Biology subjects

Ayeh-Kumi, P. F.

Publications and source records attributed to Ayeh-Kumi, P. F..

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↗

bioRxiv2018

Household cockroaches carry CTX-M-15, OXA-48 and NDM-1, and share beta-lactam resistance determinants with humans

AimHousehold insect pests, including cockroaches, have gained consideration as potential vectors for multidrug resistant pathogens of public health concern. This study was designed to investigate whether household cockroaches share beta-lactam resistance determinants with human inhabitants.\n\nMethodsFrom February through July 2016, 400 cockroaches were systematically collected from 100 households. Whole insect homogenates and faecal samples from inhabitants of all included households were cultured for cephalosporin-resistant enterobacteria (CRe). The CRe were examined for AmpC, ESBL, and carbapenemase genes; antibiotic susceptibility patterns; and conjugative transfer of antibiotic resistance mechanisms. Clonal relationships between isolates were determined by multi-locus sequence typing (MLST).\n\nResultsTwenty CRe were recovered from whole cockroach homogenates of 15 households. Five harbored ESBL genes (2 blaCTX-M-15/TEM-1; 1 blaCTX-M-15/TEM-4; 1 blaTEM-24; 1 blaSHV-4), and 3 carried carbapenemase genes (2 blaNDM-1 genes and 1 blaOXA-48 gene) all of which were transferrable by conjugation to E. coli J53 recipients. There was high clonal diversity with low inter-species similarity regardless of the beta-lactamase gene sequence. From 6 households, the pair of cockroach and human CRe shared the same antibiogram, ST and/or conjugable blaESBL gene sequence (house 34, E. coli ST9-blaTEM-4; house 37, E. coli ST44-blaCTX-15/TEM-4; house 41, E. coli ST443-blaCTX-15/TEM-1; house 49, K. pneumoniae ST231-blaSHV-13).\n\nConclusionThe findings highlight household cockroaches as reservoirs of CTX-M-15, OXA-48 and NDM-1 genes that share beta-lactam resistance determinants with humans.

microbiology↗