The repellent activity of Piper aduncum essential oil against Aedes albopictus was investigated under laboratory conditions with human volunteers. The lowest median effective dose (ED50) value was 1.5 microg/cm2 at 60 sec of exposure when compared to 90 sec (2.1 microg/cm2) and 120 sec (1.8 microg/cm2) of exposure. At 0.4 g, the essential oil gave a high protection (95.2%) against Ae. albopictus bites or landing at 2 h postapplication. The percentage of protection was reduced to 83.3% after 4 h, 64.5% after 6 h, and 51.6% after 8 h postapplication. As a comparison, treatment with 10% deet gave 100% protection against mosquito biting/landing for 4 h postapplication. There was no significant difference in percentage protection reduction between the plant extract and the commercial product deet, respectively (P = 0.739). The essential oil, which was not as good as deet, still gave moderate protection against Ae. albopictus biting even until 4 h postapplication. In conclusion, the P. aduncum essential oil has the potential to be used as a repellent against the dengue/dengue hemorrhagic fever vector, Ae. albopictus.

The control of mosquitoes is threatened by the appearance of insecticide resistance and therefore new control chemicals are urgently required. Here we show that inhibitors of mosquito peptidyl dipeptidase, a peptidase related to mammalian angiotensin-converting enzyme (ACE), are insecticidal to larvae of the mosquitoes, Aedes aegypti and Anopheles gambiae. ACE inhibitors (captopril, fosinopril and fosinoprilat) and two peptides (trypsin-modulating oostatic factor/TMOF and a bradykinin-potentiating peptide, BPP-12b) were all inhibitors of the larval ACE activity of both mosquitoes. Two inhibitors, captopril and fosinopril (a pro-drug ester of fosinoprilat), were tested for larvicidal activity. Within 24 h captopril had killed >90% of the early instars of both species with 3rd instars showing greater resistance. Mortality was also high within 24 h of exposure of 1st, 2nd and 3rd instars of An. gambiae to fosinopril. Fosinopril was also toxic to Ae. aegypti larvae, although the 1st instars appeared to be less susceptible to this pro-drug even after 72 h exposure. Homology models of the larval An. gambiae ACE proteins (AnoACE2 and AnoACE3) reveal structural differences compared to human ACE, suggesting that structure-based drug design offers a fruitful approach to the development of selective inhibitors of mosquito ACE enzymes as novel larvicides.

Heavy metals, particularly cadmium, lead, and arsenic, constitute a significant potential threat to human health. This study was conducted to determine the levels of cadmium, lead, and arsenic in nail samples from farmers at Muda Agricultural Development Authority (MADA), Kedah, Malaysia, and evaluate factors that can contribute to their accumulations. A total of 116 farmers participated in this study. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze concentration of heavy metals in the nail samples and questionnaires were given to participants to get demographic, health status, and their agricultural activities data. In this paper, the level of heavy metals was within the normal range and varies according to demographic factors. We found that there were significant correlations between working period with level of lead and arsenic (r = 0.315 and r = 0.242, resp., P < 0.01) and age with lead level (r = 0.175, P < 0.05). Our findings suggested that agricultural activities could contribute to the accumulation of heavy metals in farmers. Hence, the control of environmental levels of and human exposure to these metals to prevent adverse health effects is still an important public health issue.

