Functional Validation of Endogenous Redox Partner Cytochrome P450 Reductase Reveals the Key P450s CYP6P9a/-b as Broad Substrate Metabolizers Conferring Cross-Resistance to Different Insecticide Classes in Anopheles funestus.

The versatility of cytochrome P450 reductase (CPR) in transferring electrons to P450s from other closely related species has been extensively exploited, e.g., by using An. gambiae CPR (AgCPR), as a homologous surrogate, to validate the role of An. funestus P450s in insecticide resistance. However, genomic variation between the AgCPR and An. funestus CPR (AfCPR) suggests that the full metabolism spectrum of An. funestus P450s might be missed when using AgCPR. To test this hypothesis, we expressed AgCPR and AfCPR side-by-side with CYP6P9a and CYP6P9b and functionally validated their role in the detoxification of insecticides from five different classes. Major variations were observed within the FAD- and NADP-binding domains of AgCPR and AfCPR, e.g., the coordinates of the second FAD stacking residue AfCPR-Y456 differ from that of AgCPR-His456. While no significant differences were observed in the cytochrome c reductase activities, when co-expressed with their endogenous AfCPR, the P450s significantly metabolized higher amounts of permethrin and deltamethrin, with CYP6P9b-AfCPR membrane metabolizing α-cypermethrin as well. Only the CYP6P9a-AfCPR membrane significantly metabolized DDT (producing dicofol), bendiocarb, clothianidin, and chlorfenapyr (bioactivation into tralopyril). This demonstrates the broad substrate specificity of An. funestus CYP6P9a/-b, capturing their role in conferring cross-resistance towards unrelated insecticide classes, which can complicate resistance management.

Substrate promiscuity of key resistance P450s confers clothianidin resistance while increasing chlorfenapyr potency in malaria vectors.

Novel insecticides were recently introduced to counter pyrethroid resistance threats in African malaria vectors. To prolong their effectiveness, potential cross-resistance from promiscuous pyrethroid metabolic resistance mechanisms must be elucidated. Here, we demonstrate that the duplicated P450s CYP6P9a/-b, proficient pyrethroid metabolizers, reduce neonicotinoid efficacy in Anopheles funestus while enhancing the potency of chlorfenapyr. Transgenic expression of CYP6P9a/-b in Drosophila confirmed that flies expressing both genes were significantly more resistant to neonicotinoids than controls, whereas the contrasting pattern was observed for chlorfenapyr. This result was also confirmed by RNAi knockdown experiments. In vitro expression of recombinant CYP6P9a and metabolism assays established that it significantly depletes both clothianidin and chlorfenapyr, with metabolism of chlorfenapyr producing the insecticidally active intermediate metabolite tralopyril. This study highlights the risk of cross-resistance between pyrethroid and neonicotinoid and reveals that chlorfenapyr-based control interventions such as Interceptor G2 could remain efficient against some P450-based resistant mosquitoes.

The role of medical-grade maggots in facilitating healing of diabetic foot ulcers in Kano, northern Nigeria: a case series.

OBJECTIVE: Approximately 13% of people living with diabetes develop one or more ulcers during the course of the disease, and diabetic foot ulcer (DFU) is responsible for >60% of lower limb amputations worldwide. This case series aimed to demonstrate the effectiveness of medical-grade maggots on DFUs in promoting wound healing and reducing related hospital stays in northern Nigeria. METHOD: Maggot debridement therapy (MDT) was applied to the DFUs of patients who consented to this treatment between January-August 2021 at the Orthopaedic Unit of the Aminu Kano Teaching Hospital (AKTH), Kano, Nigeria. Sterile first instar larvae of Lucilia sericata were obtained indigenously and applied using the confinement (free-range) method under aseptic procedure. RESULTS: A total of 15 patients with DFUs of Wagner classification grades III (33.3%) and IV (66.7%), were seen and documented. The patients included 10 (66.7%) females and five (33.3%) males, giving a female:male ratio of 2:1. The mean age (±standard deviation) of the respondents was 51.6±10.8 years. The surface area of the wounds ranged from 24-140cm2, with a median value of 75cm2. Among the patients, 60% had two cycles of MDT, with a median duration of five days. Most of the wounds (53.3%) were debrided within five days; 13.3% (two wounds) took seven days to be fully debrided. A paired sample t-test showed a statistically significant association between wound surface area and therapy duration (t=8.0; p=0.000) and between wound surface area and cycles of therapy (t=8.3; p=0.000). Before maggot application, 14 (93.3%) DFUs were completely (100%) covered with slough and only one (6.7%) was 95% covered with slough. After maggot application, 10 (66.7%) wounds were completely debrided while five (33.3%) wounds required bedside surgical debridement to achieve complete debridement. A paired sample t-test showed statistically significant difference between the pre- and post-MDT slough covering the wounds (t=45.1; p=0.000). CONCLUSION: In this case series, MDT was successfully used in the debridement of DFUs, which facilitated the healing process with an encouraging clinical outcome.

