Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia

Abstract

Abstract. Nchelenge District in Luapula Province, northern Zambia, experiences holoendemic malaria despite implementation of vector control programs. The major Anopheles vectors that contribute to Plasmodium falciparum transmission in this area had not previously been well defined. Three collections performed during the 2012 wet and dry seasons and the 2013 wet season revealed Anopheles funestus sensu stricto and Anopheles gambiae sensu stricto as the main vectors, where 80-85% of each collection was composed of An. funestus. Both vectors were found to be highly anthropophilic, and An. funestus has higher sporozoite infection rates (SIRs) and entomological inoculation rates (EIRs) year-round compared with An. gambiae: SIRs of 1.8-3.0% and 0-2.5%, respectively, and EIRs of 3.7-41.5 infectious bites per 6-month period (ib/p/6mo) and 0-5.9 ib/p/6mo, respectively. Spatial and temporal changes in each vector's dynamics and bionomics were also observed. Anopheles funestus was the predominant vector in the villages near Kenani Stream in both wet and dry seasons, whereas An. gambiae was found to be the main vector in areas near Lake Mweru during the wet season. The vector data illustrate the need for broader temporal and spatial sampling in Nchelenge and present unique opportunities to further our understanding of malarial transmission and implications for malarial control in high-risk areas.

The return of chloroquine-susceptible Plasmodium falciparum malaria in Zambia

“…The study was carried out in Nchelenge district, Luapula province in the northern part of the country. This is an area of stable transmission with the entomological inoculation rate estimated at 4–48 infectious bites per 6 months in 2013 [22]. We collected and analysed specimens from pregnant women with a positive malaria smear who were enrolling the trial and before they received any antimalarial treatment.…”

Genetic diversity ofAnopheles coustaniin high malaria transmission foci in southern and central Africa

“…In the laboratory, the abdomen of each collected anopheline was separated from the head and thorax using sterile forceps, and then stored in separate tubes at −20°C. Genomic DNA was extracted from the frozen mosquito abdomens with a salt extraction method as previously described (Post et al 1993, Norris et al 2001, Das et al 2016). A fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene used for the Barcode of Life Database (BOLD), a molecular target that has been previously used for phylogeny construction of anophelines, was amplified and sequenced from specimens that were morphologically identified as An .…”

“…In Nchelenge, the primary vectors of malaria in both the dry and wet seasons have been found to be An. funestus s.s. and Anopheles gambiae s.s. (Das et al 2016, Jones et al 2018, Hast et al 2019). Malaria is also holoendemic in the DRC which borders Zambia to the north, but much less is known about malaria vectors and their phenology, other than that An.…”

Implicating Cryptic and Novel Anophelines as Malaria Vectors in Africa

“…ITS2 is a non-coding nuclear gene with conserved primer binding sites and is more variable than coding genes so can be used for fine resolution phylogenetic analyses and well as construction of diagnostic tools [60]. COI is a protein-coding gene with high copy number.…”

“…In the growing number of studies that are being done, species composition in outdoor collections is greatly different to those conducted indoors and may comprise substantial numbers of mosquitoes/vectors that have not been locally considered or even recognized. Whilst morphological keys do provide simple “low tech” methods to identify these lesser known species, molecular tools designed to detect and/or confirm these species are not commonly used and are often of limited utility for only a few select species [60,95]. Confirmation of morphological identities, therefore, largely relies on DNA sequencing studies.…”