Displaying publications 1 - 20 of 56 in total

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  1. Abdullah NR, Furuta T, Taib R, Kita K, Kojima S, Wah MJ
    Am J Trop Med Hyg, 1996 Feb;54(2):162-3.
    PMID: 8619441
    We describe here a reverse transcriptase-polymerase chain reaction method for the detection of malaria parasites. Ten in vitro-cultured isolates of Plasmodium falciparum and 16 specimens from patients infected with P. falciparum were used to examine the specificity and sensitivity of the test. The sensitivity of the test was 0.3 parasites per microliter of blood. Specificity was determined by matching the sequences of the specimens' DNA to published sequences of 18S ribosomal RNA genes in the species-specific region. The test proved to be very sensitive and specific for the detection of P. falciparum infection.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  2. Tan LL, Lau TY, Timothy W, Prabakaran D
    ScientificWorldJournal, 2014;2014:935846.
    PMID: 25574497 DOI: 10.1155/2014/935846
    Chloroquine resistance (CQR) in falciparum malaria was identified to be associated with several mutations in the chloroquine resistance transporter gene (pfcrt) that encodes the transmembrane transporter in digestive vacuole membrane of the parasite. This study aimed to investigate the point mutations across the full-length pfcrt in Plasmodium falciparum isolates in Sabah, Malaysia. A total of 31 P. falciparum positive samples collected from Keningau, Kota Kinabalu, and Kudat, Sabah, were analyzed. pfcrt was PCR amplified and cloned prior to sequence analysis. This study showed that all the previously described 10 point mutations associated with CQR at codons 72, 74, 75, 76, 97, 220, 271, 326, 356, and 371 were found with different prevalence. Besides, two novel point mutations, I166V and H273N, were identified with 22.5% and 19.3%, respectively. Three haplotypes, namely, CVMNK (29%), CVIET (3.2%), and SVMNT (67.7%), were identified. High prevalence of SVMNT among P. falciparum isolates from Sabah showed that these isolates are closer to the P. falciparum isolates from Papua New Guinea rather than to the more proximal Southeast Asian CVIET haplotype. Full-length analysis of pfcrt showed that chloroquine resistant P. falciparum in Sabah is still prevalent despite the withdrawal of chloroquine usage since 1979.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  3. Sulaiman H, Ismail MD, Jalalonmuhali M, Atiya N, Ponnampalavanar S
    Malar J, 2014;13:341.
    PMID: 25176417 DOI: 10.1186/1475-2875-13-341
    This case report describes a case of presumed acute myocardial infarction in a returned traveler who was later diagnosed to have severe malaria. Emergency coronary angiography was normal and subsequent peripheral blood film was positive for Plasmodium falciparum.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  4. Parker D, Lerdprom R, Srisatjarak W, Yan G, Sattabongkot J, Wood J, et al.
    Malar J, 2012 Aug 21;11:290.
    PMID: 22908880 DOI: 10.1186/1475-2875-11-290
    BACKGROUND: Drug and multidrug-resistant Plasmodium falciparum malaria has existed in Thailand for several decades. Furthermore, Thailand serves as a sentinel for drug-resistant malaria within the Greater Mekong sub-region. However, the drug resistance situation is highly dynamic, changing quickly over time. Here parasite in vitro drug sensitivity is reported for artemisinin derivatives, mefloquine, chloroquine and quinine, across Thailand.

    METHODS: Blood was drawn from patients infected with P. falciparum in seven sentinel provinces along Thai international borders with Cambodia, Myanmar, Laos, and Malaysia. In vitro parasite sensitivity was tested using the World Health Organization's microtest (mark III) (between 1994 and 2002) and the histidine-rich protein-2 (HRP2)-based enzyme-linked immunosorbent assay (in 2010). Following World Health Organization protocol, at least 30 isolates were collected for each province and year represented in this study. Where possible, t-tests were used to test for significant differences.

    RESULTS: There appears to be little variation across study sites with regard to parasite sensitivity to chloroquine. Quinine resistance appears to have been rising prior to 1997, but has subsequently decreased. Mefloquine sensitivity appears high across the provinces, especially along the north-western border with Myanmar and the eastern border with Cambodia. Finally, the data suggest that parasite sensitivity to artemisinin and its derivatives is significantly higher in provinces along the north-western border with Myanmar.

    CONCLUSIONS: Parasite sensitivity to anti-malarials in Thailand is highly variable over time and largely mirrors official drug use policy. The findings with regard to reduced sensitivity to artemisinin derivatives are supported by recent reports of reduced parasite clearance associated with artemisinin. This trend is alarming since artemisinin is considered the last defence against malaria. Continued surveillance in Thailand, along with increased collaboration and surveillance across the entire Greater Mekong sub-region, is clearly warranted.

