Search PubMed⌕ Search

Biomedical subjects

P Nansen

Publications and source records attributed to P Nansen.

At least 235 records · Page 13Linked to original sources
PubMed1986

Clinical pathology of Schistosoma bovis infection in goats.

The clinical pathology of Schistosoma bovis infection in West African Dwarf goats was studied for 14 weeks following experimental infection. The length of the prepatent period was six weeks and the size of the egg output reached a maximum around eight to 10 weeks after which it diminished markedly. Heavily infected animals showed reduced serum albumin, haemoglobin and packed cell volume values from week 6 to 8 onwards, but eosinophilia was not a striking feature. Liver lesions were moderate in that only 10 to 15 per cent of the total tissue egg load was confined to the liver, and neither gamma-glutamyl transpeptidase levels nor bromsulphalein clearance rates were significantly changed. However, the infected animals had markedly reduced growth rates. The results obtained in the present study are compared with those from a similar study in another breed of goats using another strain of S bovis.

Animals↗
PubMed1986

Epidemiological studies on Schistosoma bovis in Iringa Region, Tanzania.

Various aspects of the epidemiology of Schistosoma bovis were studied over a one-year period in Iringa Region, Tanzania. An abattoir survey revealed an overall prevalence rate of 30.8% in cattle and 3.8% in goats in the area, and field studies on two dairy farms both providing good opportunities for schistosome transmission provided information concerning the transmission ecology of S. bovis in relation to different types of grazing and water supply. The traditional management system on one farm with a large number of cattle utilizing a limited water resource highly suitable for sustaining populations of the snail host Bulinus africanus resulted in intensive transmission as evidenced by uptake of massive infections in calves and development of resistance to S. bovis challenge in dairy cows. On another farm, appropriate management comprising watering of cattle at a B. africanus-free pond provided the background for less intensive transmission in that transmission risk was confined to occasional contact with water contact sites of secondary importance. Besides, the transmission pattern as regards intensity and seasonality was affected markedly by the geographical and seasonal distribution of the host snail B. africanus. Thus, transmission in canals and temporary ponds was limited mainly to the dry season and the end of the rainy season, respectively, while transmission in permanent ponds occurred intermittently throughout at least most of the year. It is concluded that prevention of severe loss of productivity in domestic ruminants due to schistosome infections should be possible using strategic management procedures provided that essential information is available concerning the pattern of transmission in the particular area.

Abattoirs↗
PubMed1985

Suppression of Babesia microti infection in mice concurrently infected with Fasciola hepatica.

Blood cell parasitaemia of Babesia microti and the associated haematological changes were examined in mice harbouring patent Fasciola hepatica infections and in fluke-free control mice. B. microti parasitaemia was markedly suppressed in mice harbouring primary 7-week F. hepatica infections, as reflected in a reduction in the percentage of erythrocytes parasitised and in the incidence of multiple B. microti infections in the red cells. This suppression was accompanied by an annulment of B. microti induced reductions in haemoglobin and haematocrit levels in F. hepatica infected mice. In naive recipient mice, inoculated with blood from mice concurrently infected with F. hepatica and B. microti, the course of B. microti infection was characterised by a prolonged pre-parasitaemia period, a reduced peak parasitaemia and a delayed fall in haematocrit levels as compared to those inoculated with blood from mice infected with B. microti only. This feature may presumably be dose-related. The present study does not reveal the actual mechanism(s) involved in the suppression of the blood protozoan by F. hepatica. However, since B. microti has a preference for mature erythrocytes, the suppression may be a result of the altered erythrocyte kinetic state induced by the removal of erythrocytes by the blood-sucking fluke resulting in high levels of reticulocytes.

Animals↗
PubMed1985

Laboratory experiments to evaluate the ability of Arthrobotrys oligospora to destroy infective larvae of Cooperia species, and to investigate the effect of physical factors on the growth of the fungus.

Laboratory investigations were designed to study the influence of temperature, pH and oxygen tension on the growth of Arthrobotrys oligospora, a nematode-trapping microfungus. Experiments were performed to evaluate the potential role of A. oligospora in destroying third-stage larvae of Cooperia spp. on agar plates and in cattle faeces. The fungus had a growth rate optimum at 23 degrees C and pH 6. Anaerobic cultivation for 23 hours at 23 degrees C and 39 degrees C inhibited fungal growth, but it did not destroy the fungus, which regained growth upon a subsequent shift to aerobic conditions at 23 degrees C. Under experimental conditions in petri-dishes containing agar, the nematode-trapping efficiency of the fungus was striking in that 100% of a population of third-stage larvae of Cooperia spp. was captured within three days of the experiment. The trapping efficiency in faeces was shown to depend upon the inoculation level. At a concentration of approximately 2500 conidia per g faeces, 99% of the larvae were destroyed. The possibilities of using nematode-trapping fungi in controlling animal-parasitic nematodes are discussed.

Animals↗
PubMed1985

A comparison of the efficiency of the percutaneous and per-oral routes of infection in caprine Schistosoma bovis infections.

