Displaying publications 1 - 20 of 176 in total

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  1. Fornace KM, Alexander N, Abidin TR, Brock PM, Chua TH, Vythilingam I, et al.
    Elife, 2019 10 22;8.
    PMID: 31638575 DOI: 10.7554/eLife.47602
    Human movement into insect vector and wildlife reservoir habitats determines zoonotic disease risks; however, few data are available to quantify the impact of land use on pathogen transmission. Here, we utilise GPS tracking devices and novel applications of ecological methods to develop fine-scale models of human space use relative to land cover to assess exposure to the zoonotic malaria Plasmodium knowlesi in Malaysian Borneo. Combining data with spatially explicit models of mosquito biting rates, we demonstrate the role of individual heterogeneities in local space use in disease exposure. At a community level, our data indicate that areas close to both secondary forest and houses have the highest probability of human P. knowlesi exposure, providing quantitative evidence for the importance of ecotones. Despite higher biting rates in forests, incorporating human movement and space use into exposure estimates illustrates the importance of intensified interactions between pathogens, insect vectors and people around habitat edges.
    Matched MeSH terms: Malaria/parasitology
  2. Navien TN, Yeoh TS, Anna A, Tang TH, Citartan M
    World J Microbiol Biotechnol, 2021 Jul 09;37(8):131.
    PMID: 34240263 DOI: 10.1007/s11274-021-03097-0
    Mosquito-borne diseases are a major threat to public health. The shortcomings of diagnostic tools, especially those that are antibody-based, have been blamed in part for the rising annual morbidity and mortality caused by these diseases. Antibodies harbor a number of disadvantages that can be clearly addressed by aptamers as the more promising molecular recognition elements. Aptamers are defined as single-stranded DNA or RNA oligonucleotides generated by SELEX that exhibit high binding affinity and specificity against a wide variety of target molecules based on their unique structural conformations. A number of aptamers were developed against mosquito-borne pathogens such as Dengue virus, Zika virus, Chikungunya virus, Plasmodium parasite, Francisella tularensis, Japanese encephalitis virus, Venezuelan equine encephalitis virus, Rift Valley fever virus and Yellow fever virus. Intrigued by these achievements, we carry out a comprehensive overview of the aptamers developed against these mosquito-borne infectious agents. Characteristics of the aptamers and their roles in diagnostic, therapeutic as well as other applications are emphasized.
    Matched MeSH terms: Malaria/parasitology
  3. Thomas V, Hock SK, Leng YP
    Trop Doct, 1981 Oct;11(4):149-54.
    PMID: 7027557
    A seroepidemiological study was carried out on Orang Asli (Aborigines) children who lead a semi-nomadic life in the deep jungles of Ulu Kelantan, Malaysia. Out of a total of about 190 children below 14 years, 143 were studied. Blood was collected from finger pricks on standard "strip type" filter papers for indirect fluorescent antibody (IFA) tests with Plasmodium falciparum antigen. A positive reaction at 1:10 dilution in infants and young children was considered positive and the reasons are given. The P. falciparum antibody prevalence rate was 84.6% compared to 81.8% spleen and 43.4% parasite rates. Both P. Falciparum and P. vivax were present in children. The age-specific patterns of antibody, spleen and parasite rates were those of a hyperendemic community. There was a positive correlation between antibody and spleen rates up to the age of 9 years. In older children, the antibody rates increased while the spleen and the parasite rates dropped.
    Matched MeSH terms: Malaria/parasitology
  4. Azidah AK, Mohd Faizal MA, Lili HY, Zeehaida M
    Trop Biomed, 2014 Mar;31(1):31-5.
    PMID: 24862042 MyJurnal
    Plasmodium knowlesi has been recently identified as the "fifth human malaria species" following the discovery in Malaysian Borneo of a large focus of this simian malaria parasite in humans. Even though it shares microscopic similarities with Plasmodium malariae, it may cause severe illness with risk of fatality. We describe a case of P. knowlesi infection causing multi-organ failure in a patient who was successfully managed due to early recognition of the infection. Clinicians in this region should be more aware of the infection as it is not as rare as previously thought. This case write up highlight the case of severe malaria infection which presented with multi organ involvement which is caused by P. knowlesi.
