Aishah Hani Azil

Lymphatic filariasis is a neglected tropical disease caused by blood-borne nematode parasites known as microfilariae that poses a significant public health concern in many tropical regions, including Southeast Asia, Africa, and South America. The traditional diagnostic approach for this disease involves manually examining thick blood smears under a microscope. However, these methods suffer from low diagnostic efficiency, cumbersome procedures, strong dependence on skilled technicians, and difficulties in implementation in remote or resource-poor areas, particularly when handling high sample volumes. To address these limitations, this paper proposes an automated detection approach for microfilariae in thick blood smears based on the YOLOv10 model. This method combines lightweight convolution structures, large kernel convolution, and improved feature fusion modules (such as BiFPN), thereby enhancing the model's accuracy and robustness in small object detection scenarios. We constructed a dataset conforming to the VOC format and trained and validated the YOLOv10 model. The test results show that on the test set, the model achieved an Accuracy of 84.8%, a Precision of 86.6%, a Recall of 97.6% and an F1-score of 0.918, with an average detection accuracy of mAP@0.5:0.95 of 66.7%. Furthermore, the model can still achieve high-confidence predictions for microfilariae targets in complex background images, demonstrating good robustness and generalization ability. It has been proven that this method can achieve rapid and stable detection of microfilariae and has good practical deployment value. This study provides a feasible solution for the intelligent diagnosis of parasitic diseases, which is particularly suitable for the large-scale screening needs of primary medical institutions or public health systems.

S. Sharip, A.H. Azil, N.H. Hassan and Z. Sharip https://doi.org/10.32802/asmscj.2023.1428

Dengue is a significant public health problem in Malaysia and vector surveillance is one of the important components in a vector control program. Routinely vector surveillance in Malaysia is performed through larval surveys. However, larval surveys have several limitations. Thus ovitraps are used as an alternative method for monitoring dengue vectors. The aim of this study was to determine the effectiveness of Standard Ovitrap (SO), Mosquito larvae Trapping Device (MLTD), Double Sticky Ovitrap (DST) and NPK Fertiliser Trap to monitor the abundance of Aedes mosquitoes. Each ovitrap was placed at four different sampling points and rotated to the next position every one week. Larvae and adult mosquitoes were collected and identified in the laboratory. All four trapping methods successfully collected larvae of Aedes mosquitoes. The mean number of larvae per ovitrap in DST was significantly higher (p < 0.05) compared to SO and MLTD. DST and NPK Fertiliser Trap were capable of capturing adult mosquitoes. Ovitrap Index and the mean number of adults per ovitrap in NPK Fertiliser trap were significantly higher (p < 0.05) as compared to DST. Another set of experiments were conducted to compare NPK Fertiliser traps containing fresh NPK fertiliser solution with those containing stock NPK Fertiliser solution. The fresh solution was prepared fresh while the stock solution was stored for a month before being used in the field. Result shows no significant differences (p > 0.05) between these solutions. Findings from this study conclude that DST is the most effective ovitrap to monitor Aedes larvae, while NPK Fertiliser trap is the most effective ovitrap to trap Aedes adult mosquitoes in the study area.

Wolbachia, a naturally endosymbiotic bacteria, has shown its potential as one of biological control agents for vector borne diseases. Due to large number of mosquitoes involved in Wolbachia screening, Loop-mediated isothermal amplification (LAMP) is recommended as a convenient and time-saving technique. This study aimed to evaluate a newly developed LAMP assay for detection of Wolbachia by targeting 16S rDNA gene in samples of wild mosquito populations. The LAMP products were confirmed by colorimetric detection using hydroxy naphthol blue (HNB), digestion with RsaI restriction enzyme and gel electrophoresis. The restriction enzyme digestion of PCR products was performed to differentiate between Wolbachia supergroups A and B. Out of 765 mosquito samples tested, 349 (45.6%) and 237 (31%) of the samples were positive for LAMP and PCR techniques respectively. The prevalence of Wolbachia detected in mosquitoes was significantly higher using LAMP as compared to PCR. There is significant association between numbers of mosquitoes positive with Wolbachia detected using LAMP and PCR (chi(2)=61.31; df=1; p < 0.05) with a kappa (kappa) value of 0.27 and Phi value, 0.283. This study highlighted the potential of LAMP as a sensitive, specific and rapid tool for screening of Wolbachia in mosquitoes, thus it presents as an alternative to PCR-based assays.

Permanent mounting of fourth instar mosquito larvae is essential for identifying Aedes spp. This procedure requires extensive exposure to xylene, a clearing agent in the mounting process. We investigated wintergreen oil as a substitute for xylene. Five hundred larvae were mounted on slides to evaluate shrinkage or expansion of specimens after clearing using xylene or wintergreen oil. We examined the ventral brush and siphonal hair tufts for species identification and for preservation of morphological characteristics after clearing specimens in xylene or wintergreen oil. Shrinkage of the length of whole larvae and width of the head, thorax and abdomen after mounting was significantly greater after clearing with xylene than with wintergreen oil. The length of the comb scale nearest the ventral brush was similar for both clearing agents. The clarity of the specimens after mounting was improved by clearing with wintergreen oil, but the integrity of the ventral brush and siphonal hair tufts were similar for both clearing agents.

