Effect of artificial lights on Aedes eggs in strata residential in Selangor, Malaysia: a field cluster randomized control trial

doi:10.21203/rs.3.rs-3118147/v1

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Research Article

Effect of artificial lights on Aedes eggs in strata residential in Selangor, Malaysia: a field cluster randomized control trial

https://doi.org/10.21203/rs.3.rs-3118147/v1

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Background

Dengue fever remains the deadliest infectious disease in tropical and subtropical regions. Even though numerous vector control measures have been taken, dengue incidence has continued to rise in the country due to rapid urbanization, population increase, and vertical housing development. Few studies examine the association between light intensity and Aedes and dengue. This study assesses how artificial light interventions may affect Aedes population density and dengue incidence in strata residential buildings in Malaysia.

Methods

This study was a two-armed, single-blinded, parallel, stratified cluster-randomized trial conducted in epidemiology week (EW) 41 until EW 52 in 2022. Nine intervention sites were applied with artificial light and the standard operating procedure of dengue control. The Aedes density was measured using paddle ovitraps placed at the study sites weekly. The ovitrap index and egg density index were calculated for each site.

Results

The recovered ovitraps (50.2%) and positive ovitraps (50.3%) were higher among control sites than intervention sites. In both arm groups, positive ovitrap was the highest at a 1-month post-intervention follow-up compared to baseline and immediate post-intervention period. Among intervention sites, the total Aedes eggs were lowest during baseline (24.2%), meanwhile among control sites was during immediate post-intervention (25.2%). There was no significant difference in the ovitrap index between intervention and control sites in the study (β = -3.156, 95% CI: -10.151, 3.839, p = 0.368). Meanwhile, there was a statistically significant difference in egg density index between intervention and control sites (β = 12.607, 95% CI: 3.295, 21.918; p = 0.009).

Conclusion

Artificial light can serve as a novel approach in vector control for mitigating the transmission of Aedes-borne illnesses. This alternative method could supplement existing insecticide approaches or human behavioural prevention programs. Implementing an innovative device that integrates artificial light as a dengue control is a feasible solution in the future.

This study was registered under the Thai Clinical Trials Registry (TCTR) on April 3^rd, 2023, with the identification number is TCTR20230403006

Aedes eggs

Egg Density Index

Ovitrap Index

Artificial light

Strata residential

Dengue is a severe public health threat affecting tropical and subtropical areas worldwide. The Aedes species, namely Aedes aegypti and Ae. albopictus is very effective at spreading dangerous dengue virus from one individual to another. Dengue incidence has been the highest among neglected tropical diseases during the past decades, with cases reported in the year 2000 of 505 430 cases and about 5.2 million in 2019 (1, 2).

According to the World Health Organization (WHO), Malaysia has the highest number of dengue cases compared to other Asian countries. A recent report shows that the cumulative dengue incidence until epidemiological week 11 of 2023 had increased by 222.6% compared to the same period in 2022 (1, 3). In terms of the economic burden in Malaysia due to dengue, the government has spent a significant amount on national dengue control activities, estimated at US$73.5 million. The expenses are most used at the district level, mainly for fogging (4). Larviciding, breeding source reduction, enforcement activities, health promotion, and community empowerment are also seen in Malaysia's routine dengue vector control and prevention (5).

Malaysia has been introduced to the vertical living concept since the 1970s, and various types of vertical residential buildings have developed, especially in urban areas in the country (6). Good management and maintenance of the strata building are essential to protect the residents from the risk of communicable diseases, especially dengue. Both dengue vectors are anthropophilic and can thrive in human-dominated environments like cities and suburbs (7). Therefore, current vector control and prevention methods have become more challenging (5).

Strata residential buildings risk prolonged dengue outbreaks due to the residents' population density and mobility (8). Other contributing factors to dengue transmission are climate change, massive urbanization, and poor solid waste management (9, 10). Both Aedes spp. were abundant within the first three levels of a residential building (11). Infestation profiles of Aedes in vertical buildings in Malaysia are usually artificial containers, illegal dumping sites, vegetation areas, landscapes, 'no man's land', and defective building structures. The presence of stagnant water due to the poor physical structure of a building may lead to Aedes breeding. Other breeding sites that found positive breed Aedes are the drainage system, the walkways or roof structures for apartments, and the corridors (12, 13). The building structure, for example, the corridors of a strata building, will receive below the optimal natural lighting source. Therefore, the half-shaded surrounding attracts more Aedes to breed, consequently favoring dengue virus transmission by the vectors (14, 15).

