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Biomedical subjects

J Zinsstag

Publications and source records attributed to J Zinsstag.

45 records · Page 3Linked to original sources
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

Seroepidemiological study of African horse sickness virus in The Gambia.

An indirect enzyme-linked immunosorbent assay was used for the screening of horse sera from The Gambia for antibodies against African horse sickness virus (AHSV). The AHSV antigen used for coating was semipurified according to the method of Manning and Chen (Curr. Microbiol. 4:381, 1980); control mock-infected Vero cell antigen was treated in the same manner. A total of 459 horse serum samples were assayed at a single dilution (1:10), and their reactivities were compared with those of reference positive anti-AHSV and reference negative horse sera. A total of 81% of the horse serum samples clearly contained antibodies against AHSV; this consisted of 18% (of the total number of serum samples) strongly positive, 46.5% moderately positive, and 16.5% weakly but still clearly positive. Such results suggest a high prevalence of AHSV in the regions from whence the samples originated. Reports from investigations in other countries in this area of West Africa have also shown a high prevalence for anti-AHSV antibodies in equids. The question is raised as to how the animals became seropositive and whether the observations represent an increased resistance of horses living in a region in which AHS is enzootic.

African Horse Sickness↗
PubMed1991

A new photometric assay for testing trypanocidal activity in vitro.

A new in vitro test was developed to assess the trypanocidal activity of compounds against axenically grown Trypanosoma brucei bloodstream forms. Trypanosomes from continuous culture were exposed to series of drug dilutions in a microtiter plate. After an incubation time of 72 h at 37 degrees C, the pH indicator of the medium had changed its colour in non-inhibited cultures due to the production of pyruvate. Inhibited cultures showed less, if any, colour changes. Plates could be read by eye or using an enzyme-linked immunosorbent assay (ELISA) reader. Within the pH range of 7.0-7.5, the extinction values of phenol red at 560 nm showed a linear correlation with both the pH of the medium and the pyruvate concentration in the medium. By comparison of the decreases in extinction in test cultures with those in control cultures, IC50 values (drug concentrations causing 50% inhibition) could be determined. Minimal inhibitory concentrations (MICs) could be read by eye. The photometric test evaluation was compared with evaluation according to growth inhibition or to incorporation of radiolabelled hypoxanthine. The three methods of evaluation gave similar results.

Animals↗
PubMed1991

In vitro activity of organometallic complexes of Ir, Pt and Rh on Trypanosoma b. gambiense, T. b. rhodesiense and T. b. brucei.

A series of organometallic drugs were tested in a photometric in vitro assay for trypanocidal activity against the three subspecies of the Trypanosoma brucei group. Trypanosoma b. rhodesiense, T. b. gambiense and T. b. brucei displayed a similar sensitivity pattern. The following IC50 values (drug concentration inhibiting decrease of extinction by 50%) could be determined: IrCl6 (IV)-Pentamidine (1.5 ng/ml), IrCl6(IV)-Ro15-0216 (10 micrograms/ml), PtBr6-Metamidium (30 micrograms/ml), PtBr6(IV)-Benznidazole (20 micrograms/ml), PtBr6(IV)-Ro15-0216 (50 micrograms/ml), cis-Pt(II)-Pentamidine (0.1 micrograms/ml), Rh(I)-COD-Pentamidine (5-10 ng/ml), Rh(I)-COD-Benznidazole (10 micrograms/ml), Rh(III)-Ethylxanthate (30 micrograms/ml) and Pt(II)-Pentamidine-cis-Pt(II)(Pentamidine)(Cl)2 (2 ng/ml). The four Pentamidine complexes were the most active compounds and showed activities comparable to that of Pentamidine (IC50: 0.5 to 1 ng/ml). Since the toxicity of the Ir- and Pt-Pentamidine complexes is ten to twenty fold lower (400 to 1000 mg/kg) than that of Pentamidine (50 mg/kg), the complexes might be candidates for investigation as safer trypanocidal drugs.

Animals↗
PubMedDate not supplied

Effect of strategic gastrointestinal nematode control on faecal egg count in traditional West African cattle.

This paper reports on the effect of strategic anthelmintic treatments and other determinants on faecal egg counts (FEC) of Trichostrongyles in N'Dama cattle of a west African village. Initially, 527 animals from 13 private N'Dama cattle herds were monitored in a longitudinal study from October 1989 to December 1994. Each herd was stratified by age and animals were sequentially allocated to two groups with similar age distributions. One group received a single anthelmintic treatment of fenbendazole (7.5 mg/kg BW), in October 1989 (n = 250), whereas the other group remained untreated (n = 277) throughout the study. In the next rainy season (June to October), the treated animals were treated twice (in July and September). The same treatment schedule was used in the subsequent rainy seasons until December 1994. Biannual anthelmintic treatments decreased the level of FEC between 31% (late dry season) and 57% (rainy season), when compared to untreated controls. The highest levels of FEC were found during the rainy season from June to October. FEC levels decreased until 4 years of age, after which they remained on a constant low level. The variability of returns to anthelmintic treatments between herds did not seem to be influenced by FEC at the herd level. The financial evaluation of anthelmintic interventions cannot be predicted from FEC and must necessarily rely on the direct monitoring of livestock productivity parameters.

Africa, Western↗