Browsing by Author "Mdachi, R.E."
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Item Comparative pathogenicity of Trypanosoma brucei rhodesiense strains in Swiss white mice and Mastomys natalensis rats(Kenya Agricultural Research Institute, 1927) Muchiri, M.W.; Ndung'u, K.; Kibugu, J.K.; Thuita, J.K.; Gitonga, P.K.; Ngae, G.N.; Mdachi, R.E.; Kagira, J.M.; Kenya Agricultural and Livestock Research Organization (KALRO), Biotechnology Research Institute (BioRI), P. O. Box 362, Kikuyu, Кепуа; Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Kenya; Kenya Food Crop Research Institute, P. O. Box 30148, Nairobi, KenyaWe evaluated Mastomys natelensis rat as an animal model for Rhodesian sleeping sickness, Parasitaemia, clinical and pathological characteristics induced by T. b. rhodesiense isolates, KETRI 3439, 3622 and 3637 were compared in Mastomys rats and Swiss white mice. Each isolate was intra-peritonially injected in mice and rat groups (n-12) at 1x 10º trypanosomes/0.2 ml. Pre-patent period (PP) range for KETRI 3439 and KETRI 3622-groups was 3-6 days for mice and 4-5 days for rats while for KETRI 3637-infected mice. and rats was 5-9 and 4-12 days, respectively. Pairwise comparison between PP of mice and rats separately infected with either isolate showed no significant difference (p>0.05). The PP's of KETRI 3637-infected mice were significantly (p>0.01) longer than those infected with KETRI 3439 or KETRI 3622, a trend also observed in rats. The second parasitaemic wave was more prominent in mice. Clinical signs included body weakness, dyspnoea, peri-orbital oedema and extreme emaciation which were more common in rats. Survival time for KETRI 3439 and 3622-infected groups was significantly (p<0.05) longer in mice than rats but similar in KETRI 3637-infected groups. Inflammatory lesions were more severe in rats than mice. All mice and KETRI 3622-infected rats had splenomegaly, organ congestion with rats additionally showing prominent lymphadenopathy. KETRI 3439-infected rats showed hemorrhagic pneumonia, enteritis with moderate splenomegaly and lymphadenopathy. KETRI 3637-infected rats had the most severe lesions characterized by prominent splenomegaly, lymphadenopathy, hepatomegaly, enlarged adrenal glands, organ congestion, generalized oedemas, gastroenteritis, pneumonia and brain congestion. KETRI 3637- infected Mastomys is a suitable model for studying pathophysiology of HAT.Item Effect of aflatoxin Bl on the therapeutic efficacy of suramin in Trypanosoma brucei rhodesiense-infected mice(2011) Kibugu, J.K.; Mdachi, R.E.; Kagira, J.M.; Muchiri, M.W.; Makumi, J.N.; Ngeranwa, J.J.N.; Auma, J.E.; Ngae, G.N.; Kenya Trypanosomiasis Research Institute; Kenya Agricultural Research Institute(KARI), Trypanosomiasis Research Centre (TRC), Kikuyu Kenya, Kenyatta University Department of Biochemistry and Biotechnology, Nairobi, Kenya, KARI, Agricultural Centre-MugugaThrough immuno-suppression, aflatoxins could affect drug and vaccine efficacy. Such effects have not been evaluated in treatment of many diseases including trypanosomiasis. We assessed the effect of aflatoxin B 1 on the efficacy of suramin, the drug used for treatment of early stage sleeping sickness, in a murine model. Mice were fed daily on a diet containing 0.50 mg aflatoxin/kg body weight or a placebo. They were infected with Trypanosoma brucei rhodesiense on day 7 post-aflatoxin exposure and then treated with one of 6 different doses of suramin (4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 mg/kg body weight) at the onset of parasitemia. The mice were fed on aflatoxin diet for 30 days and the curative dose values (CD 50, 75. and 90) computed and compared using a logistic linear regression model. Aflatoxin B 1 induced transient protection of the host against T. b. rhodesiense infection and a consistent increase in suramin CD values in the mice suggesting reduced drug efficacy. Aflatoxicosis hindered curative treatment of T. b. rhodesiense infection in mice, and may contribute to reduced efficacy of suramin during treatment of sleeping sickness in man.Item Improved survival of laboratory-reared tsetse flies Glossina morsitans morsitans (Diptera: Glossinidae) through use of homidium bromide-treated blood diet(2010) Kibugu, J.K.; Mwangi, J.N.; Kiragu, J.M.; Muchiri, M.W.; Ndungu, K.; Mdachi, R.E.; Kenya Trypanosomiasis Research Institute; Kenya Agricultural Research Institute (KARI), Trypanosomiasis Research Centre, Social Economics and Biometrics Division, KARIHomidium bromide is a broad-spectrum anti-microbial trypanocide likely to be encountered as a violative residue in blood collected from abattoirs destined for feeding laboratory-reared tsetse colonies. We investigated its effects on longevity of laboratory reared Glossina morsitans morsitans Westwood. Four steers were intra-muscularly administered with 1 mg homidium bromide/kg of body weight and blood was aseptically collected from them between 15 and 30 min post-administration. This blood was defibrinated, analysed for homidium levels, screened for bacterial contamination, frozen and warmed to 37"C before feeding to tsetse flies. Teneral male (l00) and female (220) G. m. morsitans flies were fed on homidiurn-treated diet, and control flies (99 males and 187 females) on untreated blood diet and their survival monitored for 163 