Understanding the ecology and development of the dengue vector is crucial for better prevention and control of the disease in strata residential areas. Some reports study the relationship between light intensity and the Aedes population in a lab setting (16, 17). However, little is known about the data regarding the effect of artificial light on oviposition, development, and survival of Aedes mosquitoes in the natural field setting (18). Thus, this trial was carried out to study the effect of artificial light on Aedes egg density in the local environment of strata residential buildings.

Study design and study location

This study was a two-armed, single-blinded, parallel, stratified cluster-randomized trial. The cluster in this study was defined as a province under the State Legislative Assembly (DUN) in the Hulu Langat district in Selangor. The two arms were the intervention group and the control group. The clusters and building blocks were blinded for the study. The intervention group applied artificial light of solar light-emitting diode (LED) light 300 Watts with the standard operating procedure (SOP) of dengue control. In contrast, the control group only received the SOP of dengue control per protocol in Malaysia.

The trial started with a baseline period from epidemiology week (EW) 41 until EW 44 in 2022. Following the baseline, the intervention was held during EW 45 until 48, and the subsequent post-intervention period was on EW 49 until 52.

Sampling method and sample size

The sampling unit was the floor of a residential building, which had experienced more than one episode of dengue outbreak in 2020 based on the e-Dengue registry in Malaysia. The block randomized selection was made through the computer-generated numbers technique via IBM SPSS Statistics software version 25.0.0. The sample size was calculated based on cluster randomization, inflated by the design effect and population mean formula for hypothesis testing (19, 20). Therefore, there were nine clusters with a minimum of one floor from each building for each arm after considering the fixed number of equal size clusters (21).

Instruments and apparatus

Lux meter

The light intensity or illuminance of the ovitrap points was measured using a handheld MS6300 MASTECH Multi-functions Environment Tester with an accuracy of ± (5.0%+10) (22). The mean value of three readings was taken as a final measurement.

Ovitrap

Weekly surveys were carried out with a conventional paddle ovitrap to monitor the Aedes egg densities (Additional file 1: Fig. 1a-b) (23). The ovitrap was a black resin plastic container of 260 ml. In order to avoid flooding with water, a hole was drilled 3 cm above the bottom of the container. The paddle was made of a 7.5cm long wooden tongue depressor and covered by an 8 cm x 5.5 cm standard nappy liner, as shown in Additional file 2: Fig. 2 (24, 25). The paddle and the container were tagged per location with the same coding system. About 360 ovitraps were placed in the study area, emphasizing the lowest light intensity and damp spots in the corridor of the study sites.

Artificial Light

The type of artificial light used during the intervention is solar street lights with white LED lamps (300W) emitting a maximum of 13000 lumens (65 lux of light illuminance) in a 200-meter squared surface area. The light source will be from 418 LED neutral white due to the LED's correlated colour temperature (CCT), similar to the CCT of direct sunlight (26). This solar LED light's lighting angle and high brightness is 120 degrees and up to 200 square meters of lighting (Additional file 3: Fig. 3a-b). The solar street lights can be switched on using a remote control and set the timer of 12 hours of lighting time.

Entomological Indices

Every Aedes spp. egg was identified under a stereo microscope at 2.5x, Nikon Eclipse E200 (27). The counting was done with a manual hand tally counter for accuracy (Additional file 4: Fig. 4). All paddles with eggs were dry for one day and resoaked for five days as a stimulus for eggs to hatch into larvae for species identification (28). The density of the Aedes was calculated in two formulas, ovitrap index (OI) and egg density index (EDI). The ovitrap index was the number of positive ovitraps divided by the total number of recovered ovitraps multiplied by 100. Meanwhile, the egg density index was calculated as the number of total eggs divided by the number of positive ovitraps (29).

Meteorological Data

According to the Köppen-Geiger classification, the study sites had a tropical rainforest climate (Af), which implies that even in the driest month, there is much rain (30, 31). The study sites had an average annual rainfall of 2,960 mm and a temperature of 25.7°C. The mean of 24-Hour temperature and mean rainfall (mm) for the study sites were obtained as secondary data from the Malaysian Meteorological Department (MET Malaysia) (32).

