Exploring community behaviours and stakeholder challenges in engaging communities with dengue prevention behaviour in Malaysia: implementation research for a qualitative study with a community-based participatory research design.

OBJECTIVES: To use a community-based participatory research (CBPR) design to explore local community behaviours and stakeholders' challenges in engaging communities in dengue prevention behaviours in Hulu Langat, Selangor, Malaysia. DESIGN: This CBPR design in implementation comprised in-depth interviews (IDIs) and focus group discussions (FGDs). Themes were identified from the data with inductive and deductive thematic analysis. SETTING: FGDs were conducted in local community areas and IDIs were conducted in the local authority (LA) office and the Hulu Langat district health office. PARTICIPANTS: All FGD and IDI participants consented to the study, and included health authorities (n=4), LAs (n=7), community leader (n=1), faith leader (n=1), patients diagnosed with dengue (IDIs, n=2) and permanent residents of Hulu Langat who had been exposed to dengue infectious disease (FGDs, n=27). RESULTS: The main themes were categorised into community behaviour and stakeholder challenges. The community behaviour-related themes were awareness of dengue disease and Aedes mosquitoes, perception of risk and severity, and involvement of authorities. The themes related to stakeholder challenges were resource constraints and capacity issues, jurisdictional constraints and coordination, and educational dissemination and vandalism. CONCLUSIONS: The actions of the authorities shape community and stakeholder behaviours. Effective communication, including clear and aesthetically pleasing messages, motivates individuals to take appropriate actions. It is crucial for the authorities to engage in inclusive communication and consider diverse perspectives, such as those of residents and individuals exposed to dengue infection. Authorities that provide accurate and unbiased information foster transparency and enable informed decision-making by all stakeholders.

Bio-Fabrication of Silver Nanoparticles Using Citrus aurantifolia Fruit Peel Extract (CAFPE) and the Role of Plant Extract in the Synthesis.

The green synthesis of silver nanoparticles has been proposed as an eco-friendly and cost-effective substitute for chemical and physical methods. The aim of this study was to synthesize and characterize silver nanoparticles using the peel extract of Citrus aurantifolia fruit, and to determine the possible phytochemical constituents' presence in the plant extracts that might be responsible for the synthesis. Citrus aurantifolia fruit peel extraction was followed by phytochemical studies of secondary metabolites, FTIR analysis confirmation of functional groups, and GC-MS analysis. Silver nanoparticles were synthesized through bio-reduction of silver ions (Ag+) to silver nanoparticles using CAFPE and characterized using UV-Vis spectroscopy, HR-TEM, FESEM, EDX, XRD, DLS, and FTIR. The presence of plant secondary metabolites such as alkaloids, flavonoids, tannins, saponins, phenols, terpenoids, and steroids was detected. The FTIR analysis of the extract revealed the presence of functional groups like hydroxyl, carboxyl, carbonyl, amine, and phenyl, whereas the GC-MS analysis indicated presence of chemical compounds such as 1,2,4-Benzenetricarboxylic acid, Fumaric acid, nonyl pentadecyl, and 4-Methyl-2-trimethylsilyloxy-acetophenone, etc., with similar functional groups. The synthesized silver nanoparticle (AgNP) has displayed the characteristics of a surface plasmon resonance (SPR) band peak from 360-405 nm. High resolution transmission electron microscope (HR-TEM) and field emission scan electron microscope (FESEM) confirm polydisperse, spherical shaped, and smooth surface nanoparticles with an average size of 24.023 nm. Energy dispersive X-ray (EDX) analysis further revealed that silver is the most abundant element found in the micrograph of the nanoparticles, and FTIR analysis further confirmed the presence of different functional groups in the surface of the nanoparticle. The XRD analysis also confirmed that the nanoparticles synthesized are crystalline in nature. Based on the findings of this study, it is understood that the variety of natural compounds that are present in plant extracts of Citrus aurantifolia fruit peel can act as both reducing and stabilizing agents for the synthesis of silver nanoparticles. It is, therefore, concluded that Citrus aurantifolia peel extract can be potentially used for the large production of silver nanoparticles for several applications.

Impacts of climate change and environmental degradation on children in Malaysia.

The impacts of climate change and degradation are increasingly felt in Malaysia. While everyone is vulnerable to these impacts, the health and wellbeing of children are disproportionately affected. We carried out a study composed of two major components. The first component is an environmental epidemiology study comprised of three sub-studies: (i) a global climate model (GCM) simulating specific health-sector climate indices; (ii) a time-series study to estimate the risk of childhood respiratory disease attributable to ambient air pollution; and (iii) a case-crossover study to identify the association between haze and under-five mortality in Malaysia. The GCM found that Malaysia has been experiencing increasing rainfall intensity over the years, leading to increased incidences of other weather-related events. The time-series study revealed that air quality has worsened, while air pollution and haze have been linked to an increased risk of hospitalization for respiratory diseases among children. Although no clear association between haze and under-five mortality was found in the case-crossover study, the lag patterns suggested that health effects could be more acute if haze occurred over a longer duration and at a higher intensity. The second component consists of three community surveys on marginalized children conducted (i) among the island community of Pulau Gaya, Sabah; (ii) among the indigenous Temiar tribe in Pos Kuala Mu, Perak; and (iii) among an urban poor community (B40) in PPR Sg. Bonus, Kuala Lumpur. The community surveys are cross-sectional studies employing a socio-ecological approach using a standardized questionnaire. The community surveys revealed how children adapt to climate change and environmental degradation. An integrated model was established that consolidates our overall research processes and demonstrates the crucial interconnections between environmental challenges exacerbated by climate change. It is recommended that Malaysian schools adopt a climate-smart approach to education to instill awareness of the impending climate change and its cascading impact on children's health from early school age.

