Displaying publications 181 - 200 of 299 in total

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  1. Effect of ten chlorophytes on larval survival, development and adult body size of the mosquito Aedes aegypti
    Ahmad R, Chu WL, Ismail Z, Lee HL, Phang SM
    Southeast Asian J Trop Med Public Health, 2004 Mar;35(1):79-87.
    PMID: 15272748
    The effect of ten microalgal chlorophytes isolated from mosquito breeding containers on the survival, larval development and adult body size of the mosquito Aedes aegypti was investigated. All larvae fed with six of the microalgal isolates died after 7 days. These isolates were found to be resistant to digestion by mosquito larvae. Delayed pupation and body size reduction of the mosquitos fed with Chlorococcum UMACC 218 and Scenedesmus UMACC 220 were observed. In contrast, larvae fed with Ankistrodesmus convolutus UMACC 101 and Chlorococcum UMACC 213 were bigger in size than those fed with normal insectory feed. The present study showed that microalgal chlorophytes have the potential to be used as larvicidal agents for mosquitos.
    Matched MeSH terms: Insect Vectors/drug effects
  2. Fulltext Effect of sublethal dosages of malathion on the oral susceptibility of Aedes aegypti to dengue-2 virus infection
    Lee HL, Argubano RA, Ahmad R
    Southeast Asian J Trop Med Public Health, 1997 Sep;28(3):664-5.
    PMID: 9561626
    Matched MeSH terms: Insect Vectors/virology*
  3. Population cytogenetics of the malaria vector Anopheles leucosphyrus group
    Baimai V
    Southeast Asian J Trop Med Public Health, 1988 Dec;19(4):667-80.
    PMID: 3238480
    Until recently, very little was known of Anopheles species complexes and their relationships to epidemiology and malaria transmission in Southeast Asia. During the past eight years, extensive studies on the genetics of natural populations of anopheline mosquitoes in this region, involving the interdisciplinary efforts of taxonomists, operational entomologists and biologists, have revealed groups of cryptic species of Anopheles vectors, particularly the An. leucos phyrus group. This species group comprise seventeen species and two subspecies widely distributed in the forested areas of Southeast Asia. Among these species. An. dirus Peyton and Harrison, has been shown by cytogenetic and morphological studies to be a complex of at least seven isomorphic species, provisionally designated species A, B, C, D, E, F and takasagoensis, on the Southeast Asian mainland. Cytological identification of these species is based on distinct banding patterns of salivary gland polytene chromosomes as well as heterochromatin differences in mitotic karyotypes. The five species found in Thailand (A-D, F) exhibit distinct geographic distributions. Species A is widespread throughout Thailand except in the south. Species B had been found in sympatry with species C in southern Thailand and both seem to show north-south clinal geographic variation. Species D is common on the west side of southern Thailand and along the Thai-Burmese border in sympatry with species A. Species F, An. nemophilous Peyton and Ramalingam, has been found in a population at the Thai-Malaysian border in this study although it was known to be common in southern and western Thailand and Peninsular Malaysia. Species E is known only from western India. The five species found in Thailand also exhibit seasonal variation in relative abundance and different nocturnal biting cycles. Chromosomal polymorphisms have been observed in mitotic and polytene chromosomes of An. dirus A and D. Species B and C also show heterochromatin variation in the sex chromosomes, but are monomorphic for the standard sequence in polytene chromosomes. These biological characteristics of the An. dirus complex may have implications for understanding the epidemiology of malaria in Southeast Asia. Recent cytogenetic studies of wild-caught samples of An. leucosphyrus from Sumatra, Kalimantan and southern Thailand have revealed the presence of two distinct species within this taxon. Species A is widely distributed in southern Thailand, East Malaysia and Kalimantan, while species B is confined to Sumatra. The two isomorphic species are vectors of human malaria within their range of distribution.(ABSTRACT TRUNCATED AT 400 WORDS)
    Matched MeSH terms: Insect Vectors/genetics*
  4. 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: Insect Vectors*
  5. Fulltext Refractoriness of Aedes aegypti (Linnaeus) to dual infection with dengue and chikungunya virus
    Rohani A, Potiwat R, Zamree I, Lee HL
    Southeast Asian J Trop Med Public Health, 2009 May;40(3):443-8.