    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  5. Atroosh WM, Al-Mekhlafi HM, Al-Jasari A, Sady H, Al-Delaimy AK, Nasr NA, et al.
    Parasit Vectors, 2015;8:388.
    PMID: 26198252 DOI: 10.1186/s13071-015-1008-x
    The genetic variation in the Plasmodium falciparum histidine-rich protein 2 (pfhrp2) gene that may compromise the use of pfhrp2-based rapid diagnostic tests (RDTs) for the diagnosis of malaria was assessed in P. falciparum isolates from Yemen.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  6. Singh B, Bobogare A, Cox-Singh J, Snounou G, Abdullah MS, Rahman HA
    Am J Trop Med Hyg, 1999 Apr;60(4):687-92.
    PMID: 10348249
    A nested polymerase chain reaction (PCR) assay that uses Plasmodium genus-specific primers for the initial PCR (nest 1) amplification and either genus- or species-specific primers for the nest 2 amplifications was tested on laboratory and field samples. With in vitro cultured Plasmodium falciparum-infected blood samples, it was capable of detecting six parasites/microl of blood using DNA prepared from 25-microl blood spots on filter paper. The assay was evaluated on fingerprick blood samples collected on filter paper from 129 individuals living in a malaria-endemic area in Malaysia. Malaria prevalence by genus-specific nested PCR was 35.6% (46 of 129) compared with 28.7% (37 of 129) by microscopy. The nested PCR detected seven more malaria samples than microscopy in the first round of microscopic examination, malaria in three microscopically negative samples, six double infections identified as single infections by microscopy and one triple infection identified as a double infection by microscopy. The nested PCR assay described is a sensitive technique for collecting accurate malaria epidemiologic data. When coupled with simple blood spot sampling, it is particularly useful for screening communities in remote regions of the world.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  7. Ang HH, Chan KL, Mak JW
    Med Trop (Mars), 1996;56(4):349-51.
    PMID: 9112620
    Six clones were derived from each of five isolates of Malaysian Plasmodium falciparum and characterized with regard to susceptibility to schizontocidal drugs, chloroquine, mefloquine, and quinine. The 5 isolates were found to be resistant to chloroquine and sensitive to mefloquine and quinine. Most of the clones displayed susceptibility patterns similar to those of their parent isolate, except ST9/D8 clone which became sensitive to chloroquine, C/C10 and ST148/A5 clones which became resistant to mefloquine and to quinine respectively. This diversity in susceptibility to schizontocidal drugs would likely have been overlooked by assessment of natural uncloned isolates against antimalarial drugs.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  8. Hakim SL, Furuta T, Rain AN, Normaznah Y, Zamri MR, Kojima S, et al.
    Trans R Soc Trop Med Hyg, 1995 5 1;89(3):271-2.
    PMID: 7660430
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  9. Mathews HM, Dondero TJ
    Am J Trop Med Hyg, 1982 Jan;31(1):14-8.
    PMID: 7036766
    The indirect hemagglutination test was used to measure malaria antibody levels in residents of an endemic area of Malaysia. Blood specimens were collected at 4-week intervals for a year. Seropositivity rates increased with age and number of episodes of malaria in young children. Although antibody levels were variable, titers tended to rise with parasitemia and fall in the absence of detected parasites. In general, the serologic indices tended to reflect the parasitologic findings.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  10. Mathews HM, Dondero TJ
    Am J Trop Med Hyg, 1982 Jan;31(1):19-23.
    PMID: 7036769
    A cohort of 62 persons living in a malaria-endemic area was examined by serology and by blood film 14 times over a 56-week period. Serologic responses (indirect hemagglutination test) of the group as a whole reflected the malaria transmission as determined by blood slide examination. The serologic responses of individuals showed titer changes that were not always consistent with blood slide results. The use of chloroquine may have modified the host's immune response.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  11. Andre RG, Cadigan FC, Fredericks HJ, Fong YL
    Trans R Soc Trop Med Hyg, 1972;66(4):644-52.
    PMID: 4561008
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  12. Lee M, Harrison BA, Lewis GE
    Am J Trop Med Hyg, 1990 Apr;42(4):314-9.
    PMID: 2184690 DOI: 10.4269/ajtmh.1990.42.314
    A modified version of the standard 2-site sporozoite enzyme-linked immunosorbent assay (ELISA) using 3,3',5,5'-tetramethylbenzidine (TMB) as the substrate chromogen solution was adapted for rapid detection and identification of Plasmodium falciparum and P. vivax circumsporozoite (CS) proteins. The TMB-ELISA was evaluated using sporozoites from experimentally infected mosquitoes and laboratory colonized uninfected mosquitoes. Our data indicate comparable sensitivity levels between the TMB-ELISA and the standard ELISA, i.e., 50 P. falciparum or P. vivax sporozoites/50 microliters of test solution. Reactions inherent to the method were specific and background reactivity was minimal. The TMB-ELISA is rapid (1 hr), simple, uses a minimal amount of monoclonal antibodies, and is suitable for use in a wide range of laboratories.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification*
  13. Lambros C, Davis DR, Lewis GE
    Am J Trop Med Hyg, 1989 Jul;41(1):3-8.
    PMID: 2669543 DOI: 10.4269/ajtmh.1989.41.1.TM0410010003
    The drug susceptibility of 70 isolates of Plasmodium falciparum to standard and experimental antimalarials was evaluated using a radioisotope microdilution method. All isolates were from forest fringe dwelling Orang Asli, the aborigines of Peninsular Malaysia. The geometric mean IC50 values were: chloroquine, 10 ng/ml; amodiaquine, 4.7 ng/ml; mefloquine, 2.8 ng/ml; quinine, 40.5 ng/ml; halofantrine, 1.5 ng/ml; enpiroline, 3 ng/ml; and pyrimethamine, 21 ng/ml. Four isolates exhibited decreased susceptibility to chloroquine (IC50 greater than 60 ng/ml), and one exhibited decreased susceptibility to quinine (IC50 = 161 ng/ml). Three isolates showed decreased susceptibility to mefloquine (IC50 = 10-11 ng/ml). The lack of drug pressure may account for the high prevalence of P. falciparum isolates susceptible to chloroquine.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  14. Gitaka JN, Takeda M, Kimura M, Idris ZM, Chan CW, Kongere J, et al.
    Malar J, 2017 03 02;16(1):98.
    PMID: 28253868 DOI: 10.1186/s12936-017-1743-x
    BACKGROUND: Plasmodium falciparum SURFIN4.1is a putative ligand expressed on the merozoite and likely on the infected red blood cell, whose gene was suggested to be under directional selection in the eastern Kenyan population, but under balancing selection in the Thai population. To understand this difference, surf4.1sequences of western Kenyan P. falciparum isolates were analysed. Frameshift mutations and copy number variation (CNV) were also examined for the parasites from western Kenya and Thailand.

