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Biomedical subjects

P Nansen

Publications and source records attributed to P Nansen.

At least 163 records · Page 9Linked to original sources
PubMed1995

Development of the free-living stages of Hyostrongylus rubidus and Oesophagostomum spp. at different temperatures and humidities.

Faeces containing a mixture of Hyostrongylus rubidus and Oesophagostomum spp. eggs were mixed with vermiculite and water and set up at combinations of different relative humidities (65.5%, 79.5% 90.0%, and 100%) and temperatures (5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C) in order to study the rate of egg hatching and larval development. The study established that the development from egg to infective larva showed similar patterns for the two parasites. Optimum development and survival was in the temperature range from 15 degrees C to 20 degrees C and at humidities from 79.5 to 95.5%.

Animals↗
PubMed1995

The prevalence of Taenia solium metacestodes in pigs in northern Tanzania.

Eighty three carcasses of pigs were examined at three abattoirs in Moshi, Arusha and Mbulu in northern Tanzania. Taenia solium metacestodes were found in all the three abattoirs with an overall prevalence of 13.3%. During routine meat inspection in Kiboroloni, Moshi 6.2-6.9% of the pigs were found to harbour T. solium metacestodes. The mean number of hooks on the protoscolices was 27 and the length of the small hooks varied from 105 microns to 130 microns while that of the larger hooks varied from 168 microns to 174 microns confirming that the cysts were metacestodes of T. solium. Although cystlike lesions were recovered from livers of both pigs and cattle, no hooklets of sizes in the range of 5-37 microns were found indicating that no Taiwan Taenia metacestodes were recovered during carcass examination.

Abattoirs↗
PubMed1995

Experimental transfer of adult Oesophagostomum dentatum from donor to helminth naive recipient pigs: a methodological study.

This study was carried out to compare potential methods of transplanting adult Oesophagostomum dentatum from experimentally infected donor pigs to helminth naive recipient pigs. The following methods were each tested in five pigs: A. Transfer of worms by stomach tube to the gastric ventricle of pigs per os pretreated with 0.5 mg/kg cisapride to increase gastrointestinal peristalsis; B. Transfer by stomach tube to the gastric ventricle of pigs per os pre-treated with cisapride (0.5 mg/kg) and omeprazol 20 mg which blocks hydrochloric acid secretion; C. Surgical transfer of worms to caecum of pigs. Worms for transplantation to pigs were obtained after slaughter of experimentally infected donor pigs and following isolation from the contents of the large intestine, using an agar gel migration technique. A mean of 1054 nematodes were transferred into each recipient pig within 2 hours. Procedures A and B resulted in establishment rates corresponding to only 0.5% and 7.6% of the transferred worms. In contrast, surgical transfer allowed 74.2% of the transplanted worms to be established. In all groups the transplanted worms migrated to the normal predilection site, i.e. the middle part of the large intestine. More female than male worms established in all groups. It was concluded from this study that surgical transfer was the most reliable of the methods tested for experimental establishment of adult O. dentatum in helminth naive pigs.

Animals↗
PubMed1995

Trichinella infections in arctic foxes from Greenland: studies and reflections on predilection sites of muscle larvae.

Studies were carried out to determine the predilection sites of Trichinella nativa muscle larvae in arctic foxes (Alopex lagopus) caught in Greenland. The highest number of larvae per gram of tissue was found in the muscles of the eyes and the legs. With regard to predilection sites no significant differences were demonstrated either between age groups or between foxes with high and low total parasite burdens. Predilection sites were comparable with those recorded earlier in experimentally infected caged foxes and in other carnivorous species. Hypotheses on predilection sites of Trichinella muscle larvae are discussed.

Animals↗
PubMed1995

The effect of two types of diet on populations of Ascaris suum and Oesophagostomum dentatum in experimentally infected pigs.

This investigation compared the effect of two common types of diet on worm burdens and faecal egg counts of pigs inoculated with Ascaris suum and Oesophagostomum dentatum. The diets were both considered nutritionally sufficient for pigs of this age, and gave high and comparable growth rates. Pigs were inoculated with both worm species at 14 weeks of age and slaughtered 3 or 12 weeks later. At 3 weeks, A. suum larvae were numerous in the small intestine of pigs fed ground barley plus protein supplement, but were not detected from pigs fed a commercial full-constituent pelleted feed. At 12 weeks, however, average adult worm burdens were low and similar in both groups. At both slaughter times, O. dentatum worm burdens were significantly higher in pigs fed barley plus protein than in pigs given commercial feed, particularly for female worms, and the commercial diet led to worms being located further along the large intestine, and to reduced worm fecundity. The chemical composition of large intestinal contents differed significantly between pigs fed the two diets.

