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Biomedical subjects

S A Henriksen

Publications and source records attributed to S A Henriksen.

At least 19 recordsLinked to original sources
PubMed1992

Attempts to immunize cattle against Ostertagia ostertagi infections employing 'normal' and 'chilled' (hypobiosis-prone) third stage larvae.

Immunity to Ostertagia ostertagi infections in calves develops slowly and only becomes manifest towards the end of a grazing season in which they have been exposed to the parasite. In an attempt to hasten the onset of immune reactions, three immunization protocols were set up. Twenty four heifers were allocated into four groups. Beginning in January, animals in two of the groups were inoculated with four 1-monthly increasing dosages of either 'normal' or 'chilled' (hypobiosis-prone) larvae, those in the third group received a single large infection with 'chilled' larvae and those in the fourth group served as non-infected controls. All animals were turned out on a common pasture in late April. Development of immunity was evaluated through determinations of faecal egg counts, live weight gains, serum pepsinogen levels and specific serum antibody responses of three isotypes (IgG1, IgG2 and IgA). Significantly reduced egg excretions in the immunized groups were apparent early in the season, indicating that the immunizations had, in this respect, been efficacious. The 'chilled' and 'normal' larvae seemed equally efficient given as multiple and single infections. A single large dosage of 'chilled' larvae seemed to have adverse effects. Only moderate antibody responses were elicited probably because of low challenge infection level on pasture. Considerable variation in responses existed between and within the four groups, for which reason conclusions regarding correlations between antibody isotype responses and immune effects on parasites could not be made.

Animals↗
PubMed1992

In vivo passage through calves of nematophagous fungi selected for biocontrol of parasitic nematodes.

The experiment was designed to test the survival and performance of stress selected nematophagous fungi after passage through the gastro-intestinal tract of cattle. Ruminating calves were fed daily with a fixed amount of fungal material grown on barley grains. The excreted dung was collected on days four and five after the start of the feeding experiment. Barley grains were washed out of the excreted dung and incoculated on water-agar plates. After incubation for one week, nine of ten fungal isolates were re-isolated from these plates. The predatory capacity of the fungi in the excreted faeces was tested in a dung pat bioassay and a faecal culture system. In the dung pat bioassay, two fungi of the genus Arthrobotrys and six of the genus Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by 85% (61%-93%), compared to the number of larvae developed from fungus-free control pats. In seven out of these eight isolates, the reduction of larvae in the faecal cultures was 92% (76%-99%).

Animals↗
PubMed1991

Diagnostic tests for Trichinella spiralis infection in pigs. A comparative study of ELISA for specific antibody and histamine release from blood cells in experimental infections.

A study on the histamine release test (HR) for the demonstration of infections with Trichinella spiralis in pigs was carried out on 18 pigs, six infected with 200 larvae, six infected with 5000 larvae and six non-infected (control group). The results obtained by HR during a 7 week infection were compared with those of the enzyme-linked immunosorbent assay (ELISA). All inoculated pigs were found to be positive on Day 40 post-inoculation (p.i.) by necropsy examination of selected muscle groups, with mean recoveries of 7.9 and 225 larvae g-1 of tissue in the low- and high-dose group, respectively. At this time, all animals of the high-dose group and five out of six animals of the low-dose group were antibody positive in ELISA with any of three coating antigens employed (a crude muscle larva extract, an excretory/secretory (ES) antigen and a purified 45 kDa antigen). HR performed on whole blood was positive in four out of six pigs of the high-dose group and one out of six pigs of the low-dose group. The earliest ELISA seroconversions took place at Day 15 p.i. with crude and ES antigens. The earliest measurable reaction in HR performed on whole blood was found on Day 19 p.i. There was considerable individual variation regarding which test was the most sensitive for the early detection of infection. Washing of the blood cells prior to antigen provocation led to a markedly improved sensitivity of HR, all animals of the high-dose and three out of six animals of the low-dose group being positive by Day 40 p.i. The time course of the development of ELISA titres and HR reactivity indicated that this effect is due to the removal of blocking antibodies.