Evaluation of a mosquito home system for controlling Aedes aegypti.

BACKGROUND: Dengue is a significant public health issue that is caused by Aedes spp. mosquitoes. The current vector control methods are unable to effectively reduce Aedes populations and thus fail to decrease dengue transmission. Hence, there is an urgent need for new tools and strategies to reduce dengue transmission in a wide range of settings. In this study, the Mosquito Home System (MHS) and Mosquito Home Aqua (MHAQ) formulations were assessed as commercial autodissemination traps in laboratory and small-scale field trials. METHOD: Multiple series of laboratory and small-scale field trials were performed to assess the efficacy of MHS and MHAQ exposed to Ae. aegypti. In the laboratory trials, various parameters such as fecundity, fertility, wing size, oviposition preferences, residual effects, and MHAQ transference to other containers through controlled experiments were tested. For small-scale field trials, the efficacy of the MHS and MHAQ approaches was determined to ascertain whether wild mosquitoes could transfer the MHAQ formulation from MHS stations to ovitraps. RESULTS: The data revealed that Ae. aegypti was highly susceptible to low concentrations of MHAQ formulations and had a residual effect of up to 3 months, with MHAQ exposure affecting fecundity, fertility, and mosquito wing size. In the oviposition studies, gravid females strongly preferred the hay infusion compared to tap water and MHAQ during egg-laying in the laboratory. Nevertheless, the use of commercial MHAQ by MHS was highly attractive in field settings compared to conventional ovitraps among local Aedes spp. mosquitoes. In addition, MHAQ horizontal transfer activities in the laboratory and small-scale field trials were demonstrated through larval bioassays. These findings demonstrated the potential of MHAQ to be transferred to new containers in each study site. CONCLUSION: This study provided proof of principle for the autodissemination of MHAQ. Through further refinement, this technique and device could become an effective oviposition trap and offer an alternative preventive tool for vector control management.

The toxicity of angiotensin converting enzyme inhibitors to larvae of the disease vectors Aedes aegypti and Anopheles gambiae.

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.

Prevalence of intestinal protozoan infections among Orang Asli schoolchildren in Pos Senderut, Pahang, Malaysia.

The current study determined the prevalence of intestinal protozoan infections among the Orang Asli schoolchildren in Pos Senderut, Pahang, Malaysia. The overall intestinal protozoan infection rate was 85% (261 out of 307). The highest prevalence rates were due to Entamoeba coli (24.4%), Giardia lamblia (21.8%), Blastocystis hominis (21.2%) and Entamoeba histolytica (15.0%). The prevalence of Iodamoeba butschlii was only 2.9%. Among the positive samples, mixed infection with B. hominis and E. histolytica was 3.3%, B. hominis and G. lamblia was 2.9%, G. lamblia and E. histolytica was 2.0% and triple infections (B. hominis, G. lamblia and E. histolytica) was 1.0 %. The prevalence of the infection was high in all age groups (6-14 years old). Thus, we can conclude that intestinal protozoan infections are still representing a serious public health problem in aboriginal communities, especially among children.

Study of heavy metal levels among farmers of Muda Agricultural Development Authority, Malaysia.

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.

The effect of Piper aduncum Linn. (Family: Piperaceae) essential oil as aerosol spray against Aedes aegypti (L.) and Aedes albopictus Skuse.

The bioefficacy of Piper aduncum L. essential oil formulated in aerosol cans was evaluated against Aedes aegypti and Aedes albopictus in a simulated room. The aerosol spray test was based on the Malaysian test standard for aerosol (MS 1221:1991UDC 632.982.2 modified from WHO 2009 methodology) and examined the knockdown effect within 20 minutes of exposure. Mortality rate after 24 hour of holding period was also determined. A commercial aerosol spray (0.09% prallethrin 0.05% d-phenothrin) was also tested as a comparison. Our results showed that the knockdown effect of the commercial aerosol spray and P. aduncum essential oil spray (8% and 10% concentrations) was significantly higher in Ae. albopictus adult females, when compared with that of Ae. aegypti adult females (P<0.05). There was a significant difference in knockdown between commercial aerosol spray and essential oil spray for both Aedes spp. (P<0.05). The essential oil induced significantly higher mortality in Ae. aegypti (80%) than in Ae. albopictus (71.6%) (P<0.05). The commercial aerosol spray caused 97.7% and 86.5% mortality against Ae. aegypti and Ae. albopictus respectively (P<0.05). Based on these data, P. aduncum essential oil has the potential to be used as an aerosol spray against Aedes spp.

Infestation with the cat flea, Ctenocephalides felis felis (Siphonaptera: Pulicidae) among students in Kuala Lumpur, Malaysia.

This paper reports six male undergraduate students living at a local university hostel who were infested with cat fleas (Siphonaptera: Pulicidae: Ctenocephalides felis felis) in February 2009. All of them suffered from maculopapular rashes and severe pruritus after the bites. Investigation revealed the presence of a stray cat in the hostel building; five of the students had a history of contact with the cat. Six cat fleas were collected at the hostel and identified as C. felis felis. Most of the students were not aware of this infestation and did not seek medical treatment.

Repellency of essential oil of Piper aduncum against Aedes albopictus in the laboratory.

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.