Biology subjects

Owusu-Asenso, C. M.

Publications and source records attributed to Owusu-Asenso, C. M..

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↗

bioRxiv2024

Pathogens spread by high-altitude windborne mosquitoes

Recent studies have revealed that many mosquito species regularly engage in high-altitude windborne migration, but its epidemiological significance was debated. The hypothesis that high-altitude mosquitoes spread pathogens over large distances has not been directly tested. Here, we report for the first time that high-altitude windborne mosquitoes are commonly infected with arboviruses, protozoans, and helminths affecting vertebrates and humans, and provide the first description of this pathogen-vector aerial network. A total of 1,017 female mosquitoes (81.4%, N=1,249) intercepted on nets suspended from helium balloons at altitudes of 120-290 m above ground over Mali and Ghana were screened for infection with arboviruses, plasmodia, and filariae, using pan-genus qPCR analyses followed by sequencing of positive samples. The mosquito fauna collected at altitude comprised 61 species, across 9 genera, dominated by Culex, Aedes, and Anopheles. Infection and infectiousness rates of high-altitude migrant mosquitoes were 7.2% and 4.4% with plasmodia, 1.6% and 0.6% with filariae, 3.5% and 1.1% with flaviviruses, respectively. Nineteen mosquito-borne pathogens were identified, including three arboviruses: dengue, West Nile and MPoko viruses, 13 putative plasmodia species including Plasmodium matutinum and P. relictum, three filariids, including Pelecitus spp., 27 insect-specific viruses and 5 non-mosquito-borne pathogens (e.g., Trypanosoma theileri). Confirmed head-thorax (disseminated) infections of multiple pathogens in multiple mosquito species, eg., Culex perexiguus, Coquilletidia metallica, Mansonia uniformis, and Anopheles squamosus provides evidence that pathogens carried by high-altitude windborne mosquitoes are infectious and likely capable of infecting naive hosts far from their starting location. This traffic of sylvatic pathogens may be key to their maintenance among foci as well as initiating outbreaks away from them.

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↗