Animals↗
PubMed1991

In vitro stress selection of nematophagous fungi for biocontrol of parasitic nematodes in ruminants.

Laboratory experiments were designed to select nematophagous fungi that were able to survive in vitro conditions simulating passage through the gastro-intestinal tract of cattle. All of the tests were conducted at 39 degrees C. In a primary stress selection step in diluted rumen fluid, 21 isolates were obtained. Each of the primary stress selected isolates was tested in synthetic saliva, rumen fluid simulating the activity in the rumen, rumen fluid followed by pepsin-hydrochloric acid treatment simulating the additional effect of ruminal and abomasal activity, pepsin-hydrochloric acid solution simulating conditions in the abomasum and finally in a trypsin solution as an example of enzyme activity in the gut. The effect of the rumen fluid alone, or rumen fluid followed by pepsin-hydrochloric acid treatment, were responsible for the reduction in surviving fungal isolates. Only six of thirteen isolates belonging to the genus Arthrobotrys survived while seven of eight isolates of the genus Duddingtonia survived. Fourteen isolates were tested for their predatory capacity in a dung pat bioassay. Fungi of the genera Arthrobotrys and Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by approximately 75% and 96% respectively compared to the number of larvae that developed from fungus-free control pats.

Animals↗
PubMed1991

Evaluation of an enzyme-linked immunosorbent assay (ELISA) for detection of Taenia saginata cysticercosis in cattle.

Serum IgG response of cattle with cysticercosis caused by Taenia saginata was studied in an enzyme-linked immunosorbent assay (ELISA) where a T. saginata metacestode surface extract was used as antigen. In experimentally infected calves, a sharp rise in specific antibody levels was found 3-4 weeks after the infection followed by a logical level of detection corresponded to about 25 cysts. The ELISA was employed in cattle herds where cysticercosis outbreaks had occurred and also in supposedly uninfected herds. Significantly increased antibody levels were found in the herds with massive cysticercosis cases. The test was not adapted for individual diagnosis as some animals of the uninfected herds, especially within the older age groups, had elevated antibody values. The ELISA was, however, useful in the investigation of outbreaks to determine the extent and pattern of the infection in the herd. The rate of decline in antibody levels in these herds was studied by follow up sampling. The increased antibody levels in the infected herds were also reflected in colostrum-fed calves. This observation was employed to estimate the time of infection.

Animals↗
PubMed1991

A case-control study of risk factors in light Taenia saginata cysticercosis in Danish cattle.

Risk factors in light T. saginata cysticercosis in cattle herds were investigated in a case-control study. The case group consisted of farms from which cattle with low-grade cysticercosis had been detected at slaughter. The control group consisted of farms where no cases were detected during the same period. The major risk factor identified was allowing cattle access to drink from streams carrying effluent from sewage treatment plants (odds ratio = 3.6). Spreading of septic tank sludge through deliberate or accidental mixing with animal slurry, deposition of sewage sludge, and proximity to railways, camping sites or sewage treatment plants seemed to be of minor importance.

Animals↗
PubMed1991

Resistance to benzimidazole anthelmintics in small strongyles (Cyathostominae) of horses in Denmark.

This study was undertaken to establish whether anthelmintic resistance was present in nematode parasites of horses in Denmark. Sixteen horse farms were selected for faecal egg count reduction (FECR) tests to measure the efficacy of the anthelmintic used. Resistance to benzimidazole anthelmintics was found on 13 of the 16 farms, with FECR values ranging from 80.0% to -101.3%. On the remaining 3 farms FECR was 100.0%, 99.3% and 97.2%. Results of a questionnaire study on anthelmintic usage, parasite control measures and management practices showed that horses in this study were treated on average 7.1 times/year. Horse owners changed between preparations of drugs but almost only within the same class of anthelmintics. Nine owners gave an anthelmintic treatment to purchased horses before they were introduced on the farm. On 14 farms, the same paddock was grazed every year and the average stocking rate was estimated to be 2.4 horses/ha. Strategies to avoid development of anthelmintic resistance are discussed and recommendations of parasite control on horse farms are presented.

