Displaying publications 41 - 60 of 373 in total

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  1. Observations on delayed mating and post-coital impotence of spermatozoa in Aedes albopitus (Skuse) (Diptera : Culicidae)
    Chellappah WT
    Med J Malaysia, 1964 Sep;19:60-1.
    PMID: 14244223
    Matched MeSH terms: Culicidae*
  2. Fulltext The interplay of climate, intervention and imported cases as determinants of the 2014 dengue outbreak in Guangzhou
    Cheng Q, Jing Q, Spear RC, Marshall JM, Yang Z, Gong P
    PLoS Negl Trop Dis, 2017 Jun;11(6):e0005701.
    PMID: 28640895 DOI: 10.1371/journal.pntd.0005701
    Dengue is a fast spreading mosquito-borne disease that affects more than half of the population worldwide. An unprecedented outbreak happened in Guangzhou, China in 2014, which contributed 52 percent of all dengue cases that occurred in mainland China between 1990 and 2015. Our previous analysis, based on a deterministic model, concluded that the early timing of the first imported case that triggered local transmission and the excessive rainfall thereafter were the most important determinants of the large final epidemic size in 2014. However, the deterministic model did not allow us to explore the driving force of the early local transmission. Here, we expand the model to include stochastic elements and calculate the successful invasion rate of cases that entered Guangzhou at different times under different climate and intervention scenarios. The conclusion is that the higher number of imported cases in May and June was responsible for the early outbreak instead of climate. Although the excessive rainfall in 2014 did increase the success rate, this effect was offset by the low initial water level caused by interventions in late 2013. The success rate is strongly dependent on mosquito abundance during the recovery period of the imported case, since the first step of a successful invasion is infecting at least one local mosquito. The average final epidemic size of successful invasion decreases exponentially with introduction time, which means if an imported case in early summer initiates the infection process, the final number infected can be extremely large. Therefore, dengue outbreaks occurring in Thailand, Singapore, Malaysia and Vietnam in early summer merit greater attention, since the travel volumes between Guangzhou and these countries are large. As the climate changes, destroying mosquito breeding sites in Guangzhou can mitigate the detrimental effects of the probable increase in rainfall in spring and summer.
    Matched MeSH terms: Culicidae/virology
  3. Mosquito fauna of the Bengkoka Peninsula, Sabah, Malaysia
    Cheong WH, Loong KP, Mahadevan S, Mak JW, Kan SK
    Southeast Asian J. Trop. Med. Public Health, 1984 Mar;15(1):19-26.
    PMID: 6146203
    A total of 37 species of mosquitoes from seven genera were collected in six villages in the Bengkoka Peninsula, Sabah State, during two visits in 1981 in connection with studies on malaria and filariasis. Fifty-five per cent of the total mosquitoes collected were Mansonia. An. collessi constituted a new record of the species from Sabah. An. balabacensis was found to be naturally infected with sporozoites. Ma. bonneae was found to be naturally infected with Brugia, probably B. malayi. Parous rates of An. balabacensis and Ma. bonneae were very high with consequent high probability of survival ideally suiting transmission of malaria and filariasis.
    Matched MeSH terms: Culicidae/microbiology*
  4. Armigeres subalbatus incriminated as an important vector of the dog heartworm Dirofilaria immitis and the bird Cardiofilaria in urban Kuala Lumpur
    Cheong WH, Mak JW, Naidu S, Mahadevan S
    Southeast Asian J. Trop. Med. Public Health, 1981 Dec;12(4):611-2.
    PMID: 6124044
    Matched MeSH terms: Culicidae/parasitology*
  5. The known vectors of simian malaria in Malaya today
    Cheong WH, Ben Omar AH, Warren M
    Med J Malaya, 1966 Jun;20(4):327-9.
    PMID: 4380826
    Matched MeSH terms: Culicidae*
  6. New isolations of P. cynomologi and P. inui from A. b. balabacensis in Perlis
    Cheong WH, Sandosham AA, Coombs GL, Omar AH
    Med J Malaya, 1965 Sep;20(1):52.
    PMID: 4379047
    Matched MeSH terms: Culicidae*
  7. Fulltext Immunogenicity of the merozoite surface protein-1 (MSP-1) of human Plasmodium sp.
    Cheong, F.W., Lau, Y.L., Fong, M.Y.
