Publications by authors named "Lizette L Koekemoer"

and (members of the group) are generally not considered malaria vectors. However, both species were recently identified as potential vectors in South Africa. A critical factor needed to determine their role in malaria transmission is their preference for human blood.

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  • Recent research indicates that artificial light at night (ALAN) can change mosquito feeding habits, impacting the spread of diseases like malaria.
  • This study specifically investigates how different types of household lights affect the feeding behavior of the Anopheles funestus mosquito, a key malaria vector in sub-Saharan Africa.
  • Results show that exposure to incandescent lights significantly reduces feeding rates, suggesting that household lighting design could play a role in minimizing mosquito bites and curbing disease transmission.
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  • - South Africa is a malaria-endemic country with three provinces where the spread of malaria is linked to specific mosquito vectors, making vector control critical for elimination efforts.
  • - The Ehlanzeni district in Mpumalanga has been monitored for malaria vectors, particularly the Anopheles gambiae complex, and comprehensive data has been gathered from 2009 to 2021 but has not been analyzed until now.
  • - The study found that An. merus and An. arabiensis are the most common species, with different collection methods yielding varying results; however, vector abundance showed no significant link to annual climatic changes, pointing to potential data collection limitations.
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Toward repositioning the antitubercular clinical candidate SQ109 as an antimalarial, analogs were investigated for structure-activity relationships for activity against asexual blood stages of the human malaria parasite pathogenic forms, as well as transmissible, sexual stage gametocytes. We show that equipotent activity (IC) in the 100-300 nM range could be attained for both asexual and sexual stages, with the activity of most compounds retained against a multidrug-resistant strain. The multistage activity profile relies on high lipophilicity ascribed to the adamantane headgroup, and antiplasmodial activity is critically dependent on the diamine linker.

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Background: Microsporidia MB (MB) is a naturally occurring symbiont of Anopheles and has recently been identified as having a potential to inhibit the transmission of Plasmodium in mosquitoes. MB intensity is high in mosquito gonads, with no fitness consequences for the mosquito, and is linked to horizontal (sexual) and vertical (transovarial) transmission from one mosquito to another. Maximising MB intensity and transmission is important for maintaining heavily infected mosquito colonies for experiments and ultimately for mosquito releases.

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  • Anopheles funestus, a key malaria vector in East and Southern Africa, is less understood in terms of ecology and resistance to insecticides compared to other mosquitoes, leading to a large-scale study in Tanzania on its genetic resistance and susceptibility to insecticides.
  • The study used bioassays across nine regions to examine resistance, identifying universal resistance to pyrethroids that could be reversed with piperonyl-butoxide, and variable resistance to carbamates and DDT.
  • Geographic patterns showed distinct distribution of genetic markers associated with resistance, with the most complex resistance landscape found in the Tanganyika district of western Tanzania, highlighting the need for tailored vector control strategies.
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There is burgeoning interest in how artificial light at night (ALAN) interacts with disease vectors, particularly mosquitoes. ALAN can alter mosquito behaviour and biting propensity, and so must alter disease transfer rates. However, most studies to date have been laboratory-based, and it remains unclear how ALAN modulates disease vector risk.

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Anopheles mosquitoes present a major public health challenge in sub-Saharan Africa; notably, as vectors of malaria that kill over half a million people annually. In parts of the east and southern Africa region, one species in the Funestus group, Anopheles funestus, has established itself as an exceptionally dominant vector in some areas, it is responsible for more than 90% of all malaria transmission events. However, compared to other malaria vectors, the species is far less studied, partly due to difficulties in laboratory colonization and the unresolved aspects of its taxonomy and systematics.

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  • Malaria is transmitted by infected female Anopheles mosquitoes, particularly An. arabiensis in arid Africa, which undergoes a life cycle of aquatic stages (egg, larva, pupa) before becoming adult mosquitoes.
  • Current insecticide methods face challenges due to increasing resistance, highlighting the need for multi-stage targeting insecticides, preferably from natural sources like essential oils.
  • The study identified five essential oil constituents (EOCs) with significant toxic effects on An. arabiensis stages, particularly methyleugenol, which effectively inhibited egg hatching, and others showing strong larvicidal and pupicidal properties, marking potential new avenues for eco-friendly malaria control strategies.
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Malaria vector control relies on the use of insecticides for indoor residual spraying and long-lasting bed nets. However, insecticide resistance to pyrethroids among others, has escalated. Anopheles funestus, one of the major African malaria vectors, has attained significant levels of resistance to pyrethroids.

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Background: Malaria transmission can be highly heterogeneous between and within localities, and is influenced by factors such as survival and biting frequencies of Anopheles mosquitoes. This study investigated the relationships between the biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes, which currently dominate malaria transmission in south-east Tanzania. The study also examined how such relationships may influence malaria transmission and control.