    PMID: 19842428
    In this study, artificial membrane feeding technique was used to orally feed Aedes aegypti with dengue and chikungunya viruses. Virus detection was carried out by reverse transcriptase polymerase chain reaction. The study did not detect dual infection of Ae. aegypti with dengue and chikungunya virus from the same pool or from individual mosquitoes. Oral receptivity of Ae. aegypti to chikungunya virus was higher than that of dengue virus.
    Matched MeSH terms: Insect Vectors/virology*
  6. Habitat characterization and mapping of Anopheles maculatus (Theobald) mosquito larvae in malaria endemic areas in Kuala Lipis, Pahang, Malaysia
    Rohani A, Wan Najdah WM, Zamree I, Azahari AH, Mohd Noor I, Rahimi H, et al.
    Southeast Asian J Trop Med Public Health, 2010 Jul;41(4):821-30.
    PMID: 21073056
    In Peninsular Malaysia, a large proportion of malaria cases occur in the central mountainous and forested parts of the country. As part of a study to assess remote sensing data as a tool for vector mapping, we conducted entomological surveys to determine the type of mosquitoes, their characteristics and the abundance of habitats of the vector Anopheles maculatus in malaria endemic areas in Pos Senderot. An. maculatus mosquitoes were collected from 49 breeding sites in Pos Senderot. An. maculatus preferred to breed in water pockets formed on the bank of rivers and waterfalls. The most common larval habitats were shallow pools 5.0-15.0 cm deep with clear water, mud substrate and plants or floatage. The mosquito also preferred open or partially shaded habitats. Breeding habitats were generally located at 100-400 m from the nearest human settlement. Changes in breeding characteristics were also observed. Instead of breeding in slow flowing streams, most larvae bred in small water pockets along the river margin.
    Matched MeSH terms: Insect Vectors/parasitology*
  7. Current status of filariasis in Malaysia
    Marzhuki MI, Tham AS, Poovaneswari S
    Southeast Asian J Trop Med Public Health, 1993;24 Suppl 2:10-4.
    PMID: 7973937
    The Filariasis Control Program was established more than 30 years ago in the country and the disease is still a public health problem in some states. Since 1983, a total of 17 filariasis control teams were formed throughout the country to carry out filariasis control work. The teams conduct house and population censuses, nocturnal mass blood surveys and treatment of microscopically confirmed cases. Individual case follow-up is being carried out after 3-5 months while the locality is resurveyed after about 2-3 years. During the years 1988 to 1990, there appeared to be a decreasing trend in the number of filariasis cases detected countrywide. In 1991, brugian filariasis accounted for 92% of the cases detected. The microfilaria rate (MFR) also showed a decreasing trend countrywide for the years 1988 (0.57%) to 1990 (0.35%) but there was an increase in 1991 although it remained well below the 5% MFR targeted in the program objective, In 1991, the filariasis control teams and the district multi-purpose teams collected a total of 167, 151 blood slides out of which 871 were found to be positive for microfilaria. To determine the true endemicity of filariasis in the country, the malaria district multi-purpose teams are also utilized to assist in probe surveys in new areas of the district. Two species of filarial worms, namely Brugia malayi and Wuchereria bancrofti, and the mosquito vectors belonging to the Anopheles and Mansonia genera are involved in the transmission of filariasis in Malaysia. Monkeys and domestic cats are the reservoir hosts for the subperiodic strain of B. malayi.
    Matched MeSH terms: Insect Vectors/parasitology
  8. Fulltext Studies on adult mosquito vectors of Japanese encephalitis in a pig farm in Selangor, Malaysia
    Vythilingam I, Mahadevan S, Zaridah MZ, Ong KK, Abdullah G, Ong YF
    Southeast Asian J Trop Med Public Health, 1994 Jun;25(2):383-6.