    JUMMEC, 2015;18(2):1-7.
    MyJurnal
    Malaria is a major cause of mortality and morbidity globally. Great efforts have been made in the prevention and the elimination of malaria, especially in controlling the malaria vector, the mosquito. Another promising approach would be the development of malaria vaccines. Malaria vaccine studies can be focused on the pre-erythrocytic-stage antigens and the blood-stage antigens, and on the transmission blocking agents targeting the malaria gametocytes. The blood-stage antigens are the leading candidates in malaria vaccine development, as the blood-stage parasites are responsible for causing symptomatic malaria. Human acquired immunity largely targets on blood-stage antigens. This review focuses on one of the most extensively studied blood-stage antigen, the merozoite surface protein-1 (MSP-1), specifically on its evaluation and immunogenicity in rodents and primate models, and its safety and immunogenicity in human clinical trials.
    Matched MeSH terms: Culicidae
  8. Update on the bionomics of Mansonia vectors of brugian filariasis
    Chiang GL
    Southeast Asian J. Trop. Med. Public Health, 1993;24 Suppl 2:69-75.
    PMID: 7973951
    The genus Mansonia is divided into two subgenera, Mansonia and Mansonioides. The subgenus Mansonioides includes the important vectors of lymphatic filariasis caused by Brugia malayi in South and Southeast Asia. Six species of this subgenus are vectors of two types of brugian filariasis, periodic and subperiodic. All six species, viz Mansonia bonneae, Ma. dives, Ma. uniformis, Ma. annulifera, Ma. annulata and Ma. indiana are present in this country. The ecological factors governing the larval and adult biology and their control measures are discussed.
    Matched MeSH terms: Culicidae/growth & development; Culicidae/parasitology; Culicidae/physiology*
  9. A study of dispersal, survival and gonotrophic cycle estimates of Mansonia uniformis in an open swamp ecotype
    Chiang GL, Loong KP, Mahadevan S, Eng KL
    Southeast Asian J. Trop. Med. Public Health, 1988 Jun;19(2):271-82.
    PMID: 2906483
    Five mark-release-recapture experiments with wild caught Ma. uniformis were conducted in an open swamp area at Batang Berjuntai in Selangor, 40 km from Kuala Lumpur, Malaysia, between May 1983 and January 1985. A total of 64 (0.14%) from the 45,950 females released were recaptured feeding on humans and cattle and resting in cattle-sheds. Substantially fewer (0.03% to 0.09%) females were recaptured from releases of blood-fed females than from releases of unfed females (0.20% to 0.23%). More than 70% of all recaptures were taken within a radius of 1.5 km around the point of release and the longest detected flight was 3.5 km. The mean dispersal distance for blood-fed and unfed females was 1.445 +/- 1.06 and 1.706 +/- 1.03 km, respectively. However, there was no significant difference in the overall mean dispersal of the two groups of females (p greater than 0.05). The duration of the gonotrophic cycle in the field was between 3 to 4 days. Daily survivorship estimates (0.783-0.867) based on the recapture rates of date specific marked females was comparable to that estimated vertically from the dissection of unmarked females (0.751-0.795). These experiments revealed the remarkable flying ability of Ma. uniformis and the importance of reinvasion must be recognized when control operations are restricted to small areas.
    Matched MeSH terms: Culicidae/physiology*
  10. Fulltext Capture-recapture studies with Anopheles maculatus Theobald (Diptera: Culicidae) the vector of malaria in peninsular Malaysia
    Chiang GL, Loong KP, Chan ST, Eng KL, Yap HH
    Southeast Asian J. Trop. Med. Public Health, 1991 Dec;22(4):643-7.
    PMID: 1687932
    Mark-release-recapture experiments were undertaken in January 1989, in Pos Betau, Pahang, Malaysia, with the malaria vector Anopheles maculatus. On two consecutive nights, 121 and 175 blood-fed mosquitos were released. A mean recapture rate of 11.5% and survival rates of 0.699-0.705 with an estimated oviposition cycle period of 2.35 days were obtained from the releases. About 68% of all recaptures were taken within a distance of 0.5 km from their release points and the longest detected flight was 1.6 km. No heterogeneity was found between indoor and outdoor biters of An. maculatus.