days. Homidium, at 266.15ng/ml blood diet, significantly (P <0.05) improved fly survival. We concluded that homidium bromide has a beneficial effect on tsetse, probably attributable to its antimicrobial activity against unfavourable microbes mediated by the drug, and could be used as a tsetse diet additive.Item Spatial–Temporal Variations in Parasitological Prevalence and Host-Related Risk Factors of Camel Trypanosomiasis and Its Vectors in North Eastern Kenya: A Repeated Cross-Sectional Study(Hindawi, 2023-04-28) Ogolla, K.O.; Chemuliti, J.K.; Wamwiri, F.N.; Auma, J.E.; Kurgat, R.K.; Wanjala, K.B.; Mugunieri, L.G.; Alusi, P.M.; Mdachi, R.E.; Mukiria, P.W.; Okoth, S.O.; Kenya Agricultural and Livestock Research Organization ; East African Science and Technology Commission (EASTECO)/East African CommunityCamel trypanosomiasis (Surra) is endemic in the Horn of Africa. Understanding the spatiotemporal variations in Surra prevalence, vector dynamics, and host‐related risk factors is important in developing effective control strategies. A repeated cross‐sectional study was conducted to determine the Surra parasitological prevalence, livestock reservoirs, vector density/diversity, and host‐related risk factors in Kenya. Random samples of 847, 1079, and 824 camels were screened at the start of the dry season, peak dry season, and during the rainy season, respectively. Blood samples were examined using the dark ground/phase contrast buffy‐coat technique, and Trypanosoma species were identified based on their movement and morphology in wet and stained thin smears. Reservoir status for Trypanosoma evansi was assessed in 406 cattle and 372 goats. A rainy and dry seasons entomological surveys were conducted to determine the Surra vector abundance/diversity and spatiotemporal density changes. Surra prevalence was 7.1%, 3.4%, and 4.1% at the start of the dry season, peak dry season, and rainy season, respectively. Camel co‐infections by Trypanozoon (T. evansi or Trypanosoma brucei brucei) and Trypanosoma vivax were recorded. Spatial variations in Surra prevalence were recorded at the beginning of dry (X7846,N=2=110.9, p ≤ 0.001), peak dry (X71079,N=2=42.2, p ≤ 0.001), and rainy (X7824,N=2=29.1, p ≤ 0.001) seasons. The screened cattle and goats tested negative for Trypanozoon (T. evansi or T. b. brucei), while two cattle tested positive for Trypanosoma congolense. Biting fly catches were composed of a single species from Tabanus, Atylotus, Philoliche, Chrysops, and Stomoxys genera. The total catches for Philoliche, Chrysops, and Stomoxys were higher in the rainy than dry season consistent with the prevalence results. Surra remains an important camel disease in the region with its prevalence varying in space and time. Camel co‐infections by Trypanozoon (T. evansi or T. b. brucei) and T. vivax necessitate proper diagnosis of suspected cases and targeted therapy.Item Variation of Sensitivity of Trypanosoma evansi Isolates from Isiolo and Marsabit Counties of Kenya to Locally Available Trypanocidal Drugs(PLoS One, 2023-02-02) Mdachi, R.E.; Ogolla, K.O.; Auma, J.E.; Wamwiri, F.N.; Kurgat, R.K.; Wanjala, K.B.; Mugunieri, L.G.; Chemuliti, J.K.; Mukiria, P.W.; Okoth, S.O.; Kenya Agriculture and Livestock Research Organization; East African Science and Technology Commission (EASTECO)\East African Community, Kigali, RwandaTrypanocidal resistance is a major cause of treatment failure. This study evaluated the sensitivity of Trypanosoma evansi field isolates collected from Marsabit and Isiolo counties, Kenya. A total of 2,750 camels were screened using parasitological tests for trypanosomes. Of the screened camels, 113 tested positive from which 40 T. evansi isolates were tested using the single dose mice sensitivity test. Five treatment groups each comprising of 6 mice were inoculated intraperitoneally with 1x105 trypanosomes of each isolate and treated 24 hours later with isometamidium chloride at 1 mg/kg, homidium chloride at 1mg/kg, diminazene aceturate at 20 mg/kg and quinapyramine sulphate & chloride at 1 mg/kg. The fifth group was left untreated (positive control). The mice were monitored daily for 60 days. A survey on camel owners’ practices that influence development of resistance to trypanocidal drugs was then conducted. Results indicated presence of drug resistance in all the 7 study sites that had infected camels. Seven of the isolates tested were resistant to diminazene aceturate whereas, 28, 33 and 34 were resistant to isometamidium chloride, quinapyramine sulphate & chloride and homidium chloride, respectively. Seven (17.5%) isolates of the 40 tested were sensitive to all 4 drugs, whereas, 7.5%, 10%,55% and 10% were resistant to 1,2,3 and 4 drugs, respectively. The prevalence of multiple drug resistance was 75%. Survey data indicated that camel management practices influenced the prevalence and degree of drug resistance. In conclusion, the multiple drug resistance observed in the two counties may not be an indication of total trypanocidal drug failure. Judicious treatment of confirmed trypanosomiasis cases with correct dosage would still be effective in controlling the disease since the observed resistance was at the population and not clonal level. However, integrated control of the disease and the vectors using available alternative methods is recommended to reduce drug use.