Animal Feed↗
PubMed1995

Immunodiagnosis of Taenia saginata in cattle using hydrophobic antigens from T. hydatigena metacestode cyst fluid.

Hydrophobic fractions isolated from cyst fluid of Taenia hydatigena metacestodes, obtained from naturally infected goats from Tanzania, were used in an indirect ELISA and in immunoblot (Western or dot blot) procedures. The use of the most hydrophobic fractions of the cyst fluid proved to result in a better diagnostic discrimination in ELISA than the more hydrophilic fractions. Best diagnostic ratio between responses from T. saginata infected and non-infected cattle was achieved when using horse-radish peroxidase-labelled sheep antibovine IgG1 as the conjugate. When the hydrophobic fractions of T. hydatigena cyst fluid were employed as antigen in ELISA, no cross-reaction took place with sera from cattle infected with Fasciola hepatica, Ostertagia ostertagi, Cooperia oncophora, Dictyocaulus viviparus, Sarcocystis cruzi or a mixture of D. viviparus, Trichostrongylus axei and Eimeria. Using the Western blot technique, specific low molecular weight components (M(r) 10-18 kDa) of the hydrophobic fractions of the cyst fluid were reactive with sera from 14 of the 21 calves infected with T. saginata for 60 days. Also, hydrophobic fractions of T. hydatigena cyst fluid were dotted onto strips of filter membranes and reacted specifically with sera from 21 calves infected with T. saginata. This technique resulted in the highest sensitivity, detecting 17 of the 21 calves infected with T. saginata. Calves harbouring as few as 16, 26, 43, 53 and 74 cysts could be detected. Thirteen calves harbouring between 74 and 2,545 cysts were all detected. However, 4 calves harbouring 2, 22, 52 and 66 cysts, respectively, were not detected. The potential of using a dot blot technique in large scale investigations in the tropics is present. However, before accepting any of the three tests in the tropical environment, a broader spectrum of helminth infections should be evaluated for their eventual cross-reactivity.

Animals↗
PubMed1994

Epidemiology and control of helminth infections in pigs under intensive and non-intensive production systems.

Swine production systems are characterised by a high diversity with regard to management type and the level of intensity of management. The number of helminth species and their infection levels are strongly influenced by the different systems. The present paper focuses on the situation in northern Europe, with examples from Denmark, and describes a decrease in both the number of helminth species and in their infection levels as a result of a shift from non-intensive to highly intensive production systems. Differences in the basic biological requirements of the pre-infective larvae, and in the transmission characteristics and immunogenicity of the various helminth species, explain why some species are more vulnerable to manage mental changes than others. Finally, control measures for the different production systems are discussed. Even though it is well documented that proper hygiene and management may prevent transmission of helminths, use of anthelmintics is still the single most important action taken by pig farmers to control worm infections. It is emphasised that anthelmintics should not be used uncritically, but should be integrated with management practices and the production system to achieve optimum effect and to avoid development of anthelmintic resistance.

Animal Husbandry↗
PubMed1994

Effect of papaya latex against Ascaris suum in naturally infected pigs.

An experiment was carried out to investigate the anthelmintic activity of papaya latex (Carica papaya) against natural infection of Ascaris suum in pigs. Sixteen naturally infected pigs were, on the basis of faecal egg counts and body weight, allocated into four groups, each of four pigs. Three groups (groups B, C, and D) were given papaya latex per os at dose levels of 2, 4, and 8 g of papaya latex per kg body weight, respectively. The fourth group (group A) served as a non-treated control. Results of post mortem counts on day 7 post treatment revealed worm count reductions of 39.5, 80.1 and 100% in groups B, C, and D, respectively. Some of the pigs receiving the highest dose of the latex showed mild diarrhoea on the day following treatment. Otherwise, no clinical or pathological changes were observed in the treated animals. The possible future use of this traditional herbal medicine for livestock and humans is discussed.

