Browsing by Author "Irungu, Lucy"

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    Effects of Metarhizium anisopliae on sand fly populations in their natural habitats in Marigat sub- County, Baringo County, Kenya
    (Centre for Biotechnology Research & Development,, 2010) Ngure, Peter Kamau; Ngumbi, Philip; Kasili, Sichangi; Anjili, Christopher O.; Karanja, Robert M.; Kaburiae, Josyline C.; Mwangi, Milkah; Kinuthia, Geoffrey K.; Kiarie, Martha; Nzau, Anastasia; Kepha, Stella; Maniania, Nguya K.; Irungu, Lucy
    Leishmaniasis is one of the neglected tropical diseases that pose a threat to people in the endemic regions. In Africa, transmission is through the bite of an infected female phlebotomine sand fly. Disease control with chemotherapy is logistically difficult, toxic and expensive. Entomopathogenic fungi (EPF) hold great potential as alternative vector control for sandflies as demonstrated by their efficacy in recent laboratory experiments. The impressive results have merited testing of the effect of EPF on sand flies in their natural habitats. The goal of this study was to test the effect of EPF on sand fly populations on a small scale in a leishmania-endemic area in Kenya. Entomopathogenic fungi isolates were cultured on Sabourand dextrose agar (SDA) in Petri dishes and incubated at 22-280C. Conidia were produced on long white rice substrate and harvested by sifting the substrate through a 295 μm mesh size sieve and stored at 4- 2 6 0C before being used in the experiments. Metarhizium anisopliae isolates were selected for use in the field after showing 76.8 and 100% mortality in laboratory bred target insects. 2.0 x 1014 of dry conidia of the fungus were introduced into ten termite mounds through the shafts using a modified foot pump in Rabai, Marigat area of Baringo County, Kenya. The site harbours both Phlebotomus martini and P. duboscqi sandfly vectors. Sand fly densities, mycoses and survival after capture from the mounds were observed from week one post-treatment to week thirteen. Results indicate that the fungi in termite mounds caused three to ten-fold mortalities in the population of sand flies nine weeks after application. Longevity of sand flies collected from treated termite mounds was reduced to less than nine days after collection, whereas 90% of those from control mounds lived well over the nine days. Sand flies collected from the treated termite mounds during week nine had 100% mortality compared to 10.7% of those from the control mounds. Metarhizium anisopliae infection was observed in 42% of the sand fly cadavers collected from the treated termite mounds and 0% in the control group. The high susceptibility of sand flies to M. anisopliae suggests that fungi can be developed as potential vector control alternatives to synthetic chemical insecticides or preferentially be applied in integrated control strategies in order to gain maximum impact on adult sand fly populations. Further studies to determine the best methods for delivery and application in the diverse ecological settings of various leishmaniasis vectors are recommended.
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    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