    RESULTS: Positively significant departures from neutral expectations were detected on the surf4.1region encoding C-terminus of the variable region 2 (Var2) by 3 population-based tests in the western Kenyan population as similar in the Thai population, which was not covered by the previous analysis for eastern Kenyan population. Significant excess of non-synonymous substitutions per nonsynonymous site over synonymous substitutions per synonymous site was also detected in the Var2 region. Negatively significant departures from neutral expectations was detected on the region encoding Var1 C-terminus consistent to the previous observation in the eastern Kenyan population. Parasites possessing a frameshift mutation resulting a product without intracellular Trp-rich (WR) domains were 22/23 in western Kenya and 22/36 in Thailand. More than one copy of surf4.1gene was detected in western Kenya (4/24), but no CNV was found in Thailand (0/36).

    CONCLUSIONS: The authors infer that the high polymorphism of SURFIN4.1Var2 C-terminus in both Kenyan and Thai populations were shaped-up by diversifying selection and maintained by balancing selection. These phenomena were most likely driven by immunological pressure. Whereas the SURFIN4.1Var1 C-terminus is suggested to be under directional selection consistent to the previous report for the eastern Kenyan population. Most western Kenyan isolates possess a frameshift mutation that would limit the expression of SURFIN4.1on the merozoite, but only 60% of Thai isolates possess this frameshift, which would affect the level and type of the selection pressure against this protein as seen in the two extremities of Tajima's D values for Var1 C-terminus between Kenyan and Thai populations. CNV observed in Kenyan isolates may be a consequence of this frameshift mutation to increase benefits on the merozoite surface.

