fong mun yik

University of Malaya, Malaysia, Medical Parasitology, Post-Doc

Followers

135

Following

Co-authors

Public Views

A research scientist interested in malaria and its parasites
Address: Department of Parasitology, Faculty of Medicine University of Malaya, 50603 Kuala Lumpur, MALAYSIA

less

Nugrahyono Muthalib

afie nur rasyidah

Yan Sinaga

University of Sumatera Utara

Universitas Muslim Indonesia

afriodita ary

Wijaya Kusuma Surabaya University

Hellen Fusfitasari

Universitas riau

riosurya vitara

Interests

Uploads

Papers by fong mun yik

Penentuan Beberapa Metabolit Yang Diduga Merupakan Hapten Imunogenik Pada Penderita Yang Alergi Kontak Terhadap Para Fenilendiamin (PFD) Melalui Pemeriksaan Uji Transformasi Limfosit T Dan Uji Tempel

Download

Nucleotide sequences of the nonstructural protein NS1 gene of three dengue-2 viruses, M1, M2 and M3, isolated in Malaysia from patients with dengue haemorrhagic fever, dengue shock syndrome and dengue fever, respectively

Nucleic Acids Research, Mar 25, 1990

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF... more

Molecular detection of Entamoeba histolytica and Entamoeba dispar infection among wild rats in Kuala Lumpur, Malaysia

Tropical biomedicine

Entamoeba histolytica infection is the third-greatest parasitic disease responsible for death in ... more Entamoeba histolytica infection is the third-greatest parasitic disease responsible for death in the world. Wild rats harbouring E. histolytica can be the possible reservoir hosts for human amoebiasis. There were numerous studies on prevalence of intestinal parasites among wild rats in Malaysia but none has reported E. histolytica. Rats were captured from Sentul and Chow Kit areas, Kuala Lumpur, Malaysia. The preserved stool samples were used for microscopy examination and molecular analysis. Out of 137 samples collected, 12 were positive for E. histolytica / E. dispar / E. moshkovskii microscopically. Two E. histolytica (1.4%), 1 E. dispar (0.7%) and 6 mixed infections of E. histolytica and E. dispar (4.3%) were detected using PCR. This is the first report of molecular detection of E. histolytica/dispar infection among wild rats in Malaysia. This study provides useful information about the potential risks of zoonotic agents and the importance of developing control measures to preve...

Download

Comparison of three molecular methods for the detection and speciation of five human Plasmodium species

The American journal of tropical medicine and hygiene, 2015

In this study, three molecular assays (real-time multiplex polymerase chain reaction [PCR], meroz... more In this study, three molecular assays (real-time multiplex polymerase chain reaction [PCR], merozoite surface antigen gene [MSP]-multiplex PCR, and the PlasmoNex Multiplex PCR Kit) have been developed for diagnosis of Plasmodium species. In total, 52 microscopy-positive and 20 malaria-negative samples were used in this study. We found that real-time multiplex PCR was the most sensitive for detecting P. falciparum and P. knowlesi. The MSP-multiplex PCR assay and the PlasmoNex Multiplex PCR Kit were equally sensitive for diagnosing P. knowlesi infection, whereas the PlasmoNex Multiplex PCR Kit and real-time multiplex PCR showed similar sensitivity for detecting P. vivax. The three molecular assays displayed 100% specificity for detecting malaria samples. We observed no significant differences between MSP-multiplex PCR and the PlasmoNex multiplex PCR kit (McNemar's test: P = 0.1489). However, significant differences were observed comparing real-time multiplex PCR with the PlasmoNex...

Toxocara seroprevalence and childhood asthma among Malaysian children

Pediatrics International, 2001

The larva of Toxocara spp., a common animal roundworm, may infect non-compatible hosts, causing a... more The larva of Toxocara spp., a common animal roundworm, may infect non-compatible hosts, causing a profound immunological reaction with marked eosinophil and IgE responses, not unlike in atopy. In this study, we determined the seroprevalence of Toxocara exposure in 66 asthmatic and 58 non-asthmatic children. Exposure to Toxocara was determined by examining the serum samples of the children for specific IgG antibodies to L2 Toxocara larvae, using a commercially available diagnostic kit. There was no significant difference in the mean age, sex, social class, residence type and presence of domestic pets at home between the two children groups. Children with bronchial asthma were observed to have higher Toxocara seropositivity than that of the non-asthmatic controls (21.2 vs 8.6%, P=0.047). The observed relationship between exposure to Toxocara infection and bronchial asthma in Malaysian children warrants further evaluation. An understanding of any possible contribution to the pathogenesis of childhood asthma provides a potential avenue for prevention.