Data Analysis

All statistical analyses were performed using IBM SPSS Statistics software version 25.0.0 (33). The numerical data were analyzed descriptively in frequency (n) with percentage (%). A generalized linear mixed model was used in multivariate analysis, with a significant p-value below 0.05.

Building profiles

According to the e-Dengue registry, there were 838 localities with dengue outbreaks of more than two episodes in the Hulu Langat district in 2020. The final study sites were nine localities according to the nine DUN, after considering the exclusion criteria such as non-strata residential, government quarters, hostels, and non-cooperative MCs or JMBs of the residential localities (Additional file 5: Fig. 5).

Among the study sites, four localities were high-rise buildings, five middle-rise buildings, and no low-rise strata buildings. Three out of nine study sites have inactive management companies or joint management bodies to manage the maintenance of the physical and cleanliness of the residential buildings (Additional file 6: Table 1). Regarding the intervention sites, cluster S had the highest mean of light intensity during daytime at their corridors (26.0 lux ± 27.5), and cluster DT was the least lit corridor with a mean light intensity of 1.4 lux ± 0.5. A similar situation was also seen among control study sites where corridors at cluster S had the mean light intensity of 41.6 lux ± 45.2 and cluster DT was 1.3 lux ± 0.3 (Additional file 7: Table 2).

Table 1

Building profile of the study sites
	DUN	Study site	Type of building	Maintenance of the building	The estimated age of the building
1	BA	Tiara Ampang Condo	High-rise	Active	Between 11–20 years
2	LJ	Flat Taman Kosas	Low-rise	Active	More than 30 years
3	PI	Grandeur Tower	High-rise	Active	Between 21–30 years
4	T	Pandan Mewah Height Condominium	Middle-rise	Active	Between 21–30 years
5	DT	Taman Bukit Segar Apartment	High-rise	Active	Between 11–20 years
6	S	Pangsapuri Baiduri Bandar Tasik Kesuma	Low-rise	Active	Between 11–20 years
7	K	Flat Taman Bukit Kenangan	Low-rise	Not Active	Between 21–30 years
8	SR	Seksyen 1 Bandar Teknologi Apartment	Low-rise	Not Active	Between 21–30 years
9	B	Pangsapuri Taman Seri Kenari	High-rise	Not Active	Between 11–20 years
DUN: State Legilative Assembly Provincess; PI: Pandan Indah; T: Teratai; LJ: Lembah Jaya; BA: Bukit Antarabangsa; DT: Dusun Tua; SR: Sungai Ramal; B: Balakong; K: Kajang; S: Semenyih

Table 2

Characteristic of light intensity (lux) of the corridor according to group and cluster
	Light intensity (lux)
	Intervention				Control
Cluster	Min	Max	Mean	±SD	Min	Max	Mean	±SD
PI	2.0	9.3	5.2	3.7	3.8	18.3	8.5	5.7
T	4.3	26.8	10.3	9.3	11.3	72.5	24.3	27.0
LJ	1.8	9.0	3.8	3.0	1.5	5.0	2.9	1.4
BA	3.5	10.5	5.6	2.9	6.0	14.0	9.2	3.2
DT	1.0	2.0	1.4	0.5	1.0	1.8	1.3	0.3
SR	6.3	18.0	9.3	4.9	2.0	17.5	8.7	7.0
B	3.0	9.0	5.9	2.3	4.5	12.8	9.0	3.3
K	1.0	40.8	12.1	16.4	3.3	32.5	10.1	12.6
S	4.0	58.0	26.0	27.5	6.8	119.5	41.6	45.2
Min: Minimum; Max: Maximum; SD: Standard deviation; PI: Pandan Indah; T: Teratai; LJ: Lembah Jaya; BA: Bukit Antarabangsa; DT: Dusun Tua; SR: Sungai Ramal; B: Balakong; K: Kajang; S: Semenyih

Meteorological variable

The mean 24-hour temperature for both intervention and study sites during the baseline and Post2 periods was 25.0^oC, and the Post1 period was 25.9^oC. The mean rainfall of the study sites was 8.0mm during the baseline period, 19.2mm during Post1, and 11.0mm during Post2.

