Displaying publications 41 - 60 of 393 in total

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  1. Visceral larva migrans in Malaya. Report of a case
    Lee HF, Danaraj TJ
    Am J Trop Med Hyg, 1972 Mar;21(2):174-7.
    PMID: 5061275
  2. The effect of nitrogen supplementation on the efficiency of colour and COD removal by Malaysian white-rot fungi in textile dyeing effluent
    Lee KK, Kassim AM, Lee HK
    Water Sci Technol, 2004;50(5):73-7.
    PMID: 15497832
    White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.
  3. Fulltext Percutaneous dilational tracheostomy--a 3 year experience in a general hospital in Malaysia
    Tan CC, Lee HS, Balan S
    Med J Malaysia, 2004 Dec;59(5):591-7.
    PMID: 15889560
    All percutaneous tracheostomies performed in the general intensive care unit (ICU), Hospital Sultanah Aminah, Johor Bahru, Malaysia, from July 1999 to June 2002 were studied. The tracheostomies were performed as an elective bedside technique in the ICU. A total of 352 percutaneous tracheostomies were performed. Eighty-eight percent of the tracheostomies were completed within 15 minutes. The most common complication was bleeding which occurred in 52 patients (14.7%). The rest of the complications encountered were:- transient hypoxia twelve (3.4%), inability/ difficulty to insert tracheostomy tube eight (2.3%), false passage four (1.1%), transient hypotension two (0.6%), pneumothorax two (0.6%), peristomal infection two (0.6%), subcutaneous emphysema one (0.3%), cuff rupture one (0.3%), oesophageal cannulation one (0.3%), and granuloma formation one (0.3%). Conversion to conventional tracheostomies were performed on 7 patients (2%). There was one unfortunate death related to percutaneous tracheostomy. In conclusion, percutaneous dilational tracheostomy can be used safely to manage the airway of critically ill patients.
  4. Fulltext Acute appendicitis--the University Hospital experience
    Lee HY, Jayalakshmi P, Noori SH
    Med J Malaysia, 1993 Mar;48(1):17-27.
    PMID: 8341168
    A 1 year review of 529 cases of acute appendicitis, treated at the University Hospital in 1990, was performed. Perforation rate was 23.7% and delay in diagnosis was found to be significant. Patients above 50 years of age were particularly at risk. Diagnostic error was 19.3% and it was a problem not only in young women but also in children. Temperature and rectal examinations were not found to be helpful in the diagnosis in contrast to leukocytosis. Waiting time for operation was long (median 7 hours), be it for a perforated or a nonperforated appendicitis.
  5. Mechanical transport of rotavirus by the legs and wings of Musca domestica (Diptera: Muscidae)
    Tan SW, Yap KL, Lee HL
    J Med Entomol, 1997 Sep;34(5):527-31.
    PMID: 9379457
    Factors affecting the mechanical transmission of rotavirus by the legs and wings of the housefly, Musca domestica L., were examined in a laboratory study. Rotavirus was picked up when houseflies walked on thin smears of clarified rotavirus suspensions. The addition of glycerol, which increased viscosity of the virus suspension, and particulate human feces slightly increased the proportion of flies contaminated with virus. However, the addition of glycerol greatly reduced the average number of virus particles picked up per fly, whereas feces greatly increased the number of particles. The proportion of flies with virus-contaminated legs, which transferred virus to > 1 contact surface, was increased by longer contact time with the surface and when the contact surface was agar instead of glass. Most virus particles were deposited on 1st contact with the surface. Most flies dislodged virus particles inoculated on the underside of their wings soon after the start of simulated flight. Our data indicated that the nature of the virus-suspending medium has a greater effect on the level of virus contamination than on the ability to become contaminated. The importance of walking as a mode of virus transport depends on the nature of the contact surface, the risk of the contaminated fly settling first on a surface likely to come into contact with humans, and fly numbers.
  6. A novel insecticidal serotype of Clostridium bifermentans
    Seleena P, Lee HL, Lecadet MM
    J Am Mosq Control Assoc, 1997 Dec;13(4):395-7.
    PMID: 9474569
    A novel Clostridium bifermentans strain toxic to mosquito larvae on ingestion was isolated from a soil sample collected from secondary forest floor. This strain was designated as serovar paraiba (C. b. paraiba) according to its specific H antigen. Clostridium bifermentans paraiba is most toxic to Anopheles maculatus Theobald larvae (LC50 = 0.038 mg/liter), whereas toxicity to Aedes aegypti (Linn.) (LC50 = 0.74 mg/liter) and Culex quinquefasciatus Say (LC50 = 0.11 mg/liter) larvae was 20 and 3 times lower, respectively. The toxicity to An. maculatus larvae is as high as that of Bacillus thuringiensis serovar israelensis. C. b. paraiba was also found to exhibit significant per os insecticidal activity toward adult Musca domestica (Linn.).
