Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. METHODS: Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. RESULTS: There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. CONCLUSIONS: There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.

Entomological impact of indoor residual spraying with pirimiphos-methyl: a pilot study in an area of low malaria transmission in Senegal.

BACKGROUND: Scaling-up of effective anti-malarial control strategies in Central-West region of Senegal has resulted in the sharp decline in malaria prevalence in this area. However, despite these strategies, residual malaria transmission has been observed in some villages (hot spots). The objective of this study was to assess the impact of indoor residual spraying (IRS) with pirimiphos-methyl on malaria transmission in hot spot areas. METHODS: The malaria vector population dynamics were monitored in each of the six selected villages (4 of which used IRS, 2 were unsprayed control areas) using overnight human landing catches (HLC) and pyrethrum spray catches (PSC). The host source of blood meals from freshly fed females collected using PSC was identified using the direct ELISA method. Females caught through HLC were tested by ELISA for the detection of Plasmodium falciparum circumsporozoite protein and Anopheles gambiae complex was identified using PCR. RESULTS: Preliminary data shown that the densities of Anopheles populations were significantly lower in the sprayed areas (179/702) compared to the control. Overall, malaria transmission risk was 14 times lower in the intervention zone (0.94) compared to the control zone (12.7). In the control areas, three Anopheles species belonging to the Gambiae complex (Anopheles arabiensis, Anopheles coluzzii and Anopheles melas) maintained the transmission, while only An. coluzzii was infective in the sprayed areas. CONCLUSION: The preliminary data from this pilot study showed that IRS with the CS formulation of pirimiphos-methyl is likely very effective in reducing malaria transmission risk. However, additional studies including further longitudinal entomological surveys as well as ecological and ethological and genetical characterization of vectors species and their populations are needed to better characterize the entomological impact of indoor residual spraying with pirimiphos-methyl in the residual transmission areas of Senegal.

Mass drug administration to reduce malaria incidence in a low-to-moderate endemic setting: short-term impact results from a cluster randomised controlled trial in Senegal.

Background: In Africa, the scale-up of malaria control interventions, including seasonal malaria chemoprevention (SMC), has dramatically reduced malaria burden, but progress toward malaria elimination has stalled. We evaluated mass drug administration (MDA) as a strategy to accelerate reductions in malaria incidence in Senegal. Methods: We conducted an open-label, cluster-randomised controlled trial in a low-to-moderate transmission setting of Tambacounda, Senegal. Eligible villages had a population size between 200-800. All villages received pyrethroid-piperonyl butoxide bednets and proactive community case management of malaria at baseline. Sixty villages were randomised 1:1 to either three cycles of MDA with dihydroartemisinin-piperaquine+single-low dose primaquine administered to individuals aged ≥3 months, six-weeks apart starting the third week of June (intervention), or standard-of-care, which included three monthly cycles of SMC with sulfadoxine-pyrimethamine+amodiaquine administered to children aged 3-120 months starting end of July (control). MDA and SMC were delivered door-to-door. The primary outcome was clinical malaria incidence in all ages assessed during the peak transmission season (July-December), the year after intervention. Here, we report safety, coverage, and impact outcomes during the intervention year. The trial is registered at ClinicalTrials.Gov ( NCT04864444 ). Findings: Between June 21, 2021 and October 3, 2021, 6505, 7125, and 7250 participants were administered MDA and 3202, 3174, and 3146 participants were administered SMC across cycles. Coverage of ≥1 dose of MDA drugs was 79%, 82%, and 83% across cycles. During the transmission season of the intervention year, MDA was associated with a 55% [95% CI: 28%- 72%] lower incidence of malaria compared to control (MDA: 93 cases/1000 population; control: 173 cases/1000 population). No serious adverse events were reported in either arm. Interpretation: In low-to-moderate malaria transmission settings with scaled-up malaria control interventions, MDA with dihydroartemisinin-piperaquine+single-low dose primaquine is effective and well-tolerated for reducing malaria incidence. Further analyses will focus on the sustainability of this reduction. Funding: United States President's Malaria Initiative. Research in context: Evidence before this study: The current World Health Organization (WHO) guidelines recommend that malaria programmes consider mass drug administration (MDA) for Plasmodium falciparum transmission reduction in low-to-very low transmission settings (broadly defined as parasite prevalence <10% or annual malaria incidence of <250 cases per population). In moderate-to-high transmission areas, MDA is recommended for rapid reduction of disease burden, but not for transmission reduction due to the lack of published studies demonstrating its short- or long-term benefits. Among the numerous studies that contributed to this recommendation, five evaluated the antimalarial combination, dihydroartemisinin-piperaquine + single low-dose primaquine. However, none of the studies were conducted in countries implementing seasonal malaria chemoprevention as part of their routine malaria control strategy. On January 23, 2024, we conducted a PubMed search using the following term: "mass drug administration" AND "dihydroartemisinin-piperaquine". We found one additional cluster randomised controlled trial conducted in a moderate transmission setting of The Gambia (an SMC-implementing country), that evaluated mass drug administration with the antimalarial combination, dihydroartemisinin-piperaquine + ivermectin. This study demonstrated that MDA was associated with a 70% reduction in the odds of PCR-confirmed malaria two months after the last round of MDA. However, given the study demonstrated little evidence on entomological outcomes, authors concluded that much of the observed effect of MDA was likely attributable to the antimalarial efficacy of dihydroartemisinin-piperaquine.Added value of this study: Our study adds to the current evidence base demonstrating the benefits of MDA with dihydroartemisinin-piperaquine + single-dose primaquine on malaria burden reduction and may have impacts on short-term transmission. Combined with The Gambia trial results, our study provides new evidence demonstrating that MDA with dihydroartemisinin-piperaquine can have short-term benefits on transmission in low and moderate transmission settings where malaria transmission is highly seasonal.Implications of all the available evidence: As countries in sub-Sahelian and Sahelian Africa progressively scale-up their malaria control interventions, they will reach a plateau where no further gains can be made. In low and moderate transmission settings, MDA is a well-tolerated and effective intervention for rapidly reducing malaria burden and may have an impact on transmission in the short-term.