Giemsa-Stained Wet Mount Based Method for Reticulocyte Quantification: A Viable Alternative in Resource Limited or Malaria Endemic Settings

PLoS ONE, 2013

The quantity of circulating reticulocytes is an important indicator of erythropoietic activity in... more The quantity of circulating reticulocytes is an important indicator of erythropoietic activity in response to a wide range of haematological pathologies. While most modern laboratories use flow cytometry to quantify reticulocytes, most field laboratories still rely on 'subvital' staining. The specialist 'subvital' stains, New Methylene Blue (NMB) and Brilliant Crésyl Blue are often difficult to procure, toxic, and show inconsistencies between batches. Here we demonstrate the utility of Giemsa's stain (commonly used microbiology and parasitology) in a 'subvital' manner to provide an accurate method to visualize and count reticulocytes in blood samples from normal and malaria-infected individuals.

Download

Lack of Clinical Manifestations in Asymptomatic Dengue Infection Is Attributed to Broad Down-Regulation and Selective Up-Regulation of Host Defence Response Genes

PLoS ONE, 2014

Dengue represents one of the most serious life-threatening vector-borne infectious diseases that ... more Dengue represents one of the most serious life-threatening vector-borne infectious diseases that afflicts approximately 50 million people across the globe annually. Whilst symptomatic infections are frequently reported, asymptomatic dengue remains largely unnoticed. Therefore, we sought to investigate the immune correlates conferring protection to individuals that remain clinically asymptomatic. We determined the levels of neutralizing antibodies (nAbs) and gene expression profiles of host immune factors in individuals with asymptomatic infections, and whose cognate household members showed symptoms consistent to clinical dengue infection. We observed broad down-regulation of host defense response (innate, adaptive and matrix metalloprotease) genes in asymptomatic individuals as against symptomatic patients, with selective up-regulation of distinct genes that have been associated with protection. Selected down-regulated genes include: TNF α (TNF), IL8, C1S, factor B (CFB), IL2, IL3, IL4, IL5, IL8, IL9, IL10 and IL13, CD80, CD28, and IL18, MMP8, MMP10, MMP12, MMP15, MMP16, and MMP24. Selected up-regulated genes include: RANTES (CCL5), MIP-1α (CCL3L1/CCL3L3), MIP-1β (CCL4L1), TGFβ (TGFB), and TIMP1. Our findings highlight the potential association of certain host genes conferring protection against clinical dengue. These data are valuable to better explore the mysteries behind the hitherto poorly understood immunopathogenesis of subclinical dengue infection.

Comparative analysis of ITS1 nucleotide sequence reveals distinct genetic difference between Brugia malayi from Northeast Borneo and Thailand

Parasitology, 2013

Brugia malayi is one of the parasitic worms which causes lymphatic filariasis in humans. Its geog... more Brugia malayi is one of the parasitic worms which causes lymphatic filariasis in humans. Its geographical distribution includes a large part of Asia. Despite its wide distribution, very little is known about the genetic variation and molecular epidemiology of this species. In this study, the internal transcribed spacer 1 (ITS1) nucleotide sequences of B. malayi from microfilaria-positive human blood samples in Northeast Borneo Island were determined, and compared with published ITS1 sequences of B. malayi isolated from cats and humans in Thailand. Multiple alignment analysis revealed that B. malayi ITS1 sequences from Northeast Borneo were more similar to each other than to those from Thailand. Phylogenetic trees inferred using Neighbour-Joining and Maximum Parsimony methods showed similar topology, with 2 distinct B. malayi clusters. The first cluster consisted of Northeast Borneo B. malayi isolates, whereas the second consisted of the Thailand isolates. The findings of this study suggest that B. malayi in Borneo Island has diverged significantly from those of mainland Asia, and this has implications for the diagnosis of B. malayi infection across the region using ITS1-based molecular techniques.

Armigeres subalbatus incriminated as a vector of zoonotic Brugia pahangi filariasis in suburban Kuala Lumpur, Peninsular Malaysia

Parasites & Vectors, 2013

Background: In 2011, we reported occurrence of natural human infections with Brugia pahangi, a fi... more Background: In 2011, we reported occurrence of natural human infections with Brugia pahangi, a filarial worm of dogs and cats, in a surburb of Kuala Lumpur, the capital city of Malaysia. Our preliminary entomological survey at that time suggested the mosquito species Armigeres subalbatus as the vector of the zoonotic infections. In this present report, we provide biological evidence to confirm our preliminary finding.

