Displaying publications 161 - 173 of 173 in total

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  1. Arham AF, Amin L, Mustapa MAC, Mahadi Z, Yaacob M, Ibrahim M
    PLoS Negl Trop Dis, 2021 Jun;15(6):e0009493.
    PMID: 34185785 DOI: 10.1371/journal.pntd.0009493
    Outdoor Residual Spraying (ORS) technique is a complementary preventive measure for dengue. The alarming number of dengue cases in Malaysia requires an alternative method to control dengue besides the traditional method such as fogging. However, the introduction of new technologies depends on social acceptance. Therefore, this study was important to determine the factors that influence stakeholders' attitudes towards the ORS and the moderating factor. A validated instrument was used to randomly interview 399 respondents representing two stakeholder groups which consist of scientists, and the public in Klang Valley, Malaysia. The findings revealed that the stakeholders claimed to have a high degree of religiosity, a high level of trust in the key players, perceived ORS as having high benefits, and displayed highly positive attitudes towards the ORS. The attitudes model towards the ORS model was developed using the SmartPLS software version. The perceived benefit was endorsed as the most important direct predictor of attitudes towards the ORS (ß = 0.618, P<0.001), followed by trust in the key players (ß = 0.151, P<0.001). It is also interesting to note that religiosity served as a moderator for the association between perceived benefit (ß = 0.075, P = 0.024) and perceived risk (ß = 0.114, P = 0.006) with attitudes towards the ORS. The identified predictor factors of stakeholders' attitudes toward the ORS and the moderating factor can serve as indicators for social acceptance of ORS in developing countries. These indicators can help the policymakers in decision making to implement this technique.
  2. Ismail AK, Abd Hamid MNH, Ariff NA, Frederic Ng VER, Goh WC, Abdul Samat NS, et al.
    PLoS Negl Trop Dis, 2023 Jan;17(1):e0010983.
    PMID: 36598885 DOI: 10.1371/journal.pntd.0010983
    Pit vipers from the genus Tropidolaemus are identified as one of the common causes of snake bite from venomous species in Malaysia. All Tropidolaemus species bite cases referred to the Remote Envenomation Consultation Services (RECS) between 2015-2021 were included. A total of 4,718 snake-related injuries cases consulted to RECS with 310 (6.6%) involved Tropidolaemus species; of these 190 (61.3%) were T. subannulatus and 120 (38.7%) T. wagleri. All the T. subannulatus cases occurred in Sabah and Sarawak while all cases of T. wagleri occurred in Peninsular Malaysia. The majority of patients were male (74.8%) and adults between 18-59 years old (61.2%). The upper limb (56.6%) was the most frequent anatomical region involved. Most cases were non-occupationally related (75.4%). Bites from both species caused local pain (77.1%) and swelling (27.2%). Most patients complained of mild pain (48.0%). Paracetamol (40.0%) was the most common analgesic prescribed. Antivenom was not indicated in all cases. Two patients were given antivenom inappropriately before RECS consultation. Most patients (54.7%) needed hospital observation for less than 24 hours. No deaths occurred in the group studied.
  3. Shepard DS, Undurraga EA, Halasa YA
    PLoS Negl Trop Dis, 2013;7(2):e2055.
    PMID: 23437406 DOI: 10.1371/journal.pntd.0002055
    BACKGROUND: Dengue poses a substantial economic and disease burden in Southeast Asia (SEA). Quantifying this burden is critical to set policy priorities and disease-control strategies.

    METHODS AND FINDINGS: We estimated the economic and disease burden of dengue in 12 countries in SEA: Bhutan, Brunei, Cambodia, East-Timor, Indonesia, Laos, Malaysia, Myanmar, Philippines, Singapore, Thailand, and Viet Nam. We obtained reported cases from multiple sources--surveillance data, World Health Organization (WHO), and published studies--and adjusted for underreporting using expansion factors from previous literature. We obtained unit costs per episode through a systematic literature review, and completed missing data using linear regressions. We excluded costs such as prevention and vector control, and long-term sequelae of dengue. Over the decade of 2001-2010, we obtained an annual average of 2.9 million (m) dengue episodes and 5,906 deaths. The annual economic burden (with 95% certainty levels) was US$950m (US$610m-US$1,384m) or about US$1.65 (US$1.06-US$2.41) per capita. The annual number of disability-adjusted life years (DALYs), based on the original 1994 definition, was 214,000 (120,000-299,000), which is equivalent to 372 (210-520) DALYs per million inhabitants.

