goat line. Thus, goats would be infected with worms of both goat and sheep lines, whereas sheep would harbor only the sheep line.

Alcohol Dehydrogenase↗

PubMed1996

Impaired pulmonary gas exchange in ewes naturally infected by small lungworms.

Respiratory rate and blood gases were studied in 2 groups of ewes: the ewes in group 1 (9 ewes) acted as uninfected controls and those in group 2 (6 ewes) were infected with small lungworms (Muellerius, Cystocaulus, Protostrongylus and < 1% Neostrongylus). The respiratory rate was higher in infected (49 +/- 19 breath min-1) than in uninfected ewes. (20 +/- 3 breath min-1); it was strongly reduced after treatment (49 vs 22) in infected ewes. The partial carbon dioxide arterial tension (PCO2), total CO2 and HCO3- were higher (respectively 77 vs 39 mmHg, 38 vs 23 mmol-1 and 35 vs 23 mmol-1) in infected compared with uninfected ewes, whereas arterial pH (7.2 vs 7.4) and partial oxygen tension PO2 were lower (41 vs 81 mmHg) in infected ewes. Group 2 was treated with fenbendazole (at 15 mg kg-1 bodyweight) to eliminate small lungworms, and the respiratory rate and blood gases were measured 3 weeks after treatment. The values after treatment were similar to those in uninfected ewes. It is concluded that heavy infections by small lungworms in ewes impairs gas exchange, but that gas exchange improves rapidly after treatment.

Animals↗

PubMed1996

A quantitative approach to nematode lungworm burdens in goats.

Nematode lungworm burdens are difficult to evaluate of necropsy. The recovery of protostrongylid worms was achieved by three different post-mortem quantification techniques. Perfusion of the lungs under watertap pressure was successful in washing out Protostrongylus rufescens and Cystocaulus ocreatus but not Muellerius capillaris and Neostrongylus. Incubation of the lungs by pepsin and hydrochloric acid solution prior to perfusion helped to recover trapped Muellerius and Neostrongylus. Worm nodules were classified into type A, B and C, on increasing calcification process. Examination of these nodules showed that 75 to 80% of type A and B contained a parasite. Worms recovered by perfusion added to the sum of type A and B nodules were used to construct formula for quantifying the total lungworm burdens from naturally infected goat lungs and may provide a reasonable basis for assessing anthelmintic efficacy.

Animals↗

PubMed1996

Host, season and year do not play an important role on genetic variability in a trichostrongyle nematode as assessed from allozymes.

The isolates of the trichostrongyle nematode Teladorsagia circumcincta in sheep may vary from one site to another as assessed from allozyme studies. This genetic variability could be host (on the parasitic stages) or/and environmentally (on the free-living stages) induced. In the present study the role of host (susceptible to the establishment of the parasite and partly resistant ones) and environmental changes expressed by season (Autumn versus Spring) or year of sampling (1990 or 1992) were investigated. Five polymorphic enzymes were studied: glucose-phosphate-isomerase (GPI), lactate dehydrogenase (LDH), malate dehydrogenase (MHD), mannose-phosphate isomerase (MPI), and phosphoglucomutase (PGM). No significant difference in allelic frequencies was recorded between 4 susceptible lambs from a flock grazed in 1990 as well as in 3 lambs selected on their susceptibility or resistance to natural infection in a flock grazed in 1992. The mode of infection (natural--frequently repeated small infections, versus experimental--3 repeated large infections) did not modify the allelic frequencies of the nematodes. The allelic frequencies remained stable along the seasons and during the 2 years investigated. The largest distance of Rogers (0.07) and Fst (0.012) were recorded between worms originating from susceptible and resistant lambs or in Autumn versus Spring populations of worms (0.08 and Fst 0.010). A deficiency in heterozygotes of the same magnitude was recorded in the worm populations obtained from the different infections. The stability of allelic frequencies and genetic structure are surprising when one considers the evolution of the same parasite in several generations of laboratory conditions. This stability could be related to the fact that levels of disturbance on parasitic and free-living stages are neither too low (as in laboratory conditions) nor too high (as in farms when anthelmintic treatment are used regularly and destroy the adult stages).

Alleles↗

PubMed1996

Using molecular tools for diagnosis in veterinary parasitology.

The development of molecular biology has made available tools that identify parasites which are important in veterinary parasitology. PCR (polymerase chain reaction) is the most frequently used tool. Target sequences are ribosomal DNA and RNA as well as fragments derived from RAPD (random amplified polymorphic DNA). The most studied protozoan genera have been: Eimeria, Babesia, Theileria, Trypanosoma and Cryptosporidium. Trichinella species and ruminant Trichostrongylid parasites have been the most investigated helminths. The use of molecular tools for identification in veterinary parasitology, however, remains a research technique rather than one that is currently used in the field for diagnostic purposes.