Download

Comparative phylogeography reveals a shared impact of pleistocene environmental change in shaping genetic diversity within nine Anopheles mosquito species across the Indo-Burma biodiversity hotspot

by R. Butlin, Samantha O'Loughlin, and fong mun yik

Molecular Ecology, 2011

South-East Asia is one of the world's richest regions in terms of biodiversity. An understanding ... more South-East Asia is one of the world's richest regions in terms of biodiversity. An understanding of the distribution of diversity and the factors shaping it is lacking, yet essential for identifying conservation priorities for the region's highly threatened biodiversity. Here, we take a large-scale comparative approach, combining data from nine forestassociated Anopheles mosquito species and using statistical phylogeographical methods to disentangle the effects of environmental history, species-specific ecology and random coalescent effects. Spatially explicit modelling of Pleistocene demographic history supports a common influence of environmental events in shaping the genetic diversity of all species examined, despite differences in species' mtDNA gene trees. Populations were periodically restricted to allopatric northeastern and northwestern refugia, most likely due to Pleistocene forest fragmentation. Subsequent southwards post-glacial recolonization is supported by a north-south gradient of decreasing genetic diversity. Repeated allopatric fragmentation and recolonization have led to the formation of deeply divergent geographical lineages within four species and a suture zone where these intraspecific lineages meet along the Thai-Myanmar border. A common environmental influence for this divergence was further indicated by strong support for simultaneous divergence within the same four species, dating to approximately 900 thousand years ago (kya). Differences in the geographical structuring of genetic diversity between species are probably the result of varying species' biology. The findings have important implications for conservation planning; if the refugial regions and suture zone identified here are shared by other forest taxa, the unique and high levels of genetic diversity they house will make these areas conservation priorities.

Download

Entomologic investigation of Plasmodium knowlesi vectors in Kuala Lipis, Pahang, Malaysia

Malaria Journal, 2012

Background: The first natural infection of Plasmodium knowlesi in humans was recorded in 1965 in ... more Background: The first natural infection of Plasmodium knowlesi in humans was recorded in 1965 in peninsular Malaysia. Extensive research was then conducted and it was postulated that it was a rare incident and that simian malaria will not be easily transmitted to humans. However, at the turn of the 21st century, knowlesi malaria was prevalent throughout Southeast Asia and is life threatening. Thus, a longitudinal study was initiated to determine the vectors, their seasonal variation and preference to humans and macaques.

Download

Cloning, expression, and immunocharacterization of surface protein containing an altered thrombospondin repeat domain (SPATR) from Plasmodium knowlesi

Malaria Journal, 2013

Background: Plasmodium knowlesi is the fifth species identified to cause malaria in humans and is... more Background: Plasmodium knowlesi is the fifth species identified to cause malaria in humans and is often misdiagnosed as Plasmodium malariae due to morphological similarities. The development of an inexpensive, serological detection method utilizing antibodies specific to P. knowlesi would be a valuable tool for diagnosis. However, the identification of specific antigens for these parasites remains a major challenge for generating such assays. In this study, surface protein containing an altered thrombospondin repeat domain (SPATR) was selected as a potentially specific antigen from P. knowlesi. Its multistage expression by sporozoites, asexual erythrocytic forms and gametocytes, along with its possible role in liver cell invasion, suggests that SPATR could be used as a biomarker for diagnosis of P. knowlesi. Methods: The spatr gene from P. knowlesi was codon optimized and cloned (pkhspatr). Recombinant pkHSPATR protein was expressed, purified, and evaluated for its sensitivity and specificity in immunoblot and ELISA-based assays for detecting P. knowlesi infection.

Download

Acute respiratory distress syndrome and acute renal failure from Plasmodium ovale infection with fatal outcome

Malaria Journal, 2013

Background: Plasmodium ovale is one of the causative agents of human malaria. Plasmodium ovale in... more Background: Plasmodium ovale is one of the causative agents of human malaria. Plasmodium ovale infection has long been thought to be non-fatal. Due to its lower morbidity, P. ovale receives little attention in malaria research. Methods: Two Malaysians went to Nigeria for two weeks. After returning to Malaysia, they fell sick and were admitted to different hospitals. Plasmodium ovale parasites were identified from blood smears of these patients. The species identification was further confirmed with nested PCR. One of them was successfully treated with no incident of relapse within 12-month medical follow-up. The other patient came down with malaria-induced respiratory complication during the course of treatment. Although parasites were cleared off the circulation, the patient's condition worsened. He succumbed to multiple complications including acute respiratory distress syndrome and acute renal failure.

Download

Malaysian child infected with Plasmodium vivax via blood transfusion: a case report

Malaria Journal, 2013

Malaria may be a serious complication of blood transfusion due to the asymptomatic persistence of... more Malaria may be a serious complication of blood transfusion due to the asymptomatic persistence of parasites in some donors. This case report highlights the transfusion-transmitted malaria of Plasmodium vivax in a child diagnosed with germ cell tumour. This child had received blood transfusion from three donors and a week later started developing malaria like symptoms. Nested PCR and sequencing confirmed that one of the three donors was infected with P. vivax and this was transmitted to the 12-year-old child. To the best of the authors' knowledge, this is the first reported transfusion-transmitted malaria case in Malaysia.

