Malaria entomological surveillance in Kinshasa Province: A longitudinal study

Background: Malaria remains a major public health challenge in the Democratic Republic of Congo. To address the lack of contemporary entomological data, particularly in Kinshasa Province, this four-year study characterized key entomological parameters, including mosquito species composition, abundance, biting behavior, and insecticide resistance. Methods: We conducted a prospective observational cohort study (2018–2022) in three health areas representing rural, peri-urban, and urban settings in Kinshasa Province. Adult Anopheles mosquitoes were sampled using CDC miniature light traps and pyrethrum spray catches. Insecticide susceptibility of adult females was assessed using WHO tube tests, and a generalized estimating equations model evaluated the effects of year, season, site, sampling location, and collection time on mosquito abundance. Results: A total of 1,449 Anopheles mosquitoes were collected: 50% in the rural health area of Bu, 49% in peri-urban Kimpoko, and 1% in urban La Voix du Peuple. 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 entomological inoculation rate (EIR) was 4.6 infective bites per person per year, with An. gambiae s.l. contributing the highest rate. An. paludis showed a localized transmission peak in Impuru during the rainy season (EIR = 8.87). Resistance to DDT and pyrethroids was widespread, with an estimated 0.94 frequency of the kdr L1014F mutation. Bendiocarb and pirimiphos-methyl remained effective. Conclusions: This study confirms that An. gambiae s.l. remains the predominant malaria vector and plays a central role in transmission in Kinshasa. However, an emerging role of An. paludis in rural settings was observed. These findings underscore the need for vector control strategies tailored to diverse ecological settings. Continued entomological surveillance will be essential to track biting behavior and resistance patterns and ensure that interventions remain effective over time. Author summary: Malaria remains a major health problem in the Democratic Republic of the Congo, but very little recent information is available about the mosquitoes that spread the disease, especially in Kinshasa Province. To help fill this gap, we spent four years studying mosquitoes in rural, peri-urban, and urban communities. We focused on how many mosquitoes were present, which species they were, when and where they bite, and whether they were resistant to the insecticides commonly used in malaria control. We found that most mosquitoes belonged to Anopheles gambiae, the main malaria-transmitting species in Africa. These mosquitoes mostly bit indoors and late at night, when bed nets can offer good protection. However, we also observed mosquitoes biting earlier in the evening and outside, which may reduce the impact of bed nets. Another species, Anopheles paludis, played an important role in malaria transmission in some rural areas, showing that different environments can shape which mosquitoes spread the disease. We also found that many mosquitoes were resistant to widely used insecticides, although some alternative insecticides were still effective. Our findings show why it is important to monitor mosquito behavior and insecticide resistance regularly and to adapt malaria prevention strategies to local conditions.