Search Results (120)

Dengue virus infection (DVI), a mosquito-borne arboviral infection, is prevalent in tropical and subtropical regions, including Bangladesh, where incidence has surged over the past three decades—particularly in urban and peri-urban areas. This study investigates the factors influencing DVI seropositivity among clinically suspected patients admitted to the selected hospitals of Savar, Dhaka, and Chattogram. Data were collected from 850 clinically suspected patients admitted to two hospitals in Savar, Dhaka, and two in Chattogram during 2019. Questionnaire responses and laboratory test results (NS1, IgM, and IgG) were analyzed using descriptive statistics, chi-square tests, and logistic regression. Out of 450 admissions in Savar, 330 tested positive, while Chattogram reported 145 positives from 400 cases. No significant differences were observed between regions in relation to hospital type, season, gender, or household preventive measures. In Savar, DVI status was significantly associated with season, mosquito net use, and patient contact. In Chattogram, household repellent use and patient contact were key factors. Diagnostic tests varied in detection capability. These findings can inform targeted intervention strategies and public health messaging, such as promoting personal protection measures and community awareness campaigns, particularly in high-incidence urban settings. However, further research across diverse geographic and socio-ecological contexts is needed to enhance the generalizability and policy relevance of these results. Full article

Personal protection from mosquitos is dominated by topically applied aerosol sprays or lotions, which demonstrate efficacy durations of no longer than 10 h, thus encouraging the research and development of long-term insect-repelling devices. Repellent-loaded polymeric matrices have driven the development of insect-repelling apparel fabrics; however, most efforts either fail to offer the tensile properties demanded from apparel applications or only demonstrate repellency durations for multiple days. This study utilizes poly-D,L-lactic acid (PDLLA) as a compatibilizer between Nylon 12 and nootkatone for enhanced nootkatone retention throughout fabric manufacturing processes. Nootkatone-infused Nylon 12/PDLLA composites demonstrate up to a 14% increase in nootkatone retention throughout fabric manufacturing compared to pure Nylon 12, underscoring the importance of polymer/substrate miscibility on substrate retention. Moreover, while nootkatone-infused Nylon 12 filaments demonstrate decreasing tensile stress at breaks with increasing nootkatone content, Nylon 12/PDLLA filaments exhibit similar tensile properties regardless of nootkatone content. The PDLLA domains are suspected to behave as reservoirs for excess nootkatone to prevent its role as a defect within the Nylon 12 matrix. The resulting knits exhibit significant mosquito repellencies over 24 h dependent on the nootkatone concentration, thus demonstrating potential to embed insect repellent within high-performance polymeric filaments with effective mosquito repellencies. Therefore, the incorporation of PDLLA as a compatibilizer holds significant potential for enhanced nootkatone retention during Nylon 12 fabric manufacturing. Full article

Background: Coleus amboinicus (Lour.) (syn Plectranthus amboinicus) from the Lamiaceae family—a large family of aromatic herbs with many medicinally important species—is a frequently cited species within the Plectranthus genus, renowned for its traditional uses, phytochemical composition, biological activities, and applications in skin care. Methods: A systematic review was conducted following PRISMA guidelines to provide an in-depth understanding of P. amboinicus’ phytochemical composition and biological activity, particularly in dermatological contexts, underscoring its significance in traditional medicine and modern phytochemical research. Results: P. amboinicus extracts and essential oils exhibit significant antimicrobial activity against both Gram-positive and Gram-negative bacteria, and notable antifungal properties, particularly against dermatophytes. Additionally, the species demonstrates remarkable mosquito repellent and anti-parasitic effects, comparable to DEET, and potent anti-inflammatory properties by inhibiting pro-inflammatory cytokines. The plant’s rich polyphenolic content contributes to its significant antioxidant properties, preventing conditions like hyperpigmentation and premature aging. P. amboinicus also exhibits cytotoxic activity against various cancer cell lines and promotes wound healing through its analgesic, anti-inflammatory, and antioxidant abilities. Conclusions: This comprehensive exploration of P. amboinicus validates its diverse therapeutic potential across infectious diseases, oncology, and wound care. Further research and clinical trials are warranted to fully elucidate its mechanisms of action and optimize its therapeutic applications, paving the way for its integration into mainstream medical practices. Full article