  7. A new serovar of Bacillus thuringiensis possessing 28a28c flagellar antigenic structure: Bacillus thuringiensis serovar jegathesan, selectively toxic against mosquito larvae
    Seleena P, Lee HL, Lecadet MM
    J Am Mosq Control Assoc, 1995 Dec;11(4):471-3.
    PMID: 8825511
    A novel Bacillus thuringiensis strain highly toxic to mosquitoes was isolated from soil samples in Malaysia. This strain was shown to display a new subfraction of the H-28 flagellar antigen determining a new serovar H28a28c, which was designated serovar jegathesan. Bioassays indicated that Culex quinquefasciatus larvae are the most susceptible to this new isolate, whereas toxicity to Anopheles maculatus and Aedes aegypti larvae was 10 times lower. The potency of this new serotype is also comparable to most of the Malaysian B. thuringiensis H-14 isolates.
  8. Fulltext Insecticide resistance development in Aedes aegypti upon selection pressure with malathion
    Hidayati H, Nazni WA, Lee HL, Sofian-Azirun M
    Trop Biomed, 2011 Aug;28(2):425-37.
    PMID: 22041765
    Bioassay test against malathion had been carried out with larval and adult stages of Aedes aegypti. The mosquitoes were under selection pressure against malathion for forty-five consecutive generations. The rate of resistance development was measured by LC(50) and LT(50) values. The larvae and adult females, after subjection to malathion selection for 45 generations, developed high resistance level to malathion, with resistance ratio of 52.7 and 3.24 folds, respectively over control mosquitoes. Cross-resistance towards the same and different groups of insecticides was determined using the F44 and F45 malathion-selected adult females. Insecticides tested were DDT (4.0%), permethrin (0.75%), propoxur (0.1%), fenitrothion (1%), λ-cyhalothrin (0.05%) and cyfluthrin (0.15%). Results indicated that the mosquitoes were highly resistant to DDT and fenitrothion, moderately resistant to propoxur, tolerant to permethrin and λ-cyhalothrin, and very low resistant to cyfluthrin.
  9. Fulltext Detection of protozoan and bacterial pathogens of public health importance in faeces of Corvus spp. (large-billed crow)
    Lee HY, Stephen A, Sushela D, Mala M
    Trop Biomed, 2008 Aug;25(2):134-9.
    PMID: 18948884
    Parasites and bacteria are reported in the faeces of birds in the current study. Fresh faecal samples of the large-billed crow (Corvus spp.) were collected from the study site at Bangsar, an urban setting in Kuala Lumpur, Malaysia. These samples were transported to laboratory and analysed for parasites and bacteria. Pre-prepared XLD agar plates were used for culturing the bacteria in the laboratory. Using the API 20ETM Test Strips, 9 different species of bacteria were identified belonging to the family Enterobacteriacea. They were Citrobacter freundii, Enterobacter cloacae, Proteus mirabilis, Klebsiella pneumoniae, Kluyvera ascorbata, Salmonella arizonae, Salmonella typhi, Shigella flexneri and Shigella sonnei. The protozoan parasites detected include Cryptosporidium spp., Cyclospora spp., Blastocystis spp., and Capillaria hepatica and Ascaris lumbricoidus ova. Environmental air samples collected on agar plates using an air sampler in the area only produced fungal colonies. Some of these pathogens found in the crows are of zoonotic importance, especially Cryptosporidium, Blastocystis, Cyclopsora, Salmonella, Shigella and Kluyvera. The finding of Kluyvera spp. in crows in our current study highlights its zoonotic potential in an urban setting.
  10. Fulltext Wings of the common house fly (Musca domestica L.): importance in mechanical transmission of Vibrio cholerae
    Yap KL, Kalpana M, Lee HL
    Trop Biomed, 2008 Apr;25(1):1-8.
