Trends in parasite prevalence following 13 years of malaria interventions on Bioko island, Equatorial Guinea: 2004-2016.

BACKGROUND: Whilst there have been substantial reductions in malaria transmission over the past decade, in many countries in West and Central Africa the malaria burden remains high. Monitoring and evaluation of malaria transmission trends and intervention strategies are key elements for malaria control programmes. This study uses a time series of annual malaria indicator surveys to track the progress of malaria control in Bioko Island, Equatorial Guinea, over a 13 year period of intensive interventions. Malaria infection and haemoglobin were measured annually in children (1 to 14 years) in cross-sectional household surveys from 2004 to 2016 in 18 sentinel sites across the island. Trends in transmission patterns were assessed and the impact of the vector control interventions (net use and spray coverage) was evaluated. RESULTS: Between 2004 and 2016 approximately 106,500 individual tests for parasitaemia were conducted using rapid diagnostic tests. Although spray coverage remained relatively high (> 70%) over the time period, reported net usage was generally below 40%. Parasite prevalence reduced from 43.3 to 10.5% between 2004 and 2016. The prevalence of moderate to severe anaemia in children aged 1-5 years reduced from 14.9 to 1.6%. Impact in individual sites ranged from 57 to 100% reductions in parasite prevalence between 2004 and 2016. Sleeping under a net and living in a house that had been sprayed in the past 12 months were independently protective against infection (OR = 0.69 [95%CI 0.61-0.80] and OR = 0.87 [95% CI 0.78-0.97], respectively), whilst recent travel to the mainland increased the odds of infection nearly fourfold (OR = 3.94 [95%CI 2.79-5.56]). CONCLUSION: Island-wide interventions have resulted in a substantial reduction in malaria transmission on Bioko Island. This unique time series of 13 consecutive annual malaria indicator surveys clearly demonstrates the long-term effectiveness of the sustained use of two vector control interventions, indoor residual spraying and LLINs, and the value of comprehensive and sustained surveillance. Despite considerable success in reducing the burden on the island, malaria is still endemic, with populations in some areas remaining at high risk of infection.

Country-level operational implementation of the Global Plan for Insecticide Resistance Management.

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs.

A randomized phase I study comparing the pharmacokinetics of a bevacizumab (HD204) biosimilar to European Union- and United States of America-sourced bevacizumab.

PURPOSE: This first-in-human study was designed to evaluate the pharmacokinetic (PK) equivalence between HD204 and the European Union (EU)-sourced bevacizumab, between HD204 and the United States of America (US)-sourced bevacizumab, and between EU-sourced and US-sourced bevacizumab (NCT03390673). METHODS: In this randomized, double-blind, 3-way parallel group, single-dose comparative PK study, healthy male subjects were randomized to receive a single 1 mg/kg intravenous dose of HD204, EU-sourced bevacizumab or US-sourced bevacizumab. PK parameters were calculated using non-compartmental methods. PK equivalence was determined using the pre-defined equivalence margin of 0.8-1.25 in terms of AUC(0-∞) for the pairwise comparisons. FINDINGS: Baseline demographics for the 119 randomized subjects were similar across the three groups. The 90% CIs for the ratio of the geometric means of HD204 to US-sourced bevacizumab, HD204 to EU-sourced bevacizumab, and EU-sourced to US-sourced bevacizumab were all within the interval of 80% to 125% for AUC0-inf, thus demonstrating equivalency in the PK properties for all three treatment groups. Similarly, the ratio of the geometric means for AUC0-last and Cmax were all within the 80% and 125% margins, supporting the robustness of the primary findings. All other PK parameters, including the half-life (t1/2) clearance (CL), volume of distribution (Vd) and time of maximum concentration (tmax), were comparable. There was no difference between the 3 treatment arms in terms of vital signs, laboratory tests and adverse events. None of the subjects treated with HD204 had positive ADA results. IMPLICATIONS: HD204 demonstrates equivalent pharmacokinetic profiles compared to those of both US-sourced and EU-sourced bevacizumab. (NCT03390673).

Factors influencing the effectiveness of malaria control in Bioko Island, equatorial Guinea.

The Bioko Island Malaria Control Project (BIMCP) has carried out intensive interventions since early 2004 to reduce malaria transmission through indoor residual spraying (IRS) and case management. Annual parasite prevalence surveys have been carried out to monitor the effectiveness of the program. Significant overall reductions in prevalence of infection have been observed, with 42% fewer infections occurring in 2006 compared with baseline. Nevertheless, there is evidence of considerable heterogeneity in impact of the intervention. Prevalence of infection was significantly associated with spray status of the child's house, spray coverage with effective insecticide of the neighborhood of the house, bed net use, and time elapsed since last spray. Careful scheduling of spray coverage is therefore essential to maximize the effectiveness of IRS and to ensure consistent reductions in parasite prevalence. This can only be achieved if comprehensive monitoring systems are in place for both the management and evaluation of the intervention.

Reduction in infection with Plasmodium falciparum one year after the introduction of malaria control interventions on Bioko Island, Equatorial Guinea.

The Bioko Island Malaria Control Project was initiated in 2003 to substantially reduce malaria on the island of Bioko in Equatorial Guinea. The intervention consisted of generalized indoor residual spraying during the first year of the project. Case management and related measures were introduced during the second year. Two large household and parasitemia surveys of children 2 to < 15 years of age were carried out in 2004 and 2005, respectively, to assess the effect of the intervention after the first year. Patient records were collected retrospectively from one district hospital and analyzed for a comparison of pre-intervention and post-intervention periods. Overall mean prevalence of P. falciparum infection reduced from 46% (95% confidence interval [CI] = 40-51%) at baseline in 2004 to 31% (95% CI = 24-40%) in 2005 (P < 0.001). When the 12-month pre-intervention period was compared with the 12-month post-intervention period, there was a modest but statistically significant reduction in the number of malaria cases among hospital patients.