Animals↗
PubMed1990

A comparison of the filtration, concentration, and thick smear techniques in the diagnosis of Schistosoma bovis infection in cattle and goats.

The syringe and the modified Bell filtration techniques, the cellophane faecal thick smear (Kato/Katz) and Teesdale (sandwich) smear techniques, and the formol-ether concentration technique were compared for efficiency for detection of eggs of Schistosoma bovis in faeces from cattle and goats. Both filtration techniques were highly effective as revealed by high sensitivity and mean egg counts. However, efficiency declined markedly using formalin-fixed faecal material. The efficiency of the Teesdale technique was comparable to that of the filtration techniques, whereas the efficiency of the Kato/Katz technique in goats and the formol-ether concentration technique in cattle was markedly lower. The ease of performance combined with the high sensitivity make the syringe filtration and the Teesdale techniques recommendable for field diagnosis of schistosomiasis in domestic stock.

Analysis of Variance↗
PubMed1979

[Dictyocaulus viviparus in Denmark. A survey of 15 years' diagnostic examination of faeces samples (author's transl)].

On the basis of routine diagnostic examinations of 12424 bovine faeces samples for larvae of Dictyocaulus viviparus, performed during the period 1963 through 1977, some calculations and reflections have been made on the incidence and epidemiology of lungworm infection in cattle in Denmark. It seems justified to conclude that dictyocaulosis is an important disease in heifers and cows as well as in calves. A distinct seasonal variation in the incidence of lungworm infection is apparent, in that more than 85% of the faeces samples were submitted within the period July through October. Lungworm larvae could be demonstrated in faeces samples from cattle during the winter and spring- This is considered to be of great importance with a view to re-establishment of the infection in the following grazing season. Overwintering of larvae on pastures seems possible. too, since patent infections among calves were demonstrated already in May and June. A comparison of meteorological data with totals of samples submitted and with relative numbers of positive samples seems to confirm, that both the level and the spread of lungworm infections are influenced by the amount of rainfall during the period June through August.

Animals↗
PubMed1979

[Fasciola hepatica in Denmark. A survey on 15 years diagnostic examination on bovine faeces samples (author's transl)].

The results of routine diagnostic examinations of 10,540 bovine faeces samples for eggs of Fasciola hepatica during the period 1963-1977 are evaluated. 0n an average, 10.4% of the samples were positive. The frequency of positive samples was highest among samples from cows (14.4%) lowest among samples from calves (1.5%). Of samples from heifers 10.1% were found positive. Calculated on a monthly basis, the percentage of positive samples showed a clear seasonal variation, reaching a peak in the period December-March. During the period 1973-1977, the annual percentage of positive samples showed a rather pronounced declining tendency, indicating a decrease in the occurrence of bovine Fasciola hepatica infection in Denmark.

Age Factors↗
PubMed1977

[Buxtonella sulcata, an intestinal ciliate of apparently frequent occurrence in Danish cattle (author's transl)].

Faeces samples from 762 apparently healthy heifers were examined for eggs of Fasciola hepatica (sedimentation test). At the same time possible ciliate cysts were recorded. Such cysts, usually circular, and varying in size from ab. 55 micrometer to ab. 95 micrometer (average ab. 71 micrometer) were found in 71.8 % of the samples. According to morphological descriptions in literature, the cysts observed are supposed mainly to represent the species Buxtonella sulcata. Their presence in faeces samples seems to give no differential diagnostic problems relative to parasite eggs or coccidial oocysts.

Age Factors↗
PubMed1977

Trichinella spiralis in wild boars (Sus scrofa).

During the period 1.7. 1972--31.6. 1977 muscle samples from 137 wild boars were examined for Trichinella spiralis. Larvae of T. spiralis were demonstrated in 4 animals. The major part (83) of the wild boars examined, including the 4 positive ones, originated from one particular game park. The rate of infection with T. spiralis in the game park concerned was 4.8%. Calculated on the basis of the total of animals examined, the rate of infection was 2.9%.

Animal Population Groups↗