Overexpression and nonsynonymous mutations of UDP-glycosyltransferases are potentially associated with pyrethroid resistance in Anopheles funestus.

UDP-glycosyltransferases (UGTs) enzymes are pivotal in insecticide resistance by transforming hydrophobic substrates into more hydrophilic forms for efficient cell elimination. This study provides the first comprehensive investigation of Anopheles funestus UGT genes, their evolution, and their association with pyrethroid resistance. We employed a genome-wide association study using pooled sequencing (GWAS-PoolSeq) and transcriptomics on pyrethroid-resistant An. funestus, along with deep-targeted sequencing of UGTs in 80 mosquitoes Africa-wide. UGT310B2 was consistently overexpressed Africa-wide and significant gene-wise Fst differentiation was observed between resistant and susceptible populations: UGT301C2 and UGT302A3 in Malawi, and UGT306C2 in Uganda. Additionally, nonsynonymous mutations in UGT genes were identified. Gene-wise Tajima's D density curves provide insights into population structures within populations across these countries, supporting previous observations. These findings have important implications for current An. funestus control strategies facilitating the prediction of cross-resistance to other UGT-metabolised polar insecticides, thereby guiding more effective and targeted insecticide resistance management efforts.

Seasonal malaria chemoprevention in Africa and China's upgraded role as a contributor: a scoping review.

BACKGROUND: Children under five are the vulnerable population most at risk of being infected with Plasmodium parasites, especially in the Sahel region. Seasonal malaria chemoprevention (SMC) recommended by World Health Organization (WHO), has proven to be a highly effective intervention to prevent malaria. Given more deaths reported during the COVID-19 pandemic than in previous years due to the disruptions to essential medical services, it is, therefore, necessary to seek a more coordinated and integrated approach to increasing the pace, coverage and resilience of SMC. Towards this end, fully leverage the resources of major players in the global fight against malaria, such as China could accelerate the SMC process in Africa. METHODS: We searched PubMed, MEDLINE, Web of Science, and Embase for research articles and the Institutional Repository for Information Sharing of WHO for reports on SMC. We used gap analysis to investigate the challenges and gaps of SMC since COVID-19. Through the above methods to explore China's prospective contribution to SMC. RESULTS: A total of 68 research articles and reports were found. Through gap analysis, we found that despite the delays in the SMC campaign, 11.8 million children received SMC in 2020. However, there remained some challenges: (1) a shortage of fully covered monthly courses; (2) lack of adherence to the second and third doses of amodiaquine; (3) four courses of SMC are not sufficient to cover the entire malaria transmission season in areas where the peak transmission lasts longer; (4) additional interventions are needed to consolidate SMC efforts. China was certified malaria-free by WHO in 2021, and its experience and expertise in malaria elimination can be shared with high-burden countries. With the potential to join the multilateral cooperation in SMC, including the supply of quality-assured health commodities, know-how transfer and experience sharing, China is expected to contribute to the ongoing scale-up of SMC. CONCLUSIONS: A combination of necessary preventive and curative activities may prove beneficial both for targeted populations and for health system strengthening in the long run. More actions are entailed to promote the partnership and China can be one of the main contributors with various roles.

Molecular drivers of insecticide resistance in the Sahelo-Sudanian populations of a major malaria vector Anopheles coluzzii.