Descriptive analysis of recovered ovitrap, positive ovitrap, total Aedes eggs, ovitrap index, and egg density index

Generally, the study was divided into three phases: baseline, intervention, and post-intervention. Therefore, three-time points were involved for the final analysis: baseline, immediate post-intervention (Post1), and 1-month post-intervention (Post2). Eighty ovitraps were placed for each cluster per arm on every phase. Out of the total of 2,160 ovitraps that were deployed for each study arm throughout the study period, 2,106 (97.5%) ovitrap were successfully recovered at intervention sites, and 2,125 (98.4%) recovered ovitrap at control sites.

According to Additional file 8: Table 3, positive ovitrap at the Post2 timepoint was the highest (41.5%) compared to baseline (24.0%) and Post1 (34.5%) among intervention sites. A similar trend was seen among control sites where the most positive ovitrap was recorded at Post2 (39.8%), followed by Post1 (35.2%) and baseline (25.1%). The total Aedes eggs yielded for the intervention group was 6128 (59.6%), higher than the control sites (4151 eggs). The total number of Aedes eggs among intervention sites was lowest during the baseline phase (24.2%). Meanwhile, control sites had the lowest egg counts during Post1 (25.2%). The total Aedes eggs were highest at the Post2 phase for both arms, about 43.6% in intervention and control sites.

Table 3

Frequency of recovered ovitrap, positive ovitrap, total *Aedes* eggs, egg density index, and ovitrap index according to intervention and control sites.
	Baseline			Immediate Post Intervention (Post1)
Sites	RO (n, %)	PO (n, %)	Total Eggs (n, %)	RO (n, %)	PO (n, %)	Total Eggs (n, %)	RO (n, %)	PO (n, %)	Total Eggs (n, %)	RO (n, %)	PO (n, %)	Total Eggs (n, %)
Intervention	693 (32.9)	117 (24.0)	1485 (24.2)	712 (33.8)	168 (34.5)	1969 (32.1)	701 (33.3)	202 (41.5)	2674 (43.6)	2106 (100.0)	487 (100.0)	6128 (100.0)
Control	703 (33.1)	104 (25.1)	1296 (31.2)	713 (33.6)	146 (35.2)	1046 (25.2)	709 (33.4)	165 (39.8)	1809 (43.6)	2125 (100.0)	415 (100.0)	4151 (100.0)
Total	1396 (33.0)	221 (24.5)	2781 (27.1)	1425 (33.7)	314 (34.8)	3015 (29.3)	1410 (33.3)	367 (40.7)	4483 (43.6)	4231 (100.0)	902 (100.0)	10279 (100.0)
RO: Recovered ovitrap; PO: Positive ovitrap; PI: Pandan Indah; T: Teratai; LJ: Lembah Jaya; BA: Bukit Antarabangsa; DT: Dusun Tua; SR: Sungai Ramal; B: Balakong; K: Kajang; S: Semenyih

Among the three time points of the study, the ovitrap index was seen having an increasing trend among both the intervention sites (Baseline = 16.9%, Post1 = 23.6%, Post2 = 28.8%) and control sites (Baseline = 14.8%, Post1 = 20.5%, Post2 = 23.27%). The egg density index was highest during the Post2 phase among intervention sites (13.2) and at the baseline phase among control sites (12.5). Both intervention and control sites had the lowest EDI in the Post1 phase (Additional file 9: Table 4).

Table 4

Ovitrap index and egg density index according to intervention and control sites
Sites	Baseline		Post1		Post2
Sites	OI %	EDI	OI %	EDI	OI %	EDI
Intervention	16.9	12.7	23.6	11.7	28.8	13.2
Control	14.8	12.5	20.5	7.2	23.3	11.0
OI%: Percentage of ovitrap index; EDI: egg density index; PI: Pandan Indah; T: Teratai; LJ: Lembah Jaya; BA: Bukit Antarabangsa; DT: Dusun Tua; SR: Sungai Ramal; B: Balakong; K: Kajang; S: Semenyih; Post1: Immediate post-intervention; Post2: 1-month post-intervention.

