Daystar University Repository :: Browsing by Author "Tonui, Willy K."

Browsing by Author "Tonui, Willy K."

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A Review of Leishmaniasis in Eastern Africa.
(Elsevier, 2009-03) Ngure, Peter Kamau; Ng'ang'a, Zipporah W.; Rukunga, Geoffrey; Kimutai, Albert; Tonui, Willy K.
The review presents the epidemiology of leishmaniasis in the Eastern Africa region. We searched PUB MED and MEDLINE with several key words-namely, “leishmaniasis”;“cutaneous”, “diffuse cutaneous”, “mucosal”, and “visceral leishmaniasis”; “kala azar”, and “post kala azar dermal leishmaniasis”, -for recent clinical and basic science articles related to leishmaniasis in countries in the Eastern Africa region. Poverty, wars, conflicts and migration have significantly aggravated leishmaniases in Eastern Africa. Of particular concern is the increasing incidence of Leishmania-HIV co-infection in Ethiopia where 20∼40% of the persons affected by visceral leishmaniasis are HIV-co-infected. Sudan has the highest prevalence rate of post kala-azar dermal leishmaniasis(PKDL) in the world, a skin complication of visceral leishmaniasis(VL) that mainly afflicts children below age ten. In view of its spread to previously non-endemic areas and an increase in imported cases, leishmaniasis in Eastern Africa should be considered a health emergency.
Characterization and comparison of leishmania-like isolates from rodents, lizards and sand flies caught at Masinga location in Machakos district, Kenya
(African Journal of Health Sciences, 2011-06) Kinuthia, Geoffrey K.; Lugalia, Reuben; Mwanyumba, Panuel J.; Ngeiywa, Moses M.; Anjili, Christopher O.; Tonui, Willy K.
A laboratory based study was designed to characterize 43 cryo-preserved Leishmania-like flagellates. These Leishmania-like flagellates were originally obtained from non-human hosts that included spiny mice (Acomys subspinosus), plated lizards (Gerrosaurus major) and sand flies of the Genus Sergentomyia caught at Masinga location, Machakos District in Kenya. Morphological features and isoenzyme banding patterns of the flagellates were studied. The isoenzyme markers which were used for isoenzyme electrophoresis included Malate dehydrogenase (MDH), Phosphoglucomutase (PGM), Glucose phosphate isomerase (GPI), Glucose 6-phosphate dehydrogenase (G6PD), Malic enzyme (ME), 6 phosphogluconate dehydrogenase (6PGD) and Mannose phosphate isomerase (MPI). The isoenzyme banding patterns of the flagellates’ lysates were compared with those of six WHO Leishmania reference strains and those of seven well characterized reference strains of Trypanosoma, Crithidia, Herpetomonas and Leptomonas species. The results showed that the morphological changes of the Leishmania-like flagellates in the growth medium were indistinguishable from those of Leishmania WHO reference strains used. The isoenzyme profiles of the flagellates were all distinguishable from the reference strains used except for isolate NLB-1236 from G. major which had an enzyme profile identical to that of L. tropica (NLB-305) in 6 enzymes (MDH, GPI, MPI, ME, PGM, and G6PD). The banding pattern of isolate NLB-1261 from A. subspinosus was indistinguishable from that of L. major (NLB-326) in 3 enzymes only (MDH, GPI and ME) while isolate NLB-1231 from A. subspinosus had an enzyme profile identical to those of L. tropica (NLB-305) and L. arabica (NLB-664) in six enzymes (MDH, GPI, ME, PGM, MPI, and 6PGD). More than 80% of the Leishmania-like flagellates had enzyme profiles indistinguishable from each other, in all the isoenzyme markers. The morphological traits of the flagellates suggested that they were Leishmania or strains closely related to Leishmania. Isoenzyme analysis suggested that Sergentomyia sand flies most likely feed on both lizards (reptiles) and rodents (mammals). There is need to carry further investigations on NLB-1236 (from plated lizards), NLB-1261 (from wild spiny mice) and NLB-1231 (from wild spiny mice).