Animals↗

PubMed1995

Use of random amplified polymorphic DNA for identification of ruminant trichostrongylid nematodes.

The aim of this work was to evaluate random amplified polymorphic DNA (RAPD) as a source of markers for species identification and phylogenetic analysis of ruminant trichostrongylid nematodes. As these nematodes are often polymorphic, species identification may be difficult. We tested eight species and several of their morphs: Haemonchus contortus (three vulvar morphotypes: flap, smooth, and knobbed), Teladorsagia circumcincta, Ashworthius gagarini, Spiculopteragia boehmi, Ostertagia leptospicularis (and its morph Ostertagia kolchida), Cooperia oncophora (and its morph C. surnabada), Trichostrongylus colubriformis, and T. vitrinus. With five chosen 10-mer primers, genetic variations were assessed among individuals of each species or morphotype. In trichostrongylid nematodes, the identification of species is possible by means of RAPD on adult or larva DNA extracts, although the variability observed within species was very important for most species studied. The use of RAPD in phylogenetics studies is conversely questionable for this superfamily of parasitic nematodes. The interspecific distances were always larger than the intraspecific ones and did not vary much (between 0.8 and 0.9); they would not be of much use in the construction of a phylogenetic tree, at least for the species and the primers involved in this study.

Animals↗

PubMed1995

Morphological polymorphism in the nematode Teladorsagia circumcincta in relation to age of larvae, infection mode and lamb characteristics in experimental conditions.

Variations in the proportion of the less-frequent morph of Teladorsagia circumcincta, T. c. trifurcata, were studied under experimental conditions. Infections with older larvae (over 7 months of age at 4 degrees C) yield a lower proportion of T. c. trifurcata compared with those obtained from fresh larvae (15 days). This phenomenon could account for the reduction in the proportion of the morph trifurcata in two isolates that were acclimated to laboratory rearing for several generations. The infection mode (single or trickle infections did not significantly modify the proportions of both morphs. The morph trifurcata was found in higher proportions (> 5.5%) in more susceptible male and/or Romanov lambs, and in lower proportions (< 2.5%) in less susceptible female and/or Mérinos d'Arles lambs.

Animals↗

PubMed1995

Dry areas: an example of seasonal evolution of helminth infection of sheep and goats in southern Mauritania.

A total of 647 faecal egg counts and 53 necropsies were performed on sheep and goats originating from three sites of a Sahelian region of Mauritania (Gorgol) over a period of 2 years (1990-1992). Haemonchus contortus, Oesophagostomum columbianum and Stilesia globipunctata were the most prevalent species. The seasonal pattern was characterized by long survival of adults and high percentages of arrested fourth-stage larvae in the dry season, suggesting that two different strategies were used to survive from one rainy season to the next. Sheep and goats were equally infected, except for Stilesia globipunctata, which was found more often in sheep. The influence of age was limited, although kids and lambs born in the beginning of the dry season did not become infected until their first grazing in the rainy season.

Analysis of Variance↗

PubMed1995

Studies on multispecific resistance of gastrointestinal nematodes to benzimidazoles on dairy-goat farms.

Multispecific resistance to benzimidazoles was studied in three selected farms. These farms had bred dairy goats for more than 15 years. The helminths were introduced with the goats at the establishment of the farms which afterwards remained isolated. Nematode resistance could then be related to their own management practices. Faecal egg count tests and egg hatch assays were performed to assess intensity of resistance. The generic (infective larvae in faecal cultures) and specific richness (adult worms) were assessed. The resistant species were Trichostrongylus colubriformis, Teladorsagia circumcincta, Haemonchus contortus and Oesophagostomum venulosum. Faecal egg count reduction tests and egg-hatch assays did not match exactly. Faecal larval counts after treatments gave a distorted picture of multispecific resistance: Haemonchus and Oesophagostomum were very largely over represented. The number of species found in the three farms was relatively low compared with other reports in goat farms of the area. This reduction of diversity might also be due in part to characteristics of breeding management and history (use of permanent pasture and introduction of goats at the establishment of farm).

Animal Husbandry↗

PubMed1995

Ecological, morphological and genetic characterization of sympatric Haemonchus spp. parasites of domestic ruminants in Mauritania.