    PMID: 7855662
    Mosquito collections were carried out for a period of one year from January to December 1992 in a pig farm in Sungai Pelek, Selangor, Malaysia. A total of 41,022 mosquitos belonging to 52 species and 20 genera were collected. Culex tritaeniorhynchus and Cx. gelidus, the important vectors, comprised 63% of all mosquitos collected. Both these species were collected in large numbers during the wet months of May and December. The other predominant species in that area were Cx. fuscocephala, Cx. quinquefasciatus, Cx. sitiens, Aedes butleri, and Armigeres subalbatus.
    Matched MeSH terms: Insect Vectors/virology*
  9. Fulltext Novel tools for the surveillance and control of dengue: findings by the DengueTools research consortium
    Wilder-Smith A, Tissera H, AbuBakar S, Kittayapong P, Logan J, Neumayr A, et al.
    Glob Health Action, 2018;11(1):1549930.
    PMID: 30560735 DOI: 10.1080/16549716.2018.1549930
    BACKGROUND: Dengue fever persists as a major global disease burden, and may increase as a consequence of climate change. Along with other measures, research actions to improve diagnosis, surveillance, prevention, and predictive models are highly relevant. The European Commission funded the DengueTools consortium to lead a major initiative in these areas, and this review synthesises the outputs and findings of this work conducted from 2011 to 2016. Research areas: DengueTools organised its work into three research areas, namely [1] Early warning and surveillance systems; [2] Strategies to prevent dengue in children; and [3] Predictive models for the global spread of dengue. Research area 1 focused on case-studies undertaken in Sri Lanka, including developing laboratory-based sentinel surveillance, evaluating economic impact, identifying drivers of transmission intensity, evaluating outbreak prediction capacity and developing diagnostic capacity. Research area 2 addressed preventing dengue transmission in school children, with case-studies undertaken in Thailand. Insecticide-treated school uniforms represented an intriguing potential approach, with some encouraging results, but which were overshadowed by a lack of persistence of insecticide on the uniforms with repeated washing. Research area 3 evaluated potential global spread of dengue, particularly into dengue-naïve areas such as Europe. The role of international travel, changing boundaries of vectors, developing models of vectorial capacity under different climate change scenarios and strategies for vector control in outbreaks was all evaluated.

    CONCLUDING REMARKS: DengueTools was able to make significant advances in methods for understanding and controlling dengue transmission in a range of settings. These will have implications for public health agendas to counteract dengue, including vaccination programmes.

    OUTLOOK: Towards the end of the DengueTools project, Zika virus emerged as an unexpected epidemic in the central and southern America. Given the similarities between the dengue and Zika viruses, with vectors in common, some of the DengueTools thinking translated readily into the Zika situation.

    Matched MeSH terms: Insect Vectors/virology
  10. Fulltext Chikungunya virus in macaques, Malaysia
    Sam IC, Chua CL, Rovie-Ryan JJ, Fu JY, Tong C, Sitam FT, et al.
    Emerg Infect Dis, 2015 Sep;21(9):1683-5.
    PMID: 26291585 DOI: 10.3201/eid2109.150439
    Matched MeSH terms: Insect Vectors/virology
  11. Field Worker Evaluation of Dengue Vector Surveillance Methods: Factors That Determine Perceived Ease, Difficulty, Value, and Time Effectiveness in Australia and Malaysia
    Azil AH, Ritchie SA, Williams CR
    Asia Pac J Public Health, 2015 Oct;27(7):705-14.
    PMID: 25186807 DOI: 10.1177/1010539514548760
    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.
    Matched MeSH terms: Insect Vectors*
  12. Triatomines as experimental vectors of trypanosomes of Asian monkeys
    Weinman D, Wallis RC, Cheong WH, Mahadevan S
    Am J Trop Med Hyg, 1978 Mar;27(2 Pt 1):232-7.