Animals↗
PubMed1994

An attempt to implement the nematode-trapping fungus Duddingtonia flagrans in biological control of trichostrongyle infections of first year grazing calves.

An attempt was made to control Ostertagia ostertagi by feeding the nematode-trapping fungus Duddingtonia flagrans (DSM 6703) to grazing calves. One group of calves (group E) was fed the fungal material in the first two months of the grazing season while another group was a non-treated control group (group C). Group E showed significantly lower faecal egg count in August and September. On four occasions in July and September, the herbage larval counts were significantly lower on the plot with the fungal-treated group than those recorded on the control plot. The average abomasal larval and adult worm counts were significantly reduced in August in group E and the average total worm count in the abomasum of group E was reduced by 87% in August compared to the non-treated group C. In October, the difference in average abomasal worm counts between group E and C was insignificant. Due to weight loss at the end of the grazing season, the control group showed a significantly lower average weight increase.

Abomasum↗
PubMed1994

Immune responses to nematode exoantigens: sensitizing antibodies and basophil histamine release.

High levels of IgE and eosinophilia are found in both allergy and helminth infections, but allergic symptoms are rare in naturally acquired helminth infections. The interrelation of specific IgE antibodies and in vitro basophil histamine release (HR) induced by exoantigens from the larval stages (L2/L3) of the nematodes Toxocara canis and Ascaris suum was examined in 148 patients visiting an outpatient clinic for parasitic diseases. The antigen sensitivity of the basophils was found to be dependent not only on the absolute amount of antigen-specific IgE present in patient plasma, but also on the ratio between specific and total IgE. Thus, large HR was observed in some patients in response to helminth antigens despite low levels of both specific and total IgE content in plasma. Patients with eosinophilia showed greater IgE-mediated HR than the other patients examined. In contrast, only five patients showed HR after challenge with anti-IgG4, despite the presence of high levels of antigen-specific IgG4 and IgG1 in all patients showing specific IgE antibodies.

Animals↗
PubMed1994

Experimental infection of Danish Landrace/Yorkshire crossbred pigs with Schistosoma japonicum from the People's Republic of China.

This study was undertaken to assess the suitability of Danish Landrace/Yorkshire (L/Y) crossbred pigs as experimental hosts of a Chinese mainland strain of Schistosoma japonicum. Pigs were exposed to 200, 500 or 1000 cercariae and parasite burdens were determined by perfusion after either 8 or 11 weeks. All pigs became infected with onset of faecal egg excretion 6 to 7 weeks following exposure to cercariae. The pattern of faecal egg excretion differed markedly among the individual animals. Gross hepatic pathological lesions of varying degrees were noted in all of the pigs. Schistosome worm recoveries ranged from 1.5-23.4% of the cercarial exposure dose. Most schistosome eggs recovered from the tissues, expressed as eggs/g tissue, were found in the rectum (91%), caecum (3.1%) and liver (5.1%). The results show that Danish L/Y pigs may serve as appropriate experimental final hosts of the Chinese mainland strain of S. japonicum.

Animals↗
PubMed1994

A study on the transmission of Oesophagostomum dentatum and Hyostrongylus rubidus among outdoor reared pigs in Denmark.

This study was carried out to obtain basic information on the transmission of Oesophagostomum dentatum and Hyostrongylus rubidus in outdoor reared pigs in Denmark. Eighteen 10 weeks old worm-free pigs were allocated into 3 groups of 6 pigs each. In May, all pigs were turned out on the same parasitologically naive pasture, and after 2 weeks the pigs in groups 2 and 3 were experimentally infected with 10,800 O. dentatum and 8,700 H. rubidus infective larvae, respectively. Pigs in group 1 served as non-infected controls. All pigs were reared together on the experimental pasture for further 134 days until slaughter in October. Strongyle egg counts, differentiation of infective larvae at species level, serum pepsinogen, and herbage larval infectivity were monitored at regular intervals throughout. Both strongyle species established in the originally parasite-free pigs (group 1) and cross infections were established in group 2 and 3. The pigs were exposed to steadily increasing herbage infectivity of both species of strongyles. At the end of the experiment, geometric mean worm burdens of O. dentatum in groups 1, 2 and 3 were 1202, 6136 and 1431 respectively, the burden in group 2 being significantly higher (p < 0.05) than that of the 2 other groups. The geometric mean worm burdens of H. rubidus in groups 1, 2 and 3 were 4907, 3679 and 5246 respectively, showing no significant differences between groups.

