Displaying publications 1 - 20 of 132 in total

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  1. Sagara I, Dicko A, Ellis RD, Fay MP, Diawara SI, Assadou MH, et al.
    Vaccine, 2009 May 18;27(23):3090-8.
    PMID: 19428923 DOI: 10.1016/j.vaccine.2009.03.014
    A double blind, randomized, controlled Phase 2 clinical trial was conducted to assess the safety, immunogenicity, and biologic impact of the vaccine candidate Apical Membrane Antigen 1-Combination 1 (AMA1-C1), adjuvanted with Alhydrogel. Participants were healthy children 2-3 years old living in or near the village of Bancoumana, Mali. A total of 300 children received either the study vaccine or the comparator. No impact of vaccination was seen on the primary endpoint, the frequency of parasitemia measured as episodes >3000/microL/day at risk. There was a negative impact of vaccination on the hemoglobin level during clinical malaria, and mean incidence of hemoglobin <8.5 g/dL, in the direction of lower hemoglobin in the children who received AMA1-C1, although these differences were not significant after correction for multiple tests. These differences were not seen in the second year of transmission.
    Matched MeSH terms: Malaria, Falciparum/complications; Malaria, Falciparum/immunology; Malaria, Falciparum/prevention & control*
  2. Teo WH, Nurul AA, Norazmi MN
    Trop Biomed, 2012 Jun;29(2):239-53.
    PMID: 22735846 MyJurnal
    The Plasmodium falciparum serine repeat antigen (SERA) is one of the promising blood-stage malarial vaccine candidates. In this study, recombinant Mycobacterium bovis bacille Calmette-Guerin (rBCG) expressing the 22 kDa protein (SE22) from the 47 kDa Nterminal domain of serine repeat antigen (SERA), generated in favour of mycobacterium codon usage, elicited specific immune response in BALB/c mice with a mixed Th1/Th2 profile. Immunized sera containing high levels of specific IgG1 and IgG2a against the epitope (as determined by ELISA) were reactive with fixed P. falciparum merozoites as demonstrated by indirect immunofluorescence assay (IFA). Furthermore, the lymphocyte proliferative response to SE22 antigen from rBCG-immunized mice was higher than that of controls. The expression of intracellular cytokines (IL-2, IL-4 and IFNγ) in CD4+- and CD8+-cells was also enhanced following in-vitro stimulation with SE22. These findings indicate that a rBCG-based vaccine candidate expressing a blood-stage antigen of P. falciparum could enhance both humoral and cellular immune responses, thus paving the way for the rational use of rBCG as a vaccine candidate against malaria.
    Matched MeSH terms: Malaria, Falciparum/immunology; Malaria, Falciparum/prevention & control*
  3. Chua TH
    Trop Biomed, 2012 Mar;29(1):121-8.
    PMID: 22543612 MyJurnal
    According to the report of the Intergovernmental Panel on Climate Change (IPCC), Malaysia will experience an increase of 3-5°C in the future. As the development of the malaria parasite, Plasmodium falciparum, is sensitive to temperature, we investigated, using computer models, the effect of increase of 3º and 5ºC on the possible changes in the epidemiology of malaria transmission of P. falciparum in Malaysia. Four environmentally different locations were selected: Kuala Lumpur (KL), Cameron Highlands (CH), Kota Kinabalu (KK) and Kinabalu Park (KP). The extrinsic incubation period (EIP) was estimated using hourly temperatures and the mean daily temperatures. The EIP values estimated using the mean daily temperature were lower than those computed from hourly temperatures in warmer areas (KL, KK), but higher in the cooler areas (CH, KP). The computer simulations also indicated that the EIP will be decreased if the temperature was raised by 3º or 5ºC, with the effect more pronounced for the greater temperature increase, and for the cooler places. The vector cohort that is still alive at a time to transmit malaria (s(EIP)) also increased when the temperature was raised, with the increase more pronounced in the cooler areas. This study indicates an increase in temperature will have more significant effect in shortening the EIP in a cooler place (eg CH, KP), resulting in a greater s(EIP), and consequently increasing the transmission intensity and malaria risk. A temperature increase arising from the global climate change will likely affect the epidemiology of malaria in Malaysia, especially in the cooler areas.
    Matched MeSH terms: Malaria, Falciparum/epidemiology
  4. Gurpreet K
    Trop Biomed, 2009 Apr;26(1):57-66.