    Matched MeSH terms: Culicidae
  11. Comparative susceptibility of five strains of Mansonia uniformis (Diptera:Culicidae) in Malaysia to infection with subperiodic Brugia malayi
    Chiang GL, Loong KP, Eng KL
    Southeast Asian J. Trop. Med. Public Health, 1989 Jun;20(2):169-74.
    PMID: 2575285
    Five strains of Ma. uniformis from Malaysia were tested for their susceptibility to infection with subperiodic B. malayi. All were found to be susceptible with infection rates ranging from 62% to 100%. The susceptibility rates were directly related to the microfilarial densities of the cat at the time of feeding. Statistical analysis showed no significant difference (p greater than 0.05) among the means of the indices of experimental infection as well as the percentage of infective mosquitoes of the five strains and an old laboratory colony. They were all equally susceptible to subperiodic B. malayi.
    Matched MeSH terms: Culicidae/parasitology*
  12. Filariasis in Bengkoka Peninsula, Sabah, Malaysia: bionomics of Mansonia sp
    Chiang GL, Cheong WH, Samarawickrema WA
    Southeast Asian J. Trop. Med. Public Health, 1984 Sep;15(3):294-302.
    PMID: 6151743
    Studies on age groups within activity cycles, age composition and survivorship in natural populations of Mansonia in Kampung Pantai, Bengkoka Peninsula of Sabah state have been described. Early activity of 3-5 parous Ma. bonneae during the first hour after sunset was noted. Age composition of Ma. bonneae at forest shade, indoor and outdoor of house, comparative buffalo vs human bait outdoor in Kampung Pantai showed all round high parous rates ranging from 66.7 to 75.4%. Population 3-parous and older ranged from 18.8 to 26.7%. Nine of the 14 infective Ma. bonneae were 3-parous and this segment of the population was engaged in active transmission. High parous rates were observed in Ma. dives and Ma. uniformis taken in small numbers. Parous rates of Ma. bonneae taken in Kampung Delima and Kampung Taradas were also high. Estimates of daily survivorship of Ma. bonneae and Ma. dives determined by two methods were very high.
    Matched MeSH terms: Culicidae/parasitology; Culicidae/physiology*
  13. Field studies on the surveillance of Coquillettidia crassipes (Van der Wulp) and the isolation of a strain of Cardiofilaria in peninsular Malaysia
    Chiang GL, Samarawickrema WA, Eng KL, Cheong WH, Sulaiman I, Yap HH
    Ann Trop Med Parasitol, 1986 Apr;80(2):235-44.
    PMID: 2875691
    Surveillance methods for Coquillettidia crassipes were studied in an open housing estate near Kuala Lumpur using three types of traps Trinidad 10 trap, modified Lard can trap and IMR trap, each baited with chicken or pigeon. All traps attracted Cq. crassipes. There was no significant difference in the catches in the three traps. There was also no significant difference between chicken and pigeon as bait. Catches at heights of 1.5, 3, 4.5 and 6 m did not show any significant difference in density. Cq. crassipes was active at night with an early peak during the first hour of the night and a minor peak between 0100 and 0200 hours. The activity of the parous and nulliparous sections of the population was similar, except that a higher proportion of the parous females was active during the second peak compared with the nulliparous females. The parous rate was 22.3%, and the probability of survival through one day for two gonotrophic cycles was 0.711 and 0.650. The infection rate for Cardiofilaria was 29 out of 1052 (2.76%) and the infective rate (L3 larvae) was 13 out of 1052 (1.24%). 48.3% of the infected Cq. crassipes had a worm burden of more than ten larvae. One of the chickens in the traps was positive for microfilariae of Cardiofilaria four weeks after exposure as bait. Laboratory bred Cq. crassipes fed on this chicken produced infective larvae in ten days, and these were inoculated into clean chickens and pigeons. Microfilariae appeared in the chickens but not in pigeons. The adult worms recovered await identification.
