Displaying publications 21 - 40 of 137 in total

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  1. Anwar A, Numan A, Siddiqui R, Khalid M, Khan NA
    Parasit Vectors, 2019 Jun 03;12(1):280.
    PMID: 31159839 DOI: 10.1186/s13071-019-3528-2
    BACKGROUND: Species of Acanthamoeba are facultative pathogens which can cause sight threatening Acanthamoeba keratitis and a rare but deadly brain infection, granulomatous amoebic encephalitis. Due to conversion of Acanthamoeba trophozoites to resistant cyst stage, most drugs are found to be ineffective at preventing recurrence of infection. This study was designed to test the antiacanthamoebic effects of different cobalt nanoparticles (CoNPs) against trophozoites and cysts, as well as parasite-mediated host cell cytotoxicity.

    METHODS: Three different varieties of CoNPs were synthesized by utilizing hydrothermal and ultrasonication methods and were thoroughly characterized by X-ray diffraction and field emission scanning electron microscopy. Amoebicidal, encystation, excystation, and host cell cytopathogenicity assays were conducted to study the antiacanthamoebic effects of CoNPs.

    RESULTS: The results of the antimicrobial evaluation revealed that cobalt phosphate Co3(PO4)2 hexagonal microflakes, and 100 nm large cobalt hydroxide (Co(OH)2) nanoflakes showed potent amoebicidal activity at 100 and 10 µg/ml against Acanthamoeba castellanii as compared to granular cobalt oxide (Co3O4) of size 35-40 nm. Furthermore, encystation and excystation assays also showed consistent inhibition at 100 µg/ml. CoNPs also inhibited amoebae-mediated host cell cytotoxicity as determined by lactate dehydrogenase release without causing significant damage to human cells when treated alone.

    CONCLUSIONS: To our knowledge, these findings determined, for the first time, the effects of composition, size and morphology of CoNPs against A. castellanii. Co3(PO4)2 hexagonal microflakes showed the most promising antiamoebic effects as compared to Co(OH)2 nanoflakes and granular Co3O4. The results reported in the present study hold potential for the development of antiamoebic nanomedicine.

  2. Satho T, Dieng H, Ahmad MH, Ellias SB, Hassan AA, Abang F, et al.
    Parasit Vectors, 2015 May 14;8:272.
    PMID: 25966847 DOI: 10.1186/s13071-015-0874-6
    BACKGROUND: Dengue is a prevalent arboviral disease and the development of insecticide resistance among its vectors impedes endeavors to control it. Coffee is drunk by millions of people daily worldwide, which is associated with the discarding of large amounts of waste. Coffee and its waste contain large amounts of chemicals many of which are highly toxic and none of which have a history of resistance in mosquitoes. Once in solution, coffee is brownish in colour, resembling leaf infusion, which is highly attractive to gravid mosquitoes. To anticipate the environmental issues related to the increasing popularity of coffee as a drink, and also to combat insecticide resistance, we explored the deterrence potentials of coffee leachates against the ovipositing and embryonic stages of the dengue vector, Aedes albopictus.

    METHODS: In a series of choice, no-choice, and embryo toxicity bioassays, we examined changes in the ovipositional behaviours and larval eclosion of Ae. albopictus in response to coffee extracts at different concentrations.

    RESULTS: Oviposition responses were extremely low when ovicups holding highly concentrated extract (HCE) of coffee were the only oviposition sites. Gravid females retained increased numbers of mature eggs until 5 days post-blood feeding. When provided an opportunity to oviposit in cups containing coffee extracts and with water, egg deposition occurred at lower rates in those containing coffee, and HCE cups were far less attractive to females than those containing water only. Females that successfully developed in a coffee environment preferentially oviposited in such cups when in competition with preferred oviposition sites (water cups), but this trait did not continue into the fourth generation. Larval eclosion occurred at lower rates among eggs that matured in a coffee environment, especially among those that were maintained on HCE-moistened substrates.

    CONCLUSIONS: The observations of the present study indicate a pronounced vulnerability of Ae. albopictus to the presence of coffee in its habitats during the early phases of its life cycle. The observations that coffee repels gravid females and inhibits larval eclosion provide novel possibilities in the search for novel oviposition deterrents and anti-larval eclosion agents against dengue vectors.