    CONCLUSION: Dengue poses a substantial economic and disease burden in SEA with a DALY burden per million inhabitants in the region. This burden is higher than that of 17 other conditions, including Japanese encephalitis, upper respiratory infections, and hepatitis B.

  4. Perumal Samy R, Stiles BG, Sethi G, Lim LHK
    PLoS Negl Trop Dis, 2017 May;11(5):e0004738.
    PMID: 28493905 DOI: 10.1371/journal.pntd.0004738
    This review briefly summarizes the geographical distribution and clinical impact of melioidosis, especially in the tropics. Burkholderia pseudomallei (a gram-negative bacterium) is the major causative agent for melioidosis, which is prevalent in Singapore, Malaysia, Thailand, Vietnam, and Northern Australia. Melioidosis patients are increasingly being recognized in other parts of the world. The bacteria are intrinsically resistant to many antimicrobial agents, but prolonged treatment, especially with combinations of antibiotics, may be effective. Despite therapy, the overall case fatality rate of septicemia in melioidosis remains significantly high. Intracellular survival of the bacteria within macrophages may progress to chronic infections, and about 10% of patients suffer relapses. In the coming decades, melioidosis will increasingly afflict travelers throughout many global regions. Clinicians managing travelers returning from the subtropics or tropics with severe pneumonia or septicemia should consider acute melioidosis as a differential diagnosis. Patients with open skin wounds, diabetes, or chronic renal disease are at higher risk for melioidosis and should avoid direct contact with soil and standing water in endemic regions. Furthermore, there are fears that B. pseudomallei may be used as a biological weapon. Technological advancements in molecular diagnostics and antibiotic therapy are improving the disease outcomes in endemic areas throughout Asia. Research and development efforts on vaccine candidates against melioidosis are ongoing.
  5. Rasli R, Cheong YL, Che Ibrahim MK, Farahininajua Fikri SF, Norzali RN, Nazarudin NA, et al.
    PLoS Negl Trop Dis, 2021 Mar;15(3):e0009205.
    PMID: 33755661 DOI: 10.1371/journal.pntd.0009205
    BACKGROUND: In Malaysia, dengue remains a top priority disease and usage of insecticides is the main method for dengue vector control. Limited baseline insecticide resistance data in dengue hotspots has prompted us to conduct this study. The present study reports the use of a map on the insecticide susceptibility status of Aedes aegypti and Aedes albopictus to provide a quick visualization and overview of the distribution of insecticide resistance.

    METHOD AND RESULTS: The insecticide resistance status of Aedes populations collected from 24 dengue hotspot areas from the period of December 2018 until June 2019 was proactively monitored using the World Health Organization standard protocol for adult and larval susceptibility testing was conducted, together with elucidation of the mechanisms involved in observed resistance. For resistance monitoring, susceptibility to three adulticides (permethrin, deltamethrin, and malathion) was tested, as well as susceptibility to the larvicide, temephos. Data showed significant resistance to both deltamethrin and permethrin (pyrethroid insecticides), and to malathion (organophosphate insecticide) in all sampled Aedes aegypti populations, while variable resistance patterns were found in the sampled Aedes albopictus populations. Temephos resistance was observed when larvae were tested using the diagnostic dosage of 0.012mg/L but not at the operational dosage of 1mg/L for both species.

    CONCLUSION: The present study highlights evidence of a potential threat to the effectiveness of insecticides currently used in dengue vector control, and the urgent requirement for insecticide resistance management to be integrated into the National Dengue Control Program.

  6. Tobin RJ, Harrison LE, Tully MK, Lubis IND, Noviyanti R, Anstey NM, et al.
    PLoS Negl Trop Dis, 2024 Jan;18(1):e0011570.
    PMID: 38252650 DOI: 10.1371/journal.pntd.0011570
    BACKGROUND: Plasmodium knowlesi is a zoonotic parasite that causes malaria in humans. The pathogen has a natural host reservoir in certain macaque species and is transmitted to humans via mosquitoes of the Anopheles Leucosphyrus Group. The risk of human P. knowlesi infection varies across Southeast Asia and is dependent upon environmental factors. Understanding this geographic variation in risk is important both for enabling appropriate diagnosis and treatment of the disease and for improving the planning and evaluation of malaria elimination. However, the data available on P. knowlesi occurrence are biased towards regions with greater surveillance and sampling effort. Predicting the spatial variation in risk of P. knowlesi malaria requires methods that can both incorporate environmental risk factors and account for spatial bias in detection.

