Search PubMed⌕ Search

Biomedical subjects

K Pfister

Publications and source records attributed to K Pfister.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Epidemiology of gastrointestinal helminthiasis in small ruminants in the tree-cropping pasture zone in Senegal].

An epidemiological survey on gastrointestinal helminthiasis in 51 sheep and 51 goats was held in the tree-cropping pasture region in Senegal from October 1990 to September 1991. All the animals examined were infected with at least 1 helminth species. Three trematodes (Fasciola gigantica, Schistosoma bovis, Amphistomatids), 2 cestodes (Moniezia expansa, Cysticercus tenuicollis) and 9 nematodes were identified. The most important parasite in sheep was Haemonchus contortus while Trichostrongylus colubriformis predominated in goats. The worm burden in sheep was significantly higher than in goats (P < 0.001). L4 larvae of H contortus were found in 85-87% of the small ruminants. There was a negative correlation between haematocrit, number of worms and egg per gram of faeces during the rainy season. These results show that the gastrointestinal nematode burden is high during the rainy season. During the dry season (9 months) nutritional problems are aggravated by adult worms and residual larvae.

Animals↗
PubMed1995

[Epidemiology of bovine hypodermyiasis in canton Vaud: comparison of two methods of mapping the infestation with a view to strategic treatment].

The geographic distribution of bovine hypodermyiasis in the canton Vaud/Switzerland has been investigated in two ways: By direct examination of the animals by the livestock officers at the 1993 annual census and by ELISA on bulk milk sampled in January 1994. The efficacy of the two methods is compared and the distribution of hypodermyiasis presented on a map. The serological analyses have revealed a highly satisfactory degree of sensitivity and specificity (92.1% and 98.1%, resp.). The epidemiological interpretation however, is rather difficult, partly because quite often the animals are not infested on their farms but rather while being on alpine pastures. A monitoring of the herds with a view to an efficient control of hypodermyiasis could thus in a first instance be based on the indications provided by the livestock officers, whereas a serological monitoring in a second place would allow to detect the last and remaining foci of infestation.

Animals↗
PubMed1995

[Epidemiology of gastrointestinal nematodes in small ruminants in the plateau areas in Togo].

Post-mortem helminthological examinations were performed in Togo on small ruminants of the Djallonké breed (59 sheep, 60 goats), revealing the presence of eight gastrointestinal nematode species which were, in decreasing prevalence order, Trichostrongylus sp. (T. axei and T. colubriformis) (99%), Haemonchus contortus (82%), Strongyloides papillosus (67%), Cooperia curticei (43%), Oesophagostomum columbianum (40%), Gaigeria pachyscelis (36%) and Trichuris ovis (4%). The average worm burden was 1,367 +/- 146 in sheep and 1,133 +/- 102 in goats with an adult worm population peak in August-September (sheep: 2,135 +/- 494, goats: 2,066 +/- 270). During the dry season, Haemonchus contortus and Oesophagostomum columbianum populations were mainly in larval hypobiosis (L4). The number of eggs per gram faeces was usually high (> 3,000) and neither the species nor the age of the host (6 months to 3 years) played a significant role in helminth abundance.

Animals↗
PubMed1994

Frequency of trypanosomosis and gastrointestinal parasites in draught donkeys in The Gambia in relation to animal husbandry.

Prevalence of trypanosomosis, gastrointestinal strongyles and level of strongyle egg outputs were studied in relation to husbandry practices in the draught donkey population in The Gambia. Feeding regime, number of working hours per day and overnight penning practices of donkeys affected significantly (P < 0.05) the level of gastrointestinal strongyle egg output, but not (P > 0.05) trypanosomosis prevalence. Dual trypanosome and gastrointestinal strongyle infection significantly reduced the PCV (P < 0.001). Animals positive for gastrointestinal strongyles alone did not show a significantly (P > 0.05) lower PCV than those found negative. Husbandry practices to improve the situation are recommended.

Animal Husbandry↗
PubMed1994

Prolonged suppression of trichostrongyle egg output of N'Dama cattle by a single larvicidal treatment.