  3. Amir A, Sum JS, Lau YL, Vythilingam I, Fong MY
    Parasit Vectors, 2013;6:81.
    PMID: 23537404 DOI: 10.1186/1756-3305-6-81
    Anopheles cracens has been incriminated as a vector for the simian malaria parasite, Plasmodium knowlesi, that is the fifth Plasmodium species infecting humans. Little experimental data exists on this mosquito species due to the lack of its availability in laboratories.
  4. Hamady D, Ruslan NB, Ahmad AH, Rawi CS, Ahmad H, Satho T, et al.
    Parasit Vectors, 2013;6:206.
    PMID: 23856274 DOI: 10.1186/1756-3305-6-206
    Mating is a physiological process of crucial importance underlying the size and maintenance of mosquito populations. In sterile and incompatible insect technologies (SIT and IIT), mating is essential for mass production, persistence, and success of released individuals, and is a central parameter for judging the effectiveness of SIT/IIT programs. Some mosquitoes have an enormous reproductive potential for both themselves and pathogens and mating may contribute to persistence of infection in nature. As Aedes albopictus can transmit flaviviruses both sexually and horizontally, and as infected insects are usually derived from laboratory colonies, we investigated the implications of mating between a long-term laboratory colony of Ae. albopictus and wild populations.
  5. Anwar A, Khan NA, Siddiqui R
    Parasit Vectors, 2018 01 09;11(1):26.
    PMID: 29316961 DOI: 10.1186/s13071-017-2572-z
    Acanthamoeba spp. are protist pathogens and causative agents of serious infections including keratitis and granulomatous amoebic encephalitis. Its ability to convert into dormant and highly resistant cysts form limits effectiveness of available therapeutic agents and presents a pivotal challenge for drug development. During the cyst stage, Acanthamoeba is protected by the presence of hardy cyst walls, comprised primarily of carbohydrates and cyst-specific proteins, hence synthesis inhibition and/or degradation of cyst walls is of major interest. This review focuses on targeting of Acanthamoeba cysts by identifying viable therapeutic targets.
  6. Andiappan H, Nissapatorn V, Sawangjaroen N, Nyunt MH, Lau YL, Khaing SL, et al.
    Parasit Vectors, 2014;7:564.
    PMID: 25498432 DOI: 10.1186/s13071-014-0564-9
    Toxoplasma gondii, an obligate intracellular protozoan parasite, causes a disease called toxoplasmosis which can sometimes be acquired congenitally by a newborn from an infected mother. This study aimed to determine the seroprevalence of Toxoplasma infection and its associated risks among 219 and 215 pregnant women from Malaysia and Myanmar, respectively.
  7. Ishak IH, Jaal Z, Ranson H, Wondji CS
    Parasit Vectors, 2015;8:181.
    PMID: 25888775 DOI: 10.1186/s13071-015-0797-2
    Knowledge on the extent, distribution and mechanisms of insecticide resistance is essential for successful insecticide-based dengue control interventions. Here, we report an extensive resistance profiling of the dengue vectors Aedes aegypti and Aedes albopictus across Malaysia and establish the contribution of knockdown resistance mechanism revealing significant contrast between both species.
  8. Trinachartvanit W, Maneewong S, Kaenkan W, Usananan P, Baimai V, Ahantarig A
    Parasit Vectors, 2018 Dec 27;11(1):670.
    PMID: 30587229 DOI: 10.1186/s13071-018-3259-9
    BACKGROUND: Coxiella bacteria were identified from various tick species across the world. Q fever is a zoonotic disease caused by the bacteria Coxiella burnetii that most commonly infects a variety of mammals. Non-mammalian hosts, such as birds, have also been reported to be infected with the pathogenic form of "Candidatus Coxiella avium". This research increases the list of tick species that have been found with Coxiella-like bacteria in Thailand.

    METHODS: A total of 69 ticks were collected from 27 domestic fowl (Gallus gallus domesticus), 2 jungle fowl (Gallus gallus) and 3 Siamese firebacks (Lophura diardi) at 10 locations (provinces) in Thailand. Ticks were identified and PCR was used to amplify Coxiella bacteria 16S rRNA, groEL and rpoB genes from the extracted tick DNA. MEGA6 was used to construct phylogenetic trees via a Maximum Likelihood method.