Download

Glycophorin C (CD236R) mediates vivax malaria parasite rosetting to normocytes

Blood, 2014

• P vivax infected cells rosette exclusively to normocytes. Thus, rosetting does not directly fac... more

Download

Parasitic Infections in Malaysia-Review of the Last Millennium

Download

Protective Immune Response in BALB/c Mice Induced by DNA Vaccine of the ROP8 gene of Toxoplasma gondii

American Journal of Tropical Medicine and Hygiene, 2013

Toxoplasmosis in humans and other animals is caused by the protozoan parasite Toxoplasma gondii. ... more Toxoplasmosis in humans and other animals is caused by the protozoan parasite Toxoplasma gondii. During the process of host cell invasion and parasitophorous vacuole formation by the tachyzoites, the parasite secretes Rhoptry protein 8 (ROP8), an apical secretory organelle. Thus, ROP8 is an important protein for the pathogenesis of T. gondii. The ROP8 DNA was constructed into a pVAX-1 vaccine vector and used for immunizing BALB/c mice. Immunized mice developed immune response characterized by significant antibody responses, antigen-specific proliferation of spleen cells, and production of high levels of IFN-γ (816 ± 26.3 pg/mL). Challenge experiments showed significant levels of increase in the survival period (29 days compared with 9 days in control) in ROP8 DNA vaccinated mice after a lethal challenge with T. gondii. Results presented in this study suggest that ROP8 DNA is a promising and potential vaccine candidate against toxoplasmosis.

Download

Evaluation of Recombinant Plasmodium knowlesi Merozoite Surface Protein-133 for Detection of Human Malaria

American Journal of Tropical Medicine and Hygiene, 2013

Plasmodium knowlesi is now known as the fifth Plasmodium species that can cause human malaria. Th... more Plasmodium knowlesi is now known as the fifth Plasmodium species that can cause human malaria. The Plasmodium merozoite surface protein (MSP) has been reported to be potential target for vaccination and diagnosis of malaria. MSP-1(33) has been shown to be immunogenic and its T cell epitopes could mediate cellular immune protection. However, limited studies have focused on P. knowlesi MSP-133. In this study, an approximately 28-kDa recombinant P. knowlesi MSP-1(33) (pkMSP-1(33)) was expressed by using an Escherichia coli system. The purified pkMSP-1(33) reacted with serum samples of patients infected with P. knowlesi (31 of 31, 100%) and non-P. knowlesi malaria (27 of 28, 96.43%) by Western blotting. The pkMSP-1(33) also reacted with P. knowlesi (25 of 31, 80.65%) and non-P. knowlesi malaria sera (20 of 28, 71.43%) in an enzyme-linked immunosorbent assay (ELISA). Most of the non-malarial infection (49 of 52 in by Western blotting and 46 of 52 in the ELISA) and healthy donor serum samples (65 of 65 by Western blotting and ELISA) did not react with recombinant pkMSP-1(33).

Genetic diversity of Plasmodium falciparum isolates from Pahang, Malaysia based on MSP-1 and MSP-2 genes

by Nazeh Al-Abd and fong mun yik

Parasites & Vectors, 2011

Background: Malaria is still a public health problem in Malaysia especially in the interior parts... more Background: 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. Methods: Seventy-five P. falciparum isolates were genotyped by using nested-PCR of MSP-1 (block 2) and MSP-2 (block 3). Results: MSP-1 and MSP-2 allelic families were identified in 65 blood samples. RO33 was the predominant MSP-1 allelic family identified in 80.0% (52/65) of the samples while K1 family had the least frequency. Of the MSP-2 allelic families, 3D7 showed higher frequency (76.0%) compared to FC27 (20.0%). The multiplicity of P. falciparum infection (MOI) was 1.37 and 1.20 for MSP-1 and MSP-2, respectively. A total of seven alleles were detected; of which three MSP-1 allelic families (RO33, MAD20 and K1) were monomorphic in terms of size while MSP-2 alleles were polymorphic (two 3D7 and two FC27). Heterozygosity (H E ) was 0.57 and 0.55 for MSP-1 and MSP-2, respectively.

Download

Clinical situation of endemic malaria in Yemen

Malaria remains a major public health problem causing mortality and morbidity in tropical and sub... more 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.

Download

Penentuan Beberapa Metabolit Yang Diduga Merupakan Hapten Imunogenik Pada Penderita Yang Alergi Kontak Terhadap Para Fenilendiamin (PFD) Melalui Pemeriksaan Uji Transformasi Limfosit T Dan Uji Tempel

Download

Nucleic Acids Research, Mar 25, 1990

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF... more