Gambian village cattle herds were treated with a single dose of ivermectine (Ivomec, MSD-AGVET Inc. 1 ml/50 kg body weight) during the dry season. This treatment suppressed the trichostrongyle egg rise prior to the rains and led to delayed egg production for at least 6 months after the onset of the rainy season, compared to untreated animals from neighbouring villages. However, the results clearly indicate that a single treatment with ivermectine during the dry season does not lead to complete suppression of the gastrointestinal strongyle infections, since a worm population still gradually built up. During the second year the ranked level of the egg excretion was significantly lower than that of the control group throughout the year until December, except in August. The results further support the hypothesis that trichostrongyle reinfection is unimportant during the dry season in this climatic zone.

Animals↗
PubMed1994

[Quasi-absence of trichostrongylid reinfection in Gambian livestock during the dry season].

Five Ndama bulls aged between 1.5 and 2 years and 20 Djallonke rams aged between 6 to 18 months were dewormed as follows: the bulls were dewormed in November (beginning of the dry season), the sheep were divided into four groups dewormed in November, January, March and May respectively. The animals were kept on naturally infected pastures prior to and throughout the experiment. Gastrointestinal nematode egg excretion was measured weekly after starting the treatment. Egg excretion stayed practically nil for all animals except for the series of sheep treated in May which started excreting eggs on month after the first rain. The bulls were slaughtered in June and the sheep were slaughtered nine weeks after they had been initially dewormed. A complete parasitological post mortem examination confirmed the absence of any pathologically consequent reinfection by gastro-intestinal nematodes of Gambian cattle during the dry season. This confirms the strategic importance of the application of a dewormer also efficient against immature trichostrongylids at the beginning of the dry season and renders complementary deworming between November and May superfluous.

Animals↗
PubMed1993

Parasite spectrum and seasonal epidemiology of gastrointestinal nematodes of small ruminants in The Gambia.

One hundred and four post mortem examinations of randomly selected sheep (52) and goats (52) were carried out weekly from March 1990 to February 1991. Gastrointestinal parasites were identified and counted. A large spectrum of 16 helminth species was found in 101 (97%) infected animals. The nematodes infecting small ruminants were, in order of predominance: Trichostrongylus colubriformis (96% of all animals), Oesophagostomum columbianum (82%), Haemonchus contortus (67%), Strongyloides papillosus (55%), Gaigeria pachyscelis (38%), Cooperia spp. (49%) and Trichuris ovis (12%). Forty-five (43%) necropsies revealed an infection with Moniezia benedeni, Avitellina centripunctata or Stilesia globulosa. Infections with Schistosoma bovis and Paramphistomum spp. were rarely seen. Goats carried significantly lower worm burdens than sheep and were less often infected by tapeworms. Nematode worm burdens followed a similar seasonal pattern in both host species. While Trichostrongylus colubriformis was also recovered in high numbers in the mid dry season, other species such as H. contortus, Strongyloides papillosus and Oesophagostomum columbianum reached distinct peaks in the rainy season (July-October). Different survival strategies for the prolonged dry season were observed. Haemonchus contortus outlived the unfavourable climatic conditions as inhibited larvae in the abomasal mucosa, while the other nematode species survived as adults with a reduced fecundity. Egg production per adult worm specimen was found to depend heavily on the season and egg counts in the dry season (November-June) did not correspond to the size of worm burdens. Unexpectedly high worm burdens were recovered from adult and old animals. Investigations of young animals indicated that no reinfection can occur during the dry season. The findings are discussed with regard to their relevance for strategic control of gastrointestinal nematodes in small ruminants.

Abomasum↗
PubMed1993

[Efficacy of the oral antiparasitic mebendazole plus trichlorfon (telmin plus trichlorfon) against Gasterophilus in the horse].