SUMMARY We aimed to reparameterize and validate an existing dengue model, comprising an entomological component (CIMSiM) and a disease component (DENSiM) for application in Malaysia. With the model we aimed to measure the effect of importation rate on dengue incidence, and to determine the potential impact of moderate climate change (a 1 °C temperature increase) on dengue activity. Dengue models (comprising CIMSiM and DENSiM) were reparameterized for a simulated Malaysian village of 10 000 people, and validated against monthly dengue case data from the district of Petaling Jaya in the state of Selangor. Simulations were also performed for 2008-2012 for variable virus importation rates (ranging from 1 to 25 per week) and dengue incidence determined. Dengue incidence in the period 2010–2012 was modelled, twice, with observed daily weather and with a 1 °C increase, the latter to simulate moderate climate change. Strong concordance between simulated and observed monthly dengue cases was observed (up to r = 0·72). There was a linear relationship between importation and incidence. However, a doubling of dengue importation did not equate to a doubling of dengue activity. The largest individual dengue outbreak was observed with the lowest dengue importation rate. Moderate climate change resulted in an overall decrease in dengue activity over a 3-year period, linked to high human seroprevalence early on in the simulation. Our results suggest that moderate reductions in importation with control programmes may not reduce the frequency of large outbreaks. Moderate increases in temperature do not necessarily lead to greater dengue incidence.

This qualitative study aimed to describe field worker perceptions, evaluations of worth, and time costs of routine dengue vector surveillance methods in Cairns (Australia), Kuala Lumpur and Petaling District (Malaysia). In Cairns, the BG-Sentinel trap is a favored method for field workers because of its user-friendliness, but is not as cost-efficient as the sticky ovitrap. In Kuala Lumpur, the Mosquito Larvae Trapping Device is perceived as a solution for the inaccessibility of premises to larval surveys. Nonetheless, the larval survey method is retained in Malaysia for prompt detection of dengue vectors. For dengue vector surveillance to be successful, there needs to be not only technical, quantitative evaluations of method performance but also an appreciation of how amenable field workers are to using particular methods. Here, we report novel field worker perceptions of dengue vector surveillance methods in addition to time analysis for each method.

We investigated spatial autocorrelation of female Aedes aegypti L. mosquito abundance from BG-Sentinel trap and sticky ovitrap collections in Cairns, north Queensland, Australia. BG-Sentinel trap collections in 2010 show a significant spatial autocorrelation across the study site and over a smaller spatial extent, while sticky ovitrap collections only indicate a non-significant, weak spatial autocorrelation. The BG-Sentinel trap collections were suitable for spatial interpolation using ordinary kriging and cokriging techniques. The uses of Premise Condition Index and potential breeding container data have helped improve our prediction of vector abundance. Semiovariograms and prediction maps indicate that the spatial autocorrelation of mosquito abundance determined by BG-Sentinel traps extends farther compared to sticky ovitrap collections. Based on our data, fewer BG-Sentinel traps are required to represent vector abundance at a series of houses compared to sticky ovitraps. A lack of spatial structure was observed following vector control treatment in the area. This finding has implications for the design and costs of dengue vector surveillance programs.

Vector surveillance is a cornerstone of dengue management yet there is a diversity of surveillance programs evident internationally. Such diversity is described in this review to enable a broader assessment of dengue vector surveillance methods. This review describes the diversity of surveillance programs for dengue vectors in several endemic and epidemic countries. Furthermore, strengths and weaknesses of vector surveillance methods, including larval surveys, BG-Sentinel trap, and autocidal and sticky ovitraps, are also discussed. The ability to compare and contrast these programs could contribute to the finding of better methods both locally and nationally and facilitate interregional technology transfer. Health authorities in both endemic and epidemic countries alike could benefit from adopting technologies and practices from other regions.

To describe the meteorological influences on adult dengue vector abundance in Australia for the development of predictive models to trigger pre-emptive control operation. Multiple linear regression analyses were performed using meteorological data and female Aedes aegypti collection data from BG-Sentinel Mosquito traps placed at 11 monitoring sites in Cairns, north Queensland. Considerable regression coefficients (R(2) = 0.64 and 0.61) for longer- and shorter-term factor models respectively were derived. Longer-term factors significantly associated with abundance of adult vectors were mean minimum temperature (lagged 6 month) and mean daily temperature (lagged 4 month), explaining the predictable increase in abundance during the wet season. Factors explaining fluctuation in abundance in the shorter term were mean relative humidity over the previous 2 weeks and current daily average temperature. Rainfall variables were not found to be strong predictors of A. aegypti abundance in either longer- or shorter-term models. The implications of these findings for the development of useful predictive models for vector abundance risks are discussed. Such models can be used to guide the application of pre-emptive dengue vector control, and thereby enhance disease management.