BACKGROUND: Information on common markers of metabolic resistance in malaria vectors from countries sharing similar eco-climatic characteristics can facilitate coordination of malaria control. Here, we characterized populations of the major malaria vector Anopheles coluzzii from Sahel region, spanning four sub-Saharan African countries: Nigeria, Niger, Chad and Cameroon. RESULTS: Genome-wide transcriptional analysis identified major genes previously implicated in pyrethroid and/or cross-resistance to other insecticides, overexpressed across the Sahel, including CYP450s, glutathione S-transferases, carboxylesterases and cuticular proteins. Several, well-known markers of insecticide resistance were found in high frequencies-including in the voltage-gated sodium channel (V402L, I940T, L995F, I1527T and N1570Y), the acetylcholinesterase-1 gene (G280S) and the CYP4J5-L43F (which is fixed). High frequencies of the epidemiologically important chromosomal inversion polymorphisms, 2La, 2Rb and 2Rc, were observed (~80% for 2Rb and 2Rc). The 2La alternative arrangement is fixed across the Sahel. Low frequencies of these inversions (<10%) were observed in the fully insecticide susceptible laboratory colony of An. coluzzii (Ngoussou). Several of the most commonly overexpressed metabolic resistance genes sit in these three inversions. Two commonly overexpressed genes, GSTe2 and CYP6Z2, were functionally validated. Transgenic Drosophila melanogaster flies expressing GSTe2 exhibited extremely high DDT and permethrin resistance (mortalities <10% in 24h). Serial deletion of the 5' intergenic region, to identify putative nucleotide(s) associated with GSTe2 overexpression, revealed that simultaneous insertion of adenine nucleotide and a transition (T->C), between Forkhead box L1 and c-EST putative binding sites, were responsible for the high overexpression of GSTe2 in the resistant mosquitoes. Transgenic flies expressing CYP6Z2 exhibited marginal resistance towards 3-phenoxybenzylalcohol (a primary product of pyrethroid hydrolysis by carboxylesterases) and a type II pyrethroid, α-cypermethrin. However, significantly higher mortalities were observed in CYP6Z2 transgenic flies compared with controls, on exposure to the neonicotinoid, clothianidin. This suggests a possible bioactivation of clothianidin into a toxic intermediate, which may make it an ideal insecticide against populations of An. coluzzii overexpressing this P450. CONCLUSIONS: These findings will facilitate regional collaborations within the Sahel region and refine implementation strategies through re-focusing interventions, improving evidence-based, cross-border policies towards local and regional malaria pre-elimination.

Intestinal colonization against Vibrio cholerae: host and microbial resistance mechanisms.

Vibrio cholerae is a non-invasive enteric pathogen known to cause a major public health problem called cholera. The pathogen inhabits the aquatic environment while outside the human host, it is transmitted into the host easily through ingesting contaminated food and water containing the vibrios, thus causing diarrhoea and vomiting. V. cholerae must resist several layers of colonization resistance mechanisms derived from the host or the gut commensals to successfully survive, grow, and colonize the distal intestinal epithelium, thus causing an infection. The colonization resistance mechanisms derived from the host are not specific to V. cholerae but to all invading pathogens. However, some of the gut commensal-derived colonization resistance may be more specific to the pathogen, making it more challenging to overcome. Consequently, the pathogen has evolved well-coordinated mechanisms that sense and utilize the anti-colonization factors to modulate events that promote its survival and colonization in the gut. This review is aimed at discussing how V. cholerae interacts and resists both host- and microbe-specific colonization resistance mechanisms to cause infection.

The duplicated P450s CYP6P9a/b drive carbamates and pyrethroids cross-resistance in the major African malaria vector Anopheles funestus.

Cross-resistance to insecticides in multiple resistant malaria vectors is hampering resistance management. Understanding its underlying molecular basis is critical to implementation of suitable insecticide-based interventions. Here, we established that the tandemly duplicated cytochrome P450s, CYP6P9a/b are driving carbamate and pyrethroid cross-resistance in Southern African populations of the major malaria vector Anopheles funestus. Transcriptome sequencing revealed that cytochrome P450s are the most over-expressed genes in bendiocarb and permethrin-resistant An. funestus. The CYP6P9a and CYP6P9b genes are overexpressed in resistant An. funestus from Southern Africa (Malawi) versus susceptible An. funestus (Fold change (FC) is 53.4 and 17 respectively), while the CYP6P4a and CYP6P4b genes are overexpressed in resistant An. funestus in Ghana, West Africa, (FC is 41.1 and 17.2 respectively). Other up-regulated genes in resistant An. funestus include several additional cytochrome P450s (e.g. CYP9J5, CYP6P2, CYP6P5), glutathione-S transferases, ATP-binding cassette transporters, digestive enzymes, microRNA and transcription factors (FC<7). Targeted enrichment sequencing strongly linked a known major pyrethroid resistance locus (rp1) to carbamate resistance centering around CYP6P9a/b. In bendiocarb resistant An. funestus, this locus exhibits a reduced nucleotide diversity, significant p-values when comparing allele frequencies, and the most non-synonymous substitutions. Recombinant enzyme metabolism assays showed that both CYP6P9a/b metabolize carbamates. Transgenic expression of CYP6P9a/b in Drosophila melanogaster revealed that flies expressing both genes were significantly more resistant to carbamates than controls. Furthermore, a strong correlation was observed between carbamate resistance and CYP6P9a genotypes with homozygote resistant An. funestus (CYP6P9a and the 6.5kb enhancer structural variant) exhibiting a greater ability to withstand bendiocarb/propoxur exposure than homozygote CYP6P9a_susceptible (e.g Odds ratio = 20.8, P<0.0001 for bendiocarb) and heterozygotes (OR = 9.7, P<0.0001). Double homozygote resistant genotype (RR/RR) were even more able to survive than any other genotype combination showing an additive effect. This study highlights the risk that pyrethroid resistance escalation poses to the efficacy of other classes of insecticides. Available metabolic resistance DNA-based diagnostic assays should be used by control programs to monitor cross-resistance between insecticides before implementing new interventions.

