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The Lancet. Infectious Diseases Feb 2023Long-lasting insecticidal nets (LLINs) are the foundation of malaria control but resistance of mosquito vectors to pyrethroids threatens their effectiveness. We embedded... (Randomized Controlled Trial)
Randomized Controlled Trial
Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): final results of a cluster-randomised trial embedded in a national distribution campaign.
BACKGROUND
Long-lasting insecticidal nets (LLINs) are the foundation of malaria control but resistance of mosquito vectors to pyrethroids threatens their effectiveness. We embedded a cluster-randomised trial into Uganda's 2017-18 campaign to distribute LLINs. LLINs with piperonyl butoxide (PBO) reduced parasite prevalence more effectively than conventional LLINs (without PBO) for 18 months. Here, we report the final 25-month survey results.
METHODS
LLINEUP was a cluster-randomised trial conducted in 48 districts in eastern and western Uganda. 104 health subdistricts (clusters) without ongoing or planned indoor residual spraying with pirimiphos-methyl (Actellic, Basel, Switzerland) were eligible for inclusion in the trial. Clusters were randomly assigned to PBO LLINs (PermaNet 3.0 or Olyset Plus) and conventional LLINs (PermaNet 2.0 or Olyset Net) with proportionate randomisation using STATA version 14.2. LLINs were delivered from March 25, 2017, to March 18, 2018. Between April 23, 2019, and Sept 13, 2019, community surveys were conducted in 50 randomly selected households per cluster; ten households per cluster were randomly selected for entomology surveys. Mosquitoes were collected in the morning from indoor surfaces of households using Prokopack aspirators. Due to COVID-19 restrictions, only 90 of the 104 clusters were surveyed at 25 months. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population, determined using the results from the 6-month household survey on the type of LLINs received in each cluster. This trial is registered with ISRCTN, ISRCTN17516395, and is now completed.
FINDINGS
In the as-treated analysis, two clusters were excluded (no predominant LLIN received) and four were reassigned; 40 PBO LLIN clusters (30 PermaNet 3.0, ten Olyset Plus) and 48 non-PBO LLIN (36 PermaNet 2.0, 12 Olyset Net) were included. Parasite prevalence was 17·1% (506 of 2958 participants) in the PBO group and 19·8% (701 of 3534) in the non-PBO group (prevalence ratio adjusted for baseline 0·80 [95% CI 0·69-0·93], p=0·0048). Comparing within-treatment group parasite prevalence to baseline, parasite prevalence ratios were lower in the PBO groups at all timepoints, but the difference was greatest at 6 months (PBO LLINs parasite prevalence at baseline 28·8% [1001 of 3472, 95% CI 27·3-30·4] vs at 6 months 12·0% [361 of 3009, 10·9-13·2], prevalence ratio [PR] 0·43 [95% CI 0·36-0·52], p<0·0001; non-PBO LLINs parasite prevalence at baseline 25·4% [1015 of 4004, 24·0-26·7] vs 6 months 14·8% [526 of 3551, 13·7-16·0], PR 0·60 [0·54-0·68], p<0·0001) and 25 months (PBO LLINs parasite prevalence at 25 months 17·1% [506 of 2958, 15·8-18·5], PR 0·63 [95% CI 0·57-0·71], p<0·0001; non-PBO LLINs parasite prevalence at 25 months 19·8% [701 of 3534, 18·5-21·2], PR 0·79 [0·73-0·86], p<0·0001).
INTERPRETATION
In Uganda, PBO LLINs outperformed pyrethroid-only LLINs for 25 months. WHO concluded that PBO LLINs are more effective against malaria than non-PBO LLINs when resistance to pyrethroids is high and issued a conditional recommendation suggesting PBO LLINs should be deployed in areas of pyrethroid resistance.
FUNDING
The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.