The comparative efficiency of the percutaneous and per-oral routes of infection was studied in goats experimentally infected with Schistosoma bovis. The heaviest infection was obtained by the percutaneous route, but a relatively high parasite load was also achieved by the per-oral route, i.e., where goats were allowed to drink a cercarial suspension, volume of 0.9 to 1.7 litre per animal. Studies using radio-isotopically labelled cercariae were designed to clarify the cercarial penetration sites following uptake by drinking. Radioactivity could be demonstrated in the outer lips, buccal cavity, oesophagus and the reticulum, omasum and rumen. Highest counts were recorded in outer lips, reticulum and rumen constituting 41.2, 22.1 and 20.6%, respectively, of total radioactivity recovered. It is concluded that the per-oral infection route may play a larger role than hitherto anticipated in infection of ruminants, and possibly also in other mammals, with schistosomes. The epidemiological implications of the present findings are discussed.

Animals↗
PubMed1984

Trypanosoma brucei-induced blockage of expulsion of Echinostoma revolutum and of homologous E. revolutum resistance in mice.

Experiments were designed to study the effect of Trypanosoma brucei on the expulsion of Echinostoma revolutum and on the development and maintenance of homologous E. revolutum resistance in the mouse. T. brucei given 3, 2, and 1 wk before and 1 wk after infection with E. revolutum completely inhibited the expulsion of the E. revolutum worm burden for a period of at least 6 wk following infection, and T. brucei given 2 or 3 wk after infection with E. revolutum conferred a significant delay in the expulsion of the E. revolutum worm burden. T. brucei given 1 wk before and 1 wk after a primary E. revolutum infection blocked completely the resistance of the mouse to a homologous E. revolutum challenge given 2 wk after the primary infection. A similar blockage of resistance to a homologous challenge was experienced by mice given T. brucei 3 wk after the primary E. revolutum infection and challenged following another 2 wk. The mechanisms underlying the T. brucei-induced interference with the expulsion of E. revolutum and with the development and maintenance of homologous E. revolutum resistance in mice are presumably immunologically mediated.

Animals↗
PubMed1983

Comparison of three routes of administration of a water soluble anthelmintic: levamisole.

The plasma concentration of levamisole was determined by liquid chromatography in three groups of 20 heifers treated with levamisole by intramuscular administration, drenching and in drinking water respectively. Maximum concentrations were observed at three hours (1.10 +/- 0.16 microgram/ml) and six hours (0.64 +/- 0.06 microgram/ml) after intramuscular administration and drenching respectively. Large individual variations in plasma concentrations were observed following treatment in drinking water with four animals showing maximum concentrations below 0.1 microgram/ml. Variation in water intake therefore makes the latter method less reliable.

Administration, Oral↗
PubMed1982

Schistosoma intercalatum (Fisher, 1934) infection in sheep.

Parasitological and clinico-pathological aspects of Schistosoma intercalatum infection in sheep were studied after exposure to 5000 cercariae per animal. It was shown that the infection, in spite of relatively high tissue egg counts, only gave rise to low-grade clinico-pathological manifestations with almost unaffected blood parameters. The parasites were mainly located in the lower part of the intestinal tract, and the number of eggs being passed in faeces was very low.

Animals↗
PubMed1982

Clinical pathology of Schistosoma bovis infection in sheep.

The clinical pathology of Schistosoma bovis infection in sheep was studied for a period of 16 weeks. The length of the prepatent period was 10 weeks, and reduced haemoglobin and packed cell volume values and increased serum gammaglutamyl-transpeptidase levels were observed from eight to 10 weeks after infection and onwards. The bromsulphalein clearance rate was significantly reduced 16 weeks after infection. Eosinophil counts were increased six and eight weeks after infection and towards the end of the experiment.

Animals↗
PubMed1981

Further studies on resistance to Fasciola hepatica and Echinostoma revolutum in mice infected with Schistosoma sp.

Schistosoma sp. induced cross-resistance to a challenge with Fasciola hepatica and Echinostoma revolutum was studied in mice. Primary patent 56-days-old S. intercalatum and S. bovis infections stimulated a statistically significant level of resistance to a challenge with F. hepatica, and primary patent 100-day-old S. bovis infections induced an almost complete resistance to a challenge with E. revolutum. Primary single-sex S. mansoni infections, either male or female, aged 90 days did not stimulate any resistance to a challenge with E. revolutum. A primary infection with S. mansoni aged 70 days induced a marked reduction (94.1--100%) in the E. revolutum worm recovery already 2 h post-challenge as compared with that of the E. revolutum challenge control group and complete elimination of the echinostome worm population in S. mansoni infected mice had taken place 24 h after challenge. E. revolutum worm populations established in mice harbouring newly patent 36-day-old S. mansoni infections persisted unchanged for a period of at least 33 days into the patent period of the schistosome infection in spite of development of a complete resistance to a challenge with E. revolutum metacercariae during this period.

Animals↗
PubMed1981

Resistance to Fasciola hepatica in sheep harbouring primary Schistosoma bovis infections.

A substantial level of resistance to a heterologous challenge with Fasciola hepatica was demonstrated in sheep harbouring primary non-patent (two- to three-week-old) and newly patent (seven- to eight-week-old) Schistosoma bovis infections, the liver-fluke burdens being reduced by 70% and 93%, respectively, (p less than 0.01) in these groups compared with that of the challenge control group. The resistance was also reflected in less pronounced F. hepatica-induced liver damage and presumably also in a reduction of the egg-production capacity per established liver-fluke. In contrast, a corresponding heterologous resistance to challenge with F. hepatica could not be demonstrated in sheep harbouring primary 16- to 17-week-old S. bovis infections. Possible, presumably immunological, mechanisms involved in the observed cross-resistance are discussed, as is the possible practical relevance of this cross-resistance phenomenon in attempts to vaccinate sheep against F. hepatica.

Animals↗