Search Results (76)

A new generation of insecticide-treated nets (ITNs) that incorporate the synergist piperonyl butoxide (PBO) has been shown to restore susceptibility to pyrethroids where P450 enzymes are the primary mechanism conferring the resistance. The present study evaluated the efficacy of YAHE 4.0, a PBO ITN, against wild free-flying Anopheles arabiensis in experimental huts in Lower Moshi, north-eastern Tanzania. It is the first evaluation of YAHE 4.0 in the country. Bio-efficacy evaluations, including susceptibility tests and cone bioassays, were conducted using the standard WHO guidelines. DuraNet Plus, a WHO-recommended PBO ITN, and Interceptor ITNs served as active and standard comparators, respectively. Unwashed and 20 times washed nets were subjected to experimental hut trials. Multiple logistic regression was employed to analyse experimental hut trial data. The results of the susceptibility testing showed that the An. arabiensis population of Lower Moshi was resistant to pyrethroids, but susceptible to organophosphates. Particularly, low mortality was recorded for cyhalothrin (2%) and alpha-cypermethrin (38%). Mortality rates to alpha-cypermethrin pirimiphos-methyl were 38% and 100%, respectively. The non-inferiority of YAHE 4.0 to DuraNet Plus ITN in terms of mortality and blood feeding was determined according to the WHO guidelines. The results for pooled unwashed and 20 times washed ITNs showed that YAHE 4.0 was superior to Interceptor ITN (adjusted odds ratio, AOR = 1.33; 95% CI = 1.04–1.69; non-inferiority margin, NIM = 0.68; p-value = 0.023) and non-inferior to DuraNet Plus (AOR = 1.02; 95% CI = 0.78–1.35; NIM = 0.72; p-value = 0.867) in terms of mortality. In terms of blood feeding inhibition for pooled unwashed and 20× washed ITNs, YAHE 4.0 was superior to both Interceptor ITN (AOR = 0.80; 95% CI = 0.64–1.00; NIM = 1.35; p-value = 0.049) and DuraNet Plus (AOR = 0.67; 95% CI = 0.52–0.86; NIM = 1.33; p-value = 0.002). Chemical analysis showed higher wash retention of active ingredients in YAHE 4.0 LLIN (88.9% for PBO and 94.9% for alpha-cypermethrin) compared to DuraNet Plus LLIN (89.2% for PBO and 90.5% for alphaypermethrin) before the hut trial. YAHE 4.0 LLIN demonstrated superior entomological efficacy and wash durability to DuraNet Plus and Interceptor LLINs, and fulfilled WHO non-inferiority criteria for mosquito mortality and blood-feeding inhibition. Therefore, YAHE 4.0 LLIN should be considered as an addition to the current list of pyrethroid-PBO nets used for control of pyrethroid-resistant vector populations with P450 enzymes as the main mechanism conferring resistance. Full article

Myzus persicae is a worldwide insect pest with high resistance to many traditional insecticides. Cycloxaprid, a novel cis-configuration neonicotinoid insecticide, is effective in controlling neonicotinoid-resistant insect pests. Lethal and sublethal effects of cycloxaprid on M. persicae were conducted in this study. Results showed that cycloxaprid had higher toxicity to the laboratory and field resistant M. persicae than imidacloprid. Because of the resistance, imidacloprid showed lower control efficacy (<60%) against M. persicae, which falls short of the efficacy required for practical agricultural management. However, cycloxaprid exhibited higher control efficacies (>84.79%) against M. persicae in the field. In addition, in order to quantify the sublethal impacts of cycloxaprid, we conducted a life table analysis on M. persicae. When resistant M. persicae was treated with LC₂₅ of cycloxaprid or imidacloprid, the longevity and fecundity of F₁ adults were significantly decreased. Meanwhile, the intrinsic rate of increase (r_m), finite rate of increase (λ) and net reproduction rate (R_i) of F1 generation M. persicae were reduced in cycloxaprid and imidacloprid treatments. Therefore, cycloxaprid shows high potential as a candidate insecticide for managing imidacloprid-resistant M. persicae. Importantly, our laboratory data indicate that exposure to its low sublethal concentration (LC₂₅) inhibits population growth parameters, suggesting a low risk of inducing pest resurgence under such conditions. Full article