    PMID: 19696728 MyJurnal
    An epidemiological cross-sectional study was undertaken to determine the endemicity of malaria among the Orang Asli population of Raub, Pahang. Malaria endemicity was measured in terms of the prevalence of parasitaemia and splenomegaly. A total of 520 Orang Asli were examined. The point prevalence of malaria was 24.2% (95% CI 20.7-25.1), with Plasmodium falciparum (67.5%) being the predominant species. Children < 12 years were at least 3.7 times more likely to be parasitaemic compared to those older. The prevalence of malaria among children 2-<10 years was 38.1% (95% CI 31.6-50.0). Spleen rate among children 2-<10 years old was 22.3% (95% CI 17.1-28.3). The average enlarged spleen size was 1.2. These findings classify the study area as being mesoendemic. Malaria control activities among the Orang Asli should focus on protecting vulnerable subgroups like young children. Measuring the level of malaria endemicity at regular intervals is fundamental in evaluating the effectiveness of malaria control programs.
    Matched MeSH terms: Malaria, Falciparum/diagnosis; Malaria, Falciparum/ethnology; Malaria, Falciparum/epidemiology*; Malaria, Falciparum/parasitology
  5. 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, Falciparum/epidemiology*; Malaria, Falciparum/parasitology; Malaria, Falciparum/prevention & control
  6. Mahmud F, Lee PC, Abdul Wahab H, Mustaffa KMF, Leow CH, Azhar R, et al.
    Trop Biomed, 2020 Sep 01;37(3):822-841.
    PMID: 33612795 DOI: 10.47665/tb.37.3.822
    Malaria is one of the most dangerous infectious diseases due to its high infection and mortality rates, especially in the tropical belt. Plasmodium falciparum (P. falciparum), the most virulent malaria parasite in humans, was recently reported to develop resistance against the final efficient antimalarial drug, artemisinin. Little is known about the resistance mechanisms, which further complicates the problem as a proper counteraction is unable to be taken. Hence, the understanding of drug mode of action and its molecular target is valuable knowledge that needs to be considered to develop the next generation of antimalarial drugs. P. falciparum protein kinase (Pf PK) is an attractive target for antimalarial chemotherapy due to its vital roles in all P. falciparum life stages. Moreover, overall structural differences and the presence of unique Pf PKs that are absent in human kinome, suggesting specific inhibition of Pf PK without affecting human cells is achievable. To date, at least 86 eukaryotic protein kinases have been identified in P. falciparum kinome, by which less than 40 were validated as potential targets at the erythrocytes stage. In this review, recent progress of the furthest validated Pf PKs; Pf Nek-1, Pf CDPK1, Pf CDPK4, Pf PKG, and Pf CLK-3 will be briefly discussed.
    Matched MeSH terms: Malaria, Falciparum
  7. Vishalkumar P, Jayaprakash NS, Desai PK, Krishnan V, Vijayalakshmi MA
    Trop Biomed, 2020 Dec 01;37(4):1050-1061.
    PMID: 33612757 DOI: 10.47665/tb.37.4.1050
    OBJECTIVE: To evaluate the sensitivity and the stability of the monoclonal antibodies (Aa3c10, b10c1), against truncated Histidine-rich protein 2 (PfHRP2), developed using smart polymer, poly N-isopropylacrylamide, as adjuvant for malarial diagnostic applications in comparison with the available commercial antibodies.

    METHODS: Two hybridoma clones (Aa3c10, b10c1) were used for the production of ascites in BALB/c mice. Purification of monoclonal antibodies from the ascites was carried out using affinity columns. The thermal stability study of monoclonal antibodies was done by storing it at 37°C and 45°C for thirty days. The stored antibodies were analyzed using SDS-PAGE and flow-through device where the antigenantibody interaction was visualized by Protein A colloidal gold solution. Sensitivity was determined by endpoint dilution ELISA and the dissociation constant by competitive ELISA. Sensitive pair optimization was done by sandwich ELISA using biotinylated antibodies. Prototype preparation for lateral flow assay had a colloidal gold-based detection system.

    RESULTS: Thermal stability experiments showed that both mAbs (Aa3c10; b10c1) are stable up to thirty days at 45°C while the commercially available mAbs were stable up to fifteen days only. Compared to commercial antibodies, the mAb Aa3c10, showed the highest sensitivity in end-point titre. In sensitive pair optimization, it was observed that the mAb, b10c1, as a detector and the mAb, Aa3c10, as a capture antibody showed the highest absorbance to detect 50pg/ml PfHRP2 antigen. The prototype formulation of lateral flow assay using the mAbs (Aa3c10; b10c1) showed good reactivity with WHO panel and no false-positive results were observed with twenty clinically negative samples and five P. vivax positive samples.

    CONCLUSIONS: The novel monoclonal antibodies (Aa3c10, b10c1) against truncated PfHRP2, could be a strong potential candidates that can be included in making RDTs with better sensitivity and stability.

    Matched MeSH terms: Malaria, Falciparum/diagnosis*; Malaria, Falciparum/immunology
  8. Safar HF, Ali AH, Zakaria NH, Kamal N, Hassan NI, Agustar HK, et al.
    Trop Biomed, 2022 Dec 01;39(4):552-558.