The 4 species of ruminants (dromedary, zebu cattle, sheep and goat) in arid areas of Mauritania harboured Haemonchus spp. as the most frequent internal parasite. This was a rare situation where the 3 putative species, H. longistipes (dromedary), H. placei (zebu cattle) and H. contortus (sheep and goat) occurred sympatrically. The study was undertaken on hosts slaughtered at the Nouakchott abattoir, on the basis of monthly collection of worms. The environment was very unfavourable to H. placei and unfavourable to H. contortus, as intensity of infection remained low throughout the year, whereas infection in the dromedary was 10 to 20-fold higher. The survival strategies during the long, dry season were different: the surviving stages were either 4th-stage larvae in digesta (dromedaries), 4th-stage larvae either in digesta or mucosae (cattle), or 4th-stage larvae in mucosae and few adults (sheep and goats). The prolificacy of female worms, indicative of the potential to contaminate pastures, was similar for all Haemonchus spp. in the rainy season. H. longistipes behave differently during the pre-rainy season as no increase of prolificacy could be demonstrated as observed in the other species. Traits of vulvar morphology are considered as markers of ecological adaptation and were studied. The knobbed and smooth female morphs (in equal proportions) were the most frequent in H. longistipes, the knobbed morph out-numbered the other morphs in H. placei, and all 3 morphs were present in sheep and goats with the linguiform form being predominant. Genetic characterization of the 3 species was performed by means of Random Amplified Polymorphic DNA (RAPD). Three groups were obtained from analysis of these data: 1 group with individuals of H. contortus, 1 group with individuals of H. placei, and 1 group with individuals of H. longistipes. This indicated that, although the 3 species were valid, H. contortus and H. placei were more similar. Intraspecific variability was 2-fold higher in H. contortus than in the 2 other species. The ecological, morphological and genetical studies showed that H. longistipes, H. placei and H. contortus could be arranged in increasing order of variability.

Adaptation, Physiological↗

PubMed1995

Ketamine plus midazolam, a most effective paediatric oral premedicant.

Healthy children, 1.5 to seven years old, were divided into three groups of 20 each. Group 1 received midazolam 0.5 mg.kg-1, Group 2, ketamine 6 mg.kg-1 and Group 3 a mixture of midazolam 0.4 mg.kg-1 + ketamine 4 mg.kg-1. Each dose was mixed with atropine 0.02 mg.kg-1 plus an equal volume of cherry syrup and was given orally 20 to 30 min prior to surgery. A grade of 1 (asleep, difficult to arouse), 2 (asleep, easily aroused), 3 (awake, calm), 4 (awake, anxious, occasional cry), or 5 (crying, agitated), was assigned at the time of parental separation and again when mask induction was begun. A grade of 1-3 was considered successful. For parental separation, the mixture of ketamine+midazolam was 100% successful, ketamine 90% and midazolam 75%. Successful mask induction for the mixture of ketamine+midazolam was 85%, midazolam 65% and ketamine 42%. This study indicates that a mixture of ketamine+midazolam is the most effective.

Adjuvants, Anesthesia↗

PubMed1995

Individual fluctuations in efficacy of febantel against Muellerius capillaris in goats.

One hundred and eighty-seven dairy goats originating from 7 farms in western France were treated individually with febantel (probenzimidazole drug) at a dose rate of 5 mg/kg in spring 1991. Individual faecal samples were collected on d 0, 7 and 21 post-treatment and processed for counting first stage larvae of Muellerius capillaris (LPG: larvae per gram of faeces). Eggs of digestive tract strongyles were also counted on d 0 and 7 (EPG: eggs per gram of faeces). Blood samples were taken on d 0 to assess pepsinogen concentration related to abomasal damage caused by strongyle infection. The individual characteristics of the goats were recorded. The procedure was repeated on the same animals in autumn 1991. The faecal larval count reduction (FLCR) was mainly related to farm and season: farm 1 in the spring and farm 6 in the autumn showed a higher proportion of high responder (HR) goats (FLCR > 80%), whereas farm 3 exhibited a lower proportion of HR goats in the autumn. On the other hand, the characteristics of the goats (breed, physiological status, age, weight, presence or absence of wattles and horns) as well as the initial level of parasitism (LPG, EPG and pepsinogen concentration) all had a role which was limited or zero on the variability of response to treatment. Goats could not be individually categorized according to their response level because the FLCR values obtained in the spring were not repeated in the autumn, suggesting that other environmental parameters could be involved.

Animals↗

PubMed1995

Experimental study of survival strategy of Haemonchus contortus in sheep during the dry season in desert areas of the Mauritania.

The survival of the most common worm of sheep and goats of desert areas, Haemonchus contortus, during the dry season is of the utmost importance. It may be achieved through long survival of adult worms that may preserve their ability to excrete viable eggs or to inhibited development in host and survival as a larval stage. Twelve lambs were experimentally infected with larvae obtained at the end of the rainy season. The resulting adult worms were able to survive and maintain their ability to produce viable eggs that developed into infective larvae up to 50 wk after infection. It is concluded that survival of adults during the dry season played a major role in transmission from 1 rainy season to the next, rather than inhibited development and survival as a larval stage.

Animals↗