Determinants of mortality among hospitalized patients with COVID-19 during first and second waves of the pandemic: A retrospective cohort study from an isolation center in Kano, Nigeria.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has emerged as an important cause of morbidity and mortality worldwide. The aim of this study is to identify the clinical predictors of mortality among patients with COVID-19 pneumonia during first and second waves in a treatment center in northwestern Nigeria. METHODS: This was a retrospective cohort study of 195 patients hospitalized with COVID-19 between April 2020 to March 2021 at a designated COVID-19 isolation center in Kano State, Northwest Nigeria. Data were summarized using frequencies and percentages. Unadjusted odds ratios and 95% confidence intervals and p-values were obtained. To determine independent determinants of mortality, we performed a stepwise multivariate logistic regression model. RESULTS: Of 195 patients studied, 21(10.77%) patients died. Males comprised 158 (81.03%) of the study population. In the adjusted stepwise logistic regression analysis, age>64 years (OR = 9.476, 95% CI: 2.181-41.165), second wave of the pandemic (OR = 49.340, 95% CI:6.222-391.247), cardiac complications (OR = 24.984, 95% CI: 3.618-172.508), hypertension (OR = 5.831, 95% CI:1.413-24.065) and lowest systolic blood pressure while on admission greater than or equal to 90mmHg were independent predictors of mortality (OR = 0.111, 95%CI: 0.021-0.581). CONCLUSION: Strategies targeted to prioritize needed care to patients with identified factors that predict mortality might improve patient outcome.

Prevalence, severity, and correlates of erectile dysfunction among male adult patients of a primary care clinic in North-West Nigeria.

Background: Erectile dysfunction (ED) is a common sexual problem that profoundly affects intimate relationships. It is poorly studied in North-western Nigeria. Objectives: To assess the prevalence, severity and predictors of ED among adult males attending a primary care clinic in Northwest Nigeria. Methods: A cross-section of 392 males (aged ≥25 years) were randomly selected from attendees of a family medicine clinic in Kano, Nigeria. Information regarding their biodata, lifestyle factors, and clinical characteristics was obtained using a structured questionnaire. The International Index of Erectile Function Questionnaire (version 5) and Patient Health Questionnaire-2 assessed ED and depression, respectively. Results: The participants' mean age was 45±14.1 years (range: 26-86 years). Most participants were married (88.8%), had one sexual partner (71.7%), had tertiary education (44.4%) and were traders (49.7%). The prevalence of ED was 52.3% (205/392) [comprising mild (36.0%), mild-to-moderate (14.3%), moderate (1.5%) and severe (0.5%)]. Age, body mass index (BMI), marital status, number of sexual partners, monthly income, type of exercise, hypertension history, blood pressure reading, antihypertensive and peptic ulcer drug use were associated with ED (P<0.05). However, age (≥50years) (OR= 1.91, 95%CI [1.28-2.85], P=0.001) and overweight/obesity (OR =1.81, 95%CI [1.18-2.77], P=0.007) were the predictors of ED in this population. Conclusion: ED prevalence was high, although mainly of the mild form. Age (≥50years) and overweight/obesity predicted ED. Hence, the need for early screening, objective grading of ED, identification of modifiable risk factors (e.g., overweight/obesity) and commencing proper treatment and prevention in this setting.

LC-MS and GC-MS Profiling of Different Fractions of Ficus platyphylla Stem Bark Ethanolic Extract.