    PMID: 18600198
    The importance of house fly (Musca domestica L) wings in mechanical transmission of bacteria was studied. A droplet of phosphate-buffered saline containing Vibrio cholerae was rolled along one wing of each house fly. None adhered to the wings but small proportions of the bacterium were isolated from about half the wings. Vibrio cholerae was spread onto the ventral wing surfaces of each unconscious house fly which then was placed inside a bottle. When it regained consciousness, the types of activity it performed over five minutes were noted before the house fly was killed and the bacteria on its wings numerated. Control were house flies killed before inoculation. The proportion of house flies with bacteria on their wings and the mean number of bacteria remaining were significantly less on live house flies than killed controls. Among the live house flies, bacteria were detected on fewer house flies which flew (25%) than those which did not fly (81%). In addition, the mean number of bacteria on the former was significantly less than the latter (5 against 780 colonies). However, both these parameters were not significantly different between the group which performed and the group which did not perform wing grooming; takeoff and alighting over short distances, and somersaulting. Wings of unconscious house flies tethered by their thoraxes were inoculated with V. cholerae. After regaining consciousness, the house flies were allowed to move their wings in flight motions for up to 30 seconds. Small proportions of bacteria remained on all the house flies. House flies were placed in a chamber containing a liquid bait spiked with V. cholerae. After two hours, 10 were removed sequentially and cultured for V. cholerae. The bacterium was isolated from four house flies: two from the legs, and two others from their bodies minus legs and wings. In conclusion, house fly wings do not play an important role in mechanical transmission of bacteria suspended in a non-adhering liquid medium because of the low transfer rate of the bacteria to the wings and poor retention of bacteria on the wings during normal house fly activities.
  11. Fulltext Notes on some ectoparasites received by the Medical Entomology Unit, Institute for Medical Research
    Lee HL, Krishnasamy M, Jeffery J, Paramasvaran S
    Trop Biomed, 2006 Jun;23(1):131-2.
    PMID: 17041562 MyJurnal
    There were a spate of recent complaints of insect bites and the entomological specimens received from various sources were identified to be those of cat flea (Ctenocephalides felis) and rat flea (Xenopsylla cheopis), the tropical bed-bug (Cimex hemipterus) and the dog louse (Heterodoxus spiniger). Only the fleas and the bed-bug are known to attack humans.
  12. Fulltext Microalgae associated with Leptoconops breeding sites in selected sandy beaches of Malaysia
    Rohani A, Khadri MS, Lee HL
    Trop Biomed, 2006 Dec;23(2):164-71.
    PMID: 17322818 MyJurnal
    A study was carried out to investigate correlation between presence of specific microalgal species and Leptoconops biting midge larvae in its breeding habitats. Sand samples containing microalgae were collected from the beach where the midges were most commonly biting and from sand beaches which are potential as breeding habitats of Leptoconops. The survey covered sand beaches from 12 seperate islands. At all sites, the Bacillariophyta constituted the largest representatives of the microalgae community with the majority from the Naviculaceae family. A total of 24 microalgal species were identified from the sand samples collected from the study sites. Sand samples from Kentot Kecil Island had the highest number of algal species (11.0) and the highest algae species diversity ( Shanon-Weiner Diversity Index, H' = 0.884). Besar Island (Johor) had the lowest number of algal species (2.0) whereas Tengol A Island had the lowest algae species diversity (H'=0.234). Highest similarity index was recorded between sand samples collected from Tengol A Island and Tengol B Island (75.0%) followed by Besar Island (Melaka) and Tengol B Island (62.0 %). The variation between other islands were relatively high. Virtually many kinds of algae were found where Leptoconops were breeding but Fragilaria intermedia, Mastigloia minuta and Navicula advena were particularly common.
  13. Fulltext Review of forensically important entomological specimens in the period of 1972 - 2002
    Lee HL, Krishnasamy M, Abdullah AG, Jeffery J
    Trop Biomed, 2004 Dec;21(2):69-75.
    PMID: 16493401
    Forensic entomological specimens received by the Unit of Medical Entomology, IMR., from hospitals and the police in Malaysia in the last 3 decades (1972 - 2002) are reviewed. A total of 448 specimens were received. From these, 538 identifications were made with the following results: Eighteen species of cyclorrphaga flies were identified consisting of Chrysomya megacephala (Fabricius) 215 cases (47.99%), Ch. rufifacies (Masquart) 132 (29.46%), Ch. villeneuvi Patton 10 (2.23%), Ch. nigripes Aubertin 7 (1.56%), Ch. bezziana Villeneuve 4 (0.89%), Ch. pinguis (Walker) 1 (0.22%), Chrysomya sp. 47 (10.49%), Sarcophaga sp. 28 (6.25%), Lucilia sp. 21 (4.69%), Hermetia sp. 15 (3.35%), He. illucens (Linnaeus) 1 (0.22%), Hemipyrellia ligurriens (Wiedemann) 3 (0.67%), Hemipyrellia sp. 2 (0.45%), Ophyra spinigera 1 (0.22%), Ophyra sp. 6 (1.34%), Calliphora sp. 24 (5.36%), Synthesiomyia nudiseta (Wulp) 1 (0.22%) and Eristalis sp. 1 (0.22%). Other non - fly insect specimens are Pthirus pubis (Linnaeus) (Pubic louse) 2 (0.45%) and Coleoptera (Beetles) 1 (0.22%). Ch. megacephala and Ch. rufifacies were the commonest species found in cadavers from different ecological habitats. Sy. nudiseta is an uncommon species, thus far found only on cadavers from indoors. Sy. nudiseta is reported for the second time in Peninsular Malaysia. A total of 329 cases (73.44%) had a single fly infestation, 109 cases (24.33%) had double fly infestation and 10 cases (2.23%) had triple fly infestation. Five cases (1.12%) had eggs and 3 cases (0.67%) had larval stages that were not identifiable. No arthropods were retrieved from cadavers in 8 cases (1.79%). In conclusion, although large number of fly species were found on human cadavers, the predominant species are still those of Chrysomya.