Topics: Child; Animals; Humans; Insecticides; Piperonyl Butoxide; Uganda; Insecticide-Treated Bednets; COVID-19; Pyrethrins; Malaria; Mosquito Control
PubMed: 36174592
DOI: 10.1016/S1473-3099(22)00469-8 -
Toxicology Jun 2020In a 79 week bioassay the pesticide synergist piperonyl butoxide (PBO) was shown to significantly increase the incidence of hepatocellular adenoma (but not...
In a 79 week bioassay the pesticide synergist piperonyl butoxide (PBO) was shown to significantly increase the incidence of hepatocellular adenoma (but not hepatocellular carcinoma) in male CD-1 mice at dietary levels of 100 and 300 mg/kg/day PBO and in female mice at a dietary level of 300 mg/kg/day. As PBO is not a genotoxic agent, a series of investigative studies were undertaken to elucidate the mode of action (MOA) for PBO-induced mouse liver tumour formation. Male CD-1 mice were fed diets to provide intakes of 0 (control), 30, 100 and 300 mg/kg/day PBO and for purposes of comparison 500 ppm sodium phenobarbital (NaPB), a known constitutive androstane receptor (CAR) activator, for 7 and 14 days. Treatment with 100 and 300 mg/kg/day PBO and 500 ppm NaPB increased relative liver weight which was associated with hepatocyte hypertrophy, with hepatocyte replicative DNA synthesis (RDS) being increased after 7 days treatment. The treatment of CD-1 mice with 30-300 mg/kg/day PBO for 14 days resulted in significant dose-dependent increases in hepatic microsomal cytochrome P450 (CYP) content and 7-pentoxyresorufin O-depentylase (PROD) activity and in hepatic Cyp2b10 mRNA levels. In contrast, PBO produced a biphasic effect on markers of activation of the peroxisome proliferator-activated receptor alpha (PPARα), with small increases in microsomal lauric acid 12-hydroxylase activity and hepatic Cyp4a10 mRNA levels being observed in mice given 100 mg/kg/day with PBO, with either no increase or a significant inhibition being observed in mice given 300 mg/kg/day PBO. The hepatic effects of PBO in male CD-1 mice were generally similar to those produced by NaPB and were reversible after the cessation of treatment for 28 days. Studies were also performed in male C57BL/6J (wild type) mice and in hepatic CAR and pregnane X receptor (PXR) knockout mice (CAR KO/PXR KO mice), where in the CAR KO/PXR KO mice PBO had little effect on markers of CAR activation, but produced some increases in markers of PPARα activation. The treatment of male CD-1 mouse hepatocytes for 4 days with 5-50 μM PBO, 10-1000 μM NaPB and 25 ng/mL epidermal growth factor (EGF) resulted in significant increases in hepatocyte RDS. While treatment of hepatocytes from one male and one female human donor with 5-500 μM PBO and 10-1000 μM NaPB for 4 days had no effect on hepatocyte RDS, treatment with EGF resulted in significant increases in RDS in both human hepatocyte preparations. In summary, PBO is predominantly a hepatic CAR activator at carcinogenic dose levels in CD-1 mice, with activation of hepatic CAR resulting in a suppression of the effect of PBO on hepatic PPARα. A robust MOA for PBO-induced mouse liver tumour formation has been established, this MOA being similar to that previously identified for NaPB and some other rodent liver CAR activators. Based on the lack of effect of PBO on RDS in human hepatocytes, it is considered that the MOA for PBO-induced mouse liver tumour formation is qualitatively not plausible for humans.
Topics: Animals; Cell Size; DNA Replication; Diet; Gene Expression Regulation; Hepatocytes; Humans; Liver; Liver Function Tests; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Pesticide Synergists; Phenobarbital; Piperonyl Butoxide; Receptors, Calcium-Sensing
PubMed: 32320717
DOI: 10.1016/j.tox.2020.152465 -
The American Journal of Tropical... Oct 2022Despite the scale-up of interventions against malaria over the past decade, this disease remains a leading threat to health in Malawi. To evaluate the epidemiology of...
