Cotton pest management practices and the selection of pyrethroid resistance in Anopheles gambiae population in Northern Benin

<p>Abstract</p> <p>Background</p> <p>Pyrethroid insecticides, carbamate and organophosphate are the classes of insecticides commonly used in agriculture for crop protection in Benin. Pyrethroids remain the only class of insecticides recommended by the WHO for impregnation of bed nets. Unfortunately, the high level of pyrethroid resistance in <it>Anopheles gambiae </it>s.l., threatens to undermine the success of pyrethroid treated nets. This study focuses on the investigation of agricultural practices in cotton growing areas, and their direct impact on larval populations of <it>An. gambiae </it>in surrounding breeding sites.</p> <p>Methods</p> <p>The protocol was based on the collection of agro-sociological data where farmers were subjected to semi-structured questionnaires based on the strategies used for crop protection. This was complemented by bioassay tests to assess the susceptibility of malaria vectors to various insecticides. Molecular analysis was performed to characterize the resistance genes and the molecular forms of <it>An. gambiae</it>. Insecticide residues in soil samples from breeding sites were investigated to determine major factors that can inhibit the normal growth of mosquito larvae by exposing susceptible and resistant laboratory strains.</p> <p>Results</p> <p>There is a common use by local farmers of mineral fertilizer NPK at 200 kg/ha and urea at 50 kg/hectare following insecticide treatments in both the Calendar Control Program (CCP) and the Targeted Intermittent Control Program (TICP). By contrast, no chemicals are involved in Biological Program (BP) where farmers use organic and natural fertilizers which include animal excreta.</p> <p>Susceptibility test results confirmed a high resistance to DDT. Mean mortality of <it>An. gambiae </it>collected from the farms practicing CCP, TICP and BP methods were 33%, 42% and 65% respectively. <it>An. gambiae </it>populations from areas using the CCP and TICP programs showed resistance to permethrin with mortality of 50% and 58% respectively. By contrast, bioassay test results of <it>An. gambiae </it>from BP areas gave a high level of susceptibility to permethrin with an average mortality of 94%.</p> <p>Molecular analysis identified <it>An. gambiae </it>s.s, and <it>An. arabiensis </it>with a high predominance of <it>An. gambiae s.s </it>(90%). The two molecular forms, M and S, were also determined with a high frequency of the S form (96%).</p> <p>The <it>Kdr </it>gene seemed the main target- site resistance mechanism detected in CCP, TICP, and BP areas at the rates ranging from 32 to 78%. The frequency of <it>ace-1R </it>gene was very low (< 0.1).</p> <p>The presence of inhibiting factors in soil samples under insecticide treatments were found and affected negatively in delaying the development of <it>An. gambiae </it>larval populations.</p> <p>Conclusions</p> <p>This research shows that <it>Kdr </it>has spread widely in <it>An. gambiae</it>, mainly in CCP and TICP areas where pyrethroids are extensively used. To reduce the negative impact of pesticides use in cotton crop protection, the application of BP-like programs, which do not appear to select for vector resistance would be useful. These results could serve as scientific evidence of the spread of resistance due to a massive agricultural use of insecticides and contribute to the management of pesticides usage on cotton crops hence reducing the selection pressure of insecticides on <it>An. gambiae </it>populations.</p

Multiple Insecticide Resistance: An Impediment to Insecticide-Based Malaria Vector Control Program

BACKGROUND: Indoor Residual Spraying (IRS), insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are key components in malaria prevention and control strategy. However, the development of resistance by mosquitoes to insecticides recommended for IRS and/or ITNs/LLINs would affect insecticide-based malaria vector control. We assessed the susceptibility levels of Anopheles arabiensis to insecticides used in malaria control, characterized basic mechanisms underlying resistance, and evaluated the role of public health use of insecticides in resistance selection. METHODOLOGY/PRINCIPAL FINDINGS: Susceptibility status of An. arabiensis was assessed using WHO bioassay tests to DDT, permethrin, deltamethrin, malathion and propoxur in Ethiopia from August to September 2009. Mosquito specimens were screened for knockdown resistance (kdr) and insensitive acetylcholinesterase (ace-1(R)) mutations using AS-PCR and PCR-RFLP, respectively. DDT residues level in soil from human dwellings and the surrounding environment were determined by Gas Chromatography with Electron Capture Detector. An. arabiensis was resistant to DDT, permethrin, deltamethrin and malathion, but susceptible to propoxur. The West African kdr allele was found in 280 specimens out of 284 with a frequency ranged from 95% to 100%. Ace-1(R) mutation was not detected in all specimens scored for the allele. Moreover, DDT residues were found in soil samples from human dwellings but not in the surrounding environment. CONCLUSION: The observed multiple-resistance coupled with the occurrence of high kdr frequency in populations of An. arabiensis could profoundly affect the malaria vector control programme in Ethiopia. This needs an urgent call for implementing rational resistance management strategies and integrated vector control intervention

Interactive cost of Plasmodium infection and insecticide resistance in the malaria vector Anopheles gambiae

International audienceInsecticide resistance raises concerns for the control of vector-borne diseases. However, its impact on parasite transmission could be diverse when considering the ecological interactions between vector and parasite. Thus we investigated the fitness cost associated with insecticide resistance and Plasmodium falciparum infection as well as their interactive cost on Anopheles gambiae survival and fecundity. In absence of infection, we observed a cost on fecundity associated with insecticide resistance. However, survival was higher for mosquito bearing the kdr mutation and equal for those with the ace-1(R) mutation compared to their insecticide susceptible counterparts. Interestingly, Plasmodium infection reduced survival only in the insecticide resistant strains but not in the susceptible one and infection was associated with an increase in fecundity independently of the strain considered. This study provides evidence for a survival cost associated with infection by Plasmodium parasite only in mosquito selected for insecticide resistance. This suggests that the selection of insecticide resistance mutation may have disturbed the interaction between parasites and vectors, resulting in increased cost of infection. Considering the fitness cost as well as other ecological aspects of this natural mosquito-parasite combination is important to predict the epidemiological impact of insecticide resistance