Malaria control in sub-Saharan Africa lies at the intersection of changing climate suitability and the scale-up of vector control and case management. Drawing on recent evidence from Kenya, we argue that climate variability already exerts effects on malaria outcomes comparable to, and sometimes stronger than, those of commonly measured interventions at local scales. Transmission dynamics display non-linear, lagged relationships with temperature and rainfall. As a result, climate change is expected to alter prevailing conditions and extremes, reshaping the geography and seasonality of malaria risk. At the same time, socio-economic development and vector control intervention such as insecticide-treated bed nets (ITNs) and timely case management continue to reduce malaria incidence and deaths, especially among young children. However, their population-level impact depends on when and where interventions are deployed relative to climate-favoured windows of transmission. We propose a practical agenda for “climate-smart” malaria control in Kenya advocating for dynamic targeting of interventions according to observed climate lags and thresholds, sustaining protection for the youngest, and innovating approaches for school-age reservoirs of infection. Access to effective care should be re-conceptualized as a climate-adaptation strategy, and short-term, locally tailored forecasts should be embedded into routine planning to support anticipatory and equitable malaria control. Full article

The cowpea weevil, Callosobruchus maculatus (F.), stands out as one of the most destructive field-to-storage pests of leguminous crops. This study investigates the potential of essential oils derived from two Satureja species, Satureja hortensis L. and Satureja khuzistanica Jamzad, for managing C. maculatus. Bioassay results revealed that both S. hortensis (72 h LC₅₀ = 0.20 µL/g) and S. khuzistanica (72 h LC₅₀ = 0.19 µL/g) essential oils exhibited significant toxicity against C. maculatus adults. The essential oils extended development time, reduced adult longevity, and decreased fecundity of the pest. Key population parameters, including intrinsic growth rate (r) and net reproductive rate (R₀), were significantly lowered, particularly by S. hortensis essential oil. Age-specific survival (l_x) and fecundity (m_x) rates were also declined in treated groups, with delayed reproductive peaks compared to controls. Chemical analyses of S. hortensis and S. khuzistanica essential oils indicated that carvacrol (30.9% and 62.9%, respectively), γ-terpinene (25.5% and 4.3%), p-cymene (9.7% and 7.9%), and thymol (3.7% and 9.3%) were the major components. Hierarchical cluster analysis (HCA) was carried out to compare and contrast the compositions with previous works. The results demonstrated that S. hortensis and S. khuzistanica essential oils, given their lethal and sublethal effects against C. maculatus, can be introduced as natural alternatives to hazardous chemical insecticides, highlighting the need for further research in this field. Full article