Effect of artificial lights on ovitrap index and egg density index

A generalized linear mixed model (GLMM) analysis was used to investigate the effect of artificial lights on the ovitrap index and egg density index. Additional file 10: Table 5. shows the final model for the ovitrap index analysis, with an Akaike Information Criterion-Finite Sample Corrected (AICC) value of 366.087 and a Bayesian Information Criterion (BIC) corrected value of 373.731. The final analysis showed no significant difference in the ovitrap index between intervention and control sites in the study (β = -3.156, 95% CI: -10.151, 3.839, p = 0.368). Baseline light intensity significantly affects ovitrap index value (β = 0.447, 95% CI: 0.083, 0.810, p = 0.017). The group and baseline light intensity interaction showed a significant difference in ovitrap index between intervention and control sites (β = 0.809, 95% CI: 0.438, 1.180, p < 0.001). The table shows that intervention sites with building ages between 11–20 years significantly differ from those with a building age of more than 30 years (β = 7.753, 95% CI: 4.341,11.164, p < 0.001).

Table 5

Multivariate analysis of the effect of artificial lights on ovitrap index
Variable	Adjusted β	SE	95% CI		t	p-value
Variable	Adjusted β	SE	Lower	Upper	t	p-value
Intercept	8.959	2.650
Group
Control sites	Ref
Intervention sites	-3.156	3.475	-10.151	3.839	-0.908	0.368
Phase
Baseline	Ref
Immediate post-intervention	5.782	3.799	-1.866	13.430	1.522	0.135
1-month post-intervention	8.474	5.307	-2.208	19.157	1.597	0.117
Baseline Light intensity (lux)	0.447	0.181	0.083	0.810	2.473	0.017*
Interaction
Control*Baseline light intensity	Ref
Intervention*Baseline light intensity	0.809	0.184	0.438	1.180	4.390	< 0.001*
Interaction
Intervention*Building age of more than 30 years	Ref
Intervention*Building age 11–20 years	7.753	1.689	4.341	11.164	4.590	< 0.001*
^aUsing a generalized linear mixed model adjusted for baseline light intensity, dengue control activities. Significant at p < 0.05; SE: Standard Error, t: t-test; Post1: immediate post intervention; Post2: 1-month post intervention. Fixed effect for Group, F (1, 46) = 0.676, p = 0.415; Fixed effect for phase, F (2, 46) = 4.671, p = 0.014; Fixed effect for baseline light intensity, F (1, 46) = 85.307, p < 0.001; Fixed effect for interaction (GroupPhase), F (2, 46) = 0.191, p = 0.827; Fixed effect for interaction (Group*Baseline light intensity), F (1, 46) = 19.274, p < 0.001; AIC value: 366.087; BIC value: 373.731.

Meanwhile, Additional file 11: Table 6 shows the final model for the effect of artificial lights on egg density index analysis, where the AICC value was 318.045, and the BIC corrected value was 325.229. The GLMM analysis showed a proven statistically significant difference in egg density index between intervention and control sites (β = 12.607, 95% CI: 3.295, 21.918; p = 0.009) after controlling for covariates. Similar to the ovitrap index, baseline light intensity affects the egg density index in this study (β = -0.081, 95% CI: -0.154, -0.009; p = 0.028). Among intervention sites, building with ages between 21–30 years (β =-9.512, 95% CI: -14.049, -4.975; p < 0.001) and 11–20 years (β = -8.943, 95% CI: -12.467, -5.420; p < 0.001) found statistically lower EDI compared to building with age more than 30 years.