To investigate the repellent efficacy of commercially available mosquito repellents in China against Haemaphysalis longicornis, four representative DEET-based repellents and biont-derived repellents were selected. This study utilized a modified circular filter paper method repellent testing device to establish an evaluation system for assessing the repellent effects of each product against three developmental stages of H. longicornis: larvae, nymphs, and adults. In our study, for DEET-based repellents, Johnson demonstrated the highest repellency against larvae within 1 h, with an average repellency rate exceeding 80.14%. Yamei and Johnson exhibited repellency rates more than 91.11% for nymphs within 1 h, surpassing the other two DEET products. Repellency rates of Longliqi and Xiaohuanxiong fluctuated between 80.95% and 100% at different time points. Yamei, Longliqi, and Johnson achieved 100% repellency to adults within 1 h, while Xiaohuanxiong showed slightly lower efficacy. The four biont-derived repellents showed significant variations in efficacy: larval-stage repellency ranged from 14.29% to 88.89%, nymphal-stage repellency from 57.89% to 100%, and adult-stage repellency from 50% to 79.49%. CaliforniaBaby exhibited the highest efficacy, comparable or superior to DEET-based products, whereas Longhu demonstrated the weakest repellency and poor persistence. We further conducted a persistence test for CaliforniaBaby and found that it maintained >75% repellency against H. longicornis for 6 h. This study provides scientific evidence for selecting tick repellents in practice, offers guidance for purchasing commercial biont-derived tick repellents, and serves as a reference for developing safer, more effective tick repellents. Full article

Human hosts exhibit remarkable variability in their attractiveness to mosquitoes, leading to differences in biting rates. It is essential to understand the factors behind this variability if we wish to develop more effective strategies for controlling the transmission of mosquito-borne diseases. While past studies have shed significant light on the forces shaping host attractiveness to mosquitoes, we continue to lack information about variation in attractiveness within individual hosts. For example, little attention has been paid to the potential impact of the menstrual cycle. Our study explored the relationship between the menstrual cycle, host attractiveness to mosquitoes, and the effectiveness of topical mosquito repellents. We found that mosquito landing rate was higher and repellent protection time was shorter during ovulation than during menstruation and the luteal phase. By beginning to clarify the intricate interplay between human physiology and mosquito behavior, our results contribute to the growing body of knowledge regarding the factors that affect within-individual variability in attractiveness to mosquitoes, which has implications for the efficacy of protection and disease prevention strategies. Full article

Background: West Nile virus (WNV) is a mosquito-borne RNA virus, with birds as reservoirs and humans as incidental hosts. WNV often causes asymptomatic infections, but severe neuroinvasive disease occurs in fewer than 1% of human cases. Recent climatic changes and occupational exposure have increased its spread, particularly in Southern Italy. This study aimed to assess WNV seroprevalence and occupational risks among outdoor workers to guide targeted public health interventions. Methods: This cross-sectional study was conducted in the Apulia region, southeastern Italy, from November 2023 to April 2024. Participants completed a detailed questionnaire on socio-demographics, occupational exposure, travel history, and health symptoms. Blood samples were analyzed using enzyme-linked immunosorbent assay (ELISA) and neutralization assays to detect WNV-specific antibodies. Results: 250 outdoor workers in southeastern Italy were recruited, including agricultural workers, veterinarians, forestry workers, and livestock breeders. The latter showed the highest WNV prevalence at 6.5%. Protective measures such as repellent use (β = −0.145, OR = 0.95, p = 0.019) and personal protective equipment (PPE) usage (β = −0.12, OR = 0.94, p = 0.04) significantly reduced the likelihood of WNV infection. Conclusions: The study highlights the significant occupational risk posed by WNV to outdoor workers involved in livestock breeding in Southern Italy, likely due to their frequent exposure to mosquito-prone environments. Tailored public health strategies and education programs are needed to protect high-risk outdoor workers from WNV, amidst the backdrop of changing climatic conditions that favor increased transmission. Full article

