Studies on Chemoprophylaxis of Trypanosomiasis Using a Competitive Enzyme Immunoassay for the Detection of Isometamidium and Homidium in Cattle and Sheep

Mubanga, Joseph (1996) Studies on Chemoprophylaxis of Trypanosomiasis Using a Competitive Enzyme Immunoassay for the Detection of Isometamidium and Homidium in Cattle and Sheep. MVM(R) thesis, University of Glasgow.

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This thesis describes studies to improve the ELISA method for determining the concentrations of isometamidium and homidium in the serum of treated animals, and the use of the improved ELISA to monitor drug levels in the field and laboratory. Chapter One is a general review of the relevant literature. Chapter Two describes experiments that were conducted to improve the competitive enzyme immunoassay for the detection of isometamidium in the sera of treated animals. Improvements were required to this assay to reduce inter-sample variation of sera obtained from untreated animals. The use of a new conjugate isometamidium-horseradish-peroxidase produced using the n-hydroxysuccinamide-carbodiimide linkage and modifications to the assay to a sequential saturation competitive enzyme assay, successfully solved the problem of intersample variation. Following the successfull modifications to the isometamidium detection ELISA similar improvements were made to the homidium detection ELISA. Chapter Three describes the use of the new competitive enzyme immunoassay to measure the concentrations of isometamidium in the sera of 35 treated cattle reared under traditional management in a field situation in Zambia. Breakthrough trypanosome infections in the individual cattle were monitored and related to the isometamidium concentration levels at the time of trypanosome detection. One of the 10 breakthrough infections occurred when relatively high drug levels were present and this was taken to indicate that the breakthrough infection may have been drug resistant. The work in this section showed that trypanocide detection ELISAs are a useful tool for determining the drug levels in individual cattle sera and can provide indirect evidence of drug resistant trypanosomes when used in combination with parasitological monitoring methods. Chapter Four describes the evaluation of the prophylactic effect of a slow release device (SRD) containing homidium bromide. The prophylatic effect of this SRD was compared with that of the normal intramuscular (i.m.) injections of isometamidium and homidium bromide. In the SRD group 50 % of the cattle remained protected up to the fourth month after treatment. In the i.m. isometamidium group 50 % of the cattle were protected up to the third month after treatment whereas in the i.m. homidium 50 % remained protected only up to the second month. The levels of isometamidium and ethidium in the serum reflected these differences in the period of prophylaxis. Chapter Five describes an experiment to investigate influence of nutrient intake on the duration of isometamidium prophylaxis in sheep. In this experiment groups of sheep on two planes of nutrition were injected with isometamidium (0.5 mg/kg) and then challenged monthly with bloodstream forms of T. congolense by subcutaneous injection. The concentration of isometamidium in the sera of the animals declined at a similar rate in both groups and was below the lower limit of detection at the time of the breakthrough infections. The mean body weight and serum albumin levels of the animals on the high plane diet was significantly higher than those of the animals on the low plane diet throughout the experiment period. However the mean periods of prophylaxis were very similar in the high plane and low plane diet groups (121 +/- 14 days and 117 +/- 11 days respectively).

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Additional Information: Adviser: M C Eisler
Keywords: Veterinary science, Animal sciences, Parasitology
Date of Award: 1996
Depositing User: Enlighten Team
Unique ID: glathesis:1996-74903
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 27 Sep 2019 15:26
Last Modified: 27 Sep 2019 15:26

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