    RESULTS: The phylogenetic analysis based on the 16S rRNA gene showed that the Coxiella sequences detected in this study grouped in the same clade with Coxiella sequences from the same tick genus (or species) reported previously. In contrast, rpoB gene of the Coxiella bacteria detected in this study did not cluster together with the same tick genus reported previously. Instead, they clustered by geographical distribution (Thai cluster and Malaysian cluster). In addition, phylogenetic analysis of the groEL gene (the chaperonin family) showed that all Coxiella bacteria found in this study were grouped in the same clade (three sister groups).

    CONCLUSIONS: To our knowledge, we found for the first time rpoB genes of Coxiella-like bacteria in Haemaphysalis wellingtoni ticks forming two distinct clades by phylogenetic analysis. This may be indicative of a horizontal gene transfer event.

  9. Hew YX, Ya'cob Z, Adler PH, Chen CD, Lau KW, Sofian-Azirun M, et al.
    Parasit Vectors, 2023 Jul 22;16(1):248.
    PMID: 37480109 DOI: 10.1186/s13071-023-05875-1
    BACKGROUND: DNA barcoding is a valuable taxonomic tool for rapid and accurate species identification and cryptic species discovery in black flies. Indonesia has 143 nominal species of black flies, but information on their biological aspects, including vectorial capacity and biting habits, remains underreported, in part because of identification problems. The current study represents the first comprehensive DNA barcoding of Indonesian black flies using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences.

    METHODS: Genomic DNA of Indonesian black fly samples were extracted and sequenced, producing 86 COI sequences in total. Two hundred four COI sequences, including 118 GenBank sequences, were analysed. Maximum likelihood (ML) and Bayesian inference (BI) trees were constructed and species delimitation analyses, including ASAP, GMYC and single PTP, were performed to determine whether the species of Indonesian black flies could be delineated. Intra- and interspecific genetic distances were also calculated and the efficacy of COI sequences for species identification was tested.

    RESULTS: The DNA barcodes successfully distinguished most morphologically distinct species (> 80% of sampled taxa). Nonetheless, high maximum intraspecific distances (3.32-13.94%) in 11 species suggested cryptic diversity. Notably, populations of the common taxa Simulium (Gomphostilbia) cheongi, S. (Gomphostilbia) sheilae, S. (Nevermannia) feuerborni and S. (Simulium) tani in the islands of Indonesia were genetically distinct from those on the Southeast Asian mainland (Malaysia and Thailand). Integrated morphological, cytogenetic and nuclear DNA studies are warranted to clarify the taxonomic status of these more complex taxa.

    CONCLUSIONS: The findings showed that COI barcoding is a promising taxonomic tool for Indonesian black flies. The DNA barcodes will aid in correct identification and genetic study of Indonesian black flies, which will be helpful in the control and management of potential vector species.

  10. Lin C, Chen Z, Zhang L, Wei Z, Cheng KK, Liu Y, et al.
    Parasit Vectors, 2019 Jun 13;12(1):300.
    PMID: 31196218 DOI: 10.1186/s13071-019-3554-0
    BACKGROUND: Hepatic alveolar echinococcosis (HAE) is caused by the growth of Echinococcus multilocularis larvae in the liver. It is a chronic and potentially lethal parasitic disease. Early stage diagnosis for this disease is currently not available due to its long asymptomatic incubation period. In this study, a proton nuclear magnetic resonance (1H NMR)-based metabolomics approach was applied in conjunction with multivariate statistical analysis to investigate the altered metabolic profiles in blood serum and urine samples obtained from HAE patients. The aim of the study was to identify the metabolic signatures associated with HAE.