    Matched MeSH terms: Malaria/parasitology
  5. Azira NM, Zairi NZ, Amry AR, Zeehaida M
    Trop Biomed, 2012 Sep;29(3):398-404.
    PMID: 23018503 MyJurnal
    Plasmodium knowlesi is a simian malaria parasite and is recently recognized as the fifth malaria parasite infecting humans. Manifestation of the infection may resemble other infection particularly dengue fever leading to inappropriate management and delay in treatment. We reported three cases of naturally acquired P. knowlesi in Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Clinical manifestations were quite similar in those cases. Microscopically, the diagnosis might be challenging. These cases were confirmed by polymerase chain reaction method which serves as a gold standard.
    Matched MeSH terms: Malaria/parasitology
  6. Fong MY, Lau YL, Chin LC, Al-Mekhlafi AM
    Trop Biomed, 2011 Aug;28(2):457-63.
    PMID: 22041769
    The cytochrome oxidase subunit I (COXI) gene sequences of three recent (2007-2008) clinical Plasmodium knowlesi isolates from Klang Valley, peninsular Malaysia, were determined and compared with those of older (1960's) peninsular Malaysia, recent isolates from Sarawak (on Borneo Island), and an isolate from Thailand. Multiple alignment of the sequences showed that the three clinical isolates were more similar to the older peninsular Malaysia isolates than to those from Sarawak and Thailand. Phylogenetic tree based on the COXI sequences revealed three distinct clusters of P. knowlesi. The first cluster consisted of isolates from peninsular Malaysia, the second consisted of Sarawak isolates and the third composed of the Thailand isolate. The findings of this study highlight the usefulness of mitochondrial COXI gene as a suitable marker for phylogeographic studies of P. knowlesi.
    Matched MeSH terms: Malaria/parasitology
  7. Abdulsalam M Q AM, Mohammed A K M, Ahmed A A, Fong MY
    Trop Biomed, 2010 Dec;27(3):551-8.
    PMID: 21399597 MyJurnal
    Malaria remains a major public health problem causing mortality and morbidity in tropical and subtropical countries. A cross-sectional study was carried out to determine malaria prevalence and its clinical pattern during malaria season in Yemen. Blood samples were collected from 511 patients with fever who voluntary participated in this study, of them 268 were males and 242 females. Malaria was screened using Giemsa-stained thick and thin blood films. Clinical profile was recorded through physical and laboratory examinations and biodata were collected by pre-tested standard questionnaire. The overall prevalence was 15.3%. Three malaria species (Plasmodium falciparum, Plasmodium vivax and Plasmodium malarae) were detected with the predominance of P. falciparum (83.33%). People living in the rural areas had higher infection rate compared to urban areas (p < 0.005). Children were at higher risk of developing severe malaria compared to adults (p < 0.05). Severe anaemia, respiratory distress, jaundice, convulsion and bleeding were more apparent among younger age groups of malaria cases compared to older children. The study indicates that malaria is still a public health problem with children being at high risk of developing severe malaria which may lead to death.
    Matched MeSH terms: Malaria/parasitology
  8. Nurul Aiezzah Z, Noor E, Hasidah MS
    Trop Biomed, 2010 Dec;27(3):624-31.
