Larvicidal effect of Mundulea sericea (Leguminosaea) plant extract against Aedes aegypti (L.) (Diptera: Culicidae)

IntroductionThe medical importance of mosquitoes as vectors forthe transmission of serious diseases that causemorbidity, mortality, economic loss, and socialdisruption such as malaria, lymphatic filariasis, andviral diseases is well recorded (Becker et al, 2003).Aedes aegypti, the main carrier for viruses that causedengue and dengue hemorrhagic and yellow fevers, isfound majorly in the tropics and subtropics. There is noeffective vaccine against dengue, and thus the only wayof significantly lowering the incidence of this disease isthrough mosquito control (Malavige et al, 2004).Chemical measures were first tried, but they failed sincetheir overuse led to disruption of natural biologicalcontrol systems and outbreak of new insect species. Inaddition, use of insecticides led to the development ofmosquito resistance, environmental pollution, andundesirable effect on non-target organisms (Brown,1986). In a bid to resolve these problems, interest ininsecticides of natural origin, specifically plant-derivedproducts has recently received close attention.Several studies have emphasized the importance ofresearch and development of herbal substances forcontrolling mosquitoes (Shaala et al, 2005). Theirresults may vary, but natural plant products may be apossible alternative to synthetic substances, as they areeffective and compatible with human and animal lifeand the environment (Chaithong et al, 2006).The genus Mundulea consists of about 15 species,widespread throughout Africa, Madagascar, Mauritius,India, Sri Lanka and Papua New Guinea. Only a singlespecies, Mundulea sericea, is found in Southern Africa.This species occurs in South Africa, Botswana, Namibiaand Angola, north to tropical Africa, and east toMadagascar, India, Sri Lanka and Papua New Guinea(Watt and Breyer-Brandwick, 1962).Mundulea sericea is one of the commonest fish poisonswhere both bark and seeds are used (Neuwinger, 2004).In addition, the Chinese used M. sericea to controltobacco budworm Heliothis virescens (Lepidopteriae:Noctuidae) (Yoshida and Toscano, 1994).The toxic principal of the plant is rotenone, anisoflavonoid (Vedcourt and Trump, 1969). Therotenoids deguelin and tephrosin are the potent activeprinciples which have been isolated from extracts of M.sericea (Luyengi et al, 1994). Deguelin is a natural plantderivedrotenoid, most commonly used as an insecticidein Africa and South America (Udeani et al, 1997).Rotenoids from the bark of M. sericea have beencommercially used as insecticide. These chemicalcompounds in the bark, leaves and seed are the activecompounds responsible for the fish poison. It isreported that the strength varies geographically (Wattand Breyer-Brandwick, 1962).The current study involved extraction and evaluation ofroot bark and seedpod of M. sericea for larvicidalactivities on Aedes aegypt

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Choice and Sources of Antimalarial Drugs Used for Self-medication in Kisumu, Western Kenya

Background: The choice and sources of antimalarial drugs used for self-medication has important implication to the current malaria treatment policies in Kenya. However, data on the choice of antimalarial drugs used for self-medication and their sources remains scanty. Objectives: The objectives of this study were to determine the prevalence of self-medication, the choice and sources of antimalarial drugs used for malaria self-medication in Kisumu city, Western Kenya. Methodology: This was a cross-sectional community based study, in which semi-structured questionnaires were randomly administered to 338 participants, in five administrative wards of Kisumu city. Results: Overall, 250 (74%) of the participants reported self-medication for perceived malaria illness. Of the 250 participants, 219 (87.6%) had used an antimalarial drug(s), while 31 (12.4%) took other drugs (antipyretics and herbs), which they perceived to have antimalarial effect. Artemisinin-based combination therapies (ACT), was the drug of choice for majority 154 (70.3%) of those who had self-medicated. The other antimalarials used were sulphadoxine/sulphalene-pyrimethamine 25 (11.4%), amodiaquine 11 (5%), chloroquine 5 (2.3%), quinine 2 (0.9%), dihydroartemisinin 1 (0.5%), halofantrene 1 (0.5%) and 20 (9%) of participants had used two different antimalarials. The antimalarial drugs were sourced from private pharmacies/chemists (78.4%), general retail shops (29.2%), left over drugs at home (1.6%), or friends, relatives and neighbors (2.8%). Conclusion: Self-medication for perceived malaria is prevalent in Kisumu city. ACT is the drug of choice for self-medication. However, a substantial proportion of individuals use currently ineffective antimalarials or other drugs, for example antipyretics, with no known antimalarial efficacy. Pharmacies/chemists and general retail shops are the major sources for self-prescribed drugs. Key words: Self-medication, antimalarial drugs, choices, source

The effects of Mundulea sericea (Fabales: Fabaceae) water extracts on Phlebotomus duboscqi (Diptera: Psychodidae) eggs and larvae

Background: The sand fly, Phlebotomus duboscqi is the vector for zoonotic cutaneous leishmaniasis caused by Leishmania major. No definite control method for P. duboscqi is known. Of the plants known for entomocidal properties, Mundulea sericea is one, with the toxic principle being rotenone. Dried crude M. sericea powder extract mixed with water is used by the Giriama people of Coastal region, Kenya, to kill cat fleas and bedbugs. A recent laboratory study using M. sericea non-polar and polar extracts displayed remarkable entomicidal potential. Against this backdrop, M. sericea was chosen for this study. Objective: To evaluate water extracts of Mundulea sericea leaves for efficacy against P. duboscqi eggs and larvae. Methodology: The plant leaves were ground into fine powder and extracted using water. 1 g leaf powder was extracted using 100 ml distilled water, and then filtered. The eggs were then exposed to 1 ml of the filtered extract.  Further, 0.001 g of leaf powder was mixed with 1 g of larval food and fed to larvae. The eggs were incubated at 25 0C and 80% relative humidity and observed for eclosion, and larvae for hatching to adult stage. Results: The filtered extracts did not inhibit eggs from hatching. Additionally, all the larvae that were fed on food mixed with ground M. sericea leaves survived. Conclusion: These findings suggest that suggest that M. sericea water extracts do not penetrate the egg chorion, thus the lack of activity. Moreover, the inability of P. duboscqi to digest the chlorophyll of M. sericea so as to release rotenone could be responsible for absence of entomocidal effect. Key words: Mundulea sericea; Phlebotomus duboscqi; Leishmania major