The exploration of medicinal plants in traditional medicine for the treatment of diseases has been practiced for long, globally, because of its cultural acceptability, availability, and affordability. This study investigated the qualitative and quantitative estimation of phytochemicals present in Ficus platyphylla stem bark as well as determined the reducing power and antioxidant property of each fraction against DPPH and NO radicals. The study further elucidated the presence of possible compounds in different fractions (methanol, ethyl acetate, petroleum ether, and chloroform) of Ficus platyphylla stem bark (FPSB) extract using GC-MS, LC-MS, and FTIR techniques. Qualitative phytochemical analysis reveals the presence of phytochemicals: saponin, flavonoids, tannins, phenols, steroids, alkaloids, and glycoside in the ethanolic extract. The LC-MS study of methanol and ethyl acetate fractions reveals the presence of thirteen and three compounds, respectively. GC-MS analysis shows the presence of trans-13-octadecenoic acid as the main compound 38.07% and cis-vaccenic acid as the least compound (0.10%) in the petroleum ether fraction. The main compound in the chloroform fraction is 12-oleanen-3-yl acetate, (3. alpha.) with a peak area percentage of 49.25% and oleic acid been the least compound with 0.07% peak area. The FTIR analysis reveals that the fractions contain compounds with hydroxyl, aromatic, methyl, methylene, methyne, long aliphatic chain, ethers, ether-oxy, peroxides, etc. The analyzed fractions reveal compounds with potential pharmacological activity in the management of pathological conditions.

Health-related quality of life of persons with diabetic foot ulcers in a cosmopolitan city in northwestern Nigeria.

Background: Diabetic foot ulcer is one of the most serious and disabling complications of diabetes mellitus (DM). It is a major source of morbidity, mortality, and a leading cause of hospitalization. It constitutes a major burden to the patient, family, and health-care system as well as impairs quality of life (QoL). The aim of this study was to determine the QoL of persons with diabetic foot ulcers attending two major hospitals in a cosmopolitan city in northwestern Nigeria. Materials and Methods: We conducted a descriptive cross-sectional study at the diabetes outpatient clinics and wards of two major hospitals in Kano, Northwestern Nigeria. Sociodemographic characteristics, type of DM, duration of DM, and the presence of risk factors for foot ulcers were assessed. The QoL of patients with and without foot ulcer was determined a well-validated questionnaire for chronic diseases, short form 36 (SF 36) health-related QoL questionnaire. Results: We recruited 394 patients with DM (163 males and 231 females) with mean age and duration of DM of 50.8 ± 12.5 years and 7.72 ± 6.65 years, respectively. Ninety-five percent of the study participants had type 2 DM. Foot ulcers were present in 57 (14.5%) study participants. The QoL was generally poor (P < 0.001) in patients with DFU, compared with those without DFU in all domains of the SF 36, that indicated poor QoL in the physical, mental, and emotional well-being of the patients. Conclusion: Diabetic foot ulcers are quite common and impart significantly on the QoL of persons with DM affecting their physical, mental, and emotional well-being. Early detection and management of foot ulcers will reduce the burden of the disease and improve the QoL of affected individuals.

Résumé Contexte: L'ulcère du pied diabétique est l'une des complications les plus graves et les plus invalidantes du diabète sucré (DM). C'est une source majeure de 14 morbidité, mortalité, et l'une des principales causes d'hospitalisation. Il constitue un fardeau majeur pour le patient, la famille et le système de soins de santé, car 15 ans et nuit à la qualité de vie (QoL). Le but de cette étude était de déterminer la qualité de vie des personnes atteintes d'ulcères de pied diabétique fréquentant deux 16 hôpitaux principaux dans une ville cosmopolite du nord-ouest du Nigéria. Matériaux et Méthodes: Nous avons mené une étude transversale descriptive 17 dans les cliniques externes de diabète et les salles de deux grands hôpitaux à Kano, nord-ouest du Nigeria. Des caractéristiques sociodémographiques, le type 18 de DM, la durée de DM, et la présence des facteurs de risque pour des ulcères de pied ont été évalués. La qualité de vie des patients avec et sans ulcère de pied était 19 déterminé un questionnaire bien-validé pour les maladies chroniques, questionnaire court-connexe de qol de la forme 36 (SF 36). Résultats: Nous avons recruté 394 patient avec le DM (163 mâles et 231 femelles) avec l'âge moyen et la durée du DM de 50,8 ± 12,5 ans et 7,72 ± 6,65 ans, respectivement. 20 Quatre-vingt-quinze pour cent des participants à l'étude présentaient un DM de type 2. Des ulcères du pied étaient présents dans 57 (14,5 %) participants à l'étude. Le QoL était généralement pauvre (P < 0,001) dans les patients avec DFU, comparé à ceux sans DFU dans tous les domaines du SF 36, qui a indiqué le QoL pauvre dans le bien-être physique, mental, 22, et émotionnel des patients. Conclusion: Les ulcères diabétiques de pied sont tout à fait communs et transmettent de manière significative sur la QoL de 23 personnes avec le DM affectant leur bien-être physique, mental, et émotionnel. La détection et la prise en charge précoces des ulcères du pied réduiront le fardeau de la maladie et amélioreront la qualité de vie des personnes touchées. Mots-clés: Ulcère du pied diabétique, Qualité de vie liée à la santé, Nord-Ouest du Nigéria, questionnaire abrégé.

