Biology subjects

Sraku, I. K.

Publications and source records attributed to Sraku, I. K..

3 recordsLinked to original sources

bioRxiv2026

Genetic surveillance of target site mutations and copy number variants associated with the escalating insecticide resistance in Anopheles gambiae (s.l.) in Ghana

The spread of insecticide resistance in malaria vectors poses a major challenge to control programs. As insecticide-based interventions intensify, selection for resistance alleles increases, making it essential to understand the genetic mechanisms underlying resistance in local Anopheles populations. This study characterized target-site resistance mutations and copy number variants (CNVs) in Anopheles gambiae s.l. from nine sites with different malaria vector interventions and ecological contexts. WHO bioassays revealed moderate-to-high pyrethroid resistance (4-65%) at all sites, while Obuasi (IRS) showed markedly elevated organophosphate resistance (1.7%) compared to other locations. The L995F kdr mutation was strongly associated with pyrethroid resistance (P < 0.05) and occurred at high frequencies in IRS and standard LLIN sites (0.82-1.0). Additional kdr variants (L995S, N1570Y, I1527T, V402L) appeared at variable frequencies (0-0.59). The Ace-1 G280S mutation was significantly associated with pirimiphos-methyl resistance (OR=2.20, P<0.001). Ace-1 gene duplications occurred in 22.8% of mosquitoes, predominantly in individuals carrying the G280S resistance allele (P<0.001). Carboxylesterase CNVs were also identified, with Coeaxf_Dup1 (30.4%) significantly associated with pirimiphos-methyl resistance (OR = 1.68, P = 0.02). These findings demonstrate the widespread, multifaceted resistance mechanisms in An. gambiae s.l. across Ghana and highlight the need for locally tailored vector control strategies.

molecular biology↗

bioRxiv2025

Malaria vector diversity, transmission, and insecticide resistance, in island communities along the Volta Lake in southern Ghana.

Island communities along the Volta Lake in southern Ghana present unique challenges for malaria control, characterized by high transmission rates, limited vector control measures, and isolated ecosystems. This study assessed the malaria vector diversity, seasonal abundance, transmission, and insecticide resistance status of malaria vectors in these communities to inform effective control strategies. Mosquitoes were collected from three island communities (Tuanikope, Allorkpem, and Pediatorkope) using human landing catches, light traps, and prokopack aspirators during the dry and rainy seasons. Morphological and molecular techniques were used to identify mosquito species, determine blood meal sources, and detect insecticide resistance mutations. Sporozoite infections and entomological inoculation rates (EIRs) were also quantified. A total of 25,079 mosquitoes from four genera were collected; Culicine = 88.19%, Anopheline = 8.89%. Mansonia = 2.24%. The Anophelines predominantly comprised Anopheles gambiae s.l. 1,911/2,230 (85.70%), followed by An. pharoensis 236/2,230 (10.58%) and An. rufipes 83/2,230 (3.72%). Indoor biting and resting densities were high across sites and seasons, with sporozoite-positive mosquitoes more frequently found indoors. Blood meal analysis revealed a strong anthropophilic feeding pattern (HBI = 80%). Annual EIRs ranged from 37.40 (ib/m/y) to 100.08 (ib/m/y). Low frequencies of insecticide resistance mutations (Vgsc-1014F, Vgsc-1014S, ACE-1, and Vgsc-1575Y) were observed. The study indicates high indoor biting and resting densities of Anopheles mosquitoes. High sporozoite rate along with low resistance mutation frequencies observed, emphasize the urgent need for continuous resistance monitoring and the implementation of targeted vector control strategies in these hard-to-reach island communities.

microbiology↗

bioRxiv2023

First detection of Anopheles stephensi in Ghana using molecular surveillance

The invasive Anopheles stephensi mosquito has been rapidly expanding in range in Africa over the last decade, spreading from the Indian sub-continent to several East African countries (Djibouti, Ethiopia, Sudan, Somalia and Kenya) and now in West Africa, Nigeria. The rapid expansion of this invasive vector poses a major threat to current malaria control and elimination efforts. In line with the WHOs strategy to stop the spread of this invasive species by enhancing surveillance and control measures in Africa, we incorporated morphological and molecular surveillance of An. stephensi into routine entomological surveillance of malaria vectors in the city of Accra, Ghana. Here, we report on the first detection of An. stephensi in Ghana. An. stephensi mosquitoes were confirmed using PCR and sequencing of the ITS2 regions. These findings highlight the urgent need for increased surveillance and response strategies to mitigate the spread of An. stephensi in Ghana.

ecology↗