    PMID: 21399604 MyJurnal
    Malaria, caused by the Plasmodium parasite is still a health problem worldwide due to resistance of the pathogen to current anti-malarials. The search for new anti-malarial agents has become more crucial with the emergence of chloroquine-resistant Plasmodium falciparum strains. Protein kinases such as mitogen-activated protein kinase (MAPK), MAPK kinase, cyclin-dependent kinase (CDK) and glycogen synthase kinase- 3(GSK-3) of parasitic protozoa are potential drug targets. GSK-3 is an enzyme that plays a vital role in multiple cellular processes, and has been linked to pathogenesis of several diseases such as type II diabetes and Alzheimer's disease. In the present study, the antiplasmodial property of LiCl, a known GSK-3 inhibitor, was evaluated in vivo for its antimalarial effect against mice infected with Plasmodium berghei. Infected ICR mice were intraperitoneally administered with LiCl for four consecutive days before (prophylactic test) and after (suppressive test) inoculation of P. berghei-parasitised erythrocytes. Results from the suppressive test (post-infection LiCl treatment) showed inhibition of erythrocytic parasitemia development by 62.06%, 85.67% and 85.18% as compared to nontreated controls for the 100 mg/kg, 300 mg/kg and 600 mg/kg dosages respectively. Both 300 mg/kg and 600 mg/kg LiCl showed similar significant (P<0.05) suppressive values to that obtained with chloroquine-treated mice (86% suppression). The prophylactic test indicated a significantly (P<0.05) high protective effect on mice pre-treated with LiCl with suppression levels relatively comparable to chloroquine (84.07% and 86.26% suppression for the 300 mg/kg and 600 mg/kg LiCl dosages respectively versus 92.86% suppression by chloroquine). In both the suppressive and prophylactic tests, LiCl-treated animals survived longer than their non-treated counterparts. Mortality of the non-treated mice was 100% within 6 to 7 days of parasite inoculation whereas mice administered with LiCl survived beyond 9 days. Healthy non-infected mice administered with 600 mg/ kg LiCl for four consecutive days also showed decreased mortality compared to animals receiving lower doses of LiCl; three of the seven mice intraperitoneally injected with the former dose of LiCl did not survive more than 24 h after administration of LiCl whereas animals given the lower LiCl doses survived beyond four days of LiCl administration. To date, no direct evidence of anti-malarial activity in vivo or in vitro has been reported for LiCl. Evidence of anti-plasmodial activity of lithium in a mouse infection model is presented in this study.
    Matched MeSH terms: Malaria/parasitology
  9. Vythilingam I
    Trop Biomed, 2010 Apr;27(1):1-12.
    PMID: 20562807 MyJurnal
    Plasmodium knowlesi in humans is life threatening, is on the increase and has been reported from most states in Malaysia. Anopheles latens and Anopheles cracens have been incriminated as vectors. Malaria is now a zoonoses and is occurring in malaria free areas of Malaysia. It is also a threat to eco-tourism. The importance of the vectors and possible control measures is reviewed here.
    Matched MeSH terms: Malaria/parasitology*
  10. Melo JO, Padilha MAO, Barbosa RTA, Alonso WJ, Vittor AY, Laporta GZ
    Trop Biomed, 2020 Jun;37(2):513-535.
    PMID: 33235398
    After a centenary fight against malaria, Brazil has seen an opportunity for change with the proposal of the malaria elimination policy set by the Brazilian government, in line with malaria elimination policies in other Latin American countries. Brazilian malaria experts regard eliminating malaria by 2030 to be within reach. Herein we evaluated the likelihood that malaria elimination can be accomplished in Brazil through systematic review of the literature on malaria elimination in Brazil and epidemiological analysis. Fifty-two articles referring to malaria eradication/elimination in Brazil were analyzed to identify challenges and technological breakthroughs for controlling malaria. Monthly deaths (1979-2016) and monthly severe malaria cases (1998-2018) were analyzed according to age groups, geographic region and parasite species. As a result, we observed that the declining malaria burden was mostly attributable to a decline in Plasmodium falciparum-malaria. At the same time, the proportional increase of Plasmodium vivax-malaria in comparison with P. falciparum-malaria was notable. This niche replacement mechanism was discussed in the reviewed literature. In addition, the challenges to P. vivax-malaria elimination outnumbered the available technological breakthroughs. Although accumulated and basic information exists on mosquito vector biology, the lack of specific knowledge about mosquito vector taxonomy and ecology may hamper current attempts at stopping malaria in the country. An impressive reduction in malaria hospitalizations and mortality was seen in Brazil in the past 3 decades. Eliminating malaria deaths in children less than 5 years and P. falciparum severe cases may be achievable goals under the current malaria policy until 2030. However, eliminating P. vivax malaria transmission and morbidity seems unattainable with the available tools. Therefore, complete malaria elimination in Brazil in the near future is unlikely.
