Browsing by Author "Masiga, D.K."
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Item The Development and Application of a Polymerase Chain Reaction Methodology for Identification of African Trypanosomes(Daniel K M, 1994) Masiga, D.K.The accurate identification of different trypanosome species, subspecies and strains is a fundamental problem in studies of the epidemiology of trypanosomiasis in Africa. Indeed the risk to livestock and man can only be fully appreciated if pathogenic trypanosomes are identified unequivocally. Using conventional methodologies for identifying trypanosomes, it is difficult to distinguish between species with different pathogenicities, since some species are morphologically indistinguishable, and may share developmental sites in the tsetse fly vector. Until recently, identification of the latter relied on location in the fly, which is only accurate to subgenus level. This method also fails to detect mixed infections, for example of Nannomonas and Duttonella, or to identify immature infections where trypanosomes are found only in the midgut.Item Financial Implications of Rearing Sheep and Goats under Natural Trypanosomosis Challenge at Galana Ranch, Kenya(2002) Irungu, P.; Nyamwaro, S.O.; Masiga, D.K.; Kenya Trypanosomiasis Research Institute; Kenya Trypanosomiasis Research Institute, PO Box 362, Kikuyu, KenyaA study to compare the profitability of rearing sheep and goats under natural trypanosomosis challenge was carried out on Galana ranch m south-eastern Kenya between July 1996 and October 1997. Seventy-nine male weaner sheep and 79 male weaner goats were monitored monthly for weight changes and fortnightly for trypanosomosis. The animals of each species were divided into two groups Group I was an untreated control, while group 2 was treated with Isometamidium chloride (Samonn) at 0.5 mg/ kg body weight every 3 months In both groups, trypanosome infections were detected by microscopy and treated With diminazene aceturate (Venben), at 3.5 mg/kg body weight, when the packed cell volume reached 17";', or below The profitability of each drug regime was expressed as the marginal revenue over the cost of trypanosomosis (MOT) There were greater losses occasioned by trypanosomosls m sheep than m goats. Animals of both species on chemoprophylaxis gave higher MOT values than those that received chemotherapy on diagnosis However, the MOT values for the chemoprophy-lactic regime were higher for sheep than for goats, suggesting that the greater weight gam by sheep more than compensated for the higher cost of maintaining them under high trypanosomosls challenge Thus, a Galana rancher would be better off keeping sheep rather than goats, other things being equal. The marginal revenue per dose of Samonn was lower than that of Venben for both species, suggesting that strategic use of Samorin timed to precede the peak incidence of trypanosomosls might be a better option to raise the overall profitability in sheep and goatsItem Growth and Mortality in Sheep and Goats under High Tsetse(2002) Masiga, D.K. ; Okech, G.; Irungu, P. ; Ouma, J; Wekesa, S. ; Ouma, B.; Guya, S.O.; Ngung'u, J.M.; Kenya Trypanosomiasis Research Institute; Kenya Tryponosomiasis Research Institute; Kenya Trypanosomiasis Research Institute (KETRI), PO Box 362, Kikuyu, KenyaTrypanosomosis is a major Impediment to livestock production and economic development In those areas of Africa where It IS endemic Although small ruminants appear to perform better than cattle In various agro ecological zones, the Importance of trypanosomosis has not been extensively Investigated m these livestock This study was designed to Investigate the prevalence of trypanosomosis In sheep and goats In an endemic area and to evaluate the performance of different breeds under high tsetse challenge and the potential role of chemoprophylaxis In the control of the disease The results showed that tsetse flies reed readily on small ruminants, and that these al1lmals are susceptible to trypanosomosls The Small East African goats acqll1red fewer Infections than the Black Head Persian and Dorper sheep used In the study. In both sheep and goats, chemoprophylaxis With Isometanidium chloride (Samonn, Rhone Meneux, and Annecy, France) was protective, resulting in fewer infections and higher body weight gain. Trypanosomosls caused anaemia in both sheep and goats, and animals whose PCV fell below IS'X, rarely recovered, even with trypanocidal drug treatment. The peak transmission period was between 1 and 3 months after the peak tsetse fly density, which raises the possibility of effective strategic prophylaxis.Item A high prevalence of mixed trypanosome Infections In Tsetse flies in Sinfra, Cote d'Ivoire, detected by DNA amplification(1996) Masiga, D.K.; McNamara, J.J.; Laveissiere, C.; Truc, P.; Gibson, C.W.; Kenya Trypanosomiasis Research Institute; Department of Pathology and Microbiology, School of Veterinary Science, University of Bristol, Longford House, Bristol BS18 7DY, UK, Department of Clinical Veterinary Science, University of Bristol, Longford House, Bristol BS18 7D Y, UK Institut Pierre Richet/OCCGE, BP 1500, Bouaké, Côte d'IvoireThe prevalence of various species and subgroups of trypanosomes in the Sinfra area of Cote d' I voir was determined using the polymerase chain reaction (PCR). Using this technique to amplify specific satellite DNA, targets, it was possible. To identify developmental-stage trypanosomes in the midguts and the proboscides of tsetse without expansion .of parasite populations. The predominant tsetse species in the area was Glossina palpalis, which G pallicera and G. nigrofusca were also present. Microscopical examination of 811 non- teneral flies revealed an infection rate of 14% in midguts and or proboscides. Three subgroups of Trypanosoma congolense (Savannah, Forest & Kilifi), T. simiae, T. gadfreyi, West African T vivax and T brucei ssp. were identified using PCR. T. congolense Forest was the most abundant of the Nannomonas trypanosomes approximately 40 % of all infections were mixed, and there was a significantly higher prevalence of apparently mature T brucei ssp. trypanosomes than has previously been reported. The present study demonstrates the PCR facilitates the easy Identification of mature trypanosome infections in tsetse, providing a reliable estimation of trypanosomiasis challenge.Item A repetitive DNA sequence specific for Trypanosoma (Nannomonas) godfreyi(Elsevier, 1996) Masiga, D.K.; McNamara, J.J.; Gibson, C.W.; Kenya Trypanosomiasis Research Institute; Department of Pathology and Microbiology, School of Veterinary Science, University of Bristol, Langford, UK.The satellite DNA sequence of Trypanosoma (Nannomonas) godfreyi, a recently described parasite of Suidae, was determined. The sequence is 373bp in length, and contains two imperfect internal repeats of approximately 170bp. Like other trypanosome satellite DNAs, it has no extensive open reading frames and is probably non-Coding. There is no significant homology with other major repetitive DNAs within subgenus Nannomonas. We have developed after test that is specific for T. godfreyi and used it to identify the parasite in natural tsetse infections from Zimbabwe and Cote d'Ivoire. This test shows no cross reaction with non-target trypanosomes, even within subgenus Nannomonas, and will be invaluable in studies of the prevalence and I distribution of T. godfreyi.