Despite the scale-up of interventions against malaria over the past decade, this disease remains a leading threat to health in Malawi. To evaluate the epidemiology of both Plasmodium falciparum infection and malaria disease, the Malawi International Center of Excellence for Malaria Research (ICEMR) has developed and implemented diverse and robust surveillance and research projects. Descriptive studies in ICEMR Phase 1 increased our understanding of the declining effectiveness of long-lasting insecticidal nets (LLINs), the role of school-age children in malaria parasite transmission, and the complexity of host-parasite interactions leading to disease. These findings informed the design of ICEMR Phase 2 to test hypotheses about LLIN use and effectiveness, vector resistance to insecticides, demographic targets of malaria control, patterns and causes of asymptomatic to life-threatening disease, and the impacts of RTS,S vaccination plus piperonyl butoxide-treated LLINs on infection and disease in young children. These investigations are helping us to understand mosquito-to-human and human-to-mosquito transmission in the context of Malawi's intransigent malaria problem.
Topics: Animals; Child; Child, Preschool; Humans; Insecticide Resistance; Insecticide-Treated Bednets; Insecticides; Malaria; Malawi; Mosquito Control; Mosquito Vectors; Piperonyl Butoxide
PubMed: 36228915
DOI: 10.4269/ajtmh.21-1263 -
Toxicology Reports Dec 2023Piperonyl butoxide (PBO) is a popular insecticide synergist present in thousands of commercial, agricultural, and household products. PBO inhibits cytochrome P450...
Piperonyl butoxide (PBO) is a popular insecticide synergist present in thousands of commercial, agricultural, and household products. PBO inhibits cytochrome P450 activity, impairing the ability of insects to detoxify insecticides. PBO was recently discovered to also inhibit Sonic hedgehog signaling, a pathway required for embryonic development, and rodent studies have demonstrated the potential for PBO exposure to cause structural malformations of the brain, face, and limbs, or more subtle neurodevelopmental abnormalities. The current understanding of the pharmacokinetics of PBO in mice is limited, particularly with respect to dosing paradigms associated with developmental toxicity. To establish a pharmacokinetic (PK) model for oral exposure, PBO was administered to female C57BL/6J mice acutely by oral gavage (22-1800 mg/kg) or via diet (0.09 % PBO in chow). Serum and adipose samples were collected, and PBO concentrations were determined by HPLC-MS/MS. The serum concentrations of PBO were best fit by a linear one-compartment model. PBO concentrations in visceral adipose tissue greatly exceeded those in serum. PBO concentrations in both serum and adipose tissue decreased quickly after cessation of dietary exposure. The elimination half-life of PBO in the mouse after gavage dosing was 6.5 h (90 % CI 4.7-9.5 h), and systemic oral clearance was 83.3 ± 20.5 mL/h. The bioavailability of PBO in chow was 41 % that of PBO delivered in olive oil by gavage. Establishment of this PK model provides a foundation for relating PBO concentrations that cause developmental toxicity in the rodent models to Sonic hedgehog signaling pathway inhibition.
PubMed: 37789951
DOI: 10.1016/j.toxrep.2023.09.017 -
Journal of Agricultural and Food... Sep 2022As one of the sources of biodiesel, microalgae are expected to solve petroleum shortage. In this study, different concentrations of piperonyl butoxide were added to the...
As one of the sources of biodiesel, microalgae are expected to solve petroleum shortage. In this study, different concentrations of piperonyl butoxide were added to the culture medium to investigate their effects on the growth, pigment content, lipid accumulation, and content of carotenoids in . The results showed that piperonyl butoxide addition significantly decreased the biomass, chlorophyll content, and total carotenoid content but hugely increased the lipid accumulation. With the treatment of 150 ppm piperonyl butoxide combined with 8000 Lux light intensity, the final lipid accumulation and single-cell lipid content were further increased by 21.79 and 76.42% compared to those of the control, respectively. The lipid accumulation in is probably related to the increased expression of in under the action of piperonyl butoxide. The phylogenetic trees of and other oil-rich plants were constructed by multiple sequence alignment of , demonstrating their evolutionary relationship, and the tertiary structure of was predicted. In conclusion, piperonyl butoxide has a significant effect on lipid accumulation in , which provides valuable insights into chemical inducers to enhance biodiesel production in microalgae to solve the problem of diesel shortage.