Table 6

Multivariate analysis of the effect of artificial lights on egg density index
Variable	Adjusted β	SE	95% CI		t	p-value
Variable	Adjusted β	SE	Lower	Upper	t	p-value
Intercept	14.442	2.945
Group
Control sites	Ref
Intervention sites	12.607	4.617	3.295	21.918	2.730	0.009*
Phase
Baseline	Ref
Immediate post-intervention	-3.891	3.154	-10.251	2.469	-1.234	0.224
1-month post-intervention	-2.208	3.897	-10.067	5.652	-0.566	0.574
Building age
Building age of more than 30 years	Ref
Building age 21–30 years	-2.545	1.236	-5.037	-0.052	-2.059	0.046*
Building age 11–20 years	-1.249	1.442	-4.157	1.658	-0.866	0.391
Baseline Light intensity (lux)	-0.081	0.036	-0.154	-0.009	-2.275	0.028*
Interaction
Control* Building age of more than 30 years	Ref
Intervention* Building age 21–30 years	-9.258	1.721	-12.728	-5.787	-5.379	< 0.001*
Intervention* Building age 11–20 years	-8.663	1.508	-11.705	-5.621	-5.743	< 0.001*
^aUsing a generalized linear mixed model adjusted for baseline light intensity, building age, and dengue control activities. Significant at p < 0.05; SE: Standard Error, t: t-test. Fixed effect for Group, F (1, 43) = 25.197, p < 0.001; Fixed effect for phase, F (2, 43) = 1.965, p = 0.152; Fixed effect for baseline light intensity, F (1, 43) = 5.176, p = 0.028; Fixed effect for building age, F (2, 43) = 34.332, p < 0.001; Fixed effect for interaction (GroupPhase), F (2, 43) = 0.021, p = 0.979; Fixed effect for interaction (Group*Building age), F (2, 43) = 26.878, p < 0.001; AIC value: 318.045; BIC value: 325.229.

This study showed the distribution of Aedes eggs, ovitrap index, and egg density index of two independent groups: intervention sites that received artificial lights during daytime and control sites that did not. At baseline, cluster S had the highest and lowest light intensity cluster DT. Cluster S is a low-rise residential building situated in a suburban area. No other high-rise building surrounded the area of cluster S and the corridors were open to the building light wells; therefore, it explained the finding. In contrast to cluster DT, the structure of the building was a high-rise building, and the corridors were shared between the resident units with few light wells. Thus, there was low natural daylight entering the corridor (15).

The positivity of the ovitraps and the total Aedes eggs may be attributed to the study climates. Environmental temperatures and rainfalls have been shown to alter Aedes' physiology, biology, and ecology life history traits (11, 34–37). Post2 timepoint was the cumulative data from EW 49 to EW 52 in December. The finding was similar to a study from Brazil, where the highest positive ovitraps were observed in December and the lowest frequency in October (baseline period in the current study) (29). Rainfall was less during the Post2 period than during the Post1 period. The decreasing climate component may explain the decrease in the supply of suitable breeding sites as the primary role of oviposition sites. Therefore, the water availability in the study's ovitraps was the primary preference of the adult mosquitoes at that time. The findings corroborated another study from Brazil (29), although other research has shown a strong relationship between precipitation and vector life cycle (38, 39).

The lowest egg counts during the Post1 period could be attributed to increased rainfall, which drove Aedes eggs away from the ovitraps near the light wells. The scenario aligns with a study from Dhaka city by Karim et al. 2012 (40). In addition, during the Post1 period, there was an increase in temperature, which facilitated the immature Aedes became to adult mosquitoes. Therefore, the total number of Aedes eggs was the lowest (25). This study's findings, however, contrasted studies from northeast Sri Lanka and Brazil, where the egg density peaked during high precipitation months in December (41, 42). As the temperature rises, larval development may speed up. The optimal temperature for Aedes development, egg viability, and adult fecundity was between 23^oC and 31^oC (25, 37, 43). Therefore, it explains the findings of this study where the highest total Aedes eggs were seen during the Post2 period for both intervention and control sites.

In the current study, group and baseline light intensity interaction showed an increment in the intervention group's ovitrap index and egg density index compared to the control group. This finding is corroborated by a study from Sri Lanka, where OI was higher in containers exposed longer to natural sunlight than indoor containers (44). The utilization of artificial light may augment the biting behaviour of adult mosquitoes. Consequently, the intervention phase is expected to increase blood-fed events, stimulating the oviposition of adult Aedes. This factor has been demonstrated in prior studies (45, 46). The study findings indicate that the activation of artificial lighting during daylight hours resulted in an extended duration of light exposure at the research locations. Thus, this particular environment expedites the maturation process of juvenile Aedes, resulting in a shortened course until adulthood. Consequently, mature mosquitoes in the designated research locations resulted in a subsequent rise in the overall quantity of eggs produced (17, 47). Another lab study revealed that the effect of exposure to white light on gravid female Aedes with more prolonged exposure to artificial lights had a higher fecundity rate (48).

