Temporal escalation of Pyrethroid Resistance in the major malaria vector Anopheles coluzzii from Sahelo-Sudanian Region of northern Nigeria

Abstract

Despite the highest global burden of malaria, information on bionomics and insecticide resistance status of malaria vectors is grossly lacking in the densely populated Sahelo-Sudanian region of Nigeria. To support evidence-based vector control we characterised transmission and resistance profiles of Anopheles coluzzii populations from three sites in northern Nigeria. High sporozoite infection (~19.51%) was found in the An . coluzzii populations. A high pyrethroid resistance was observed with only 1% mortality against deltamethrin, a high LD 50 (96.57 µg/ml), and a high LT 50 (170.27 min, resistance ratio of ~51 compared with the fully susceptible Ngoussou colony). Moderate carbamate resistance was observed. Synergist bioassays significantly recovered deltamethrin susceptibility implicating CYP450s (mortality = 85%, χ 2 = 134.04, p < 0.0001) and esterases (mortality = 56%, χ 2 = 47.31, p < 0.0001). Reduced bed net efficacy was also observed, with mortalities on exposure to the roof of PermaNet3.0 (PBO + deltamethrin) more than 22 times compared to the side panel (deltamethrin). TaqMan genotyping revealed a high frequency of 1014F kdr mutation (82%) with significant difference in genotype distribution associated with permethrin resistance [OR = 4.69 (CI:1.53–14.35, χ 2 = 8.22 p = 0.004]. Sequencing of exons 18–21 of the VGSC led to detection of two additional nonsynonymous mutations, Ile10148Asn and Ser1156Gly. These findings highlight the threats posed by the highly resistant An . coluzzii to malaria control in Nigeria.

Resistance status of Anopheles gambiae (s.l.) to four commonly used insecticides for malaria vector control in South-East Nigeria

“…The inclusions of these resistance mechanisms would have provided a clear profile of insecticide resistance in southeast Nigeria. However, a recent study conducted by Ibrahim et al [36] demonstrated that metabolic resistance (CYP450) is present in the malaria vector population with a synergist significant recovery observed after exposure of wild An. gambiae (s.l.)…”

Exploring the Mechanisms of Multiple Insecticide Resistance in a Highly Plasmodium-Infected Malaria Vector Anopheles funestus Sensu Stricto from Sahel of Northern Nigeria

“…Resistance intensity was established by comparing the LT 50 from the Gajerar Giwa An. funestus populations to the LT 50 previously established for the fully susceptible Anopheles coluzzii lab colony [5]. This type of inter-species comparison of using An.…”

“…gambiae s.l. [5][6][7], the major malaria vector An. funestus from the Sudan/Sahel savannah of northern Nigeria has been neglected for decades, after comprehensive works conducted by several pioneers, before 1960.…”

Understanding the importance of malaria control tools by pregnant and nursing mothers is key to ending malaria burden in Nigeria: A case study of eight communities in South-South Nigeria

“…Adopting these newer bed nets will require evidence-based research about the insecticide resistance profile of the malaria vectors in Nigeria. While a number of reports on this resistance profile are already available, there is the need to establish the more complex resistance mechanisms (Awolola et al, 2009;Djouaka et al, 2016;Ibrahim et al, 2019).…”

“…About 190 million people in Nigeria are said to be at risk of malaria infection, with a significant 145 million people, including women and children considered to be at high risk (WHO, 2018) Among others, key strategies of the elimination program are: to scale up significantly, Indoor Residual Spray (IRS); universal coverage of Long Lasting Insecticide Net (LLIN); strategic use of larval source management; use of Intermittent Preventive Therapy (IPT) for pregnant women; emphasis on parasite confirmation before malaria treatment, and the deployment of Seasonal Malaria Chemoprevention (SMC) (Nigeria, 2014;Tesfazghi et al, 2015).Implementation of vector control tools such as LLIN and IRS, in combination with malaria drugs, has significantly changed the malaria status of a number of malaria endemic regions from that of "malaria burden" to "malaria elimination" stages (Bhatt et al, 2015;WHO, 2018;Weedall et al, 2019). This desired outcome has remained unattained across Nigeria and this is thought to be largely due to the development of resistance by the malaria vectors against the main insecticides in use for vector control tools, thereby threatening the actual objectives of the NMSP (2014-2020) (Awolola et al, 2009;Djouaka et al, 2016;Ibrahim et al, 2019). Notwithstanding the development of insecticide resistance, LLINs still offer significant protection against malaria.…”