    PMID: 36602215 DOI: 10.47665/tb.39.4.011
    Diplazium esculentum is an edible fern commonly consumed by the local community in Malaysia either as food or medicine. Isolation work on the ethyl acetate extract of the stem of D. esculentum resulted in the purification of two steroids, subsequently identified as stigmasterol (compound 1) and ergosterol5,8-endoperoxide (compound 2). Upon further testing, compound 2 displayed strong inhibitory activity against the Plasmodium falciparum 3D7 (chloroquine-sensitive) strain, with an IC50 of 4.27±1.15 µM, while compound 1 was inactive. In silico data revealed that compound 2 showed good binding affinity to P. falciparum-Sarco endoplasmic reticulum calcium-dependent ATPase (PfATP6); however, compound 1 did not show an antiplasmodial effect due to the lack of a peroxide moiety in the chemical structure. Our data suggested that the antiplasmodial activity of compound 2 from D. esculentum might be due to the inhibition of PfATP6, which resulted in both in vitro and in silico inhibitory properties.
    Matched MeSH terms: Malaria, Falciparum*
  9. Barber BE, Grigg MJ, William T, Yeo TW, Anstey NM
    Trends Parasitol, 2017 03;33(3):242-253.
    PMID: 27707609 DOI: 10.1016/j.pt.2016.09.002
    Plasmodium knowlesi occurs across Southeast Asia and is the most common cause of malaria in Malaysia. High parasitaemias can develop rapidly, and the risk of severe disease in adults is at least as high as in falciparum malaria. Prompt initiation of effective treatment is therefore essential. Intravenous artesunate is highly effective in severe knowlesi malaria and in those with moderately high parasitaemia but otherwise uncomplicated disease. Both chloroquine and artemisinin-combination therapy (ACT) are highly effective for uncomplicated knowlesi malaria, with faster parasite clearance times and lower anaemia rates with ACT. Given the difficulties with microscope diagnosis of P. knowlesi, a unified treatment strategy of ACT for all Plasmodium species is recommended in coendemic regions.
    Matched MeSH terms: Malaria, Falciparum/drug therapy
  10. Singh B, Choo KE, Ibrahim J, Johnston W, Davis TM
    Trans R Soc Trop Med Hyg, 1998 12 23;92(5):532-7.
    PMID: 9861371
    To determine whether glucose turnover is increased in acute falciparum malaria compared to enteric fever in children, steady-state 6,6-D2-glucose turnover was measured in 9 Malaysian children with uncomplicated malaria (6 males and 3 females; median age 10 years, body weight 22 kg) and in 12 with uncomplicated enteric fever (8 males and 4 females; median age 10 years, body weight 24 kg) in acute illness, after quinine (5 malaria patients) and in convalescence. Baseline plasma glucose concentrations in malaria and enteric fever were similar (all values are medians [ranges in brackets]) 5.6 [3.2-11.3] vs. 5.5 [4.2-8.0] mmol/L), as were serum insulin levels (5.6 [0.4-26.5] vs. 6.8 [1.1-22.5] milliunits/L; P > 0.4). Glucose turnover in the malaria patients was higher than in patients with enteric fever (6.27 [2.71-6.87] vs. 5.20 [4.50-6.08] mg/kg.min; P = 0.02) and in convalescence (4.74 [3.35-6.79] mg/kg.min; P = 0.05 vs. acute malaria study), and fell after quinine together with a rise in serum insulin (P = 0.03). Basal plasma lactate concentrations were higher in enteric fever than in malaria (3.4 [1.8-6.4] vs. 0.8 [0.3-3.8] mmol/L; P < 0.0001) and correlated inversely with glucose turnover in this group (rs = -0.60; n = 12; P = 0.02). These data suggest that glucose turnover is 20% greater in malaria than in enteric fever. This might reflect increased non-insulin-mediated glucose uptake in falciparum malaria and/or impaired gluconeogenesis in enteric fever, and may have implications for metabolic complications and their clinical management in both infections.
    Matched MeSH terms: Malaria, Falciparum/metabolism*
  11. Khoo A, Furuta T, Abdullah NR, Bah NA, Kojima S, Wah MJ
    Trans R Soc Trop Med Hyg, 1996 1 1;90(1):40-1.
    PMID: 8730308
    Matched MeSH terms: Malaria, Falciparum/diagnosis*
  12. Lokman Hakim S, Sharifah Roohi SW, Zurkurnai Y, Noor Rain A, Mansor SM, Palmer K, et al.
    Trans R Soc Trop Med Hyg, 1996 5 1;90(3):294-7.