The combined drug Mebendazole plus Trichlorfon (Telmin plus Trichlorfon, Janssen Pharmaceutica, Beerse/Belgium) has been tested in a field trial against naturally acquired Gasterophilus spp. infestations in horses. 44 foals (1 to 1.5 years old, 350-450 kg body-weight) originating from different endemic areas of Switzerland, have been randomly allocated to two groups as follows: 28 foals were treated with Mebendazole plus Trichlorfon, 16 animals served as untreated controls. The drug (paste) was administered and dosed according to the user's instruction. Macroscopic examinations of the digestive tractus and the larval counting has been performed immediately after slaughtering, i.e. 30 and 33 days after treatment, resp.. The efficacy of the product against Gasterophilus spp. amounts to 97.04% which is considered as highly effective. A further proof for the high efficacy is the observation of a lot of larvae-carrying foals in the control group. Since the larvae of Gasterophilus spp.--according to their life cycle--are essentially found in their hosts between November and February, an appropriate treatment should be performed during that period of time.

Animals↗
PubMed1993

[Endoparasites--prevention in ungulates in fenced enclosures: experiences with a pilot project in the Dählhölzli Zoo in Bern].

In the animal zoo Dählhölzli Berne all ungulates are continuously monitored since 1984 (qualitatively and quantitatively) in the context of an epidemiological study on gastrointestinal strongyles. Fecal sampling occurs every two weeks in the "parasite risk group", every four to six weeks in the so called "non-risk group". Risk group-animals repeatedly show increased fecal egg counts, whereas among non-risk group-animals only ascarid eggs in Przewalski-horses and wild boars can become significant. The animals are treated (metaphylactically) only at a high egg production or at a steadily increasing egg production. A resulting slight but constant reinfection allows the build-up of an immunity, leading thereby to a decreased frequency of treatment. During the monitoring period (1984-1990) only four animals out of 80 post-mortem analysed animals had a diagnoses of an endoparasitoses as a cause of death.

Animals↗
PubMed1992

The interaction of Trypanosoma congolense and Haemonchus contortus infections in trypanotolerant N'Dama cattle.

The interactions between Trypanosoma congolense and Haemonchus contortus infections were studied in N'Dama calves. A total of 38 N'Dama bulls was divided into four groups and each group infected either with H. contortus 1 week after infection with T. congolense or with T. congolense 4 weeks after infection with H. contortus, or with either infection singly. Parasitological (faecal egg counts, parasitaemia), haematological (packed cell volume, white blood cell counts, albumin) and clinical parameters (body weight change, mortality rate) were compared among the various groups. The results showed a reduced prepatent period and a markedly increased pathogenicity of H. contortus infections in animals with a concurrent T. congolense infection. The most harmful combination was a H. contortus infection 1 week after the T. congolense infection which resulted in a progressive and severe anaemia, accompanied by hypoalbuminaemia, increased weight loss and high mortality. The anaemia induced by dual infections showed a low responsiveness to chemotherapy and in several cases supportive treatment did not help recovery. The results also showed that animals with a concurrent T. congolense and H. contortus infection ran a higher risk of succumbing during the infection, and also during 10 weeks following treatment. Although infections with T. congolense alone produced no clinical signs, they were found to significantly reduce the ability of infected animals to mount a normal response to a subsequent H. contortus infection. It was concluded that the increased H. contortus egg excretion observed in animals infected with both parasites might significantly increase the risk of nematode infections and that the reduced prepatent period might necessitate more frequent anthelmintic treatments. These interactions should, therefore, be considered wherever attempts are made to control these two diseases.

Animals↗
PubMed1991

Cellular reactions in the small intestine of rats after infection with Fasciola hepatica.

Groups of five rats each were infected with metacercariae of Fasciola hepatica according to two experimental procedures. In the first experiment, they received 20 metacercariae 0, 1, 2 or 3 times at intervals of 4 weeks. In the second, both the inoculation dose and the interval between doses were varied. After the animals had been killed, the small intestine was prepared for histology and tissue sections were stained for the detection and quantification of mucosal mast cells (MMCs), eosinophils and goblet cells. The density of eosinophils and MMCs increased significantly with each reinfection in the first experiment; in the second, the MMC reaction reached a peak at 4 weeks post-infection (p.i.), whereas the eosinophils peaked at 4 and 17 weeks p.i. In addition, the reaction of these cells depended on the infectious dose. In both experiments, goblet cells reacted only weakly. These findings thus clearly reflect a considerable intestinal response against migrating juvenile F. hepatica. The pattern of these defence reactions in the small intestine suggests some similarities with the mechanisms of antibody-dependent cell-mediated cytotoxicity that have been shown to take place during Schistosoma mansoni reinfection.