Formulation, stability testing, and analytical characterization of melatonin-based preparation for clinical trial.

A new institutional clinical trial assessed the improvement of sleep disorders in 40 children with autism treated by immediate-release melatonin formulation in different regimens (0.5 mg, 2 mg, and 6 mg daily) for one month. The objectives of present study were to (i) prepare low-dose melatonin hard capsules for pediatric use controlled by two complementary methods and (ii) carry out a stability study in order to determine a use-by-date. Validation of preparation process was claimed as ascertained by mass uniformity of hard capsules. Multicomponent analysis by attenuated total reflectance Fourier transformed infrared (ATR-FTIR) of melatonin/microcrystalline cellulose mixture allowed to identify and quantify relative content of active pharmaceutical ingredients and excipients. Absolute melatonin content analysis by high performance liquid chromatography in 0.5 mg and 6 mg melatonin capsules was 93.6%±4.1% and 98.7%±6.9% of theoretical value, respectively. Forced degradation study showed a good separation of melatonin and its degradation products. The capability of the method was 15, confirming a risk of false negative <0.01%. Stability test and dissolution test were compliant over 18 months of storage with European Pharmacopoeia. Preparation of melatonin hard capsules was completed manually and melatonin in hard capsules was stable for 18 months, in spite of low doses of active ingredient. ATR-FTIR offers a real alternative to HPLC for quality control of high-dose melatonin hard capsules before the release of clinical batches.

Pharmaceutical and safety considerations of tablet crushing in patients undergoing enteral intubation.

Medication in patients undergoing enteral intubation addresses various challenging issues considering safety and treatment efficiency. Ideally, other routes of administration (i.e. intravenous or intramuscular routes) or especially dedicated formulations should be used. However, in absence of liquid dosage form, tablets or pills must be crushed and suspended in a vehicle before administration. The administration of oral dosage forms by enteral tube is usually performed by the nursing staff facing (i) pharmaceutical relevance of crushing, (ii) loss and concomitant aero-contamination of drug substance, (iii) drug-nutriment interactions and (iv) enteral feeding tube clogging. In the present study, different combinations of either open or confined crushing and suspending protocols were compared by taking into account the crushing yield, the stability and granulometry of the solid oral form suspension and finally the extend of aerosol contamination during crushing and suspending. All protocols exhibited comparable crushing efficiency and suspending properties, but significantly higher aerosolisation of tablet particles was observed in both open crushing and suspending protocol. Therefore, both confined crushing and suspending protocol constitutes an efficient, time saving and safe alternative to the absence of available liquid dosage form for intubated patients.