  14. Fulltext Adult and larval insecticide susceptibility status of Culex quinquefasciatus (Say) mosquitoes in Kuala Lumpur Malaysia
    Nazni WA, Lee HL, Azahari AH
    Trop Biomed, 2005 Jun;22(1):63-8.
    PMID: 16880755 MyJurnal
    The susceptibility of Culex quinquefasciatus to chemical insecticides in two field sites in Kuala Lumpur was evaluated using the WHO standard susceptibility test. Less then 7 days old female mosquitos, reared from wild caught females were exposed to discriminating dosages of insecticides at recommended exposure periods. The larval bioassay were conducted using the multiple concentrations and the LC50 value was determined. The results indicated that cyfluthrin is the most effective among all the insecticides tested with LT50 value of 29.95 min and 28.59 min, for the strain from Ampang Hill and Pantai Dalam, respectively. It was surprisingly to note that both these field strains showed 0% mortality when tested against malathion and DDT. The LC50 value indicated that both strains were highly resistant to malathion with resistance ratio of 17,988 folds and 14,053 folds, respectively. This concludes that resistance at larval stages is extremely high compared to adult stages.
  15. Fulltext Rapid detection of chikungunya virus in laboratory infected Aedes aegypti by Reverse-Transcriptase- Polymerase Chain Reaction (RT-PCR)
    Rohani A, Yulfi H, Zamree I, Lee HL
    Trop Biomed, 2005 Dec;22(2):149-54.
    PMID: 16883281 MyJurnal
    A study of chikungunya virus was carried out to establish Reverse Transcriptase- Polymerase Chain Reaction (RT-PCR) as a rapid detection technique of the virus. The susceptibility of lab-colonized Aedes aegypti to chikungunya virus was also determined. Artificial membrane feeding technique was used to orally feed the mosquitoes with a human isolate of chikungunya virus. A total of 100 fully engorged female Ae. aegypti were obtained and maintained for 7 days. Seventy of them survived and then pooled at 10 individuals per pool. Total RNA was extracted from the samples and RT-PCR amplifications were carried out. Five out of 7 pools showed positive PCR band at 350-bp, indicating Ae. aegypti is a potential vector of chikungunya virus. The minimum infection rate (MIR) was 71% within these laboratory colonies. RT-PCR is a sensitive technique that is useful in detecting infected mosquitoes in epidemic areas. This technique can de used as a rapid detection method and provide an early virologic surveillance systems of chikungunya virus infected mosquitoes.
  16. Fulltext Field bioefficacy of deltamethrin residual spraying against dengue vectors
    Rozilawati H, Lee HL, Mohd Masri S, Mohd Noor I, Rosman S
    Trop Biomed, 2005 Dec;22(2):143-8.
    PMID: 16883280 MyJurnal
    Field bioefficacy of residual-sprayed deltamethrin against Aedes vectors was evaluated in an urban residential area in Kuala Lumpur. The trial area consisted of single storey wood-brick houses and a block of flat. The houses were treated with outdoor residual spraying while the flat was used as an untreated control. Initial pre-survey using ovitrap surveillance indicated high Aedes population in the area. Deltamethrin WG was sprayed at a dosage of 25mg/m2 using a compression sprayer. The effectiveness of deltamethrin was determined by wall bioassay and ovitrap surveillance. The residual activity of 25mg/m2 deltamethrin was still effective for 6 weeks after treatment, based on biweekly bioassay results. Bioassay also indicated that both Aedes aegypti and Aedes albopictus were more susceptible on the wooden surfaces than on brick. Aedes aegypti was more susceptible than Ae. albopictus against deltamethrin. Residual spraying of deltamethrin was not very effective against Aedes in this study since the Aedes population in the study area did not reduce as indicated by the total number of larvae collected using the ovitrap (Wilcoxon Sign Test, p> 0.05). Further studies are required to improve the effectiveness of residual spraying against Aedes vectors.