    METHODS & RESULTS: We extend and apply an environmental niche modelling framework as implemented by a previous mapping study of P. knowlesi transmission risk which included data up to 2015. We reviewed the literature from October 2015 through to March 2020 and identified 264 new records of P. knowlesi, with a total of 524 occurrences included in the current study following consolidation with the 2015 study. The modelling framework used in the 2015 study was extended, with changes including the addition of new covariates to capture the effect of deforestation and urbanisation on P. knowlesi transmission.

    DISCUSSION: Our map of P. knowlesi relative transmission suitability estimates that the risk posed by the pathogen is highest in Malaysia and Indonesia, with localised areas of high risk also predicted in the Greater Mekong Subregion, The Philippines and Northeast India. These results highlight areas of priority for P. knowlesi surveillance and prospective sampling to address the challenge the disease poses to malaria elimination planning.

  7. Idrus NL, Md Jamal S, Abu Bakar A, Embong H, Ahmad NS
    PLoS Negl Trop Dis, 2023 Dec;17(12):e0011839.
    PMID: 38113250 DOI: 10.1371/journal.pntd.0011839
    BACKGROUND: The timely identification of severe dengue in peadiatric patients is of utmost importance, as any delay in diagnosis could lead to an irreversible state of shock potentially leading to fatal consequences. The primary aim of our study was to characterize dengue severity in paediatric patients based on initial symptoms, signs, and laboratory investigation of their presentation in the emergency department.

    METHODOLOGY: We conducted a retrospective data retrieval from the medical records of 254 paediatric patients who had been diagnosed with confirmed cases of dengue fever. The clinical characteristics were compared between severe and non-severe dengue. Multiple logistic regression analysis was utilised to elucidate the variables that exhibited associations with severe dengue.

    RESULTS: A total of 254 paediatric patients were included, among whom 15.4% (n = 39) were diagnosed with severe dengue. Multiple logistic regression analysis identified lethargy, systolic blood pressure (SBP) below 90 mmHg, capillary refilled time (CRT) longer than 2 seconds, ascites, and hepatomegaly were independently associated with severe dengue.

    CONCLUSION: In paediatric patients, severe dengue is associated with specific clinical indicators, including lethargy, low systolic blood pressure, prolonged capillary refill time (CRT), and the presence of ascites and hepatomegaly. Identifying these clinical features early is crucial for primary care physicians, as it enables accurate diagnosis and timely intervention to manage severe dengue effectively.