    PMID: 417639
    Systematic surveys of the wild macaques of South Asia by blood culture resulted in the discovery that trypanosomiasis is enzootic in the simians of Indonesia, Malaysia, India, and Thailand. The isolates obtained differ in morphology, metabolism, and ability to multiply in arthropods. Following this discovery, interest focused on possible transmissions of these trypanosomiases. Laboratory-reared and wild-caught insects were studied to determine which are satisfactory intermediate hosts and potential natural vectors. Successful results were obtained with insectary-reared reduviids and Indonesian isolates. In Rhodnius prolixus and Triatoma rubrofasciata the Indonesian trypanosomes multiply for periods which can exceed 40 days. The flagellate infections are in the digestive tract, whereas trypanosomes have never been seen in the salivary glands or in the hemolymph. The feces of trypanosome-carrying reduviids are infective, suggesting a stercoreal method of infection of mammals, and infection was produced in experiments in which feeding by the insects was not possible. The relevance of these findings to natural transmission in Indonesia is not known. Experiments with insects and all other trypanosomal isolates have been negative. The natural transmission mechanism(s) of the simian trypanosomiases in South Asia remains an unsolved problem.
    Matched MeSH terms: Insect Vectors*
  13. The impact of permethrin impregnated bednets on the malaria vector Anopheles maculatus (Diptera: Culicidae) in aboriginal villages of Pos Betau Pahang, Malaysia
    Vythilingam I, Foo LC, Chiang GL, Chan ST, Eng KL, Mahadevan S, et al.
    Southeast Asian J Trop Med Public Health, 1995 Jun;26(2):354-8.
    PMID: 8629075
    The effect of permethrin impregnated bednets on Anopheles maculatus Theobald was studied in four villages in Pos Betau, Pahang, Malaysia from August 1990 to July 1992. Collections of mosquitos were carried out indoors and outdoors from 1900 to 0700 hours. All mosquitos were dissected for sporozoites and parity. In May 1991 two villages received bednets impregnated with permethrin at 0.5 g/m2 and two villages received placebo bednets. There was a significant difference in the sporozoite and parous rates between the treated and control villages after the distribution of bednets (p < 0.05). There was no significant difference in the bites/man/night of An. maculatus between the pre and post treatment periods in the control villages. However there was a significant difference in bites/man/night between pre and post treatment in the treated villages (p < 0.001).
    Matched MeSH terms: Insect Vectors/drug effects
  14. Fulltext Cost of Dengue Vector Control Activities in Malaysia
    Packierisamy PR, Ng CW, Dahlui M, Inbaraj J, Balan VK, Halasa YA, et al.
    Am J Trop Med Hyg, 2015 Nov;93(5):1020-1027.
    PMID: 26416116 DOI: 10.4269/ajtmh.14-0667
    Dengue fever, an arbovirus disease transmitted by Aedes mosquitoes, has recently spread rapidly, especially in the tropical countries of the Americas and Asia-Pacific regions. It is endemic in Malaysia, with an annual average of 37,937 reported dengue cases from 2007 to 2012. This study measured the overall economic impact of dengue in Malaysia, and estimated the costs of dengue prevention. In 2010, Malaysia spent US$73.5 million or 0.03% of the country's GDP on its National Dengue Vector Control Program. This spending represented US$1,591 per reported dengue case and US$2.68 per capita population. Most (92.2%) of this spending occurred in districts, primarily for fogging. A previous paper estimated the annual cost of dengue illness in the country at US$102.2 million. Thus, the inclusion of preventive activities increases the substantial estimated cost of dengue to US$175.7 million, or 72% above illness costs alone. If innovative technologies for dengue vector control prove efficacious, and a dengue vaccine was introduced, substantial existing spending could be rechanneled to fund them.