  17. Prevalence of elevated body mass index condition and its associated demographic variables among adults in urban areas in Johor, Malaysia
    Rozita Z, Lim MT, Lee HS
    Med J Malaysia, 2019 04;74(2):145-150.
    PMID: 31079126
    INTRODUCTION: The prevalence of overweight and obesity is increasing at an alarming rate. It is a major factor for many other metabolic disorders. This study aimed to determine the prevalence of increase body mass index (BMI) and obesity and their associated demographic characteristics among adults in an urban area.

    METHODS: A retrospective study was conducted where data was extracted from the Health Status Screening Form (BSSK) at health clinics in Johor Bahru. Using the World Health Organization (WHO), criteria for obesity, BMI≥30.0 kg/m2 was specified as obese and combination of both BMI ranges for overweight (25.0-30.0kg/m2) and obesity (≥30.0kg/m2) as elevated BMI.

    RESULTS: The overall prevalence of elevated BMI and obesity was 54.6% and 20.1% respectively. Men had a higher prevalence of elevated BMI (57.4%) with odds of 1.28 higher (95%CI: 1.04-1.58). High prevalence of elevated BMI and obesity were seen among the Indians (elevated BMI - 60.2%, obesity - 19.4%) followed by Malays (elevated BMI -57.8%, obesity - 23.1%) and Chinese showed the lowest (elevated BMI - 39.0%, obesity - 8.8%). The odds of elevated BMI and obesity were lower among younger adults as compared to older adults (≥30 years old).

    CONCLUSION: Using WHO criteria, about one in two adults had elevated BMI while one in five were obese. Elevated BMI and obesity disparities were evident in age and ethnicity, but sex differences were encountered in elevated BMI group.

  18. Hemorrhagic fever with renal syndrome: report of a case in Malaysia
    Lim TW, Mangalam S, Lee HW
    J Infect Dis, 1987 Dec;156(6):1035-6.
    PMID: 2890691
  19. Thermal application of Bacillus thuringiensis serovar israelensis for dengue vector control
    Seleena P, Lee HL, Chiang YF
    J Vector Ecol, 2001 Jun;26(1):110-3.
    PMID: 11469179
  20. Compatibility of Bacillus thuringiensis serovar israelensis and chemical insecticides for the control of Aedes mosquitoes
    Seleena P, Lee HL, Chiang YF
    J Vector Ecol, 1999 Dec;24(2):216-23.
    PMID: 10672551
    The compatibility of the commercial aqueous Bacillus thuringiensis serovar israelensis (B.t.i.) formulation, Vectobac 12AS, with the chemical insecticides Actellic 50EC, Aqua Resigen, Resigen, and Fendona SC, for the simultaneous control of Aedes larvae and adults was studied by dispersing nine different formulations using a portable mist blower, in single story half-brick houses. The effectiveness of the treatment was evaluated by measuring the larval mortality, adult mortality, and droplet analysis at varying distances from the sprayer. Persistence of the larvicidal activity of the chemical insecticides and B.t.i was also determined by measuring the larval mortality in the test samples 7 days posttreatment. The sprayed particles in all the trials were 50-60 microns in size, indicating that the particles were those of mist spray. Test samples placed within 3 m from the sprayer gave the maximum larval and adult mortality. Chemical insecticides exhibited maximum larval mortality in the 1 h posttreatment test samples and it was comparable to the larvicidal activity of B.t.i. The larvicidal toxins of B.t.i were more stable and were able to affect sufficient larval mortality for 7 days posttreatment. The larvicidal activity of the mixtures, i.e., chemical insecticides with B.t.i, in the 1 h posttreatment test samples was not significantly different from the larvicidal activity of the chemical insecticides and it was comparable to the larvicidal activity of B.t.i alone. However, the larvicidal activity of the mixtures was significantly more than the chemical insecticides alone in the 7 days posttreatment test samples except for the Actellic 50EC and Vectobac 12AS mixture. In all the trials, with or without B.t.i, there was no significant difference in adult mortality, indicating that this B.t.i formulation, Vectobac 12AS, was not antagonistic to the adulticidal activity of the chemical insecticides. From this study, it can be concluded that chemical insecticides can be used effectively for both adult and larval control, but the chemical insecticides do not exhibit residual larvicidal activity. Hence, for an effective control of both Aedes larvae and adults, it is advisable to add B.t.i. to the chemical insecticides, as B.t.i is specifically larvicidal and is also able to effect extended residual larvicidal activity.
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