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Anopheles funestus is one of the major malaria vectors in Africa. As with the other main vectors, insecticide resistance in this species threatens existing vector control strategies. Unfortunately, scientific investigations, which could improve understanding of this vector species or lead to the development of new control strategies, are currently limited by difficulties in laboratory rearing of the species.

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Current studies on Anopheles anticholinesterase insecticides are focusing on identifying agents with high selectivity towards Anopheles over mammalian targets. Acetylcholinesterase (AChE) from electric eel is often used as the bioequivalent enzyme to study ligands designed for activity and inhibition in human. In this study, previously identified derivatives of a potent AChE, donepezil, that have exhibited low activity on electric eel AChE were assessed for potential AChE-based larvicidal effects on four African malaria vectors; An.

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The insect nervous system is critical for its functional integrity. The cholinergic system, of which acetylcholinesterase (AChE) is a key enzyme, is essential to the (consisting of major malaria vector species) nervous system. Furthermore, the nervous system is also the primary target site for insecticides used in malaria vector control programs.

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  • * Chemoproteomics studies identified multiple kinase targets, confirming sapanisertib's effective inhibition of PI4Kβ and PKG, which play key roles in the parasite's survival.
  • * The drug's ability to disrupt parasite metabolism and its effectiveness in vivo suggest it can be repositioned as a promising treatment for malaria, especially given the rise of drug resistance.
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The International Centers of Excellence for Malaria Research (ICEMR) were established by the National Institute of Allergy and Infectious Diseases more than a decade ago to provide multidisciplinary research support to malaria control programs worldwide, operating in endemic areas and contributing technology, expertise, and ultimately policy guidance for malaria control and elimination. The Southern and Central Africa ICEMR has conducted research across three main sites in Zambia and Zimbabwe that differ in ecology, entomology, transmission intensity, and control strategies. Scientific findings led to new policies and action by the national malaria control programs and their partners in the selection of methods, materials, timing, and locations of case management and vector control.

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For a decade, the Southern and Central Africa International Center of Excellence for Malaria Research has operated with local partners across study sites in Zambia and Zimbabwe that range from hypo- to holoendemic and vary ecologically and entomologically. The burden of malaria and the impact of control measures were assessed in longitudinal cohorts, cross-sectional surveys, passive and reactive case detection, and other observational designs that incorporated multidisciplinary scientific approaches: classical epidemiology, geospatial science, serosurveillance, parasite and mosquito genetics, and vector bionomics. Findings to date have helped elaborate the patterns and possible causes of sustained low-to-moderate transmission in southern Zambia and eastern Zimbabwe and recalcitrant high transmission and fatality in northern Zambia.

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  • * The study assessed three IRS campaigns in the Magude project, finding high coverage rates (over 90% structures sprayed and 86% people covered) and varying efficacy based on wall types and timing of mosquito mortality.
  • * Recommendations include using longer-lasting IRS products and adjusting efficacy calculations to incorporate IRS coverage, spraying pace, and wall type to enhance protection during high malaria transmission seasons.
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The "Magude project" aimed but failed to interrupt local malaria transmission in Magude district, southern Mozambique, by using a comprehensive package of interventions, including indoor residual spraying (IRS), pyrethroid-only long-lasting insecticide treated nets (LLINs) and mass-drug administration (MDA). Here we present detailed information on the vector species that sustained malaria transmission, their association with malaria incidence and behaviors, and their amenability to the implemented control interventions. Mosquitoes were collected monthly between May 2015 and October 2017 in six sentinel sites in Magude district, using CDC light traps both indoors and outdoors.

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Background: To eliminate malaria in southern Mozambique, the National Malaria Control Programme and its partners are scaling up indoor residual spraying (IRS) activities in two provinces, Gaza and Inhambane. An entomological surveillance planning tool (ESPT) was used to answer the programmatic question of whether IRS would be effective in target geographies, given limited information on local vector bionomics.

Methods: Entomological intelligence was collected in six sentinel sites at the end of the rainy season (April-May 2018) and the beginning of the dry season (June-July 2018).

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Background: Nchelenge District in northern Zambia suffers from holoendemic malaria transmission despite a decade of yearly indoor residual spraying (IRS) and insecticide-treated net (ITN) distributions. One hypothesis for this lack of impact is that some vectors in the area may forage in the early evening or outdoors. Anopheles gibbinsi specimens were identified in early evening mosquito collections performed in this study area, and further insight was gleaned into this taxon, including characterizing its genetic identity, feeding preferences, and potential role as a malaria vector.

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Background: Malaria vector control using insecticide-based approaches has proven to be an effective strategy. However, widespread insecticide resistance among malaria vector populations across sub-Saharan Africa threatens to derail control efforts. This study was conducted in Chikwawa district, an area in rural southern Malawi characterised by persistent malaria transmission and reports of insecticide resistance in the local mosquito population.

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