Dengue fever is endemic and remains a public health concern in Malaysia. The highest number of dengue cases occurred in Selangor in 2015. The majority of hotspot and outbreak areas in Malaysia were located in residential areas. Despite the high number of dengue prevalence in Malaysia, evidence for the level of community knowledge and practice of methods for Aedes control and prevention in the country remains scant. This cross-sectional study aimed to assess the demographic factors associated with the knowledge and practice of Aedes control and prevention methods. It also aimed to assess the associations and relationships between the public knowledge and practice of Aedes control and preventive activities involving Aedes larvae ovitraps (ALOTs), Mousticide, Denguard and other methods. Two residential areas that were considered as dengue hotspots were selected for the introduction of Aedes control and prevention programs. A sample size was calculated using G*power and a total of 152 residents who attended the dengue awareness events held at Section 3 and Section 8, Bandar Baru Bangi, Selangor, were recruited. A purposive sampling approach was adopted, and data were collected by using a pretested questionnaire with three subsections on sociodemographic information and on the knowledge and practice of Aedes control and prevention methods. No statistically significant (p>0.05) relationship between demographic factors and knowledge and practice scores was found. The results of χ 2 square test showed a strong (φ-coefficient = 0.605) and significant (p<0.001) association between knowledge and practice scores. In addition, a strong and significant positive correlation (r=0.648, p<0.001) existed between knowledge and practice scores. In conclusion, health promotion programs that focus on educating the public regarding the use of Aedes larvae ovitraps (ALOTs), Mousticide, Denguard and other methods to prevent and control Aedes mosquitoes and that involve multiple stakeholders, such as government officials and responsible authorities, and the active participation of communities are crucial in the war against Aedes.

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BackgroundPesticide exposure possesses risk of genotoxicity to humans, particularly farmers. Despite accumulating evidences linking genotoxicity to pesticide exposure, epidemiological studies to address pesticide toxicity in occupationally exposed farmers in Malaysia remain underreported. Thus, this study was aimed to determine the presence of nuclear abnormalities through the assessment of micronucleus (MN) and binucleus (BNu) frequencies in exfoliated buccal epithelial cells from farmers who were exposed to pesticides. A cross-sectional study of farmers among different agricultural activities farmers in Bachok and Pasir Puteh, Kelantan, North East of Peninsular Malaysia was done to evaluate the presence of nuclear abnormalities and its correlation with their health status and farming activities.ResultsAnalysis of buccal cells revealed that the frequency of MN was significantly higher (p < 0.05) in farmers as compared to controls. In contrast, no significant difference (p > 0.05) was observed for BNu frequency in between groups. Correlation analysis showed that apart from a significant (p < 0.05) and positive correlation between the duration of fertilizers exposure and frequencies of MN (r = 0.42, P = 0.001) and BNu (r = 0.37, P = 0.02), no other correlation of various confounding factors on the formation of MN and BNu were observed.ConclusionIn conclusion, pesticide and fertilizers exposure may contribute to the promotion of nuclear anomalies among Malaysian farmers who are engaged in mixed plantation activities. Further assessment of larger populations is important to address and overcome the potential risk of pesticide-induced genotoxicity.

Pesticide exposure may cause genotoxic effects by inducing the formation of micronucleus (Mn). Mn are fragments of chromosomes that remains after cells division. The increase in Mn may increase the risk of cancer formation. Our study aimed to determine the effects of lifestyle and pesticide exposure on the formation of Mn in epithelial cells from buccal swabs among paddy farmers in Malaysia. About 40 farmers who were exposed to pesticides were chosen as subjects and 30 personnels whose not directly exposed to pesticides, were chosen as the control group. Demographic and anthropometric data were obtained from questionnaires developed. Analysis of Mn formation was done using Giemsa staining (10% v/v) and the frequency of Mn formation was scored from 1000 cells per sample. Kruskal-Wallis test done between Mn frequency with age group showed a significant increase (p < 0.05) in Mn frequency in farmers as compared to the control in the age group of 30-39 , 40-49 years, and 50-59 years. Significant increased (p < 0.05) were observed between Mn frequency groups of normal BMI, pre-obese, and grade 1 obese as compared to control. Significant increase of Mn frequency (p < 0.01) was also seen among smokers and farmer's group (15.39 ± 3.34) as compared to controls (4.76 ± 1.26). The maximum numbers of Mn found in farmers are 7 Mn per cell whereas for control group is only 3 Mn. However, most farmers had only 1 Mn (81.75 ± 6.42%) and 2 Mn (15.28 ± 5.14%). Mn frequency with the duration of exposure to pesticides in a month and the use of PPE revealed no significant difference (p = 0.27). In conclusion, the increased frequency of Mn was influenced by age, gender, BMI and smoking status of farmers besides commonly repeated duration of exposures and the use of PPE. Further studies are needed to analyze the causes of an increased in Mn among farmers.