Malaria persists as a paradigmatic model of co-evolutionary complexity, emerging from the dynamic interplay among a human host, Anopheles vectors, and Plasmodium falciparum parasites. In human populations, centuries of selective pressures have sculpted an intricate and heterogeneous immunogenetic landscape. Classical adaptations, such as hemoglobinopathies, are complemented by a diverse array of genetic polymorphisms that modulate innate and adaptive immune responses. These genetic traits, along with the acquisition of functional immunity following repeated exposures, mitigate disease severity but are continually challenged by the parasite’s highly evolved mechanisms of antigenic variation and immunomodulation. Such host adaptations underscore an evolutionary arms race that perpetually shapes the clinical and epidemiological outcomes. Intermediaries in malaria transmission have evolved robust responses to both natural and anthropogenic pressures. Their vector competence is governed by complex polygenic traits that affect physiological barriers and immune responses during parasite development. Recent studies reveal that these mosquitoes exhibit rapid behavioral and biochemical adaptations, including shifts in host-seeking behavior and the evolution of insecticide resistance. Mechanisms such as enhanced metabolic detoxification and target site insensitivity have emerged in response to the widespread use of insecticides, thereby eroding the efficacy of conventional interventions like insecticide-treated bed nets and indoor residual spraying. These adaptations not only sustain transmission dynamics in intervention saturated landscapes but also challenge current vector control paradigms, necessitating the development of innovative, integrated management strategies. At the molecular level, P. falciparum exemplifies evolutionary ingenuity through extensive genomic streamlining and metabolic reconfiguration. Its compact genome, a result of strategic gene loss and pruning, is optimized for an obligate parasitic lifestyle. The repurposing of the apicoplast for critical anabolic functions including fatty acid, isoprenoid, and haem biosynthesis highlights the parasite’s ability to exploit host derived nutrients efficiently. Moreover, the rapid accumulation of mutations, coupled with an elaborate repertoire for antigenic switching and epigenetic regulation, not only facilitates immune escape but also accelerates the emergence of antimalarial drug resistance. Advanced high throughput sequencing and functional genomics have begun to elucidate the metabolic epigenetic nexus that governs virulence gene expression and antigenic diversity in P. falciparum. By integrating insights from molecular biology, genomics, and evolutionary ecology, this study delineates the multifaceted co-adaptive dynamics that render malaria a recalcitrant global health threat. Our findings provide critical insights into the molecular arms race at the heart of host–pathogen vector interactions and underscore promising avenues for the development of next generation therapeutic and vector management strategies aimed at sustainable malaria elimination. Full article

The tomato leafminer (Tuta absoluta) is a globally invasive pest that causes severe yield losses in tomato crops. Nanotechnology-based strategies offer promising alternatives to conventional insecticides. This study examines the physiological, biochemical, and demographic responses of T. absoluta following exposure to mesoporous silica nanoparticles (MSNs) applied to tomato leaves at concentrations of 0, 3, 30, and 300 mg L⁻¹. Comprehensive assessments were conducted, including digestive and detoxifying enzyme activities in the insect, neurotoxicity indicators, life table parameters, and antioxidant responses in the host plant. At 30 mg L⁻¹, MSNs significantly impaired larval development, fecundity, and survival of T. absoluta without inducing phytotoxicity. Tomato plants treated at this concentration exhibited enhanced antioxidant enzyme activity (SOD, CAT, POD) and a reduced malondialdehyde (MDA) content, indicating an active oxidative defense. These plant responses were significantly correlated with changes in insect fitness traits, suggesting a plant-mediated effect on pest physiology. Digestive enzyme disruption, decreased acetylcholinesterase activity, and extended developmental periods contributed to suppressed population growth, as evidenced by reductions in the intrinsic rate of increase (r), net reproductive rate (R₀), and fecundity. At 300 mg L⁻¹, however, severe phytotoxicity and enzymatic collapse were observed in both plant and insect systems. These findings highlight moderate concentration of MSNs (30 mg L⁻¹) as a promising dose for sustainable and host-safe pest management, offering multi-targeted suppression of T. absoluta through combined plant and insect biochemical pathways. Full article

Background: Long-lasting insecticidal nets (LLINs) have significantly reduced the malaria burden in recent decades, and this malaria prevalence reduction has been achieved through the upgrading of pyrethroid long-lasting insecticidal nets. However, this reduction has stalled due to many factors, including rapidly developing pyrethroid resistance. Method: The protocol was registered in PROSPERO, and we used Cochrane methodology to assess bias and evidence quality. Three reviewers extracted data from individual studies, and a meta-analysis was performed using Excel and STATA version 17, expressing the data as a risk ratio. Result: A study involving 21,916 households from 11 randomized controlled trials showed that the chlorfenapyr treatment group had a 10% reduction in malaria infection risk, with a pooled overall prevalence of 25.96 per 100 children in the chlorfenapyr group and 32.38 per 100 children in the piperonyl butoxide group, compared to 41.60 per 100 children in the control (pyrethroid-only) group. This meta-analysis determined that the entomological outcomes of effectiveness and efficacy showed that these treatments effectively reduced vector density per household per night and mean inoculation rates, with a 23% reduction in chlorfenapyr, a 7% reduction in pyrethroid-only treatments, and a 12% reduction in piperonyl-butoxide-treated groups. This study shows that chlorfenapyr (CFP) and pyriproxyfen (PPF) LLINs are highly effective and more efficacious in reducing malaria infection, case incidence, and anemia among children, as well as in reducing mean indoor vector density, mean entomological inoculation rate, and sporozoite rate, compared to pyriproxyfen (PPF) LLINs in Africa. Conclusions: This study found that chlorfenapyr (CFP) LLINs are highly effective and more efficacious in reducing malaria infection, case incidence, and anemia among children in Africa. Therefore, policymakers and health planners should place strong emphasis on addressing the effectiveness, efficacy, and resistance management of LLINs as part of their current public health agenda to eliminate malaria. Full article