In this study, electrically conductive polymer composites based on repellent N,N-diethyl-3-methylbenzamide with concentrations ranging from 6 to 30 wt% were developed. The electrical resistivity of repellent composites, as determined by electrochemical impedance spectra, ranges from 150 to 171 Ohm, which allows such materials to be used when a low voltage is applied. The study of the rheological properties of the obtained repellent composites and the analysis of the TGA curves demonstrated that the dynamic viscosity of the materials has a significant effect on the thermal diffusion of the repellent. The study of the thermal diffusion of N,N-diethyl-3-methylbenzamide demonstrated that a higher yield of repellent (up to 36.4 × 10⁻⁸ mol) is achieved when the material is applied in the form with the shortest conductor length of 14 mm. The graphs showing the relationship between the electrical flux and the concentration of N,N-diethyl-3-methylbenzamide, which was calculated via the Peltier and Thompson equations, show that, according to Onsager’s theory, the total flux of the substance is highest when a voltage is applied to the material with the shortest conductor length. Thus, the developed repellent composite is a promising material for protection against blood-sucking insects. Full article

The quality control of insect repellents contributes to the population’s health since these products prevent mosquito bites and vector-borne diseases. In this study, we developed and validated a novel analytical method using high-performance liquid chromatography with a diode array detector (HPLC-DAD) for the quantification of icaridin in insect repellent lotions. The analysis was performed on a phenyl chromatographic column 150 × 4.6 mm, 3.5 μm and stabilized at 30 °C. The detection of icaridin was achieved at 4.5 min with a 20 μL injection volume of the samples. The active ingredient was extracted from the lotion samples with isopropanol and water (50:50 v/v) and then diluted to the working concentration at 0.6 mg/mL with the mobile phase. The calibration curve was linear in the concentration range of 0.1 to 1.2 mg/mL. The method was robust, specific and precise (relative standard deviations—RSD < 2%). The accuracy of the method was demonstrated by icaridin recovery. The limit of detection and quantification were 0.03 mg/mL and 0.1 mg/mL, respectively. The present report puts forward a novel analytical method for the quantification of icaridin, contributing to improving the quality control and efficacy of marketed formulations and their different presentations such as lotions, gels and sprays, demonstrating its good applicability. Full article

The mosquito Aedes albopictus is a vector of several harmful viruses, necessitating the development of safer and more sustainable repellents than DEET. This study evaluated the potential of plant-based EOs extracted via steam distillation from Aloysia citrodora and Bursera graveolens plants harvested in Ecuador. A. citrodora EO exhibited a high sensory pleasantness with a citral-like aroma, while B. graveolens EO had lower sensory appeal due to off-flavors. At 200 µL L⁻¹, B. graveolens EO demonstrated strong ovideterrent activity, reducing egg laying by 64%, whereas A. citrodora EO displayed the highest larvicidal activity with an LC₅₀ value of 88.54 µL L⁻¹. Both EOs, applied at 0.20 µL cm⁻² on human skin, provided comparable repellency for over 45 min. The RD₅₀ values were 0.104 µL cm⁻² for A. citrodora EO and 0.136 µL cm⁻² for B. graveolens EO. When compared to DEET at 0.04 µL cm⁻², no significant differences in repellency were observed within the first 15 min post-application. These findings suggest that both EOs are effective alternatives to synthetic repellents, and A. citrodora EO emerges as a promising candidate due to its superior sensory attributes and larvicidal activity. Full article