    Matched MeSH terms: Culicidae/parasitology*; Culicidae/physiology
  14. Effectiveness of repellent/insecticidal bars against malaria and filariasis vectors in peninsular Malaysia
    Chiang GL, Tay SL, Eng KL, Chan ST
    Southeast Asian J. Trop. Med. Public Health, 1990 Sep;21(3):412-7.
    PMID: 1981629
    Field tests were conducted to compare the degree of protection from bites of Mansonia species and Anopheles maculatus by applying two repellent/insecticidal bars, MOSBAR and MOSKIL, to exposed arms and legs. Human test subjects were exposed to natural populations of mosquitos for an 8-hour night time period while using the repellent/insecticidal bars. MOSBAR gave good protection against the bites of Mansonia and An. maculatus. MOSKIL was effective against An. maculatus but not against Mansonia. High mortality was observed among the mosquitos collected from human test subjects treated with the repellent/insecticidal bars. Use of MOSBAR in terms of cost-effectiveness and safety by field and health workers entering into malaria and filariasis endemic areas is discussed.
    Matched MeSH terms: Culicidae*
  15. Field and laboratory observations on Coquillettidia crassipes in relation to transmission of Brugia malayi in Peninsular Malaysia
    Chiang GL, Samarawickrema WA, Mak JW, Cheong WH, Sulaiman I, Yap HH
    Ann Trop Med Parasitol, 1986 Feb;80(1):117-21.
    PMID: 2873797
    Field observations were made on Coquillettidia crassipes during a study of Mansonia in a swamp forest ecotype in Tanjong Karang. There was an increase in abundance in July consistent with the increase in abundance of Mansonia and an increase in rainfall. The biting cycle showed a dramatic early peak during the period 1900-2000 hours. The probability of daily survival through one day for the first three gonotrophic cycles was 0.770, 0.722 and 0.759. Two of the 54 Cq. crassipes dissected were infective, with two and 25 L3 larvae of Brugia. Both subperiodic B. malayi and B. pahangi developed into L3 larvae in laboratory bred Cq. crassipes. The index of experimental infection was higher for B. pahangi. Mansonia bonneae and Ma. uniformis showed higher indices of experimental infection than Cq. crassipes for subperiodic B. malayi. It is concluded that in an endemic area with a high density of Cq. crassipes it could act as a secondary vector of Brugian filariasis.
    Matched MeSH terms: Culicidae/parasitology*; Culicidae/physiology
  16. Laboratory colonization of Mansonia uniformis, Ma. indiana and Ma. bonneae in Malaysia
    Chiang GL, Cheong WH, Loong KP, Eng KL, Samarawickrema WA
    J Am Mosq Control Assoc, 1985 Jun;1(2):186-90.
    PMID: 2906664
    Methods are described for the laboratory colonization of Mansonia uniformis, Ma. indiana and Ma. bonneae in Malaysia. Gravid females oviposited in 500 ml beakers with a layer of water covered with small leaves of Salvinia. Newly hatched larvae were set up in a basal medium of guinea pig dung and water or liver powder, yeast powder and water. Larvae attached to aquatic plants or 'Keaykolour' ruffia snow white paper. The cultures with paper gave better yields than those with plants. Production of Ma. uniformis was higher than the other two species. Twelve generations of Ma. uniformis and 11 generations of Ma. indiana and Ma. bonneae were monitored in the laboratory.
    Matched MeSH terms: Culicidae/growth & development*
  17. The thiamine content of human milk in Malaya. II. The effect of the administration of supplementary thiamine on the thiamine level of human milk
    Chow AY, Simpson IA
    J Trop Pediatr (Lond), 1956 Sep;2(2):69-76.
    PMID: 24544134
    (1) The effect has been studied of the oral administration of supplementary thiamine on the thiamine content of milk from sixteen women, whose initial thiamine content was low ; and of the parenteral administration of thiamine to ten women, some of whom initially showed mild, clinical symptoms of beriberi.
    (2) The response in the milk content of thiamine to supplementary thiamine, administered either orally or by injection, showed marked variation in different women. While comparatively small doses taken by mouth evoked a marked response in some women, fairly large doses administered by injection failed to produce much response in others.
    (3) In some women, a marked increase in the thiamine content of their milk occurred soon after the administration of thiamine, either orally or parenterally. In others, the response was slow and meagre.