    Matched MeSH terms: Malaria/parasitology
  11. Mohd Ridzuan MA, Sow A, Noor Rain A, Mohd Ilham A, Zakiah I
    Trop Biomed, 2007 Jun;24(1):111-8.
    PMID: 17568384 MyJurnal
    Eurycoma longifolia, locally known as 'Tongkat Ali' is a popular local medicinal plant that possess a lot of medicinal properties as claimed traditionally, especially in the treatment of malaria. The claims have been proven scientifically on isolated compounds from the plant. The present study is to investigate the anti malaria properties of Eurycoma longifolia standardized extract (root) (TA164) alone and in combination with artemisinin in vivo. Combination treatment of the standardized extract (TA164) with artemisinin suppressed P. yoelii infection in the experimental mice. The 4 day suppressive test showed that TA164 suppressed the parasitemia of P. yoelii-infected mice as dose dependent manner (10, 30 and 60 mg/kg BW) by oral and subcutaneous treatment. By oral administration, combination of TA164 at 10, 30 and 60 mg/kg BW each with artemisinin respectively showed a significant increase in the parasitemia suppression to 63, 67 and 80 percent as compared to artemisinin single treatment (31%). Using subcutaneous administration, at 10 mg/kg BW of TA164 in combination with 1.7 mg/kg BW of artemisinin gave a suppression of 80% of infection. This study showed that combination treatment of TA164 with artemisinin gives a promising potential anti malaria candidate using both oral and subcutaneous route, the later being the most potent.
    Matched MeSH terms: Malaria/parasitology
  12. Ng YL, Fong MY, Lau YL
    Trop Biomed, 2021 Jun 01;38(2):159-164.
    PMID: 34172705 DOI: 10.47665/tb.38.2.052
    The Plasmodium knowlesi apical membrane antigen-1 (PkAMA-1) plays an important role in the invasion of the parasite into its host erythrocyte, and it has been regarded as a potential vaccine candidate against human knowlesi malaria. This study investigates genetic diversity and natural selection of the full length PkAMA-1 of P. knowlesi clinical isolates from Peninsular Malaysia. Blood samples were collected from P. knowlesi malaria patients from Peninsular Malaysia. The PkAMA-1 gene was amplified from DNA samples using PCR, cloned into a plasmid vector and sequenced. Results showed that nucleotide diversity of the full length PkAMA-1 from Peninsular Malaysia isolates (π: 0.006) was almost similar to that of Sarawak (π: 0.005) and Sabah (π: 0.004) isolates reported in other studies. Deeper analysis revealed Domain I (π: 0.007) in the PkAMA-1 had the highest diversity as compared to Domain II (π: 0.004) and Domain III (π: 0.003). Z-test indicated negative (purifying) selection of the gene. Combined alignment analysis at the amino acid level for the Peninsular Malaysia and Sarawak PkAMA-1 sequences revealed 34 polymorphic sites. Thirty-one of these sites were dimorphic, and 3 were trimorphic. The amino acid sequences could be categorised into 31 haplotypes. In the haplotype network, PkAMA-1 from Peninsular Malaysia and Sarawak were separated into two groups.
    Matched MeSH terms: Malaria/parasitology
  13. Thomas V, Chan WC
    Trop Geogr Med, 1982 Jun;34(2):145-9.
    PMID: 6750883
    Matched MeSH terms: Malaria/parasitology
  14. Cooper DJ, Plewes K, Grigg MJ, Rajahram GS, Piera KA, William T, et al.
    Trials, 2018 Apr 24;19(1):250.
    PMID: 29690924 DOI: 10.1186/s13063-018-2600-0
    BACKGROUND: Plasmodium knowlesi is the most common cause of human malaria in Malaysia. Acute kidney injury (AKI) is a frequent complication. AKI of any cause can have long-term consequences, including increased risk of chronic kidney disease, adverse cardiovascular events and increased mortality. Additional management strategies are therefore needed to reduce the frequency and severity of AKI in malaria. In falciparum malaria, cell-free haemoglobin (CFHb)-mediated oxidative damage contributes to AKI. The inexpensive and widely available drug paracetamol inhibits CFHb-induced lipid peroxidation via reduction of ferryl haem to the less toxic Fe3+ state, and has been shown to reduce oxidative damage and improve renal function in patients with sepsis complicated by haemolysis as well as in falciparum malaria. This study aims to assess the ability of regularly dosed paracetamol to reduce the incidence and severity of AKI in knowlesi malaria by attenuating haemolysis-induced oxidative damage.