Are Fear of COVID-19 and Vaccine Hesitancy Associated with COVID-19 Vaccine Uptake? A Population-Based Online Survey in Nigeria.

This study examined the association between COVID-19 and fear of contracting COVID-19 and reasons for vaccination refusal. A population-based online survey was conducted via social media in Nigeria using the Fear of COVID-19 scale and items related to vaccination refusal/hesitancy items. Individuals aged 13 years and older were invited to participate. Data were analysed using binary logistic regression to calculate odds ratios (ORs) and associated 95% confidence intervals (CIs) at a p-value of less than 0.05. The study enrolled 577 individuals with a mean age of 31.86 years, 70% of whom were male and 27.7% of whom had received at least one dose of the vaccine against COVID-19. None of the variables on the Fear of COVID-19 scale significantly predicted vaccine uptake in multivariate analysis. However, individuals who were fearful of COVID-19 were more likely to be vaccinated in bivariate analysis (OR: 1.7, 95% CI: 1.06-2.63). The most significant factors among the vaccination refusal items associated with COVID-19 vaccination were doubts about vaccination (adjusted OR: 2.56, 95% CI: 1.57-4.17) and misconceptions about vaccine safety/efficacy (adjusted OR: 2.15, 95% CI: 1.24-3.71). These results suggest that uptake of the vaccine against COVID-19 in Nigeria can be predicted by factors associated with vaccination refusal, but not by fear of COVID-19. To contain the pandemic COVID-19 in Nigeria, efforts should be made to educate people about the efficacy of the vaccine and to increase their confidence in vaccination.

Prevalence of Anxiety and Depression Among the General Population in Africa During the COVID-19 Pandemic: A Systematic Review and Meta-Analysis.

Background: Medical and socio-economic uncertainties surrounding the COVID-19 pandemic have had a substantial impact on mental health. This study aimed to systematically review the existing literature reporting the prevalence of anxiety and depression among the general populace in Africa during the COVID-19 pandemic and examine associated risk factors. Methods: A systematic search of the following databases African Journal Online, CINAHL, PubMed, Scopus, and Web of Science was conducted from database inception until 30th September 2021. Studies reporting the prevalence of anxiety and/or depression among the general populace in African settings were considered for inclusion. The methodological quality of included studies was assessed using the Agency for Healthcare Research and Quality (AHRQ). Meta-analyses on prevalence rates were conducted using Comprehensive Meta-analysis software. Results: Seventy-eight primary studies (62,380 participants) were identified from 2,325 studies via electronic and manual searches. Pooled prevalence rates for anxiety (47%, 95% CI: 40-54%, I2 = 99.19%) and depression (48%, 95% CI: 39-57%, I2 = 99.45%) were reported across Africa during the COVID-19 pandemic. Sex (female) and history of existing medical/chronic conditions were identified as major risk factors for anxiety and depression. Conclusions: The evidence put forth in this synthesis demonstrates the substantial impact of the pandemic on the pervasiveness of these psychological symptoms among the general population. Governments and stakeholders across continental Africa should therefore prioritize the allocation of available resources to institute educational programs and other intervention strategies for preventing and ameliorating universal distress and promoting psychological wellbeing. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021228023, PROSPERO CRD42021228023.

Pyrethroid resistance in the New World malaria vector Anopheles albimanus is mediated by cytochrome P450 CYP6P5.