  8. Tan AF, Sakam SSB, Piera K, Rajahram GS, William T, Barber BE, et al.
    PLoS Negl Trop Dis, 2024 Aug;18(8):e0012424.
    PMID: 39150978 DOI: 10.1371/journal.pntd.0012424
    The risk of severe malaria from the zoonotic parasite Plasmodium knowlesi approximates that from P. falciparum. In severe falciparum malaria, neutrophil activation contributes to inflammatory pathogenesis, including acute lung injury (ALI). The role of neutrophil activation in the pathogenesis of severe knowlesi malaria has not been examined. We evaluated 213 patients with P. knowlesi mono-infection (138 non-severe, 75 severe) and 49 Plasmodium-negative controls from Malaysia. Markers of neutrophil activation (soluble neutrophil elastase [NE], citrullinated histone [CitH3] and circulating neutrophil extracellular traps [NETs]) were quantified in peripheral blood by microscopy and immunoassays. Findings were correlated with malaria severity, ALI clinical criteria, biomarkers of parasite biomass, haemolysis, and endothelial activation. Neutrophil activation increased with disease severity, with median levels higher in severe than non-severe malaria and controls for NE (380[IQR:210-930]ng/mL, 236[139-448]ng/mL, 218[134-307]ng/mL, respectively) and CitH3 (8.72[IQR:3.0-23.1]ng/mL, 4.29[1.46-9.49]ng/mL, 1.53[0.6-2.59]ng/mL, respectively)[all p<0.01]. NETs were higher in severe malaria compared to controls (126/μL[IQR:49-323] vs 51[20-75]/μL, p<0.001). In non-severe malaria, neutrophil activation fell significantly upon discharge from hospital (p<0.03). In severe disease, NETs, NE, and CitH3 were correlated with parasitaemia, cell-free haemoglobin and angiopoietin-2 (all Pearson's r>0.24, p<0.05). Plasma NE and angiopoietin-2 were higher in knowlesi patients with ALI than those without (p<0.008); neutrophilia was associated with an increased risk of ALI (aOR 3.27, p<0.01). In conclusion, neutrophil activation is increased in ALI and in proportion to disease severity in knowlesi malaria, is associated with endothelial activation, and may contribute to disease pathogenesis. Trials of adjunctive therapies to regulate neutrophil activation are warranted in severe knowlesi malaria.
  9. Wang Y, Li C, Zhao S, Wei Y, Li K, Jiang X, et al.
    PLoS Negl Trop Dis, 2024 Apr;18(4):e0012158.
    PMID: 38683870 DOI: 10.1371/journal.pntd.0012158
    Vector-borne infectious disease such as dengue fever (DF) has spread rapidly due to more suitable living environments. Considering the limited studies investigating the disease spread under climate change in South and Southeast Asia, this study aimed to project the DF transmission potential in 30 locations across four South and Southeast Asian countries. In this study, weekly DF incidence data, daily mean temperature, and rainfall data in 30 locations in Singapore, Sri Lanka, Malaysia, and Thailand from 2012 to 2020 were collected. The effects of temperature and rainfall on the time-varying reproduction number (Rt) of DF transmission were examined using generalized additive models. Projections of location-specific Rt from 2030s to 2090s were determined using projected temperature and rainfall under three Shared Socioeconomic Pathways (SSP126, SSP245, and SSP585), and the peak DF transmissibility and epidemic duration in the future were estimated. According to the results, the projected changes in the peak Rt and epidemic duration varied across locations, and the most significant change was observed under middle-to-high greenhouse gas emission scenarios. Under SSP585, the country-specific peak Rt was projected to decrease from 1.63 (95% confidence interval: 1.39-1.91), 2.60 (1.89-3.57), and 1.41 (1.22-1.64) in 2030s to 1.22 (0.98-1.51), 2.09 (1.26-3.47), and 1.37 (0.83-2.27) in 2090s in Singapore, Thailand, and Malaysia, respectively. Yet, the peak Rt in Sri Lanka changed slightly from 2030s to 2090s under SSP585. The epidemic duration in Singapore and Malaysia was projected to decline under SSP585. In conclusion, the change of peak DF transmission potential and disease outbreak duration would vary across locations, particularly under middle-to-high greenhouse gas emission scenarios. Interventions should be considered to slow down global warming as well as the potential increase in DF transmissibility in some locations of South and Southeast Asia.
  10. Al-Mekhlafi HM, Al-Maktari MT, Jani R, Ahmed A, Anuar TS, Moktar N, et al.
    PLoS Negl Trop Dis, 2013;7(10):e2516.
    PMID: 24205426 DOI: 10.1371/journal.pntd.0002516
    Giardia duodenalis infection and malnutrition are still considered as public health problems in many developing countries especially among children in rural communities. This study was carried out among Aboriginal (Orang Asli) primary schoolchildren in rural peninsular Malaysia to investigate the burden and the effects of Giardia infection on growth (weight and height) of the children.
  11. Tay ST, Mohamed Zan HA, Lim YA, Ngui R
    PLoS Negl Trop Dis, 2013;7(8):e2341.
    PMID: 23936576 DOI: 10.1371/journal.pntd.0002341
    BACKGROUND: Limited data is available on the current status of scrub typhus infection in the aboriginal population in Malaysia. This study was aimed to provide recent data on the degree of exposure of 280 individuals from seven aboriginal subgroups to Orientia tsutsugamushi (causative agent of scrub typhus) in West Malaysia. The environment, socioeconomic and behavioural risk factors associated with the disease were also investigated.

    METHODS/FINDINGS: The antibody prevalence to O. tsutsugamushi ranged from 0 to 36.4% in seven subgroups, with high prevalence rates noted in subgroups involved in agricultural activity and the lowest prevalence rates noted in subgroups whose main occupations were associated to fishing. Univariate analysis indicated populations with age above 18 years (OR = 1.15, 95% CI = 1.02-1.30, P = 0.015), working (OR = 1.99, 95% CI = 1.01-3.92, P = 0.044), working at agriculture area (OR = 1.18, 95% CI = 0.98-1.42, P = 0.031), receiving household income less than US$ 166.7 (RM500) per month (OR = 2.43, 95% CI = 1.16-5.11, P = 0.016) and having close contact with animal pets (OR = 4.06, 95% CI = 1.20-13.76, P = 0.016) are significantly associated with exposure to O. tsutsugamushi. Multivariate analysis confirms that participants who are above 18 years old, receiving household income less than US$ 166.7 (RM500) per month and having close contact with animal pets are 3.6 times (95% CI = 1.81-7.03, P<0.001), 1.3 times (95% CI = 1.14-1.64, P = 0.002) and 1.2 times (95% CI = 1.05-1.06, P = 0.006) more likely to have exposure to O. tsutsugamushi, respectively.