    METHODS: PACKNOW is a two-arm, open-label randomised controlled trial of adjunctive paracetamol versus no paracetamol in patients aged ≥ 5 years with knowlesi malaria, conducted over a 2-year period at four hospital sites in Sabah, Malaysia. The primary endpoint of change in creatinine from enrolment to 72 h will be evaluated by analysis of covariance (ANCOVA) using enrolment creatinine as a covariate. Secondary endpoints include longitudinal changes in markers of oxidative stress (plasma F2-isoprostanes and isofurans) and markers of endothelial activation/Weibel-Palade body release (angiopoietin-2, von Willebrand Factor, P-selectin, osteoprotegerin) over 72 h, as well as blood and urine biomarkers of AKI. This study will be powered to detect a difference between the two treatment arms in a clinically relevant population including adults and children with knowlesi malaria of any severity.

    DISCUSSION: Paracetamol is widely available and has an excellent safety profile; if a renoprotective effect is demonstrated, this trial will support the administration of regularly dosed paracetamol to all patients with knowlesi malaria. The secondary outcomes in this study will provide further insights into the pathophysiology of haemolysis-induced oxidative damage and acute kidney injury in knowlesi malaria and other haemolytic diseases.

    TRIAL REGISTRATION: Clinicaltrials.gov, NCT03056391 . Registered on 12 October 2016.

    Matched MeSH terms: Malaria/parasitology
  15. 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: Malaria/parasitology
  16. Cox-Singh J, Singh B
    Trends Parasitol, 2008 Sep;24(9):406-10.
    PMID: 18678527 DOI: 10.1016/j.pt.2008.06.001
    Several questions on public health impact have arisen from the discovery of a large focus of the simian malaria parasite, Plasmodium knowlesi, in the human population. P. knowlesi malaria is not newly emergent and was overlooked until molecular tools to distinguish between P. knowlesi and the morphologically similar Plasmodium malariae became available. Knowlesi malaria is a zoonosis that is widely distributed in Southeast Asia and can be fatal. Information on knowlesi malaria should be included in medical and public health guidelines to encourage the accurate diagnosis and treatment of patients, and monitor the incidence and distribution of cases. A complete emergence of P. knowlesi into the human population could be overwhelming and, although challenging, the prevention of this situation deserves serious consideration.
    Matched MeSH terms: Malaria/parasitology*
  17. Singh B, Cox-Singh J, Miller AO, Abdullah MS, Snounou G, Rahman HA
    Trans R Soc Trop Med Hyg, 1996 9 1;90(5):519-21.
    PMID: 8944260
    A modified nested polymerase chain reaction (PCR) method for detection of Plasmodium falciparum, P. vivax and P. malariae was combined with a simple blood collection and deoxyribonucleic acid (DNA) extraction method and evaluated in Malaysia. Finger-prick blood samples from 46 hospital patients and 120 individuals living in malaria endemic areas were spotted on filter papers and dried. The simple Chelex method was used to prepare DNA templates for the nested PCR assay. Higher malaria prevalence rates for both clinical (78.2%) and field samples (30.8%) were obtained with the nested PCR method than by microscopy (76.1% and 27.5%, respectively). Nested PCR was more sensitive than microscopy in detecting mixed P. falciparum and P. vivax infections, detected 5 more malaria samples than microscopy on the first round of microscopical examination, and detected malaria in 3 microscopically negative samples. Nested PCR failed to detect parasite DNA in 2 microscopically positive samples, an overall sensitivity of 97.4% compared to microscopy. The nested PCR method, when coupled with simple dried blood spot sampling, is a useful tool for collecting accurate malaria epidemiological data, particularly in remote regions of the world.