Pyrethroid resistance in the malaria vector Anopheles albimanus presents an obstacle to malaria elimination in the Americas. Here, An. albimanus CYP6P5 (the most overexpressed P450 in a Peruvian population) was functionally characterized. Recombinant CYP6P5 metabolized the type II pyrethroids, deltamethrin and α-cypermethrin with comparable affinities (KM of 3.3 µM ± 0.4 and 3.6 µM ± 0.5, respectively), but exhibited a 2.7-fold higher catalytic rate for α-cypermethrin (kcat of 6.02 min-1 ± 0.2) versus deltamethrin (2.68 min-1 ± 0.09). Time-course assays revealed progressive depletion of the above pyrethroids with production of four HPLC-detectable metabolites. Low depletion was obtained with type I pyrethroid, permethrin. Transgenic expression in Drosophila melanogaster demonstrated that overexpression of CYP6P5 alone conferred type II pyrethroid resistance, with only 16% and 55.3% mortalities in flies exposed to 0.25% α-cypermethrin and 0.15% deltamethrin, respectively. Synergist bioassays using P450 inhibitor piperonylbutoxide significantly recovered susceptibility (mortality = 73.6%, p < 0.001) in synergized flies exposed to 4% piperonylbutoxide, plus 0.25% α-cypermethrin, compared to non-synergized flies (mortality = 4.9%). Moderate resistance was also observed towards 4% DDT. These findings established the preeminent role of CYP6P5 in metabolic resistance in An. albimanus, highlighting challenges associated with deployment of insecticide-based control tools in the Americas.

The cytochrome P450 CYP325A is a major driver of pyrethroid resistance in the major malaria vector Anopheles funestus in Central Africa.

The overexpression and overactivity of key cytochrome P450s (CYP450) genes are major drivers of metabolic resistance to insecticides in African malaria vectors such as Anopheles funestus s.s. Previous RNAseq-based transcription analyses revealed elevated expression of CYP325A specific to Central African populations but its role in conferring resistance has not previously been demonstrated. In this study, RT-qPCR consistently confirmed that CYP325A is highly over-expressed in pyrethroid-resistant An. funestus from Cameroon, compared with a control strain and insecticide-unexposed mosquitoes. A synergist bioassay with PBO significantly recovered susceptibility for permethrin and deltamethrin indicating P450-based metabolic resistance. Analyses of the coding sequence of CYP325A Africa-wide detected high-levels of polymorphism, but with no predominant alleles selected by pyrethroid resistance. Geographical amino acid changes were detected notably in Cameroon. In silico homology modelling and molecular docking simulations predicted that CYP325A binds and metabolises type I and type II pyrethroids. Heterologous expression of recombinant CYP325A and metabolic assays confirmed that the most-common Cameroonian haplotype metabolises both type I and type II pyrethroids with depletion rate twice that the of the DR Congo haplotype. Analysis of the 1 kb putative promoter of CYP325A revealed reduced diversity in resistant mosquitoes compared to susceptible ones, suggesting a potential selective sweep in this region. The establishment of CYP325A as a pyrethroid resistance metabolising gene further explains pyrethroid resistance in Central African populations of An. funestus. Our work will facilitate future efforts to detect the causative resistance markers in the promoter region of CYP325A to design field applicable DNA-based diagnostic tools.

2La Paracentric Chromosomal Inversion and Overexpressed Metabolic Genes Enhance Thermotolerance and Pyrethroid Resistance in the Major Malaria Vector Anopheles gambiae.

Changes in global temperature are impacting the spread/intensity of vector-borne diseases, including malaria, and accelerating evolutionary/adaptive changes in vector species. These changes, including chromosomal inversions and overexpression and/or changes in allele frequencies of thermotolerance-associated genes, may facilitate insecticide resistance through pleiotropy. This study investigated the impact of thermotolerance on pyrethroid resistance in four populations of the malaria vector An. gambiae s.l., from the savanna/sub-Sahel of northern Nigeria. Anopheles coluzzii and An. gambiae s.s. were the only malaria vectors found, sympatric in all the sites, with the former species predominant. High thermotolerance was observed, with no mortality at 38 °C, and LT50 of ~44 °C. Significantly high permethrin resistance was observed (mortality < 50%) in 44 °C heat-hardened (exposure to an intermediately high temperature provides protection to a more severe temperature or insecticide) larvae from two sites, BUK and Pantami, compared with the control, and heat-hardened adult females from Auyo (mortality = 3.00% ± 1.20, χ2 = 5.83, p < 0.01) compared with the control (12.00% ± 4.65). The 2La chromosomal inversion was detected at ~50% in subset of larvae and 58% in subset of adult females genotyped. A significant association was observed (OR = 7.2, p < 0.03) between permethrin resistance and the 2La/+a rearrangement compared with 2L+a/+a, in BUK larvae. For all sites, permethrin resistance correlated with 2La/a homozygosity in adult females (R = 5.02, p = 0.01). qRT-PCR identified six genes commonly induced/overexpressed, including the heat shock protein 70 (AGAP004581) which was 2468× and 5× overexpressed in heat-hardened and permethrin-resistant females, respectively; trehalose-6-phosphate synthase (AGAP008227); and the ionotropic glutamate receptor genes, IR25a (AGAP010272) and IR21a (AGAP008511). This study highlights challenges associated with insecticide-based malaria vector control, and the epidemiological significance of taking climate variables into account for the design/choice of control measures.

