Comparative Analysis of Diversity, Infectivity and Biting Rates of Anopheline Vectors and Their Role in Local Malaria Transmission in Afikpo-North LGA, Ebonyi State, Nigeria

Abstract

Falciparum malaria remains a major public health burden in the rainforest region of Nigeria, where Anopheles mosquitoes serve as primary vectors. Effective malaria control requires high-quality case management, vector control, and robust surveillance. However, the emergence of drug-resistant Plasmodium falciparum strains and widespread insecticide resistance in mosquito populations threaten progress in malaria elimination. Recent advances in parasite genetics and genomics now offer new opportunities for improved surveillance. This study aimed to identify endophilic malaria vectors and assess their vectorial status and importance in two villages, Oziza–Ameta and Amachara–Elu, Afikpo-North LGA, Ebonyi State, Nigeria. Adult female mosquitoes were sampled indoors from twenty households using the pyrethrum spray catch (PSC) method. Molecular identification of Anopheles gambiae was performed using polymerase chain reaction (PCR). Natural Plasmodium infection and parasite genotypes were detected through PCR and whole-genome sequencing. Human biting rate (HBR) was estimated indirectly as the proportion of freshly fed mosquitoes relative to the number of occupants who slept in the room the night before collection. A total of 331 female mosquitoes belonging to seven species Culex quinquefasciatus, Anopheles gambiae sensu lato (s.l.), Anopheles funestus group, Mansonia uniformis, Mansonia africana, Anopheles coustani complex, and Culex poicilipes were collected. Culex quinquefasciatus was the most abundant species (61.63%), followed by An. gambiae s.l. (28.10%). Culex poicilipes and An. coustani had the lowest abundance (0.30%). Species abundance differed significantly between the two villages (p = 0.005). Malaria vector abundance was higher in Oziza–Ameta than in Amachara–Elu, with An. gambiae s.l. predominating in both locations. PCR characterization revealed An. gambiae sensu stricto (s.s.) as the dominant sibling species, with an infectivity rate of 0.035 (95% CI: 0.0059–0.1058) for Plasmodium falciparum. Genetic diversity (M-form and S-form) was detected within An. gambiae s.s., showing identity matches of 97.43% and 98.00% to AF470112.1 and AF470113.1, respectively, while the detected P. falciparum genotype matched LR131493.1 with 100% similarity. The highest human biting rates were recorded in October (40% and 50%). Endophilic female mosquitoes in Afikpo-North serve as important vectors of malaria and other diseases of public health and economic relevance, placing residents at high risk of infection. This study provides baseline information on indoor-resting malaria vectors and parasite genotypes necessary for site-specific vector control planning under Integrated Vector Management (IVM). Strengthening environmental sanitation and improving drainage systems are recommended as part of comprehensive vector control strategies.