    (4) The highest thiamine level obtained in a sample of milk was 38.9 ug./100 ml., after the injection, twice daily, of 20 mg. thiamine for six days — a total intake of 240 mg. of thiamine parenterally. The initial milk thiamine level in this case was 2.3 ug./100 ml., but had increased to 16.2ug./100 ml., by the supply of a good diet alone, before the course of injections was commenced.
    (5) It would appear, that, in cases where the thiamine content of the milk is low, initial parenteral administration of thiamine must be supplemented by a continued intake of additional thiamine, if a satisfactory level of thiamine in the milk is to be maintained.
    Matched MeSH terms: Culicidae*
  18. The structure of the head of some anopheline larvae
    Crawford R
    Malayan Medical Journal, 1933;8:25-38.
    Matched MeSH terms: Culicidae
  19. Bone breaking infections - A focus on bacterial and mosquito-borne viral infections
    Cui YC, Wu Q, Teh SW, Peli A, Bu G, Qiu YS, et al.
    Microb Pathog, 2018 Sep;122:130-136.
    PMID: 29909241 DOI: 10.1016/j.micpath.2018.06.021
    The recent global resurgence of arthritogenic alphaviruses, including Ross River, chikungunya, and dengue, highlights an urgency for the development of therapeutic strategies. Currently, dengue represents the most rapidly transmitting mosquito-borne viral disease worldwide. By contracting bone breaking diseases, patients experience devastating clinical manifestations involving muscle pain and bone loss. The bone self-repair and regeneration mechanisms can be damaged by the presence of viruses and bacteria. The rapid establishment of dengue epidemic and the severity of bacterial and viral infections affecting the bone stress the urgent need of developing effective interventions. Herein, we review current knowledge on bone breaking infections, covering both bacterial and mosquito-borne viral ones. The mechanisms exploited by these diseases to significantly affect the bone, including interferences with self-repair and regeneration routes, were discussed. In the final section, challenges for future research aimed to treat and prevent bacterial and mosquito-borne bone-breaking infections have been outlined.
    Matched MeSH terms: Culicidae
  20. Factors associated with mosquito control among construction workers: A systematic review
    Dapari R, Mohd Fadzil MF, Hanzir MY, Mohamed Jais JS, Safarudin NF, Albar A
    PLoS One, 2024;19(5):e0303330.
    PMID: 38718075 DOI: 10.1371/journal.pone.0303330
    INTRODUCTION: Workers in the construction industry frequently work in construction sites with numerous areas that can potentially accumulate water, such as tanks, wet cement surfaces, or water puddles. These water collection sites become ideal breeding grounds for mosquito infestation, which leads to a higher prevalence of mosquito-borne diseases, especially malaria and dengue among construction workers. Despite that numerous factors have been identified in controlling vector-borne diseases, the specific factors that influence mosquito control at construction sites have yet to be explored.

    AIMS: This systematic review aims to determine the factors associated with mosquito control among construction workers.

    METHODS: Primarily, articles related to factors associated with mosquito control among construction workers were collected from two different online databases (ScienceDirect and EBSCOhost). Two independent reviewers were assigned to screen the titles and abstracts of the collected data, stored in Microsoft Excel, against the inclusion and exclusion criteria. Afterwards, the quality of the included articles was critically assessed using the Mixed Method Appraisal Tool (MMAT). Of the 171 articles identified, 4 were included in the final review.

    RESULTS: Based on the thorough evaluation, mosquito-related knowledge, practical mosquito prevention measures, and Larval Source Management (LSM) were identified as vital factors associated with mosquito control among construction workers. The significant association between mosquito-related knowledge and control practices indicates higher knowledge linked to effective practices, particularly among female workers and those who were recently infected with malaria. Concurrently, there were notable challenges regarding sustainable preventive measures and larval control methods in construction settings.

    CONCLUSION: Implementing effective mosquito control, including knowledge and practice on mosquito control together with vector control, is highly required to suppress the expanding mosquito population. It is recommended that employers provide continuous mosquito control education and training to their employees and reward them with incentives, while employees should comply with the guidelines set by their employers to ensure successful mosquito control and reduce the spread of mosquito-borne diseases in the construction industry.

    Matched MeSH terms: Culicidae/physiology
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