    RESULTS: A total of 21 distinct metabolic differences between HAE patients and healthy individuals were identified, and they are associated with perturbations in amino acid metabolism, energy metabolism, glyoxylate and dicarboxylate metabolism. Furthermore, the present results showed that the Fischer ratio, which is the molar ratio of branched-chain amino acids to aromatic amino acids, was significantly lower (P 

  11. Gan SJ, Leong YQ, Bin Barhanuddin MFH, Wong ST, Wong SF, Mak JW, et al.
    Parasit Vectors, 2021 Jun 10;14(1):315.
    PMID: 34112220 DOI: 10.1186/s13071-021-04785-4
    Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides remain the most effective vector control approach for Aedes mosquitoes. Four main classes of insecticides are widely used for mosquito control: organochlorines, organophosphates, pyrethroids and carbamates. Here, we review the distribution of dengue fever from 2000 to 2020 and its associated mortality in Southeast Asian countries, and we gather evidence on the trend of insecticide resistance and its distribution in these countries since 2000, summarising the mechanisms involved. The prevalence of resistance to these insecticides is increasing in Southeast Asia, and the mechanisms of resistance are reported to be associated with target site mutations, metabolic detoxification, reduced penetration of insecticides via the mosquito cuticle and behavioural changes of mosquitoes. Continuous monitoring of the status of resistance and searching for alternative control measures will be critical for minimising any unpredicted outbreaks and improving public health. This review also provides improved insights into the specific use of insecticides for effective control of mosquitoes in these dengue endemic countries.
  12. Uni S, Mat Udin AS, Agatsuma T, Junker K, Saijuntha W, Bunchom N, et al.
    Parasit Vectors, 2020 Feb 06;13(1):50.
    PMID: 32028994 DOI: 10.1186/s13071-020-3907-8
    BACKGROUND: The genus Onchocerca Diesing, 1841 includes species of medical importance, such as O. volvulus (Leuckart, 1893), which causes river blindness in the tropics. Recently, zoonotic onchocercosis has been reported in humans worldwide. In Japan, O. dewittei japonica Uni, Bain & Takaoka, 2001 from wild boars is a causative agent for this zoonosis. Many filarioid nematodes are infected with Wolbachia endosymbionts which exhibit various evolutionary relationships with their hosts. While investigating the filarial fauna of Borneo, we discovered an undescribed Onchocerca species in the bearded pig Sus barbatus Müller (Cetartiodactyla: Suidae).

    METHODS: We isolated Onchocerca specimens from bearded pigs and examined their morphology. For comparative material, we collected fresh specimens of O. d. dewittei Bain, Ramachandran, Petter & Mak, 1977 from banded pigs (S. scrofa vittatus Boie) in Peninsular Malaysia. Partial sequences of three different genes (two mitochondrial genes, cox1 and 12S rRNA, and one nuclear ITS region) of these filarioids were analysed. By multi-locus sequence analyses based on six genes (16S rDNA, ftsZ, dnaA, coxA, fbpA and gatB) of Wolbachia, we determined the supergroups in the specimens from bearded pigs and those of O. d. dewittei.

    RESULTS: Onchocerca borneensis Uni, Mat Udin & Takaoka n. sp. is described on the basis of morphological characteristics and its genetic divergence from congeners. Molecular characteristics of the new species revealed its close evolutionary relationship with O. d. dewittei. Calculated p-distance for the cox1 gene sequences between O. borneensis n. sp. and O. d. dewittei was 5.9%, while that between O. d. dewittei and O. d. japonica was 7.6%. No intraspecific genetic variation was found for the new species. Wolbachia strains identified in the new species and O. d. dewittei belonged to supergroup C and are closely related.

    CONCLUSIONS: Our molecular analyses of filarioids from Asian suids indicate that the new species is sister to O. d. dewittei. On the basis of its morphological and molecular characteristics, we propose to elevate O. d. japonica to species level as O. japonica Uni, Bain & Takaoka, 2001. Coevolutionary relationships exist between the Wolbachia strains and their filarial hosts in Borneo and Peninsular Malaysia.