Ionized Magnesium Levels In Patients With Moderate-To-Advanced Chronic Kidney Disease: Relationship With Total Magnesium And Associated Factors

International audienceAbstract Background and Aims Magnesium (Mg) is involved in a multitude of essential physiological processes. In chronic kidney disease (CKD), the mechanisms compensating for the decrease in glomerular filtration rate (eGFR) become insufficient and Mg excretion tends to decrease, potentially resulting in hypermagnesemia. On the other hand, hypomagnesemia seems also to be common in CKD, due to changes in Mg intake through diet, reduced absorption and drug-induced hypomagnesemia. To date, a few studies have shown an association between increased cardiovascular risk in CKD and either low or high total Mg levels. However, the physiologically active fraction of extracellular Mg is ionized Mg (iMg), which is not routinely measured. In critical ill patients, the correlation between iMg and total Mg has been shown to be poor. Similar data on patients with CKD would be important to future studies aiming at clarifying the link between Mg and outcomes, and ultimately to determine the interest of iMg assay in routine practice. The objectives of this study are i) to study the correlation between total Mg and iMg and ii) to evaluate the relation between serum ionized magnesemia, estimated GFR (eGFR) and demographic and biologic parameters. Method CKD-REIN is a French, prospective, nationally representative cohort study of 3033 CKD patients under nephrology care not receiving maintenance dialysis (stage 3-5: eGFR&lt;60 mL/min/1.73 m² based on 2009 CKD-EPI equation). Baseline iMg and total Mg serum concentrations were respectively centrally measured using the NOVA BIOMEDICAL Stat Profile PRIME ES analyser and with Atellica® CH SIEMENS analyser. Normal range of serum total Mg considered was 0.66 to 1.06 mmol/L (from Atellica®). Mean ± standard deviation (SD) ionized Mg level evaluated in a cohort of 457 healthy volunteers (age = 45 ± 17 years; eGFR = 72.3 ± 13 mL/min/1.73m²) was 0.49 ± 0.05 mmol/L (median [tertile 1 – tertile 3] = 0.49 [0.45-0.52] mmol/L). Correlation between iMg and total Mg was estimated overall. Multivariate linear regressions were performed to identify factors associated with iMg and total Mg levels. Results Among 1741 patients with iMg and total Mg at baseline, the median age was 68 years [59-76], 65% were men, and the mean eGFR was 35 ± 14 mL/min/1.73m². The mean baseline iMg level was 0.48 ± 0.1 mmol/L, 615 patients had an ionized Mg &lt;0.45 mmol/L (Tertile 1), 599 had an iMg between 0.46 and 0.52 mmol/L (Tertile 2), and 527 had an iMg &gt;0.52 mmol/L (Tertile 3). Compared to healthy volunteers, mean iMg levels were significantly lower in CKD patients. However, the difference was small (difference CKD-heatlhy = 0.01 mmol/L). Most of patients were within the total Mg normal range (n = 1522), 12% (n = 208) and 1% (n = 11) presented hypo- and hypermagnesemia, respectively. Correlation between iMg and total Mg was very high (r = 0.88; p&lt;0.001). (Figure). Ionized Mg was weakly inversely correlated with eGFR (r = -0.22; p&lt;0.001). Consequently, the mean iMg level differed according to CKD stages, being more elevated in the advanced stages (0.45 mmol/L in stages 2-3A; 0.47 mmol/L in stage 3B; 0.50 mmol/L in stages 4-5 (p&lt;0.001)). In a fully adjusted linear regression model, iMg concentration was significantly associated with age, decline of eGFR, history of cardiovascular disease and the use of diuretics, and inversely associated with calcium and triglycerides levels, systolic blood pressure, diabetes, and the use of proton pump inhibitors and potassium chelators. The same factors were associated with total Mg. Conclusion Total Mg and iMg were strongly correlated. Decline of kidney function was associated to an increase of iMg in patients with moderate-to-advanced CKD. Additional studies need to compare the difference between total Mg and iMg as a biomarker to predict hard outcomes

Outpatient laparoscopic sacrocolpopexy: Feasibility and patient satisfaction

International audienceObjective: Laparoscopic sacrocolpopexy is the standard surgery to correct apical pelvic organ prolapse. It is currently mainly practiced in the context of a conventional hospitalization, but more and more practitioners are developing it as an outpatient procedure. The objective of this study was to evaluate the feasibility of outpatient laparoscopic sacrocolpopexy and patient satisfaction. Methods: This was a retrospective study comparing outpatients with inpatients who had undergone laparoscopic sacrocolpopexy. The main outcome was the rate of unscheduled visits and the number of early readmissions (i.e., &lt;1 month). Secondary outcomes were complication rates and patient satisfaction. Results: Eighty-four patients were included with 42 women in each group. The rate of unscheduled consultations was 16.7 %(n = 7/42) in the outpatient group and 21 %(n = 9/42) in the inpatient group. 2.4 %(n = 1/42) of outpatients and 4.8 % (n = 2/42) of inpatients were re-hospitalized within a month after surgery. The complication rate was not significantly different between the groups. In the outpatient group, 88.2 % of patients were satisfied compared with 97.5 % in the inpatient group (p = 0.17) Conclusions: Outpatient laparoscopic sacrocolpopexy can be considered a safe and satisfactory option. (C) 2021 Published by Elsevier Masson SAS