Effect of Leaf Crude Extracts of Tarchonanthus Camphoratus (Asteraceae), Acalypha Fruticosa (Fabacea) and Tagetes Minuta (Asteraceae) on Fecundity of Phlebotomus Duboscqi
(American International Journal of Contemporary Research, 2012-08) Mong’are, Samuel ; Ng’ang’a, Zipporah; Maranga, Rosebella; Osiemo, Zipporah; Ngure, Peter Kamau; Ngumbi, Philip; Tonui, Willy K.
Purpose: This study was carried out to find out the effects of Tarchonanthus Camphoratus (Asteraceae), Acalypha fruticosa (Fabacea) and Tagetes minuta (Asteraceae) crude extracts on the fecundity of P. duboscqi. Materials and Methods: The extracts were prepared from the dried aerial parts of T. camphoratus, A. fruticosa, and T. minuta. Ten female sand flies were aspirated into vials where they were fed on a mixture of the plant extracts and sucrose solution prepared in a ratio of 1:1. Results: These crude plant extracts were found to reduce the fecundity of P. duboscqi significantly (P< 0.05). The extracts were found to reduce the fecundity of P. duboscqi by 73% (A. fruticosa), 53% (T. minuta) and 26% (T. camphoratus) (P< 0.05). Conclusion: The higher level of A. fruticosa, T. minuta and T. camphoratus activities would potentially reduce the population of sand flies. This study has provided proof of the effects of these medicinal plants on the vectorial capacity of sand flies.
Evaluation of the Adjuvanticity of Artemisinin with Soluble Leishmania Major Antigens in BALB/C Mice
(Elsevier, 2009) Karanja, Muhia Robert; Ngure, Peter Kamau; Ingonga, Johnstone; Gicheru, Michael M.; Kepha, Stella; Njeru, Laban Ireri; Wachira, Dorcas; Mwangi, Milkah; Nyamwamu, Lydia B.; Kimutai, Albert; Tonui, Willy K.
Objective; To determine the adjuvant potential of artemisinin with a soluble leishmanial antigen in vaccinating BALB/c mice. Methods; Seventy two female BALB/c mice were randomly assigned into six groups. The mice were vaccinated with soluble leishmania antigens (SLA) alone, artemisinin co-administered with SLA, SLA and Bacille Calmette Guérin (BCG) vaccine, and artemisinin and BCG alone. Unvaccinated mice formed the control group. The induction of cell-mediated immunity following vaccination was determined by measuring in vitro lymphocyte proliferation and the production of interleukin (IL)-4, IL-5 and gamma interferon (IFN-γ) determined by flow cytometry. Protection against L. major was determined by quantifying parasite burdens in L. major infected footpads using a limiting dilution assay and by measuring lesion sizes of the infected footpad compared to the contralateral uninfected footpad. Results; Mice receiving SLA plus artemisinin produced significantly high levels of IL-4 and IL-5 (P < 0.05) and low levels of IFN-γ, resulting in exacerbated disease. In addition, subcutaneous administration of SLA + artemisinin, artemisinin alone or SLA alone resulted in the development of large footpad swellings and high parasite loads that were comparable to those of the control unvaccinated mice (P > 0.05), resulting in exacerbated disease. Conclusion; These data suggest that artemisinin is not a suitable adjuvant for Leishmania vaccines. However, since artemisinin has been shown to be effective against Leishmania parasites in vitro and in vivo, further studies ought to be conducted to determine its immunochemotherapeutic potential when co-administered with Leishmania antigens.
Evaluation of the immunochromatographic strip test for the rapid diagnosis of antenatal syphilis in women in Eldoret, Kenya.