Malaria, typhoid fever, respiratory tract infections, and urinary tract infections significantly impact women, especially in remote, resource-constrained settings, due to limited access to quality healthcare and certain risk factors. Most studies have focused on vector control measures, such as insecticide-treated nets and time series analysis, often neglecting emerging yet critical risk factors vital for effectively preventing febrile diseases. We address this gap by investigating the use of machine learning (ML) models, specifically extreme gradient boost and random forest, in predicting adult females’ susceptibility to these diseases based on biological, environmental, and socioeconomic factors. An explainable AI (XAI) technique, local interpretable model-agnostic explanations (LIME), was applied to enhance the transparency and interpretability of the predictive models. This approach provided insights into the models’ decision-making process and identified key risk factors, enabling healthcare professionals to personalize treatment services. Factors such as high cholesterol levels, poor personal hygiene, and exposure to air pollution emerged as significant contributors to disease susceptibility, revealing critical areas for public health intervention in remote and resource-constrained settings. This study demonstrates the effectiveness of integrating XAI with ML in directing health interventions, providing a clearer understanding of risk factors, and efficiently allocating resources for disease prevention and treatment. Full article

The private sector in Tanzania has played an essential role in improving coverage and access to mosquito nets. This follow-up study assessed the overall market share for untreated and insecticide-treated nets (ITNs) and misleading or counterfeit ITN products in commercial markets. This study was conducted from March to April 2024 in ten regions in Tanzania. The study used mixed methods: (1) a quantitative survey among sampled outlets supported by photographic documentation of all net products and (2) key informant interviews of retailers and wholesalers. We assessed the relationship between market share and population access using ANOVA and Pearson correlation. No counterfeit or misleading nets were found, consistent with results from 2017, 2021, and 2022 surveys. Untreated nets dominated all markets, comprising 99% of all products observed and 99% of estimated net sales 3 months before the survey. Legitimate ITNs were crowded out from the studied markets. Leaked nets from free distributions were present but extremely limited (1%) and at their lowest level of the survey rounds. Untreated nets were more expensive than leaked ITNs for both regular- and queen-size nets. Despite ongoing efforts, increasing the share of legitimate ITNs remains a significant challenge in a context of large-scale public sector distributions. Full article

Democratic Republic of the Congo (DRC) is among the countries that have a high malaria incidence. In an effort to combat this public health challenge, innovative tools and strategies are being developed and evaluated. Among the new generation of nets with improved effectiveness of insecticides, those treated with a combination of piperonyl butoxide (PBO) and pyrethroids appear to be a promising malaria control tool. This study evaluated the effectiveness of this combination under community conditions of use in the DRC. A quasi-experimental study was carried out from January to December 2018, in Kisantu Health Zone. Thirty villages were randomly allocated as clusters (1:1) to receive one of two types of long-lasting insecticidal nets (LLIN) treated with deltamethrin alone, or PBO with deltamethrin. After the intervention, the assessments were conducted monthly, quarterly, and every six months for malaria infection, mosquito density, and LLIN durability, respectively. Comparison of changes in different indices between the two groups was made using generalized linear models to correct for non-linear effects. A total of 1790 children were included. There was a significant non-linear effect of time (months) on the malaria infection incidence. The malaria infection incidence was higher in January–March, May–June, and November. It remained higher in the control group compared to the intervention group over time. Similarly, there was a significant non-linear effect of time on the density of both Anopheles funestus s.l. and Anopheles gambiae s.l. These densities decreased after the first month following the intervention and increased after 6 months. Twelve months later, a cohort follow-up showed that the bio-efficacy of LLINs was better in the intervention group. The nets treated with the combination of PBO and deltamethrin appear to be more effective for malaria control under community conditions in the DRC, but a loss of chemical durability is noted after the first year of use. Full article

