Speaker
Description
Background: Malaria transmission in Ghana varies across ecological zones, shaped by vector diversity and the spread of insecticide resistance. Understanding how Anopheles species composition, biting behavior, and resistance alleles influence local transmission is essential for guiding targeted control strategies.
Methods: The study was conducted in two ecological zones of Ghana: Afamanso in the Ashanti Region and Obom in the Greater Accra Region. Quarterly entomological surveys were performed during rainy and dry seasons. Adult mosquitoes were collected indoors and outdoors using human landing catches (HLC). Specimens were morphologically identified and Plasmodium falciparum sporozoite infections were detected using circumsporozoite protein ELISA. Molecular PCR assays were used for species identification within the An. gambiae complex. Allele-specific PCR was employed to detect knockdown resistance (kdr-East and kdr-West) and acetylcholinesterase-1 (Ace-1) mutations. Entomological inoculation rate (EIR), were calculated to assess transmission intensity.
Key findings: A total of 8,022 Anopheles mosquitoes were collected across the two zones. An. gambiae s.l. was the predominant vector, with An. Coluzzii (47.5 %) and An. gambiae s.s (52.5 %). most frequent, while An. arabiensis and An. melas were not present. Sporozoite ELISA confirmed P. falciparum infections in both zones, with higher infection prevalence in Obom. HBR and EIR were significantly higher in Obom compared to Afamanso. Molecular genotyping revealed widespread kdr mutations, with kdr-East more frequent in Obom and kdr-West dominant in Afamanso. Ace-1 mutations were detected at lower frequencies but often co-occurred with kdr alleles, indicating multiple resistance mechanisms in circulation.
Implications for public health: Malaria transmission in Ghana is influenced by ecological differences in vector diversity, biting behavior, and insecticide resistance. The co-occurrence of kdr and Ace-1 mutations highlights an emerging challenge for vector control. Continuous surveillance is critical to sustain malaria control and support elimination goals.
Key words: Malaria transmission, knockdown resistance acetylcholinesterase-1 mutations and EIR