(Elsevier, 2009) Nyamwamu, Lydia B.; Gicheru, Michael M.; Sharma, Rekha R.; Kimutai, Albert; Tonui, Willy K.; Kamau, Ngure Peter
Objective; This study compared the performance of the immunochromatographic strip (ICS) to the Venereal Disease Research Laboratory (VDRL) test and Treponema pallidum hemagglutination assay (TPHA) at a primary health care setting. Methods; The study group was comprised of 150 females randomly drawn from a population of pregnant women attending their first antenatal visit or follow-up visits at West Maternity Hospital in Eldoret Kenya, but without a previous syphilis test during that pregnancy. On-site VDRL, ICS and TPHA tests were performed and immediate treatment provided where appropriate. The performance of the three tests was compared. Results; The zero-prevalence of syphilis as determined by the VDRL test was 3%. There was no significant difference between the ICS and the VDRL test (P > 0.05). The sensitivity and specificity of the ICS test were 80% and 98.6% respectively, while the negative predictive value (NPV) and positive predictive value (PPV) were both 100%. On the other hand, the sensitivity and specificity of the VDRL test were 66.7% and 99.3%, while the NPV and PPV were 80% and 98.6% respectively. The Treponema pallidum hemagglutination assay was used as a reference test and had sensitivity, specificity, NPV and PPV of 100%.
Immunostimulatory responses to crude extracts of Warburgia ugandensis (sprague) subsp ugandensis (canellaceae) by Balb/c mice infected with Leishmania major
(Pan African Medical Journal., 2014-01-18) Ngure, Peter Kamau; Ng’ang’a, Zipporah; Kimutai, Albert; Kepha, Stella; Mong’are, Samuel; Ingonga, Johnnie; Tonui, Willy K.
Introduction: To determine the immunostimulatory potential of crude extracts of Warburgia ugandensis subsp. ugandensis with a soluble leishmanial antigen in vaccinating BALB/c mice. Methods: Seventy two female BALB/c mice were randomly assigned into six groups. The mice were vaccinated with soluble leishmania antigens (SLA) alone, hexane, ethyl acetate, and dichloromethane extract co-administered with SLA. Unvaccinated mice formed the control group. The induction of cell-mediated immunity following vaccination was determined by measuring in vitro lymphocyte proliferation and the production of interleukin (IL)-4 and gamma interferon (IFN-γ) determined by flow cytometry. Protection against L. major was determined by quantifying parasite burdens in L. major infected footpads using a limiting dilution assay and by measuring lesion sizes of the infected footpad compared to the contralateral uninfected footpad. Results: On vaccination with extracts of W. ugandensis subsp. ugandensis alone or as adjuvants when used in combination with Leishmania antigens, the hexane extract and the dichloromethane extract plus SLA stimulated moderate production of IFN-γ and low levels of IL-4.These mice were partially protected from cutaneous leishmaniasis as shown by the slow development of lesions and comparatively less parasite burdens. Conclusion: These data suggest that extracts of W. ugandensis subsp. ugandensis are suitable adjuvants for Leishmania vaccines. However, since W. ugandensis subsp. ugandensis has been shown to be effective against Leishmania parasites in vitro and in vivo, further studies ought to be conducted to determine its immunochemotherapeutic potential when co-administered with a soluble leishmanial antigen in vaccinating BALB/c mice.
In Vitro Effects of Warburgia Ugandensis, Psiadia Punctulata and Chasmanthera dependens on leishmania major promastigotes.
