Browsing by Author "Murilla, G."
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Item A comparative study in direct cryopreservative efficacy between Triladly and EDTA saline glucose 10% glycerol cryopreservative media for human and non-human infective trypanosomes(2009) Ndungu, K.; Gitonga, P.; Mulinge, M.; Kangethe, J.; Kibugu, J. K.; Munga, L. K.; Maina, N.; Kagira, J. M.; Ngae, G. N.; Murilla, G.; Kenya Trypanosomiasis Research Institute; Tryponosomiasis Research Centre-KARI, Jomo Kenyatta University of Agricultural & Technology, National Agricultural Centre - KARIThe efficacy of Triladyl®, a commercial cryomedium for bull semen, in the cryopreservation of both human and animal infective trypanosomes as compared to EDT a Saline Glucose (ESG) 10% glycerol was evaluated in the current study. Cryopreserved Trypanosoma brucei rhodesiense, T. evansi, T. b. brucei and T. congolense were first propagated in irradiated mice. At the peak of parasitemia, parasites were harvested by cardiac puncture and 106,105,104103,102 and 10 dilutions made using whole blood bled from clean mice. These dilutions were divided into two equal portions of 0.5 ml each and cryopreserved in both ESG 10% glycerol and neat Triladly®. The procedure was also repeated with T. congolense and T. vivax species of trypanosomes directly Isolated from naturally infected cattle. After 1 month of cryopreservation, 0.4 ml each portion of this dilution was injected intraperitonially into irradiated Swiss white mice. Results on pre-patent period (PPP) and progression of parasitemia showed no difference in the recovery of samples cryopreserved using the 2 media. However, mice injected with T. b. brucei cryopreserved in the 2 media showed highly significantly (p < 0.01 by t-test) lower PPP when compared to the other species of trypanosomes which had no significant difference. However, the PPP in mice injected with trypanosomes cryopreserved in ESG 10% glycerol was significantly lower (p < 0.05 by t-test) when compared to those cryopreserved in Triladyl®. The interaction between media and species was highly significant indicating therefore that the difference in cryopreservation between the two media varies from one species of trypanosome to the other. The interaction between dose and species was also highly significant (p < 0.01 by t-test) implying therefore that the effect of the inoculum dose varied from one species to the other leading to the conclusion therefore that although Triladyl® appears as good a cryopreservative medium as ESG 10% glycerol, the choice will be determined by the species of trypanosome.Item Estimation of tsetse challenge and its relationship with trypanosomosis incidence in cattle kept under pastoral production systems in Kenya( 2nd May ,2008) Bett, B.; Irungu, P.; Nyamwra, S.O.; Murilla, G.; Kitala, P.; Gathuma, J.; Randolph, T.F.; McDermott, J.; Trypanosomiasis Research Centre, Kenya Agricultural Research Institute, P.O. Box 362-00902, Kikuyu, Kenya, International Livestock Research Institute, P.O. Box 30709-00100, Nairobi, Kenya, Department of Agricultural Economics, University of Nairobi, P.O. Box 29053-00625, Kangemi, Nairobi, Kenya, Department of Public Health Pharmacology and Toxicology, University of Nairobi, P.O. Box 29053-00625, Nairobi, KenyaIn an on-farm trial conducted amongst the Maasai pastoralists in Nkuruman and Nkineji areas of Kenya between April 2004 and August 2005 designed to evaluate the effectiveness of a synthetic tsetse repellent technology, we assessed the relationship between tsetse challenge and trypanosomosis incidence in cattle. Six villages were used in each area. Each of these villages had a sentinel cattle herd that was screened for trypanosomosis on monthly basis using buffy coat technique. Animals found infected at each sampling were treated with diminazene aceturate at 7 mg kg - I body weight. Treatments administered by the owners over the sampling intervals were recorded as well. Tsetse flies were trapped at the time of sampling using baited stationary traps and apparent tsetse density estimated as flies per trap per day (FrD). A fixed proportion (10%) of the flies was dissected and their infection status determined through microscopy. Blood meals were also collected from some of the flies and their sources identified using enzymelinked immunosorbent assay (ELISA). Tsetse challenge was obtained as a product of tsetse density, trypanosome prevalence and the proportion of blood meals obtained from cattle. This variable was transformed using logarithmic function and fitted as an independent factor in a Poisson model that had trypanosomosis incidence in the sentinel cattle as the outcome of interest. The mean trypanosomosis incidence in the sentinel group of cattle was 7.2 and 10.2% in Nkuruman and Nkineji, respectively. Glossina pallidipes