Factors influencing the prevalence of trypanosomosis in Orma Boran (trypanotolerant) and Teso zebu (trypanosusceptible) cattle crosses in Teso District, western Kenya

The objective of this study was to determine factors associated with occurrence of trypanosomosis in the first generation (F1) crossbreds between trypanotolerant Orma Boran and trypanosusceptible Teso zebu cattle in a trypanosomosis endemic area in Teso District, western Kenya. The offspring were screened for trypanosomosis and other haemoparasites using parasitological methods. Packed cell volume (PCV), body weights and tsetse density (FTD) were also determined. Factors considered in the analysis included sex, age, body weight and season of the year. Generalized linear mixed models (GLMM) were used for multivariable analysis to account for clustering of observations at the animal level and estimate outcome variance parameters. The overall trypanosomosis prevalence was 2.3% (n=477) probably corresponding to low FTD in the area (<1fly/trap/day). The risk of trypanosomosis infection was higher in dry than wet season (OR = 5.4) and in older than younger offspring (OR = 1.1). The variance parameters obtained indicated that variation of trypanosomosis prevalence lay only at the animal level. Intercurrent haemoparasites detected included Anaplasma marginale, Theileria and Babesia species. Overall, the results suggested that when the tsetse density is very low, control of trypanosomosis in the Orma-Teso zebu offspring in western Kenya require targeting of individual affected animals in the dry seasons

Short Communication Report: Evaluation of Indirect Enzyme-Linked Immunosorbent Assay (ELISA) systems for the serodiagnosis of bovine trypanosomosis in disease endemic areas of Kenya

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Resistance to trypanocidal drugs - suggestions from field survey on drug use in Kwale district, Kenya

A household survey was conducted in 21 villages of Kwale district, Kenya, to assess farmers' trypanocidal drug use characteristics for treatment of bovine trypanosomosis and their relationship to drug effectiveness. Descriptive statistical tools were used to summarize the farmers' drug use patterns. The chi-square test was done to establish the relationship between proper drug use and recovery. The results indicate that the farmers had considerable knowledge about trypanocidal drugs with 82% (n=65) having used these drugs within 6 months preceding the survey. Cases of incorrect drug use were reported. This study established that there was no significant relationship between correct drug use and recovery of the treated animals, suggesting the presence of drug resistance in Kwale district.The articles have been scanned with a HP Scanjet 8300; 600dpi, saved in TIFF format. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Evaluation of isometamidium levels in the serum of sheep and goats after prophylactic treatment against trypanosomosis

years, but recently there have been reports of prophylaxis failure under natural conditions. In this study, use of the drug for prophylactic purpose against trypanosomosis in small ruminants was investigated. Forty-two sheep and 44 goats were divided into four treatment groups. Groups 1 and 2 were treated with isometamidium chloride (Samorin(R), Rhone Merieux, Lyon, France) at 3-month intervals while groups 3 and 4 were used as controls. All the animals were exposed to natural tsetse challenge and monitored for serum isometamidium levels and anti-trypanosome antibodies. Seven days after drug administration, isometamidium levels were significantly higher in goats 13.7 + 0.07 ng/mℓ than in sheep 6.2 + 0.06 ng/mℓ. However, the elimination half-life in the sheep was 14.2 + 0.92 days and was significantly higher (P > 0.05) than that of the goats 12 + 0.5 days. This study established that isometamidium metabolism differs between sheep and goats and this difference may have important implications in high tsetse challenge areas

Investigation into the effects of Trypanosoma congolense infections on the pharmacokinetics of Homidium in Boran cattle

Control of trypanosomes in cattle, sheep and goats in endemic areas has depended largely on the use of chemotherapeutic or chemoprophylactic agents. One such agent is homidium. The normal use of homidium has been in the treatment of infections due to both Trypanosoma congolense and T.vivax in cattle, sheep and goats at the recommended does rate of 1.0 mg kg-1b.w. This paper describes the results of an investigation into the chemotherapeutic activity of homidium against T.congolense infections in cattle. Two groups of five Boran cattle were infected with two populations of T.Congolense; one drug-sensitive IL 1180 and one drug-resistant (IL 3330). Parasitaemia was estimated using the methods of Murray et al. (1977); the serum drug levels by the method described by Murilla (1996) and the pharmacokinetic parameters using the formulae described by Baggot (1977). After infection, there was a rapid drop in packed cell volume (PCV) values from a mean pre-infection value of approximately 40% to approximately 25% within 14 days of infection in cattle infected with IL 1180. However, in cattle infected with IL 3330, the drop in PCV was more gradual from approximately 40% to approximately 30% within the same period of time. The animals were treated with homidium bromide at a dose rate of 1.0 mg kg-1 body weight (b.w.) seven days after the last animal in each group was detected positive. Following intermuscular (i.m.) treatment of cattle infected with drug-sensitive trypanosomes, no parasites were detected in the bloodstream of four out of five cattle within 24 hours; the fifth within 48 hours. During this period and for the next 10 days after treatment, an accelaration in the rate of drug elimination was observed. Thereafter, the rate of elimination reverted back to that observed in Non-infected cattle (Murilla, 1996). This was accompanied by an elevation in PCV to pre-infection values. The animals remained aparasitaemic up to the end of the 90 days observation period with low serum drug concentrations of between 0.1 and 0.3 ng ml-1 in circulation

The effects of drug-sensitive and drug-resistant Trypanosoma congolense infections on the pharmacokinetics of homidium in Boran cattle