    Matched MeSH terms: Malaria/parasitology
  18. Jamaiah I, Rohela M, Nissapatorn V, Khoo BL, Khoo PS, Radhiyah M, et al.
    PMID: 16438181
    Malaria is still one of the most important vector-borne diseases in Malaysia, particularly in remote areas. This retrospective study was carried out to find the prevalence of malaria among patients admitted to UMMC Kuala Lumpur, from 1994-2003. A total of 86 malaria cases were analyzed. Most cases occurred among foreigners [57% (49 cases)] while Malaysians constituted 43% (37 cases). Among foreigners, Indonesians constituted the most [57% (28 cases)]. Among Malaysians, most cases occurred among the Chinese [35% (13 cases)] followed by the Malays [30% (11 cases)]. Males [70%(60 cases)] were more commonly affected. The majority of cases were within the 20-39 year age group (69%). Three species of malaria parasites were reported, of which Plasmodium vivax constituted the most [55%( 47 cases)], followed by Plasmodium falciparum [29% (25 cases)], and only four cases (5%) of Plasmodium malariae. Nine percent (8 cases) were mixed infections. In this study, 12%(10 cases) developed chloroquine resistance: 7 cases of P. falciparum, and 3 cases of P. vivax. The most common complications were jaundice and anemia [77% (23 cases)], followed by blackwater fever [13% (4 cases)] and cerebral malaria [10% (3 cases)]. Most of the complications were due to P. falciparum [43% (13 cases)]. There were no reported deaths. This new source of malaria coming from foreigners must be given serious attention, as it has great potential of increasing malaria cases in urban Malaysia.
    Matched MeSH terms: Malaria/parasitology
  19. Ali WN, Ahmad R, Nor ZM, Ismail Z, Ibrahim MN, Hadi AA, et al.
    PMID: 23413702
    Many of the most widely spread vector-borne diseases are water related, in that the mosquito vectors concerned breed or pass part of their lifecycle in or close to water. A major reason for the study of mosquito larval ecology is to gather information on environmental variables that may determine the species of mosquitoes and the distribution of larvae in the breeding habitats. Larval surveillance studies were conducted six times between May 2008 and October 2009 in Pos Lenjang, Kuala Lipis, Pahang. Twelve environmental variables were recorded for each sampling site, and samples of mosquito larvae were collected. Larval survey studies showed that anopheline and culicine larvae were collected from 79 and 67 breeding sites, respectively. All breeding sites were classified into nine habitat groups. Culicine larvae were found in all habitat groups, suggesting that they are very versatile and highly adaptable to different types of environment. Rock pools or water pockets with clear water formed on the bank of rivers and waterfalls were the most common habitats associated with An. maculatus. Environmental variables influence the suitability of aquatic habitats for anopheline and culicine larvae, but not significantly associated with the occurrence of both larvae genera (p>0.05). This study provides information on mosquito ecology in relation to breeding habitats that will be useful in designing and implementing larval control operations.
    Matched MeSH terms: Malaria/parasitology
  20. Sermwittayawong N, Nishibuchi M, Sawangjaroen N, Vuddhakul V
    PMID: 26867373
    During 2009 to 2010, a total of 408 blood samples collected from malaria patients in Ranong (149) and Yala (259) Provinces, Thailand were investigated for Plasmodium spp using microscopic examination. There are no statistical differences in the prevalence of P. falciparum and P. vivax in samples collected from Ranong and Yala (46% vs 52%, and 54% vs 45%, respectively). Single nucleotide polymorphism of codon 86 in pfmdr1 (encoding P. falciparum multidrug resistance protein 1) was investigated among 75 samples of P. falciparum and 2 samples of P. knowlesi. A pfmdr1 N86Y mutation was detected in 1 out of 29 samples and 45 out of 46 samples obtained from Ranong and Yala Provinces, respectively. It is interesting that pfmdr1 was detected in two P. knowlesi DNA samples obtained previously from Ranong Province which was 99% homologous to pfmdr1 obtained from falciparum parasites in the same area but the mutation was not observed. The difference in multidrug resistance protein in Plasmodium obtained from those two border areas of Thailand will be of use in monitoring drug resistance in these border regions of the country.
    Matched MeSH terms: Malaria/parasitology
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