Topics: Biofuels; Carotenoids; Chlorophyceae; Chlorophyll; Lipids; Microalgae; Petroleum; Phylogeny; Piperonyl Butoxide
PubMed: 36122177
DOI: 10.1021/acs.jafc.2c03006 -
Molecules (Basel, Switzerland) Jan 2023In this work, we have studied the benzofurans of (aerial parts and transformed roots), (aerial parts and transformed roots), (aerial parts), and (aerial parts and...
In this work, we have studied the benzofurans of (aerial parts and transformed roots), (aerial parts and transformed roots), (aerial parts), and (aerial parts and roots). This work has permitted the isolation of the new benzofurans 10-ethoxy-11-hydroxy-10,11-dihydroeuparin (), (-)-eupachinin A ethyl ether (), 11,15-didehydro-eupachinin A (), 10,12-dihydroxy-11-angelyloxy-10,11-dihydroeuparin (), 2,4-dihydroxy-5-formyl-acetophenone () isolated for the first time as a natural product, 11-angelyloxy-10,11-dihydroeuparin (), and 12-angelyloxyeuparone (), along with several known ones (-). In addition, the incubation of the abundant component, 6-hydroxytremetone (), with the fungus has been studied. Benzofurans in the tremetone series (, , -, , ), the euparin series (, , , -, , ), and the eupachinin-type (, ) were tested for antifeedant effects against the insect . The antifeedant compounds (, , , , ) were further tested for postingestive effects on larvae. The most antifeedant compounds were among the tremetone series, with 3-ethoxy-hydroxy-tremetone () being the strongest antifeedant. Glucosylation of by its biotransformation with gave inactive products. Among the euparin series, the dihydroxyangelate was the most active, followed by euparin (). The eupachinin-type compounds (, ) were both antifeedants. Compounds and showed antifeedant effects without postingestive toxicity to orally dosed larvae. Euparin ( had postingestive toxicity that was enhanced by the synergist piperonyl butoxide.
Topics: Animals; Insecta; Mucor; Larva; Benzofurans; Spodoptera; Insecticides
PubMed: 36770655
DOI: 10.3390/molecules28030975 -
Reproductive Toxicology (Elmsford, N.Y.) Mar 2021A semi-synthetic methylenedioxyphenyl compound piperonyl butoxide (PBO) has been used as a ubiquitous synergist to increase the insecticidal effect of pesticides for...
A semi-synthetic methylenedioxyphenyl compound piperonyl butoxide (PBO) has been used as a ubiquitous synergist to increase the insecticidal effect of pesticides for agricultural and household use. Despite previously demonstrated effects of PBO, the detailed mechanism of PBO in spermatozoa and reproductive toxic effects on male germ cells have not been fully elucidated. Therefore, this study evaluated the effects of PBO on various sperm functions during capacitation and clarified the mechanisms of reproductive toxic effects on male fertility at different concentrations of PBO (0.1, 1, 10, and 100 μM). Sperm motility and kinematics were assessed using computer-assisted sperm analysis and the status of capacitation was evaluated using combined H33258/chlortetracycline (CTC) staining. Intracellular adenosine triphosphate (ATP) and cell viability levels were also measured. In addition, protein kinase A (PKA) activity and protein tyrosine phosphorylation were evaluated. In addition, in vitro fertilization was performed to determine the effects of PBO on cleavage and blastocyst formation rates. We found that PBO significantly decreased sperm motility, kinematics, and acrosome-reacted and capacitated spermatozoa. In addition, PBO suppressed the intracellular ATP levels and directly affected cell viability. Moreover, PBO detrimentally decreased the activation of PKA and altered the levels of tyrosine-phosphorylated proteins. Consequently, cleavage and blastocyst formation rates were significantly reduced in a dose-dependent manner. In line with our observations, the synergist of pesticides PBO may directly and/or indirectly cause disorder in male fertility. Hence, we suggest that careful attention is made to consider reproductive toxicity when using PBO as a synergist.