High pyrethroid/DDT resistance in major malaria vector Anopheles coluzzii from Niger-Delta of Nigeria is probably driven by metabolic resistance mechanisms.

Entomological surveillance of local malaria vector populations is an important component of vector control and resistance management. In this study, the resistance profile and its possible mechanisms was characterised in a field population of the major malaria vector Anopheles coluzzii from Port Harcourt, the capital of Rivers state, in the Niger-Delta Region of Nigeria. Larvae collected in Port-Harcourt, were reared to adulthood and used for WHO bioassays. The population exhibited high resistance to permethrin, deltamethrin and DDT with mortalities of 6.7% ± 2.4, 37.5% ± 3.2 and 6.3% ± 4.1, respectively, but were fully susceptible to bendiocarb and malathion. Synergist bioassays with piperonylbutoxide (PBO) partially recovered susceptibility, with mortalities increasing to 53% ± 4, indicating probable role of CYP450s in permethrin resistance (χ2 = 29.48, P < 0.0001). Transcriptional profiling revealed five major resistance-associated genes overexpressed in the field samples compared to the fully susceptible laboratory colony, Ngoussou. Highest fold change (FC) was observed with GSTe2 (FC = 3.3 in permethrin exposed and 6.2 in unexposed) and CYP6Z3 (FC = 1.4 in exposed and 4.6 in unexposed). TaqMan genotyping of 32 F0 females detected the 1014F and 1575Y knockdown resistance (kdr) mutations with frequencies of 0.84 and 0.1, respectively, while 1014S mutation was not detected. Sequencing of a fragment of the voltage-gated sodium channel, spanning exon 20 from 13 deltamethrin-resistant and 9 susceptible females revealed only 2 distinct haplotypes with a low haplotype diversity of 0.33. The findings of high pyrethroid resistance but with a significant degree of recovery after PBO synergist assay suggests the need to move to PBO-based nets. This could be complemented with carbamate- or organophosphate-based indoor residual spraying in this area.

Polymorphism Analysis of pfmdr1 and pfcrt from Plasmodium falciparum Isolates in Northwestern Nigeria Revealed the Major Markers Associated with Antimalarial Resistance.

Suspicion of failure in the effectiveness of artemisinin-based combination therapies (currently the first-line treatment of malaria, worldwide) is leading to the unofficial use of alternative antimalarials, including chloroquine and sulfadoxine/pyrimethamine, across northern Nigeria. To facilitate evidence-based resistance management, antimalarial resistance mutations were investigated in Plasmodium falciparum multidrug resistance-1 (pfmdr1) and chloroquine resistance transporter (pfcrt), in isolates from Kano, northwestern Nigeria. Out of the 88 samples genotyped for pfmdr1N86Y mutation using PCR/restriction fragment length polymorphism, one sample contained the 86Y mutation (86Yfrequency = 1.14%). The analysis of 610 bp fragments of pfmdr1 from 16 isolates revealed two polymorphic sites and low haplotype diversity (Hd = 0.492), with only 86 Y mutations in one isolate, and 184 F replacements in five isolates (184Ffrequency = 31.25%). The analysis of 267 bp fragments of pfcrt isolates revealed high polymorphism (Hd = 0.719), with six haplotypes and seven non-synonymous polymorphic sites. Eleven isolates (61.11%) were chloroquine-resistant, CQR (C72V73I74E75T76 haplotype), two of which had an additional mutation, D57E. An additional sequence was CQR, but of the C72V73M74E75T76 haplotype, while the rest of the sequences (33.33%) were chloroquine susceptible (C72V73M74N75K76 haplotype). The findings of these well characterized resistance markers should be considered when designing resistance management strategies in the northwestern Nigeria.