    PMID: 8758083
    Uncomplicated falciparum malaria patients were randomly assigned to receive either 25 mg/kg chloroquine (CHL) over 3 d or a statim dose of 25 mg/kg sulfadoxine (SDX) plus 1.25 mg/kg pyrimethamine (PYR). Patients were followed up for 28 d and the parasite response graded according to World Health Organization criteria. Overall resistance to CHL was 63.3% and 47.4% to SDX/PYR. RI, RII and RIII rates were 9.1%, 42.4% and 12.1% for CHL and 10.5%, 21.1% and 15.8% for SDX/PYR, respectively. Degree and rates of resistance to CHL were significantly correlated with pre-treatment parasite density, but not those to SDX/PYR. Plasma CHL and SDX/PYR levels were within the reported ranges and were not significantly different in patients with sensitive and resistant responses.
    Matched MeSH terms: Malaria, Falciparum/blood; Malaria, Falciparum/drug therapy*
  13. 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: Malaria, Falciparum/diagnosis
  14. CONTACOS PG, LUNN JS, COATNEY GR
    Trans R Soc Trop Med Hyg, 1963 Nov;57:417-24.
    PMID: 14081296
    Matched MeSH terms: Malaria, Falciparum*
  15. MONTGOMERY R, EYLES DE
    Trans R Soc Trop Med Hyg, 1963 Nov;57:409-16.
    PMID: 14081295
    Matched MeSH terms: Malaria, Falciparum*
  16. Norahmad NA, Abdullah NR, Yaccob N, Jelip J, Dony JF, Ruslan KF, et al.
    PMID: 22299399
    Chloroquine (CQ) remains the first line drug for the prevention and treatment of malaria in Malaysia in spite of the fact that resistance to CQ has been observed in Malaysia since the 1960s. CQ-resistance is associated with various mutations in pfcrt, which encodes a putative transporter located in the digestive vacuolar membrane of P. falciparum. Substitution of lysine (K) to threonine (T) at amino acid 76 (K76T) in pfcrt is the primary genetic marker conferring resistance to CQ. To determine the presence of T76 mutation in pfcrt from selected areas of Kalabakan, Malaysia 619 blood samples were screened for P. falciparum, out of which 31 were positive. Blood samples were collected on 3 MM Whatman filter papers and DNA was extracted using QIAmp DNA mini kit. RFLP-PCR for the detection of the CQ-resistant T76 and sensitive K76 genotype was carried out. Twenty-five samples were shown to have the point mutation in pfcrt whereas the remaining samples were classified as CQ-sensitive (wild-type). In view of the fact that CQ is the first line anti-malarial drug in Malaysia, this finding could be an important indication that treatment with CQ may no longer be effective in the future.
    Matched MeSH terms: Malaria, Falciparum/drug therapy; Malaria, Falciparum/genetics*; Malaria, Falciparum/parasitology
  17. 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, Falciparum/epidemiology*; Malaria, Falciparum/parasitology
  18. Chang MS, Matusop A, Sen FK
    PMID: 10774651
    Anopheles mosquitos were surveyed using three trapping technics in four longhouse settlements and their respectively farming zone in western Sarawak, Malaysia. The study area was mountainous with tropical rain forest. An. leucosphyrus and An. donaldi were predominant in the farm huts. An. tessellatus and An. subpictus were more abundant in the village settlements. In both ecotypes, human baited traps yielded a significantly greater proportion of Anopheles mosquito than CDC light traps and landing biting catches. Circumsporozoite antigen positively rate, mosquito survival rate and parasite rate showed that malaria transmission is more intense in farm huts than in longhouse settlements. The entomological inoculation rate of An. donaldi and An. leucosphyrus in farm huts was 0.035 and 0.023, respectively. No sporozoite infections were observed in the main settlements.
    Matched MeSH terms: Malaria, Falciparum/transmission*
  19. Lim PK, Looareesuwan S, Chindanond D, Saleh AM, Tan SK
    PMID: 10437950
    Matched MeSH terms: Malaria, Falciparum/drug therapy; Malaria, Falciparum/parasitology*
  20. Rahman WA, Adanan CR, Abu Hassan A
    PMID: 10437952
    A study on the distribution of malaria in Hulu Perak district, Peninsular Malaysia was carried out between January and December 1993. The study encompassed the distribution of malaria cases according to sex, age and profession. A total of 332 cases were recorded, with 182 cases occurring in males. The highest infection was observed in the above 15 years old age group. Forest workers (loggers, rattan collectors and forest product gatherers) were the group most exposed to the disease (32.8%), followed by both plantantion workers (32.2%) and aboriginal communities (32.2%). Army and police personnels (2.1%) were also infected. Plasmodium falciparum was the most common species of malaria in the area.
    Matched MeSH terms: Malaria, Falciparum/epidemiology*
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