ABSTRACT
Background & objectives: Leishmaniasis is a growing health problem in many parts of the world. Efforts to find new chemotherapeutics for leishmaniasis remain a priority. This study was carried out to determine the effect of combination and monotherapies using plant extracts and herbicides on Leishmania major infection in BALB/c mice. Methods: The herbicides and saponin extract were purchased from Sigma. Roots of Plumbago capensis were collected from Karura forest, Nairobi, Kenya. Plant extractions were done in KEMRI at Center for Traditional Medicines and Drugs Research. Results: Lesion sizes after infection of BALB/c mice were similar in all the experimental groups till the onset of therapeutic treatments (p >0.05). At 15 days post-treatment, significant differences (p < 0.05) were discerned in the lesion sizes of the BALB/c mice in all the mono- and combined-treated groups. However, the combined therapies caused total elimination of the parasites from the lesions and significantly reduced parasite burden in liver and spleen compared to the untreated controls at the end of the experiment. Interpretation & conclusion: The results of this study demonstrate that combination therapy using alternative administration of saponin, acriflavine, trifluralin and plumbagin is effective in treating L. major infection in mice. In this regard, an investigation into the efficacy of these combined therapies against other Leishmania strains should be explored further. Furthermore, studies with these combination therapies should be done on non-human primates such as the vervet monkey (Cercopithecus aethiops).
ABSTRACT
Visceral and cutaneous leishmaniases are endemic in some parts of Kenya, where they are transmitted by phlebobotomine sandflies of genus Phlebotomus. This review is a compilation of the currently known distribution of phlebotomine sandflies in the parts of Kenya that have been studied, from the time sandflies were first reported in the country. So far 48 species of sandflies have been identified falling in the genera Phlebotomus Rondani & Berte and Sergentomyia Franca & Parrot. Genus Phlebotomus in Kenya is represented in five subgenera, namely Phlebotomus, Larroussius, Synphlebotomus, Paraphlebotomus and Anaphlebotomus. Genus Sergentomyia has the largest number of sandflies, and is represented in four subgenera, namely Sergentomyia, Sintonius, Grassomyia and Parvidens.
ABSTRACT
Background & objectives: Several plant products have been tested and found to possess antileishmanial activity. The present study was undertaken to establish whether methanolic extract of Allium sativum Linn has antileishmanial activity in comparison to standard drugs. Methods: Methanolic extract of A. sativum bulbs was screened for in vitro and in vivo antileishmanial activity against Leishmania major strain (NLB 145) and L. donovani strain (NLB 065). Pentostam® and Amphotericin B® were used as standard drugs. BALB/c mice and golden hamsters (Mesocricetus auratus) were used in in vivo studies on L. major and L. donovani respectively. Results: The extract exhibited very low cytotoxicity (IC50 >450 μg/ml) against Vero cells. The extract had significantly better (p <0.001) leishmanicidal activity against both species (IC50 34.22 μg/ml to L. major, 37.41 μg/ml to L. donovani) than Pentostam. However, the activity was significantly lower (p <0.001) than that of Amphotericin B against both the species. At a concentration of 250 μg/ml, the extract induced the production of 60 μM of nitric oxide, a ten-fold up-regulation in activated macrophages. The multiplication indices for L. major amastigotes treated in 100 μg/ml were significantly different (p <0.05). Treatment with the extract, daily for 28 days led to a significant reduction (p <0.05) in footpad swelling in BALB/c mice; similar activity noticed in the treatment with standard drugs. The Leishman-Donovan Units (LDU) for the extract treated animals were significantly higher (p <0.05) than those of standard drugs, but lower compared to the negative control. Interpretation & conclusion: Since the mechanism of action for the methanolic extract is apparently immunomodulatory, garlic compounds could be purified and tried as complementary medicine in the management of leishmaniases.
ABSTRACT
Background & objectives: Phlebotomine sandflies are vectors of leishmaniases and other diseases. Long-lasting insecticidal nets (LLINs) as possible tools for control have not been widely tested against them. The objective of this study was to determine the efficacy of Olyset® Net and PermaNet® LLINs alongside a local brand, K-O Tab® treated net (Supanet) against Phlebotomus duboscqi female sandflies. Methods: Four replicates of unwashed and 20x washed Olyset Nets and PermaNets, K-O Tabtreated and untreated Supanet and ‘no net’ treatments were evaluated against sandflies within the laboratory by tunnel tests and in semi-field conditions in the greenhouse model for their efficacy. Results: All bednets allowed entry of P. duboscqi sandflies and subsequent blood-feeding. Olyset net’s blood feeding inhibition was significantly higher than that of Supanet in the laboratory but not in semi-field condition. Of the LLINs, only Olyset net had sandflies that could not feed significantly more than those of Supanet. Additionally, no significant efficacy difference was observed between LLINs washed 20x and unwashed ones. The only significant difference noted in number of sandflies that were found dead or paralyzed within bednets in the semi-field condition was between Olyset and K-O Tab treated Supanet. In the laboratory, unwashed Olyset had a significantly higher number of sandflies killed than all other bednet treatments. Conclusion: Olyset net use in areas where sandflies are nuisance biters and/or disease vectors could be more beneficial in preventing sandfly bites than other tested bednets. It is recommended that mesh sizes of LLINs should be smaller for control of sandflies than those used for control of mosquitoes.
ABSTRACT
Background & objectives: In order to understand sandfly bionomics, vector species identification, and to develop methods for sandfly control, there is a need to sample sandflies in any particular habitat. This survey was aimed at determining the best method of sampling Phlebotomus (Phlebotomus) duboscqi (Diptera: Psychodidae) in the field. Methods: Different animal baits and CO2-baited CDC light traps were used to attract sandflies released in an insect-proof screen-house located in the sandfly’s natural habitat in Marigat, Baringo district of Kenya. Results: Attraction of hungry P. duboscqi female sandflies by the goat (Capra hircis) was significantly higher than that of hamster (Mesocricetus auretus), Nile grass rat (Arvicanthis niloticus), gerbil (Tatera robusta) and chicken (Gallus domestica). However, two rodent species, A. niloticus and T. robusta did not differ significantly. A linear regression analysis of weights of animal baits and number of sandflies attracted revealed an insignificant result. The fluorescent dyes used to distinguish sandflies of different day experiments seemed not to influence the sandfly numbers in relation to the studied sandfly behaviour. Interpretation & conclusion: The similar attraction pattern of P. duboscqi in semi-field environment by CO2-baited CDC light trap and the goat provides hope for solution to the problem of fast dissipating dry ice (CO2 source) in the field. Goats can, therefore, also be utilized as deflectors of vectors of cutaneous leishmaniasis from humans in zooprophylaxis in Leishmania major endemic areas where the sandfly is found.