    CONCLUSION: The present study indicates that scrub typhus is still an important disease in the aboriginal population in Malaysia. Awareness about the disease and education on the preventive measures are important in reducing the risk of acquiring scrub typhus in the population studied.

  12. Gyamfi E, Delvallez G, Cheng S, Meng S, Oeurn K, Sam C, et al.
    PLoS Negl Trop Dis, 2024 Nov;18(11):e0012652.
    PMID: 39541393 DOI: 10.1371/journal.pntd.0012652
    Melioidosis is a neglected tropical disease caused by Burkholderia pseudomallei, endemic to Southeast Asia and Northern Australia. Despite its increasing global public health and clinical significance, the molecular epidemiology of melioidosis and genetic diversity of B. pseudomallei in Cambodia remains poorly understood. This study aims to elucidate the genetic diversity and antibiotic susceptibility profiles of B. pseudomallei isolates responsible for melioidosis in humans. For this purpose, 14 clinical isolates cryopreserved at the Medical Biology Laboratory at Institut Pasteur du Cambodge from 2016 to 2020 were subjected to antimicrobial susceptibility testing and Multilocus Sequence Typing (MLST). Phenotypic testing revealed that 92.86% (13/14) of the isolates were sensitive to all tested antibiotics, while one isolate exhibited resistance to trimethoprim-sulfamethoxazole. MLST analysis resolved our isolates into 14 unique Sequence Types (STs), including 10 previously documented in Southeast Asia. Notably, ST1858, ST2064, ST2065, and ST2066 were identified as novel STs, while ST54, ST99, ST211, and ST1359 were reported in Cambodia for the first time in this study. Comparing our MLST data with available sequences on PubMLST (n = 165), our study unveiled a high genetic diversity of B. pseudomallei in Cambodia. The identified STs were closely associated with isolates from other Southeast Asian countries, particularly Thailand, Vietnam, and Malaysia. In conclusion, this study provided insight into the genetic diversity among B. pseudomallei clinical isolates in Cambodia and their close genetic association with Southeast Asian isolates. To further our understanding, a One Health approach, incorporating human, environmental (mainly soil), and animal compartments, is essential to decipher the epidemiology of B. pseudomallei in Cambodia.
  13. Li B, Zhai JQ, Wu YJ, Shan F, Zou JJ, Hou FH, et al.
    PLoS Negl Trop Dis, 2024 Nov;18(11):e0012667.
    PMID: 39576834 DOI: 10.1371/journal.pntd.0012667
    The traditional concept of "tonic food" and demand for traditional Chinese medicine make pangolins the largest population of illegally smuggled mammals in the world. Illegal hunting and trade are not only responsible for the sharp decline in pangolin populations but also provide conditions for pathogenic transmission. In 2021, we rescued 21 confiscated unhealthy Malayan pangolins, none of which survived. This study aimed to investigate the reasons for their unexpected deaths and the potential pathogens that may be transmitted during smuggling. Physical examination found that more than 80% pangolins were parasitized with A. javanense ticks. Autopsy and pathological staining analysis revealed multiple organ damage in the deceased pangolins. Pathogens nucleic acid detection of 33 tick samples showed that the positive rate of Rickettsia spp., Anaplasma spp., Ehrlichia spp. Babesia spp., and Colpodella spp. were 90.91%, 6.06%, 6.06%, 15.15% and 18.18%, respectively. Furthermore, pangolin samples were positive for Rickettsia spp. (42.86%, 9/21), Ehrlichia sp. (4.76%, 1/21), and Babesia sp. (4.76%, 1/21). This study confirmed that spotted fever triggered by Rickettsia spp. from A. javanense might accelerate the most death of confiscated pangolins, while Ehrlichia sp., and Babesia sp. infection potentially accelerating a few deaths. Of note, A. javanense ticks carrying Colpodella spp. were detected for the first time in Malayan pangolins. However, whether Colpodella spp. are pathogenic to pangolins is unknown. Further research on the diagnosis, treatment, surveillance, and elimination of ticks and tick-borne diseases in humans, livestock, and wildlife should provide insight into wildlife conservation and zoonotic disease prevention.
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