Topics: Acrosome Reaction; Animals; Cell Survival; Embryonic Development; Female; Fertilization; Infertility, Male; Male; Mice; Mice, Inbred ICR; Pesticide Synergists; Piperonyl Butoxide; Reproduction; Sperm Capacitation; Sperm Motility; Spermatozoa
PubMed: 33515694
DOI: 10.1016/j.reprotox.2021.01.010 -
Infectious Diseases of Poverty Dec 2021Long-lasting insecticide nets (LLINs) are a core malaria intervention. LLINs should retain efficacy against mosquito vectors for a minimum of three years. Efficacy and... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Long-lasting insecticide nets (LLINs) are a core malaria intervention. LLINs should retain efficacy against mosquito vectors for a minimum of three years. Efficacy and durability of Olyset Plus, a permethrin and piperonyl butoxide (PBO) treated LLIN, was evaluated versus permethrin treated Olyset Net. In the absence of WHO guidelines of how to evaluate PBO nets, and considering the manufacturer's product claim, Olyset Plus was evaluated as a pyrethroid LLIN.
METHODS
This was a household randomized controlled trial in a malaria endemic rice cultivation zone of Kirinyaga County, Kenya between 2014 and 2017. Cone bioassays and tunnel tests were done against Anopheles gambiae Kisumu. The chemical content, fabric integrity and LLIN survivorship were monitored. Comparisons between nets were tested for significance using the Chi-square test. Exact binomial distribution with 95% confidence intervals (95% CI) was used for percentages. The WHO efficacy criteria used were ≥ 95% knockdown and/or ≥ 80% mortality rate in cone bioassays and ≥ 80% mortality and/or ≥ 90% blood-feeding inhibition in tunnel tests.
RESULTS
At 36 months, Olyset Plus lost 52% permethrin and 87% PBO content; Olyset Net lost 24% permethrin. Over 80% of Olyset Plus and Olyset Net passed the WHO efficacy criteria for LLINs up to 18 and 12 months, respectively. At month 36, 91.2% Olyset Plus and 86.4% Olyset Net survived, while 72% and 63% developed at least one hole. The proportionate Hole Index (pHI) values representing nets in good, serviceable and torn condition were 49.6%, 27.1% and 23.2%, respectively for Olyset Plus, and 44.9%, 32.8% and 22.2%, respectively for Olyset Net but were not significantly different.
CONCLUSIONS
Olyset Plus retained efficacy above or close to the WHO efficacy criteria for about 2 years than Olyset Net (1-1.5 years). Both nets did not meet the 3-year WHO efficacy criteria, and showed little attrition, comparable physical durability and survivorship, with 50% of Olyset Plus having good and serviceable condition after 3 years. Better community education on appropriate use and upkeep of LLINs is essential to ensure effectiveness of LLIN based malaria interventions.