Two groups of five Boran (Bos indicus) cattle were infected with one of two populations of Trypanosoma congolense; one drug-sensitive (IL1180), and one drug-resistant (IL3330). The animals were then treated intramuscularly with homidium bromide at a dose rate of 1.0 mg kg - bodyweight 7 days after trypanosomes were detected in the peripheral blood of all the five animals in each grouFollowing treatment of cattle infected with drug-sensitive trypanosomes. parasites could no longer be detected in the bloodstream of four out of five cattle after 24 h, and after 48 h for the fifth animal. The animals remained aparasitaemic up to the end of the observation period of 90 days and serum drug concentrations determined by enzyme-linked immunosorbent assay (ELISA) remained above the detection limit of 0.1 ng ml for the entire period. Following treatment of cattle infected with drug-resistant trypanosomes. parasites did not disappear from the bloodstream in any of the five animals. The rate of drug elimination was greater in cattle infected with drug-resistant trypanosomes and the drug was no longer detectable approximately 3 weeks after treatment. Non-compartmental pharmacokinetic analysis showed that the values for t1 beta, of 75.5 ± 16.9 h, the area under the curve (AUC a-x ) of 1.33 ± 0.156 mce g h ml - and the MRT a-x of 32.8 ± 4.45 h obtained in cattle infected with the drug-resistant trypanosome population were significantly lower than the values of 424 ± 146 h for tJl, 1.67 ± 0.233 mug h ml -1 for AUC a-x and 297 ± 159 h for MRT a-x obtained in cattle infected with the drug sensitive population. The persistence of drug-resistant infections in cattle following homidium treatment was associated with more rapid drug elimination than in those in which infections with drug-sensitive parasites were cleared by the drug

The effects of drug-sensitive and drug-resistant Trypanosoma congolense infections on the pharmacokinetics of homidium in Boran cattle

Two groups of five Boran (Bos indicus) cattle were infected with one of two populations of Trypanosoma congolense; one drug-sensitive (IL1180), and one drug-resistant (IL3330). The animals were then treated intramuscularly with homidium bromide at a dose rate of 1.0 mg kg−1 bodyweight 7 days after trypanosomes were detected in the peripheral blood of all the five animals in each group. Following treatment of cattle infected with drug-sensitive trypanosomes, parasites could no longer be detected in the bloodstream of four out of five cattle after 24 h, and after 48 h for the fifth animal. The animals remained aparasitaemic up to the end of the observation period of 90 days and serum drug concentrations determined by enzyme-linked immunosorbent assay (ELISA) remained above the detection limit of 0.1 ng ml−1 for the entire period. Following treatment of cattle infected with drug-resistant trypanosomes, parasites did not disappear from the bloodstream in any of the five animals. The rate of drug elimination was greater in cattle infected with drug-resistant trypanosomes and the drug was no longer detectable approximately 3 weeks after treatment. Non-compartmental pharmacokinetic analysis showed that the values for tView the MathML sourceβ of 75.5±16.9 h, the area under the curve (AUC0−∞) of 1.33±0.156 μg h ml−1 and the MRT0−∞ of 32.8±4.45 h obtained in cattle infected with the drug-resistant trypanosome population were significantly lower than the values of 424±146 h for tView the MathML sourceβ, 1.67±0.233 μg h ml−1 for AUC0−∞ and 297±159 h for MRT0−∞ obtained in cattle infected with the drug-sensitive population. The persistence of drug-resistant infections in cattle following homidium treatment was associated with more rapid drug elimination than in those in which infections with drug-sensitive parasites were cleared by the drug

Evidence of improper usage of veterinary drugs in cattle in Maasailand, Kenya

The extent of farm-level extra-label drug use in Kenya is not well documented in spite of its important implications on food safety, human health and international trade. One hundred and thirteen farmers in Kajiado and Narok districts were interviewed between October 2005 and February 2006 using a pre-tested questionnaire. The aim was to gather information on farmers’ veterinary drug use practices at the farm level. Descriptive and regression analyses were undertaken on the data. There was a high level of extra-label usage of veterinary drugs in cattle in the two study areas. Specifically, farmers used lower than recommended doses of all available trypanocides in all classes of cattle except in adult bulls where they overdosed with Veriben®, Novidium® and Tryzan®. Adamycin®, the most commonly used antibiotic in the two study sites, was underdosed at all concentrations in all classes of cattle. Except for Novidium® which farmers dissolved correctly, farmers in the two study sites used less than the recommended volume of water to prepare trypanocidal drugs. Farmers also used less than the recommended strength of acaricides for tick control, except for Dominex®. They also sprayed more cattle at each acaricide strength than the number recommended by the manufacturers. The propensity to use veterinary drugs correctly was positively correlated with farmer’s age and district of origin (p<0.1), but negatively associated with years of formal education of the household head (p<0.05). Policy suggestions are made based on the results

Diamidines for human African trypanosomiasis

Aromatic diamidines are potent trypanocides. Pentamidine, a diamidine, has been used for more than 60 years to treat human African trypanosomiasis (HAT); however, the drug must be administered parenterally and is active against first-stage HAT only, prior to the parasites causing neurological deterioration through invasion of the CNS. A major research effort to design novel diamidines has led to the development of orally active prodrugs and, remarkably, a new generation of compounds that can penetrate the CNS. In this review, progress in the development of diamidines for the treatment of HAT is discusse