Animal Husbandry↗
PubMed1994

A study on the predilection sites of Trichinella spiralis muscle larvae in experimentally infected foxes (Alopex lagopus, Vulpes vulpes).

Studies were carried out on the predilection sites of Trichinella spiralis muscle larvae in experimentally infected arctic foxes (Alopex lagopus) and silver foxes (Vulpes vulpes) reared in cages. The highest number of larvae per gram tissue was found in the muscles of the legs, eyes, diaphragm, and tongue. The 2 fox species showed no significant differences with regard to predilection sites.

Animals↗
PubMed1993

Response to repeated inoculations with Ascaris suum eggs in pigs during the fattening period. II. Specific IgA, IgG, and IgM antibodies determined by enzyme-linked immunosorbent assay.

Experimental trickle inoculations of pigs with low doses (2 x 25 eggs/week) and high doses (2 x 500 eggs/week) of Ascaris suum were followed by enzyme-linked immunosorbent assay (ELISA) during a 14-week period. Three antigens were employed for coating: hatching fluid of embryonated eggs, excretory/secretory antigens from in vitro-cultivated infective larvae (L2/L3-ES), and adult body fluid. Seroconversion times (week 2 for the high-dose group and week 4 for the low-dose group) were essentially identical for the three antigens. The assay employing L2/L3-ES, however, produced significantly higher readings. Specific serum antibody in the IgA and IgG classes showed very similar time courses in both groups. A weak and transient, specific IgM response was recorded in the high-dose group. Mean ELISA responses to L2/L3-ES did not differ significantly between the groups at the termination of the experiment. Specific antibody correlated weakly with the number of liver milk spots recorded at slaughter.

Animals↗
PubMed1993

The effect of experimental trichostrongyle infections of housed young calves on the subsequent course of natural infection on pasture.

The present studies were designed to investigate whether experimental, mixed trichostrongyle infections of stabled calves prior to their first grazing season could confer sufficient immunity to significantly reduce egg excretion after turnout, and thereby prevent loss-producing infections later on. The study comprised four groups, each of seven calves. During spring, two of the groups received two different dose levels of infective larvae twice weekly, and one group received larger larval doses at monthly intervals. One group served as non-experimentally exposed controls. In May all groups grazed separately on similarly contaminated plots. All experimental groups had reduced egg counts, and herbage infectivity of their plots was significantly lower than that of the controls. These findings were reflected in serum pepsinogen levels and in specific serum antibody responses. Additionally, clinical disease was only observed in the control group animals.

Animals↗
PubMed1993

Experimental concurrent infections with Ostertagia ostertagi and Cooperia oncophora in the calf.

An experiment was conducted to investigate the effects of experimental concurrent infection with Ostertagia ostertagia and Cooperia oncophora compared with the effects of monospecific infections with O ostertagi under conditions designed to mimic natural conditions on pasture during a grazing season. The present experiment was not able to demonstrate any significant effect of C oncophora on the course of an O ostertagi infection. Neither did C oncophora influence the build up of immunity to O ostertagi as demonstrated by post mortem worm count results from challenge infections with hypobiosis-prone larvae.

Abomasum↗
PubMed1993

Serum anti-trichostrongyle antibody responses fo first and second season grazing calves.

Serum anti-Ostertagia ostertagi and anti-Cooperia oncophora antibody responses were assessed in first season and second season calves grazing permanent paddocks. Calves without previous exposure to trichostrongyles were found to mount significant parasite-specific IgG1 antibody responses within two months of introduction to the pastures. A significant serum IgA response to O ostertagi and IgG2 responses to both O ostertagi and C oncophora antigens were also observed, but these responses were weaker. No consistent serum anti-trichostrongyle IgM responses were discernible in either age group. Second season grazing calves had significantly elevated IgG1, IgG2 and IgA antibody levels at turnout when compared to first season calves, but only IgA antibody levels against O ostertagi increased during the second grazing season. Comparison of serum antibody levels in first and second season calves grazed separately or together suggests that mixed grazing had no discernible effect on antigen priming.

Aging↗