Topics: Insecticides; Kenya; Permethrin; Piperonyl Butoxide
PubMed: 34930459
DOI: 10.1186/s40249-021-00916-2 -
Chemosphere Feb 2021Piperonyl butoxide (PBO) is a semisynthetic chemical present in hundreds of pesticide formulations used in agricultural, commercial, and residential settings. PBO acts... (Review)
Review
Piperonyl butoxide (PBO) is a semisynthetic chemical present in hundreds of pesticide formulations used in agricultural, commercial, and residential settings. PBO acts as a pesticide synergist by inhibiting insect cytochrome P450 enzymes and is often present at much higher concentrations than active insecticidal ingredients. PBO was recently discovered to also inhibit Sonic hedgehog (Shh) signaling, a key molecular pathway in embryonic development and in brain and face morphogenesis. Recent animal model studies have shown that in utero PBO exposure can cause overt craniofacial malformations or more subtle neurodevelopmental abnormalities. Related adverse developmental outcomes in humans are etiologically heterogeneous, and, while studies are limited, PBO exposure during pregnancy has been linked to neurodevelopmental deficits. Contextualized in PBO's newly recognized mechanism as a Shh signaling inhibitor, these findings support more rigorous examination of the developmental toxicity of PBO and its potential contribution to etiologically complex human birth defects. In this review, we highlight environmental sources of human PBO exposure and summarize existing animal studies examining the developmental impact of prenatal PBO exposure. Also presented are critical knowledge gaps in our understanding of PBO's pharmacokinetics and potential role in gene-environment and environment-environment interactions that should be addressed to better understand the human health impact of environmental PBO exposure.
Topics: Animals; Embryonic Development; Female; Hedgehog Proteins; Humans; Insecticides; Morphogenesis; Pesticides; Piperonyl Butoxide; Pregnancy
PubMed: 33007564
DOI: 10.1016/j.chemosphere.2020.128414 -
Archives of Public Health = Archives... Nov 2023Pyrethroid-PBO nets have demonstrated improved impact against clinical malaria transmitted by pyrethroid resistant mosquito vectors and are being scaled up across...
Community evaluation of the physical and insecticidal durability of DuraNet® Plus, an alpha-cypermethrin and piperonyl butoxide incorporated mosquito net: protocol for a multi-country study in West, Central and East Africa.
BACKGROUND
Pyrethroid-PBO nets have demonstrated improved impact against clinical malaria transmitted by pyrethroid resistant mosquito vectors and are being scaled up across Africa. However very little is known about their physical and insecticidal durability under operational conditions. This study will investigate the attrition, fabric integrity, insecticide content and bioefficacy of DuraNet® Plus, a new WHO prequalified alphacypermethrin and PBO incorporated net developed by Shobikaa Impex Private Limited over 3 years of field use in communities in Benin, Cameroon and Tanzania.
METHODS
The study will be conducted in parallel in selected villages in Zakpota District in Benin, Mbalmayo, District in Cameroon and Muheza District in Tanzania. In each country, ~ 1800 households will be recruited and randomised to receive DuraNet® Plus or DuraNet® (a WHO prequalified alphacypermethrin-only ITN). Follow up surveys will be performed at 1 month post distribution to investigate adverse events and subsequently every 6-12 months to assess ITN attrition and fabric integrity following standard WHO procedures. A second cohort of nets will be withdrawn every 6-12 months and assessed for alpha-cypermethrin and PBO content and for entomological activity in laboratory bioassays (cone bioassays and tunnel tests). Alpha-cypermethrin bioefficacy will be monitored using the susceptible Anopheles gambiae Kisumu strain in cone bioassays while PBO bioefficacy will be monitored using pyrethroid resistant strains with overexpressed P450 enzymes in tunnel tests to determine the proportion of efficacious nets (≥ 95% knockdown, ≥ 80% mortality or ≥ 90% blood feeding inhibition in tunnels) at each time point. Nets withdrawn at 12, 24 and 36 months from each country will also be tested in experimental hut trials against wild free-flying pyrethroid resistant Anopheles gambiae sl in Côvè Benin to investigate the superiority of DuraNet® Plus over DuraNet® at each time point under semi field conditions.
CONCLUSION
This large-scale multi country trial will provide useful information on the durability of a pyrethroid-PBO net (DuraNet® Plus) in 3 different regions in sub-Saharan Africa. The methods proposed for bioefficacy testing could also contribute towards the development of new standardised guidelines for monitoring the insecticidal efficacy of pyrethroid-PBO nets under operational conditions.
PubMed: 37986195
DOI: 10.1186/s13690-023-01217-w