(Afr. J. Traditional, Complementary and Alternative Medicines, 2010) Githinji, Edward K.; Irungu, Lucy; Tonui, Willy K.; Rukunga, Geoffrey; Mutai, Charles; Muthaura, Charles N.; Lugalia, Reuben; Gikandi, Geoffrey; Wainaina, Caroline W.; Ingonga, Johnston M.; Wanjoya, Antony
Plant extracts from Warburgia ugandensis Sprague (Family: Canellaceae), Psiadia punctulata Vatke (Family: Compositae) and Chasmanthera dependens Hoschst (Family: Menispermaceae) were tested for activity on Leishmania major promastigotes (Strain IDU/KE/83 = NLB-144) and infected macrophages in vitro. Plants were collected from Baringo district, dried, extracted, weighed and tested for antileishmanial activity. Serial dilutions of the crude extracts were assayed for their activity against Leishmania major in cell free cultures and in infected macrophages in vitro. Inhibitory concentrations and levels of cytotoxicity were determined. Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens had an IC50 of 1.114 mg/ml, 2.216 mg/ml and 4.648 mg/ml, respectively. The cytotoxicity of the drugs on BALB/c peritoneal macrophage cells was insignificant as compared to the highly toxic drug of choice Pentostam®. The supernatants from control and Leishmania infected macrophages were analyzed for their nitrite contents by Griess reaction and nitrite absorbance measured at 540 nm. Warburgia ugandensis (stem bark water extract), Chasmanthera dependens (stem bark water extract) and Psiadia punctulata (stem bark methanol extract) produced 112.3%, 94% and 88.5% more nitric oxide than the untreated infected macrophages respectively. Plant crude extracts had significant (p<0.05) anti-leishmanial and immunomodulative effects but insignificant cytotoxic effects at 1mg/ml concentration. All experiments were performed in triplicate. Statistical analysis of the differences between mean values obtained from the experimental group compared to the controls was done by students’t test. ANOVA was used to determine the differences between the various treatment groups. The analysis program Probit was used to determine IC
In Vivo Efficacy of Oral and Intraperitoneal Administration of Extracts of Warburgia Ugandensis (Canellaceae) in Experimental Treatment of Old World Cutaneous Leishmaniasis caused by Leishmania Major.
(Afr. J. Traditional, Complementary and Alternative Medicines, 2009) Ngure, Peter Kamau; Ng’ang’a, Zipporah; Ingonga, Johnstone M.; Rukunga, Geoffrey; Tonui, Willy K.
The antileishmanial activity of extracts of Warburgia ugandensis Spraque (Canellaceae), a known traditional therapy in Kenya was evaluated in vivo. Treatment of infected BALB/c mice with W. ugandensis extracts orally resulted in a reduction of the size of lesions compared to the untreated control. The lesion sizes differed significantly for the four extracts (p=0.039) compared to the untreated control. For mice treated by intraperitoneal injection, the lesion sizes increased initially for the hexane, dichloromethane and ethyl acetate extracts and healed by day 42. The lesion sizes for mice treated with methanol increased steadily from 2.47mm to 3.57mm. The parasitic burden was significantly higher (p<0.001) in mice treated with methanol extracts and PBS compared to those treated with hexane, dichloromethane and ethyl acetate. This study demonstrated the antileishmanial potential of extracts of W. ugandensis.
Leishmaniasis in northern and western Africa: a review
(Afr. J. Infect. Dis., 2009) Kimutai, Albert; Ngure, Peter Kamau; Tonui, Willy K.; Gicheru, Michael Muita; Nyamwamu, Lydia Bonareri
Leishmaniasis, one of the highly neglected diseases is currently a significant health problem in northern Africa with a rising concern in western Africa because of co-infection with the Human Immunodeficiency Virus (HIV). In this review, we present a summarized analysis of the epidemiology, infective species, parasites reservoirs, diagnosis, treatment and control measures of leishmaniasis in northern and western Africa region. In northern Africa, the disease is prevalent in Morocco, Algeria, Tunisia, Egypt and Libya. Comparatively, there are low prevalence rates of the disease in West African countries including Cameroon, Ghana, Burkina Faso, Niger, Mali, Nigeria and Senegal. In North Africa, visceral leishmaniasis (VL) is caused by L. infantum and transmitted by Phlebotomus perniciosus and P. longicuspis. On the other hand, cutaneous leishmaniasis (CL) is mainly caused by L. major and transmitted by P. papatasi, P. duboscqi and P. pedifer with L. infantum and L. tropica causing lower incidences of the disease. Notably, Algeria is one of the countries that constitute 90% of CL cases worldwide. In Western Africa; CL is caused by L. major while VL is caused by L. donovani. In these regions, zoonotic and anthroponotic cutaneous and visceral leishmaniasis is a health problem that should be addressed urgently.
