Combination and monotherapy of Leishmania major infection in BALB/c mice using plant extracts and herbicides

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).

The phlebotomine sandfly fauna (Diptera: Psychodidae) of Kenya

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.

Effects of long-lasting insecticidal nets and zooprophylaxis on mosquito feeding behaviour and density in Mwea, central Kenya

BACKGROUND & OBJECTIVES

Zooprophylaxis is a strategy that can control malaria by attracting mosquitoes to domestic animals that act as dead-end hosts. The objective of this study was to establish the effects of zooprophylaxis and long-lasting insecticidal nets (LLINs) on malaria transmission in an agro-based ecosystem with seasonal transmission.

METHODS

The mosquito samples were collected indoors using the space spray catch method before and after intervention between October 2005 and March 2006 to determine the mosquito densities and the feeding patterns of Anopheles spp in Mwea, Kenya.

RESULTS

A total of 4148 mosquito samples were collected, out of which 11 (0.2%) were tested positive for sporozoites. Ten were Anopheles gambiae species and one was An. funestus species. Results on blood meal ELISA showed that in the household categories that used bednets and kept one cow there was a decrease in relative change ratio (post-/pre-intervention) of 87.5 and 19.6% (p <0.05) in human and cattle blood intake respectively. For households that kept 2-4 cattle and used bednets, there was a decrease in cattle blood index (CBI) by 61.9% and an increase in human blood index (HBI) by 2%, which was not significant (p <0.05). In households with <4 cattle and bednet, there was significant reduction (p >0.05) in CBI of 37.5% as compared to the reduction of 10.3% in HBI. The ratios of man biting rates (MBR) decreased significantly, as you move up from households with one cattle with or without LLINs to households with more than four cattle with or without LLINs with a regression coefficient of -0.96; SE = 0.834; p = 0.017. Similarly, the HBI decreased significantly with the regression coefficient of 0.239; SE = 0.039; p = 0.015 (p <0.05) especially in households with >4 cattle.

INTERPRETATION & CONCLUSION

This study demonstrated that there were additive effects of zooprophylaxis and LLINs in the control of mosquito density and reduction of human risk to the mosquito bites. However, in Integrated Vector Management (IVM), the number of animals per household should not be more than four.