    Matched MeSH terms: Insect Vectors/virology*
  15. Fulltext INVESTIGATIONS LEADING TO THE IDENTIFICATION OF MEMBERS OF THE ANOPHELES UMBROSUS GROUP AS THE PROBABLE VECTORS OF MOUSE DEER MALARIA
    Wharton RH, Eyles DE, Warren M, Moorhouse DE, Sandosham AA
    Bull World Health Organ, 1963;29:357-74.
    PMID: 14058228
    Although mosquitos of the Anopheles umbrosus group have long been recognized as important vectors of human malaria in Malaya, there have been doubts about the origin of some of the malaria infections found, especially in A. umbrosus and A. letifer. Investigations have accordingly been carried out in the Malayan swamp-forest, in conjunction with laboratory studies, into the nature of malaria infections in wild-caught mosquitos, the biting behaviour of anophelines and the presence of malaria infection in man and animals. The authors conclude from the results reported in this paper that A. umbrosus is a vector of mouse deer malaria and rarely, if ever, transmits primate malaria; that A. letifer transmits both human and mouse deer malaria; and that A. baezai and A. roperi are probably vectors of mouse deer malaria.
    Matched MeSH terms: Insect Vectors*
  16. Fulltext Plasmodium knowlesi malaria an emerging public health problem in Hulu Selangor, Selangor, Malaysia (2009-2013): epidemiologic and entomologic analysis
    Vythilingam I, Lim YA, Venugopalan B, Ngui R, Leong CS, Wong ML, et al.
    Parasit Vectors, 2014;7:436.
    PMID: 25223878 DOI: 10.1186/1756-3305-7-436
    While transmission of the human Plasmodium species has declined, a significant increase in Plasmodium knowlesi/Plasmodium malariae cases was reported in Hulu Selangor, Selangor, Malaysia. Thus, a study was undertaken to determine the epidemiology and the vectors involved in the transmission of knowlesi malaria.
    Matched MeSH terms: Insect Vectors/classification; Insect Vectors/parasitology*
  17. Larvicidal, oviposition, and ovicidal effects of Artemisia annua (Asterales: Asteraceae) against Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus (Diptera: Culicidae)
    Cheah SX, Tay JW, Chan LK, Jaal Z
    Parasitol Res, 2013 Sep;112(9):3275-82.
    PMID: 23835922 DOI: 10.1007/s00436-013-3506-0
    This study focuses on the larvicidal, oviposition, and ovicidal effects of a crude extract of Artemisia annua against Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus. Dried cells of Artemisia annua from cell suspension cultures were extracted using hexane. The extract showed moderate larvicidal effects against mosquitoes. At 24-h post treatment, the LC50 values for Anopheles sinensis, Aedes aegypti, and Culex quinquefasciatus were recorded as 244.55, 276.14, and 374.99 ppm, respectively. The percentage mortality of larvae was directly proportional to the tested concentration. Anopheles sinensis was found to be the most susceptible species, whereas Culex quinquefasciatus was the most tolerant to the Artemisia annua extract. The results indicated that the Artemisia annua extract showed concentration-dependent oviposition deterrent activity and had a strong deterrent effect. At 500 ppm, the percentage effective repellency was more than 85% compared with the control group for all the species, with oviposition activity index values of -0.94, -0.95, and -0.78 for Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus, respectively. In the ovicidal assay, the percentage hatchability of eggs after treatment with 500 ppm of Artemisia annua extract was significantly lower than the control, with values of 48.84 ± 4.08, 38.42 ± 3.67, and 79.35 ± 2.09% for Aedes aegypti, Anopheles sinensis, and Culex quinquefasciatus, respectively. Artemisia annua was found to be more effective against Aedes aegypti and Anopheles sinensis compared with Culex quinquefasciatus. This study indicated that crude extract of A. annua could be a potential alternative for use in vector management programs.
    Matched MeSH terms: Insect Vectors/drug effects; Insect Vectors/physiology
  18. Monkey malaria kills four humans
    Galinski MR, Barnwell JW
    Trends Parasitol, 2009 May;25(5):200-4.