    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  15. Foster D, Cox-Singh J, Mohamad DS, Krishna S, Chin PP, Singh B
    Malar J, 2014;13:60.
    PMID: 24548805 DOI: 10.1186/1475-2875-13-60
    Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, infects humans and can cause fatal malaria. It is difficult to diagnose by microscopy because of morphological similarity to Plasmodium malariae. Nested PCR assay is the most accurate method to distinguish P. knowlesi from other Plasmodium species but is not cost effective in resource-poor settings. Rapid diagnostic tests (RDTs) are recommended for settings where malaria is prevalent. In this study, the effectiveness of three RDTs in detecting P. knowlesi from fresh and frozen patient blood samples was evaluated.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  16. Fatih FA, Staines HM, Siner A, Ahmed MA, Woon LC, Pasini EM, et al.
    Malar J, 2013;12:425.
    PMID: 24245918 DOI: 10.1186/1475-2875-12-425
    Evidence suggests that Plasmodium knowlesi malaria in Sarawak, Malaysian Borneo remains zoonotic, meaning anti-malarial drug resistance is unlikely to have developed in the absence of drug selection pressure. Therefore, adequate response to available anti-malarial treatments is assumed.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  17. Atroosh WM, Al-Mekhlafi HM, Mahdy MA, Saif-Ali R, Al-Mekhlafi AM, Surin J
    Parasit Vectors, 2011;4:233.
    PMID: 22166488 DOI: 10.1186/1756-3305-4-233
    Malaria is still a public health problem in Malaysia especially in the interior parts of Peninsular Malaysia and the states of Sabah and Sarawak (East Malaysia). This is the first study on the genetic diversity and genotype multiplicity of Plasmodium falciparum in Malaysia.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  18. William T, Rahman HA, Jelip J, Ibrahim MY, Menon J, Grigg MJ, et al.
    PLoS Negl Trop Dis, 2013;7(1):e2026.
    PMID: 23359830 DOI: 10.1371/journal.pntd.0002026
    BACKGROUND: The simian parasite Plasmodium knowlesi is a common cause of human malaria in Malaysian Borneo and threatens the prospect of malaria elimination. However, little is known about the emergence of P. knowlesi, particularly in Sabah. We reviewed Sabah Department of Health records to investigate the trend of each malaria species over time.

    METHODS: Reporting of microscopy-diagnosed malaria cases in Sabah is mandatory. We reviewed all available Department of Health malaria notification records from 1992-2011. Notifications of P. malariae and P. knowlesi were considered as a single group due to microscopic near-identity.

    RESULTS: From 1992-2011 total malaria notifications decreased dramatically, with P. falciparum peaking at 33,153 in 1994 and decreasing 55-fold to 605 in 2011, and P. vivax peaking at 15,857 in 1995 and decreasing 25-fold to 628 in 2011. Notifications of P. malariae/P. knowlesi also demonstrated a peak in the mid-1990s (614 in 1994) before decreasing to ≈ 100/year in the late 1990s/early 2000s. However, P. malariae/P. knowlesi notifications increased >10-fold between 2004 (n = 59) and 2011 (n = 703). In 1992 P. falciparum, P. vivax and P. malariae/P. knowlesi monoinfections accounted for 70%, 24% and 1% respectively of malaria notifications, compared to 30%, 31% and 35% in 2011. The increase in P. malariae/P. knowlesi notifications occurred state-wide, appearing to have begun in the southwest and progressed north-easterly.

    CONCLUSIONS: A significant recent increase has occurred in P. knowlesi notifications following reduced transmission of the human Plasmodium species, and this trend threatens malaria elimination. Determination of transmission dynamics and risk factors for knowlesi malaria is required to guide measures to control this rising incidence.

    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  19. Vythilingam I, Sidavong B, Chan ST, Phonemixay T, Vanisaveth V, Sisoulad P, et al.
    Trans R Soc Trop Med Hyg, 2005 Nov;99(11):833-9.
    PMID: 16112154
    Surveys were conducted in malaria-endemic villages in the southern province of Attapeu, Lao PDR during various seasons over a 3-year period. All-night mosquito landing collections, blood surveys and a case-control study were conducted. Plasmodium falciparum was the predominant species, and slide positivity rates were higher during the transition/dry season compared with the wet season. Anopheles dirus A was found to be the primary vector, and sporozoite rates were highest during the transition/dry season. Anopheles dirus was found to be endophagic and endophilic. Not using insecticide-treated bed nets, houses close to breeding sites and sleeping away from home were risk factors associated with malaria.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  20. Cox-Singh J, Zakaria R, Abdullah MS, Rahman HA, Nagappan S, Singh B
    Am J Trop Med Hyg, 2001 6 27;64(1-2):28-31.
    PMID: 11425158
    Dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr) alleles were typed in 67 Malaysian Plasmodium falciparum isolates. The isolates were collected from two geographically distinct locations: 51 from Sabah, Malaysian Borneo, where sulfadoxine/pyrimethamine (SDX/PYR) is used to treat uncomplicated malaria and 16 from Peninsular Malaysia where in vivo resistance to SDX/PYR has been reported. A total of seven dhps alleles were identified with no significant difference in allele frequency between the 2 populations. Two of the dhps alleles described here have not been previously reported. Four dhfr alleles were detected in 67 P. falciparum isolates. Eighty-seven percent of the isolates from the Peninsula, where clinical SDX/PYR failure has been reported, had dhfr alleles with triple point mutations while all of the isolates from Sabah had dhfr alleles with 2 or less point mutations. The difference in dhfr allele frequency between the two populations was highly significant. There was no correlation between in vitro PYR response and accumulation of dhfr point mutations.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
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