Potential Effects Of Pyrethrin Incorporated In Sucrose Baits Against Phlebotomus Duboscqi Neveu Lemaire (diptera: Psychodidae) In Leishmaniasis Control Strategies
(Webmedcentral, 2010-11-06) Ireri, Laban N.; Mucheru, Obadiah; Ngure, Peter Kamau; Kepha, Stella; Kimutai, Albert; Cirindi, Josyline; Tonui, Willy K.
Background: Due to challenges of controlling leishmaniasis in Kenya through the vector, the efficacy of pyrethrin EC (Pymos™ 0.6% W/V) a mosquito adulticide was evaluated against Phlebotomus duboscqi while incorporated in sucrose as a possible complementary method. Methods: Pyrethrin was prepared into concentrations of 0.08, 0.25and 0.5 mg/ml using 10% sucrose. Ten male and female sand flies were each aspirated into jars and fed separately with the prepared solutions using cotton wool pads placed atop experimental jars and mortality monitored each day. The experiments were replicated three times. Results: Significant mortality (P< 0.05) for both sexes was observed. The concentration of 0.08mg/ml gave low adult mortality in 24 hours but amplified with time. In the 0.25 bioassay, mortality of females were 10 (33.3%) and males had 21 (70%) in 24 hours. The LD50 for females and males tied at 0.1 mg/ml in 48 hours of exposure. The concentration of 0.25 mg/ml was ideal at 48 hours of feeding where majority of the sand flies succumbed to the insecticide. There were significant mortality differences (P <0.05) between the concentrations but no significant difference (P>0.05) was observed in male and female mortality at 48 hours of exposure however. Although we cannot rule out sand fly mortality due to contact with the test material, the results of this study however suggest that control strategies using low-dose pyrethrin-sugar combinations as baits may be effective against phlebotomine sand flies and other sugar feeding pests of medical importance.
The potential of the extracts of Tagetes minuta Linnaeus (Asteraceae), Acalypha fruticosa Forssk (Euphorbiaceae) and Tarchonanthus camphoratus L. (Compositae) against Phlebotomus duboscqi Neveu Lemaire (Diptera: Psychodidae), the vector for Leishmania major Yakimoff and Schokhor
(Journal of Vector Borne Diseases, 0201-09) Ireri, Laban N.; Kongoro, Jedida; Ngure, Peter Kamau; Mutai, Charles; Langat, Bernard; Tonui, Willy K.; Kimutai, Albert; Mucheru, Obadiah
Background & objectives: Harmful effects of synthetic chemical insecticides including vector resistance, environmental pollution and health hazards have necessitated the current significance in the search for plant-based insecticide products that are environmentally safe and effective to leishmaniases control. The insecticidal activity of Tagetes minuta Linnaeus (Asteraceae), Acalypha fruticosa Forssk (Euphorbiaceae) and Tarchonanthus camphoratus L. (Compositae) extracts were investigated against Phlebotomus duboscqi Neveu Lemaire (Diptera: Psychodidae). Methods: The extracts were prepared from dried aerial parts soaked in methanol and ethyl acetate twice until the filtrates became clear, filtered and dried out by rotary evaporation at 30–35oC. The solid extracts obtained were later prepared into 2.5, 5 and 10 mg/ml. Two millilitres of the solutions were blotted on filter papers, which were dried overnight and placed into jars where adult sandflies were aspirated. Males and females were assayed separately. Results & conclusion: The extracts had significant mortality (p<0.05) in both males and females bioassays but were not significantly different between sexes. The extracts of Acalypha fruticosa and Tagetes minuta had significantly higher mortality rates than those of Tarchonanthus camphoratus and the different concentrations used showed significantly different mortality rates and 10 mg/ml was the most effective concentration. Cent percent mortality was obtained at 96 h of exposure to 5 and 10 mg/ml concentrations except for Tarchonanthus camphoratus which had a mortality of only 46.7% in 10 mg/ml bioassay. These extracts were found to be insecticidal to adult sandflies.

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