Visceral leishmaniasis (VL), a chronic disease caused by Leishmania infantum, is more prevalent in males than females. Control strategies that do not take this disparity into account can be suboptimal. We extended a sex-structured VL model by introducing four control variables: insecticide-treated bed nets, vector control, medical treatment, and animal culling. The study evaluates six intervention strategies and calculates the incremental cost-effectiveness ratio to assess their impact on disease transmission and cost-effectiveness. The analysis shows that, without interventions, the disease remains endemic with significant health and socioeconomic consequences. The proposed strategy, which applies all four controls, emerges as the most effective and cost-efficient strategy, leading to an exponential reduction in disease prevalence across human, vector, and animal populations. Strategies without animal culling and vector control followed in effectiveness. Moreover, it was found that applying up to 50% of the controls to females, compared to males, can still eliminate VL within the planning period. Full article

Background: Indoor residual spraying (IRS) is a core insecticide-based vector control tool employed in most malaria-affected settings globally. However, mosquito vectors have developed resistance to nearly all of the insecticides currently used in IRS. This has necessitated a transition to new classes of insecticides, from mostly using dichlorodiphenyltrichloroethane (DDT) and pyrethroids from 1997 to 2010 to carbamates in 2011 and organophosphates in 2013. In addition, other vector control measures, like the use of long-lasting insecticide-treated bed nets (LLINs), have also been employed for malaria control. Despite the implementation of these mosquito vector control interventions, malaria remains a disease of public health concern, especially in sub-Saharan Africa, which bears over 90% of the disease burden. This review will thus collate evidence on the effectiveness of IRS for malaria control in sub-Saharan Africa. Methods and analysis: The systematic review will be conducted following a priori criteria developed using the PRISMA guidelines. Articles will be obtained through a search of the Web of Science, Google Scholar, Medline via PubMed, Scopus and Embase databases. Mesh terms and Boolean operators (“AND”, “OR”) will be used in the article search. Additionally, websites of malaria research institutions will be searched. The article search will be conducted by two independent librarians (AAK and RS). All identified articles will be transferred to EPPI-reviewer v6.15.1.0 software. Article screening and data abstraction will be performed in duplicate by four reviewers (KOO, LN, GK and MO), and any further disagreements will be resolved through discussion and consensus. We shall extract data on the country, region, study design, insecticide combination, season, susceptibility procedure used, vector control interventions, population, mosquito species, malaria incidence or prevalence, insecticide efficacy, susceptibility, genotypic resistance, vector mortality and knockdown effect. Data analysis will be performed using STATA v17.0. Effect sizes will be statistically pooled using inverse-variance-weighted random-effects meta-analysis. Heterogeneity and publication bias in the articles will be assessed using the I² statistic and a funnel plot, respectively. For the studies that will not be included in the meta-analysis, a narrative synthesis will be written following the Cochrane Consumer and Communication Review Group format. Results: The findings of this review will help generate evidence on the effectiveness of indoor residual spraying using WHO pre-qualified insecticides in malaria control in sub-Saharan Africa. This protocol was registered in PROSPERO, registration number CRD42024517119. Full article