The presence of artificial lighting has decreased the egg density index in structures that are less than 30 years old. The study revealed that vegetation in the environment was more pronounced in older buildings than their younger counterparts. Residents utilized the corridor for various purposes such as bulk waste disposal, temporary storage of personal belongings, placement of potted plants and disused containers, and even construction of permanent illegal structures at light wells. Hence, despite the supplementation of artificial light during the daytime, the illumination within the interior of the building was inadequate. Insufficient lighting in residential structures attracts Aedes mosquitoes, facilitating their search for prey to fulfill the gonadotropic cycle, encompassing oviposition events.

This research was done to understand better how environmental influences, particularly those related to high-rise buildings, may affect the abundance of Aedes in Malaysian residential areas. From the study's findings, the density of Aedes was found to increase immediately post-intervention. Therefore, the high capture of the Aedes population with artificial light can be used as one of the preventive or control tools for dengue preventive management with the new invention of light-ovitrap. The light may act as an attractant to trap the Aedes and eventually be trapped in the device. This light-ovitrap is less harmful to public health because no chemicals are being used, like fogging. In addition, the cost is much lower than fogging methods. It is advised to carry out the same intervention for a more extended period to create a more reliable study outcome. This is because differences in physical environmental factors can be distinguished clearly, and the effect of artificial light can be extensively investigated in a natural setting. Future researchers may modify this study by integrating the intervention with time series analysis. A more apparent interaction of the variables with confounding factors may be obtained with the time series analysis if the data is analyzed weekly by epidemiological week. Aside from that, future researchers may conduct a predictor study involving real-world physical environment variables, including the light intensity of the study sites.

Ae.: Aedes, spp.: species, DUN: State Legislative Assembly Provinces, LED: solar light-emitting diode, SOP: standard operating procedure, EW: epidemiology week, CCT: correlated color temperature, Af: tropical rainforest climate, Post1: Immediate post-intervention, Post2: 1-month post-intervention, RO: Recovered ovitrap; PO: Positive ovitrap; OI: Ovitrap index; EDI: Egg density index; SD: Standard deviation, S: Semenyih, DT: Dusun Tua, GLMM: Generalized linear mixed model, AICC: Akaike Information Criterion-Finite Sample Corrected, BIC (Bayesian Information Criterion).

Acknowledgments

We thank Mr. Noor Azree Mohd Hanifiah, Dr. Sumaiyah Isamail, and Mr. Hadhri Tarmizi for their dedicated efforts as research assistants in the field; Mr. Shahrul Sirajuddin, Madam Arniniyati Azmi and Mr. Azirul from Hulu Langat District Health Office on technical inputs of the study; and Dr. Nabilah, Madam Evi Diana and Madam Zuraida from National Institute of Health Malaysia on statistical aspects of the study.

Authors’ contribution

LF developed the hypothesis, analyzed and interpreted the data, and authored most of the manuscript. SS and MRB assisted in the analysis and conception of the research idea, the main contributor in writing the manuscript, and provided statistical guidance on interpreting the results for the paper. ZS and LSM guided the primary data collection for this study. All authors read and approved the final manuscript.

Funding

The study was self-funded by the principal researcher.

Availability of data and materials

The raw data sets generated and analyzed data during the current study are not published publicly as they are the property of Universiti Putra Malaysia. However, the data are available from the corresponding author on reasonable request.

Ethics approval and consent to participate

The Medical Research & Ethics Committee, Ministry of Health Malaysia reviewed the study with approval number (NMRR ID-22-01224-DS0 (IIR)). A written informed consent also was obtained from each management corporation (MC) or joint management body (JMB) of the strata building before the trial commenced.

Consent for publication

Not applicable.

Competing interests

The author declared that there was no competing interest in this study.

Author Details

¹Department of Community Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. ² Hulu Langat District Health Office, Selangor State Health Department, Kajang, Selangor. ³ State Vector Borne Disease Control Unit, Selangor State Health Department, Shah Alam, Selangor, Malaysia.

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No competing interests reported.

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Effect of artificial lights on Aedes eggs in strata residential in Selangor, Malaysia: a field cluster randomized control trial

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Abstract

Figures

Background

Methods

Study design and study location

Sampling method and sample size

Instruments and apparatus

Lux meter

Ovitrap

Artificial Light

Entomological Indices

Meteorological Data

Data Analysis

Results

Building profiles

Meteorological variable

Effect of artificial lights on ovitrap index and egg density index

Discussion

Conclusions

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

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