was the most prevalent tsetse species in Nkuruman while G. swynnertoni was prevalent in Nkineji. The proportions of tsetse that had mature infections in the respective areas were 0.6 and 4.2%. Most tsetse (28%) sampled in Nkuruman had blood meals from warthogs while most of those sampled in Nkineji (30%) had blood meals from cattle. A statistically significant association between tsetse challenge and trypanosomosis incidence was obtained only in Nkuruman when data was pooled and analyzed at the area but not at the village-level. In the later scenario, lagging tsetse challenge by I month improved the strength but not the significance of the association. These findings show that when the spatial unit of analysis in observational studies or on-farm trials is small, for instance a village, it may not be possible to demonstrate a statistically significant association between tsetse challenge and trypanosomosis incidence in livestock so as to effectively control for tsetse challenge.Item Pathogenicity of bloodstream and cerebrospinal fluid forms of Trypanosoma brucei rhodesiense in Swiss White Mice(2008) Ndungu, K.; Ngotho, M.; Kinyua, J.; Kagira, J.; Guya, S.; Ndungu, J.; Murilla, G.; Kenya Trypanosomiasis Research InstituteTrypanosoma brucei rhodesiense (T.b.r.), the causative agent of the East African form of human African trypanosomiasis (HAT), is capable of crossing the blood brain barrier and invade the central nervous system (CNS). However, it is not clear whether bloodstream forms (BSF) of T.b.rhodesiense differ in biological characteristics from the cerebrospinal fluid (CSF) forms. The present study was carried out to compare the pathogenicity of CSF and BSF of T.b. rhodesiense parasites in Swiss white mice following intraperitoneal inoculation with 106 trypanosomes. The parasites were tested for presence of the serum resistance associated (SRA) gene. Parasitaemia, body weight, packed cell volume (PCV) and survival of the mice was monitored daily until the experiment was terminated. Data was analyzed using general linear model. Both forms of parasite were positive for the SRA gene, and there was no significant difference in progression of parasitaemia, PCV values or survival of the mice. However, the weights of BSF infected mice initially dropped faster than those of CSF infected mice (P<0.001). Key words: Trypanosoma brucei rhodesiense, bloodstream and CSF forms, pathogenicity, and mice.Item Standardised tests in mice cattle for the detection of drug resistance in tsetse-transmitted trypanosomes of African domestic cattle(2001) Eisler, M. C.; Brandt, J.; Bauer, B.; Clausen, P. H.; Delespaux, V.; Holmes, P. H.; Ilemobade, A.; Machila, N.; Mbwambo, H.; McDermott, J.; Mehlitz, D.; Murilla, G.; Ndung'u, J. M.; Peregrine, A. S.; Sidibé, I.; Sinyangwe, L.; Kenya Trypanosomiasis Research Institute; Department of Veterinary Clinical Studies, University of Glasgow, Bearsden Road, G61 1QH, Scotland, GlasgowResistance to the drugs used to control African animal trypanosomosis is increasingly recognised as a constraint to livestock production in sub-Saharan Africa. The most commonly used tests for detection of trypanocidal drug resistance are: tests using mice or ruminants, but these suffer from lack of standardisation and hence it may be difficult to compare the results of different investigators. Tests in mice are less expensive than tests in ruminants, but while tests in mice I they may be useful as a general guide to resistance in a geographic area they should not be extrapolated to cattle on an individual trypanosome level. Moreover, the commonly used protocols are too laborious for their application to large number of trypanosome isolates on an area-wide basis. This paper presents guidelines for standardised testing of trypanocidal drugs in vivo, and introduces a simplified single-dose test for use in mice, which is convenient for use in areas with limited laboratory facilities. The single-dose test is appropriate for characterisation of geographic areas in terms of trypanocidal drug resistance using large numbers of trypanosome isolates, for making comparisons between areas, and for monitoring changes in trypanocidal drug resistance over time. Multiple-dose tests may be I used to determine the degree of resistance of I individual stabilates to be determined precisely in mice are also described, but for logistical reasons these will rarely be conducted on more than a few stabilates, and testing of a larger number of stabilates in the single-dose test will generally provide more useful information. Finally, we describe tests in cattle that may be used to determine the efficacy of recommended curative doses of trypanocidal drugs for the treatment of, infection with individual trypanosome isolates, including Trypanosoma vivax, which is rarely infective for mice.
