Effect of the Mass Distribution of ITNs in an Endemic Area with a High Entomological Index, the Case of Bandundu-City, Kwilu, DRC

The bio-efficacy of Yorkol-branded ITNs collected from Bandundu-city was assessed on the Kisumu strain and wild specimens of Anopheles gambiae. The susceptibility of the wild An. gambiae s.l. was tested to select insecticides. Adult An. gambiae s.l. sampled by PSC and HLC were screened for the presence of Plasmodium falciparum. Blood samples were diagnosed by microscopy and RDTs. ITN distributed in Bandundu-city were fully effective on the Kisumu strain, but on wild An. gambiae s.l. population (22.3 ± 11.5%). Anopheles gambiae s.l. was the main vector in Bandundu. No significant difference was observed between the entomological indices before and after the deployment of nets (OR = 0.8; p = 0.39). Wild An. gambiae s.l. populations were resistant to pyrethroids and DDT, with the restoration of the susceptibility to pyrethroids post pre-exposure to PBO. Plasmodium falciparum was the main parasite species and was found alone or mixed with. P. malariae or P. ovale. The confirmation rates by microscopy and RDT were respectively 57.9% and 53.6%. Nets deployed in Bandundu-city were not effective on wild An. gambiae s.l. populations. This operational failure is likely explained by the observed resistance to pyrethroids. In the future only PBO-net should be deployed Bandundu-city.