    PMID: 19345613 DOI: 10.1016/j.pt.2009.02.002
    Four human deaths caused by Plasmodium knowlesi, a simian malaria species, are stimulating a surge of public health interest and clinical vigilance in vulnerable areas of Southeast Asia. We, and other colleagues, emphasize that these cases, identified in Malaysia, are a clear warning that health facilities and clinicians must rethink the diagnosis and treatment of malaria cases presumed to be caused by a less virulent human malaria species, Plasmodium malariae.
    Matched MeSH terms: Insect Vectors/classification; Insect Vectors/parasitology
  19. Fulltext Bionomics of Anopheles latens in Kapit, Sarawak, Malaysian Borneo in relation to the transmission of zoonotic simian malaria parasite Plasmodium knowlesi
    Tan CH, Vythilingam I, Matusop A, Chan ST, Singh B
    Malar J, 2008;7:52.
    PMID: 18377652 DOI: 10.1186/1475-2875-7-52
    A large focus of human infections with Plasmodium knowlesi, a simian parasite naturally found in long-tailed and pig-tailed macaques was discovered in the Kapit Division of Sarawak, Malaysian Borneo. A study was initiated to identify the vectors of malaria, to elucidate where transmission is taking place and to understand the bionomics of the vectors in Kapit.
    Matched MeSH terms: Insect Vectors/classification; Insect Vectors/parasitology
  20. Earthworm-mediated synthesis of silver nanoparticles: A potent tool against hepatocellular carcinoma, Plasmodium falciparum parasites and malaria mosquitoes
    Jaganathan A, Murugan K, Panneerselvam C, Madhiyazhagan P, Dinesh D, Vadivalagan C, et al.
    Parasitol Int, 2016 Jun;65(3):276-84.
    PMID: 26873539 DOI: 10.1016/j.parint.2016.02.003
    The development of parasites and pathogens resistant to synthetic drugs highlighted the needing of novel, eco-friendly and effective control approaches. Recently, metal nanoparticles have been proposed as highly effective tools towards cancer cells and Plasmodium parasites. In this study, we synthesized silver nanoparticles (EW-AgNP) using Eudrilus eugeniae earthworms as reducing and stabilizing agents. EW-AgNP showed plasmon resonance reduction in UV-vis spectrophotometry, the functional groups involved in the reduction were studied by FTIR spectroscopy, while particle size and shape was analyzed by FESEM. The effect of EW-AgNP on in vitro HepG2 cell proliferation was measured using MTT assays. Apoptosis assessed by flow cytometry showed diminished endurance of HepG2 cells and cytotoxicity in a dose-dependent manner. EW-AgNP were toxic to Anopheles stephensi larvae and pupae, LC(50) were 4.8 ppm (I), 5.8 ppm (II), 6.9 ppm (III), 8.5 ppm (IV), and 15.5 ppm (pupae). The antiplasmodial activity of EW-AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of Plasmodium falciparum. EW-AgNP IC(50) were 49.3 μg/ml (CQ-s) and 55.5 μg/ml (CQ-r), while chloroquine IC(50) were 81.5 μg/ml (CQ-s) and 86.5 μg/ml (CQ-r). EW-AgNP showed a valuable antibiotic potential against important pathogenic bacteria and fungi. Concerning non-target effects of EW-AgNP against mosquito natural enemies, the predation efficiency of the mosquitofish Gambusia affinis towards the II and II instar larvae of A. stephensi was 68.50% (II) and 47.00% (III), respectively. In EW-AgNP-contaminated environments, predation was boosted to 89.25% (II) and 70.75% (III), respectively. Overall, this research highlighted the EW-AgNP potential against hepatocellular carcinoma, Plasmodium parasites and mosquito vectors, with little detrimental effects on mosquito natural enemies.
    Matched MeSH terms: Insect Vectors/drug effects; Insect Vectors/parasitology
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