  13. Hajissa K, Zakaria R, Suppian R, Mohamed Z
    Parasit Vectors, 2015;8:315.
    PMID: 26062975 DOI: 10.1186/s13071-015-0932-0
    Serological investigation remains the primary approach to achieve satisfactory results in Toxoplasma gondii identification. However, the accuracy of the native antigen used in the current diagnostic kits has proven to be insufficient as well as difficult to standardize, so significant efforts have been made to find alternative reagents as capture antigens. Consequently, multi-epitope peptides are promising diagnostic markers, with the potential for improving the accuracy of diagnostic kits. In this study, we described a simple, inexpensive and improved strategy to acquire such diagnostic markers. The study was aimed at producing novel synthetic protein consisting of multiple immunodominant epitopes of several T. gondii antigens.
  14. Benacer D, Mohd Zain SN, Sim SZ, Mohd Khalid MK, Galloway RL, Souris M, et al.
    Parasit Vectors, 2016;9:117.
    PMID: 26927873 DOI: 10.1186/s13071-016-1400-1
    Leptospirosis is an emerging infectious disease of global significance, and is endemic in tropical countries, including Malaysia. Over the last decade, a dramatic increase of human cases was reported; however, information on the primary vector, the rat, and the Leptospira serovars circulating among the rat population is limited. Therefore, the present study was undertaken to isolate Leptospira and characterise the serovars circulating in the urban rat populations from selected main cities in Peninsular Malaysia.
  15. Al-Delaimy AK, Al-Mekhlafi HM, Lim YA, Nasr NA, Sady H, Atroosh WM, et al.
    Parasit Vectors, 2014;7:416.
    PMID: 25179100 DOI: 10.1186/1756-3305-7-416
    This study was carried out to develop a health education learning package (HELP) about soil-transmitted helminth (STH) infections, and to evaluate what impact such a package could have in terms of reducing the incidence and intensity of STH infections among Orang Asli schoolchildren in Pahang, Malaysia.
  16. Marlina S, Shu MH, AbuBakar S, Zandi K
    Parasit Vectors, 2015;8:579.
    PMID: 26553263 DOI: 10.1186/s13071-015-1104-y
    The xCELLigence real-time cell analysis (RTCA) system is an established electronic cell sensor array. This system uses microelectronic biosensor technology that is verified for real-time, label-free, dynamic and non-offensive monitoring of cellular features, including detection of viral cytopathic effect (CPE). Screening viral replication inhibitors based on presence of CPE has been applied for different viruses, including chikungunya virus (CHIKV). However, most CPE-based methods, including MTT and MTS assays, do not provide information on the initiation of CPE nor the changes in reaction rate of the virus propagation over time. Therefore, in this study we developed an RTCA method as an accurate and time-based screen for antiviral compounds against CHIKV.
  17. Amir A, Cheong FW, De Silva JR, Lau YL
    Parasit Vectors, 2018 01 23;11(1):53.
    PMID: 29361963 DOI: 10.1186/s13071-018-2617-y
    Every year, millions of people are burdened with malaria. An estimated 429,000 casualties were reported in 2015, with the majority made up of children under five years old. Early and accurate diagnosis of malaria is of paramount importance to ensure appropriate administration of treatment. This minimizes the risk of parasite resistance development, reduces drug wastage and unnecessary adverse reaction to antimalarial drugs. Malaria diagnostic tools have expanded beyond the conventional microscopic examination of Giemsa-stained blood films. Contemporary and innovative techniques have emerged, mainly the rapid diagnostic tests (RDT) and other molecular diagnostic methods such as PCR, qPCR and loop-mediated isothermal amplification (LAMP). Even microscopic diagnosis has gone through a paradigm shift with the development of new techniques such as the quantitative buffy coat (QBC) method and the Partec rapid malaria test. This review explores the different diagnostic tools available for childhood malaria, each with their characteristic strengths and limitations. These tools play an important role in making an accurate malaria diagnosis to ensure that the use of anti-malaria are rationalized and that presumptive diagnosis would only be a thing of the past.
  18. Ngui R, Angal L, Fakhrurrazi SA, Lian YL, Ling LY, Ibrahim J, et al.
    Parasit Vectors, 2012;5:187.
    PMID: 22947430
    In this study, a total of 426 human faecal samples were examined for the presence of Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii infection via a combination of microscopic examination and nested polymerase chain reaction (PCR) targeting 16S ribosomal RNA of Entamoeba species.
  19. Takaoka H, Low VL, Sofian-Azirun M, Otsuka Y, Ya'cob Z, Chen CD, et al.
    Parasit Vectors, 2016;9:136.
    PMID: 26961508 DOI: 10.1186/s13071-016-1393-9
    A species of Simulium in the Simulium melanopus species-group of the subgenus Simulium (formerly misidentified as S. laterale Edwards from Sabah and Sarawak, Malaysia) is suspected to have dimorphic male scutal color patterns linked with different numbers of upper-eye facets. This study aimed to confirm whether or not these two forms of adult males represent a single species.
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