Malaria entomological surveillance in Kinshasa Province: A longitudinal study

Malaria remains a major public health challenge in the Democratic Republic of Congo. To address the lack of contemporary entomological data, this four-year study characterized key entomological parameters in Kinshasa Province. We conducted a prospective observational cohort study (2018-2022) in three health areas. Adult mosquitoes were sampled using CDC light traps and pyrethrum spray catches. Sporozoite rates were estimated using ELISA, and trap collections were used as proxy measures of host-seeking mosquito activity to estimate light trap rates and annualized entomological inoculation rate (EIR) estimates. Insecticide susceptibility of adult females was assessed using WHO tube tests. A generalized estimating equations model evaluated the effects of key variables on mosquito abundance. A total of 1,449 Anopheles were collected, with 50% from rural, 49% from peri-urban, and 1% from urban areas. The species captured were An. gambiae s.l. (85%), An. paludis (11%), and An. funestus (4%). An. gambiae s.l. was significantly more abundant indoors and after 10 PM. The overall EIR estimate was 4.7 infective mosquitoes per trap per year, with An. gambiae s.l. contributing the highest transmission intensity. A localized increase in the transmission intensity associated with An. paludis was observed in one site during the rainy season, although mosquito numbers were small. Resistance to DDT and pyrethroids was widespread, with an estimated 0.94 frequency of the kdr L1014F mutation. Bendiocarb and pirimiphos-methyl remained effective. This study found that An. gambiae s.l. remains the predominant malaria vector in Kinshasa. The findings also suggest a possible contribution of An. paludis to malaria transmission in some rural settings, although additional longitudinal studies with larger sample sizes are needed. Because sporozoite detection was based on ELISA, additional molecular confirmation studies would be valuable. Continued entomological surveillance is essential to track biting behavior and resistance patterns and ensure that selected interventions remain effective.