Background: This study investigates the relationship between climate variables and malaria incidence in Ethiopia’s Gambella region, a hotspot for malaria transmission. Methods: Utilizing 30 years of satellite-derived climate data and 10 years of malaria incidence records from the Ethiopian Public Health Institute, this research analyzed trends and correlations. Climate variables, including rainfall, temperature, and relative humidity, were extracted using GPS data and global climate models from NASA. Autoregressive modeling was employed to assess the impact of these variables on malaria incidence at different time lags (lag 0, 1, and 2). Results: The analysis revealed significant upward trends in rainfall, relative humidity, and temperature over the 30-year period, coinciding with a rise in malaria cases over the past decade. Rainfall exhibited delayed effects on malaria incidence, while relative humidity demonstrated both immediate and persistent impacts. Relative humidity at lag 0 had the strongest influence (IRR = 1.002, 95% CI: 1.001–1.003), whereas temperature showed minimal effects (IRR = 1.000, 95% CI: 1.000–1.001). Conclusions: These findings underscore the critical role of climate variables in driving malaria transmission and highlight the urgent need for climate adaptation strategies, early warning systems, and strengthened health infrastructure. Leveraging climate data for predictive modeling and expanding targeted interventions, such as insecticide-treated nets (ITNs), is essential to mitigate climate-driven malaria risks and protect vulnerable communities in Gambella and similar regions Full article

Chlorantraniliprole, serving as a substitute for traditional insecticide, has been widely utilized in controlling lepidopteran pests. Loxostege sticticalis (Lepidoptera: Crambidae) is a polyphagous insect and poses a significant threat as a migratory insect. This study investigated the life history traits of a field-collected population in response to chlorantraniliprole exposure based on an age-stage, two-sex life table. After treating the third-instar larvae of L. sticticalis with three different doses of chlorantraniliprole, namely LC₁₀, LC₂₅, and LC₅₀, the survival, development, and fecundity of L. sticticalis were affected significantly in a dose-dependent manner. Chlorantraniliprole at doses of LC₁₀, LC₂₅, and LC₅₀ prolonged the average generation time (T) compared to the control group. The net reproductive rate (R₀) and intrinsic growth rate (r) were significantly higher in the LC₁₀ group but significantly lower in the LC₂₅ and LC₅₀ groups. Chlorantraniliprole used at a dose of LC₁₀ was shown to increase the finite growth rate (λ), while it decreased λ at doses of LC₂₅ and LC₅₀. These results suggested that chlorantraniliprole induces hormetic effects by enhancing fecundity and reproductive potential at lower sublethal concentration (LC₁₀), while reducing the reproductive output at higher doses (LC₂₅ and LC₅₀). Our results provide useful information for developing management strategies for L. sticticalis involving the use of chlorantraniliprole. Full article

Background and Objectives: Malaria poses significant threats to pregnant women, particularly in endemic regions. Preventive measures against it include insecticide-treated bed nets, intermittent preventive treatment, and various supplements. We aimed to assess and compare the safety and effectiveness of malaria preventive measures in pregnant women, considering their HIV status. Methods: We conducted a systematic search of PubMed, the Cochrane Library, Scopus, Embase, and Web of Science through January 2024. A network meta-analysis was performed using R 4.3.3 software on 35 studies (50,103 participants). Results: In HIV-positive pregnant women, Co-trimoxazole with dihydroartemisinin significantly reduced malaria incidence compared to Co-trimoxazole alone (RR = 0.45, 95% CI [0.30; 0.68]) and sulfadoxine–pyrimethamine (SP) (RR = 0.14, 95% CI [0.04; 0.48]). Mefloquine was also effective compared to controls and SP. In HIV-negative women, azithromycin–piperaquine significantly reduced infections compared to SP, bed nets, and controls (RR = 0.03, 95% CI [0.00; 0.83]; RR = 0.03, 95% CI [0.00; 0.86]; and RR = 0.03, 95% CI [0.00; 0.77], respectively). Conclusion: Different combinations of preventive measures show varying effectiveness based on HIV status. Co-trimoxazole with dihydroartemisinin and mefloquine are effective for HIV-infected pregnant women, while azithromycin–piperaquine and mefloquine work well for those without HIV. Customized prevention strategies considering HIV status are crucial for optimal protection. Full article