Plant-based oils have a long history of use as insect repellents. In an earlier study, we showed that in a 10% concentration, geraniol, 2-phenylethl propionate, and the plant-based essential oils clove and cinnamon effectively protected from mosquito bites for over 60 min. To expand on this study, we reanalyzed our GC–MS data to identify the short organic constituents of these oils. We then used an arm-in-cage assay to test the repellency of different concentrations and combinations of these oils and pure compounds. We found a sigmoidal relationship between the complete protection time from mosquito bites and the concentration of these oils. The complete protection times we recorded for combinations of these oils suggest an absence of additive effects. The results of this study can inform the development of novel, effective, and plant-based insect repellents. Full article

Citrus fruit peels are a rich source of essential oils (EOs), which contain biologically active compounds; however, they are often discarded as waste, which causes pollution. The fresh peels of eight citrus cultivars growing in Pakistan were used to extract EOs through steam distillation. Gas chromatography-mass spectrometry (GC-MS) analysis of fresh peel EOs revealed that limonene was the most abundant compound, constituting 94.5%, 96.1%, 95.3%, 93.3%, 56.2%, 91.5%, 96.4%, and 96.7% of Citrus jambhiri, C. aurantium, C. sinensis var. Malta cv. Blood Malta, C. sinensis var. Malta cv. Shakri Malta, C. limon, C. pseudolimon, C. reticulata var. Mandarin cv. Feutrell’s Early, and C. reticulata var. Mandarin cv. Kinnow, respectively. The dried peel EO of C. reticulata var. Mandarin cv. Kinnow contained 95.2% limonene. C. limon peel EO exhibited the highest antibacterial activity among all citrus peel EOs with the minimum inhibitory concentration of 312 μg/mL against Staphylococcus aureus. The C. aurantium and C. sinensis var. Malta cv. Shakri Malta peel EOs exhibited the highest mosquito repellent activity against Ae. aegypti females, providing protection for 45 min when tested at a concentration of 166 µg/cm². This study showed C. aurantium and Shakri Malta peel EOs could be used to formulate natural mosquito repellent. Full article

Background/Objectives: Household insecticide use may impact the health of young children in urban communities, but little is known about its acute effects. This cross-sectional study aimed to investigate the symptoms that may have been related to residential insecticide exposure and its associated factors in young children in urban areas. Methods: The study included 375 primary caregivers of children aged 6 months to 5 years from the Bangkok Metropolitan Region, Thailand, who had used insecticides in their homes within the past 6 months. An interviewer-administered questionnaire collected data on caregiver and child demographics, household insecticide use and exposure, child behaviors, and the history of child symptoms following insecticide use. Results: The findings revealed that 9.6% of young children had experienced symptoms at some point during or after household insecticide use, with coughing (66.7%), skin rash/irritation (44.4%), and runny nose (25.0%) being the most common. The final logistic regression model using backward selection indicated that factors statistically significantly associated with symptoms included being a male child (OR = 3.38; 95% CI = 1.48–7.71), hand/object-to-mouth behaviors (OR = 2.69; 95% CI = 1.26–5.74), weekly use of insecticides (OR = 2.77; 95% CI = 1.22–6.26), use of insecticide chalk (OR = 3.64; 95% CI = 1.32–10.08), and use of mosquito repellent spray/lotion (OR = 2.51; 95% CI = 1.13–5.61). Additionally, the use of insecticide spray (OR = 2.72; 95% CI = 0.97–7.65), opening doors/windows for ventilation (OR = 0.46; 95% CI = 0.21–1.02), and consistently cleaning floors with a wet cloth after use (OR = 0.52; 95% CI = 0.24–1.11) were marginally associated. Conclusions: Residential exposure to household insecticides can lead to acute health effects, primarily respiratory symptoms, in young children in urban communities. Caregivers should be informed of these health risks to reduce children’s exposure. Full article