Animals↗
PubMed1991

[The epidemiology of gasterophilosis of horses in Switzerland].

Between March 1988 and December 1989, 198 gastrointestinal tracts from slaughtered horses from different areas of Switzerland have been analysed for the presence and the frequency of Gasterophilus spp. During the same period--always between July and November--200 horses from selected areas of Western Switzerland have been checked for the presence of eggs and their subsequent developmental stages in order to investigate further clinical and biological aspects of this infection. The evaluation has been performed according to origin, age, sex, colour of the horse and seasonal pattern of the cases and the various larval stages, respectively. The prevalence of Gasterophilus spp. amounts to 64.6%, showing a marked seasonal distribution. Only Gasterophilus intestinalis has been detected and the Western part of Switzerland appears to be considerably more contaminated than the other areas of the country. The reasons are discussed. It is possible that an intensive horse-traffic at the border is partly responsible. Horses with a dark coat are more often parasitized whereas no difference occurs with regard to age and sex. The observed high prevalence of this parasite infection in the Swiss horse population confirms that gasterophilosis has to be taken into serious consideration and prophylactic measures might be indicated.

Animals↗
PubMed1991

[Intestinal cellular reaction of cattle after infection by Fasciola hepatica].

Defence reactions of cattle against Fasciola hepatica take place not only in the liver but also on a prehepatic level. The aim of the present experiments is to identify and quantify the cellular response in the small intestine. Five groups of two bulls (Simmental x Red Holstein, 6 months old) were infected by oesophageal probe with metacercariae of F. hepatica (MC) according to two experimental procedures. Two groups of bulls served as controls. In the first experiment both infected groups received 1000 MC once or twice at an interval of five weeks. The intestinal tissue was taken before infection and 5, 10 and 19 weeks p.i., respectively 5 and 14 weeks p. reinf. (p.ri.). In the second experiment, three infected groups received 400, 2 x 400 MC (at an interval of five weeks) and 800 MC respectively. Biopsies were taken one week ante infectionem, 6, 11 and 19 weeks p.i., respectively 1, 6 and 14 weeks post reinfectionem (p. ri.). The biopsies of the small intestine were prepared for histology and the tissue sections stained as follows: Astra blue for mucosal mast cells (MMC), Lendrum for eosinophils (EOS) and Periodic Acid Schiff (PAS) for goblet cells (GC). The density of the three cell populations in the mucosa was determined microscopically and quantified. In both experiments the density of the MMC and EOS increased with each reinfection and depended on the infectious dose. There was no significant variation of the GC-numbers. The described intestinal cellular reactions suggest a participation of the small intestinal wall in the immunity against the common liver fluke.

Animals↗
PubMed1990

The seasonal epidemiology of gastrointestinal nematodes in N'Dama cattle in The Gambia.

From June 1987 to June 1988, a total of 180 N'Dama cattle were necropsied to identify and enumerate parasites present, including 39 sick calves and 25 dead calves from local village herds, and 116 adult cattle from a local abattoir. Of 175 animals infected with one or more helminths (97%), Haemonchus contortus was found in 67% of all necropsied animals, Cooperia punctata in 75%, Cooperia pectinata in 55%, Oesophagostomum radiatum in 71% and Bunostomum phlebotomum in 21%. There was a wide range of worm burdens (0-22 925) and a pronounced seasonal pattern occurred. Eighty-two percent of the total adult Haemonchus burden occurred during the rainy season (June-October). By the end of the rainy season, almost 100% of the Haemonchus burden was present as inhibited larvae. By contrast, a different survival strategy appeared to occur in Cooperia spp.; Oesophagostomum spp. and Bunostomum spp., which were found as adults throughout the year. Results indicated that, apart from malnutrition during the dry season, gastrointestinal nematode infections, especially haemonchosis, represent a major constraint on the health and productivity of N'Dama cattle under West African savanna conditions.

Abomasum↗