Mosquito-borne diseases are a global health concern, necessitating effective and long-lasting insect repellents. This study investigated the physicochemical properties, stability, release kinetics, and efficacy of nanostructured lipid carriers (NLCs) and conventional emulsions (CEs) containing essential oils (NLC EOs) for insect-repellent applications. The droplet size of the CE was 18.46 ± 1.78 μm (Span 0.27 ± 0.06), while the NLC measured 136 ± 10.7 nm (PDI 0.26 ± 0.2) with a ζ-potential of –68 mV ± 2.2 mV (width 4.3 ± 0.1). EO incorporation did not significantly alter droplet size or ζ-potential. Gas chromatography–mass spectrometry confirmed an EO content of 8.57 ± 0.15 mg/mL in the CE EO and 7.75 ± 0.05 mg/mL in the NLC EO, with the NLC retaining a higher EO content over 90 days. Stability tests demonstrated consistent droplet sizes and ζ-potential for both formulations during storage. Release kinetics revealed diffusion-based release mechanisms, with the NLC providing a more sustained release than the CE. In a field test against mosquito species most frequently found in Greece, the NLC EO exhibited a significantly longer complete protection time (CPT) of 45 min, demonstrating more effective, long-lasting insect-repellent action. These findings revealed the NLC’s ability to retain volatile EO components efficiently, offering promising implications for long-lasting insect-repellent action. Full article

Chestnut (Castanea mollissima) is an economically important forest tree species, and its flowers possess functions such as repelling mosquitoes, killing bacteria, and clearing heat. However, the regulatory mechanisms of floral volatile organic compounds (VOCs) in chestnut are still unclear. This study analyzed the contents of major volatile compounds and related gene expression levels in chestnut flowers during the initial flowering stage (IFS) and full-flowering stage (FFS) using metabolomics and transcription techniques. In total, 926 volatile compounds were detected, mainly terpenes, heterocyclic compounds, and esters. Acetylenone, styrene, and β-pinene had contents that exceeded 5% in FFS chestnut flowers. In total, 325 differential metabolites between the IFS and FFS were significantly (p < 0.05) enriched in the biosynthetic pathways of sesquiterpenes and triterpenes, as well as the ethylbenzene metabolic pathway. In total, 31 differentially expressed genes (DEGs) were related to terpenoid biosynthesis. There were only two DEGs related to the ethylbenzene metabolic pathway. In summary, we identified the volatile components of chestnut flowers and analyzed the changes in the contents of major volatile compounds in the flowers and the expression patterns of the related genes. The research results are helpful for understanding the regulation of VOCs in chestnut flowers. Full article

Infectious diseases that cause illness and/or death in humans can be contracted from mosquito bites. A viable and alternate method of personal protection that can lower the danger of human exposure to mosquito-borne diseases is the use of plant-based repellents. Using a high-throughput screening system, the current work examined the toxicity, contact irritancy, and spatial repellency of Andrographis paniculata crude extract and its fractions against Aedes aegypti, Anopheles minimus, and An. dirus. Five fractions (i.e., F1, F2, F3, F4, and F5) were separated from the crude extract by column and thin layer chromatography and analyzed using high-performance liquid chromatography and mass spectrometry. The major active compounds identified from F3 and F5 were 4-deoxy-11,12-didehydroandrographolide and andrographolide. Three concentrations (1.0, 2.5, and 5.0%) for each of the crude extracts and the five fractions were individually impregnated on nylon netting strips and evaluated against the three mosquito species. Results showed that the highest contact irritancy was elicited by the crude extract at 5% concentration against Ae. aegypti (43.70% escaped). Results of the spatial activity index (SAI) showed that fractions F3 and F5 at 2.5% demonstrated the strongest repellency against Ae. aegypti (SAI = 0.84) and An. minimus (SAI = 0.83), respectively. Both the crude extract and its components did not cause any knockdown or mortality. These findings suggest that fractionation of A. paniculata extracts is valuable in assessing their spatial repellent efficacy against mosquitoes. Fractions F3 and F5 hold promise as natural mosquito repellents and could contribute to developing effective mosquito control strategies. Full article