Displaying publications 61 - 80 of 131 in total

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  1. Fulltext Molecular characterization of Leishmania species isolated from cutaneous leishmaniasis in Yemen
    Mahdy MA, Al-Mekhlafi HM, Al-Mekhlafi AM, Lim YA, Bin Shuaib NO, Azazy AA, et al.
    PLoS One, 2010 Sep 20;5(9).
    PMID: 20862227 DOI: 10.1371/journal.pone.0012879
    BACKGROUND: Cutaneous leishmaniasis (CL) is a neglected tropical disease endemic in the tropics and subtropics with a global yearly incidence of 1.5 million. Although CL is the most common form of leishmaniasis, which is responsible for 60% of DALYs lost due to tropical-cluster diseases prevalent in Yemen, available information is very limited.

    METHODOLOGY/PRINCIPAL FINDINGS: This study was conducted to determine the molecular characterization of Leishmania species isolated from human cutaneous lesions in Yemen. Dermal scrapes were collected and examined for Leishmania amastigotes using the Giemsa staining technique. Amplification of the ribosomal internal transcribed spacer 1(ITS-1) gene was carried out using nested PCR and subsequent sequencing. The sequences from Leishmania isolates were subjected to phylogenetic analysis using the neighbor-joining and maximum parsimony methods. The trees identified Leishmania tropica from 16 isolates which were represented by two sequence types.

    CONCLUSIONS/SIGNIFICANCE: The predominance of the anthroponotic species (i.e. L. tropica) indicates the probability of anthroponotic transmission of cutaneous leishmaniasis in Yemen. These findings will help public health authorities to build an effective control strategy taking into consideration person-to-person transmission as the main dynamic of transmission of CL.

  2. Fulltext First Molecular Characterization of Leishmania Species Causing Visceral Leishmaniasis among Children in Yemen
    Mahdy MA, Al-Mekhlafi AM, Abdul-Ghani R, Saif-Ali R, Al-Mekhlafi HM, Al-Eryani SM, et al.
    PLoS One, 2016;11(3):e0151265.
    PMID: 26966902 DOI: 10.1371/journal.pone.0151265
    Visceral leishmaniasis (VL) is a debilitating, often fatal disease caused by Leishmania donovani complex; however, it is a neglected tropical disease. L. donovani complex comprises two closely related species, L. donovani that is mostly anthroponotic and L. infantum that is zoonotic. Differentiation between these two species is critical due to the differences in their epidemiology and pathology. However, they cannot be differentiated morphologically, and their speciation using isoenzyme-based methods poses a difficult task and may be unreliable. Molecular characterization is now the most reliable method to differentiate between them and to determine their phylogenetic relationships. The present study aims to characterize Leishmania species isolated from bone marrows of Yemeni pediatric patients using sequence analysis of the ribosomal internal transcribed spacer-1 (ITS1) gene. Out of 41 isolates from Giemsa-stained bone marrow smears, 25 isolates were successfully amplified by nested polymerase chain reaction and sequenced in both directions. Phylogenetic analysis using neighbor joining method placed all study isolates in one cluster with L. donovani complex (99% bootstrap). The analysis of ITS1 for microsatellite repeat numbers identified L. infantum in 11 isolates and L. donovani in 14 isolates. These data suggest the possibility of both anthroponotic and zoonotic transmission of VL-causing Leishmania species in Yemen. Exploring the possible animal reservoir hosts is therefore needed for effective control to be achieved.
  3. Molecular characterization of Giardia duodenalis isolated from Semai Pahang Orang Asli (Peninsular Malaysia aborigines)
    Mahdy AK, Surin J, Mohd-Adnan A, Wan KL, Lim YA
    Parasitology, 2009 Sep;136(11):1237-41.
    PMID: 19660153 DOI: 10.1017/S0031182009990527
    This study was conducted to determine the genotypes of Giardia duodenalis isolated from human faecal samples at Pos Betau, Pahang, Malaysia. Faecal specimens were collected and examined for G. duodenalis cysts using Trichrome staining techniques. Molecular identification was carried out by the amplification of a region of the small subunit of the nuclear ribosomal RNA (SSU rRNA) gene using nested PCR and subsequent sequencing. The sequences from 15 isolates from G. duodenalis were subjected to phylogenetic analysis (including appropriate outgroups) using the neighbor-joining and maximum parsimony methods. The trees identified G. duodenalis assemblages A and B, with a predominance of assemblage B. The predominance of anthroponotic genotypes indicates the possibility of anthroponotic transmission of these protozoa in this Semai Pahang Orang Asli community.
  4. Fulltext Mitochondrial DNA markers reveal high genetic diversity but low genetic differentiation in the black fly Simulium tani Takaoka & Davies along an elevational gradient in Malaysia
    Low VL, Adler PH, Takaoka H, Ya'cob Z, Lim PE, Tan TK, et al.
    PLoS One, 2014;9(6):e100512.
    PMID: 24941043 DOI: 10.1371/journal.pone.0100512
    The population genetic structure of Simulium tani was inferred from mitochondria-encoded sequences of cytochrome c oxidase subunits I (COI) and II (COII) along an elevational gradient in Cameron Highlands, Malaysia. A statistical parsimony network of 71 individuals revealed 71 haplotypes in the COI gene and 43 haplotypes in the COII gene; the concatenated sequences of the COI and COII genes revealed 71 haplotypes. High levels of genetic diversity but low levels of genetic differentiation were observed among populations of S. tani at five elevations. The degree of genetic diversity, however, was not in accordance with an altitudinal gradient, and a Mantel test indicated that elevation did not have a limiting effect on gene flow. No ancestral haplotype of S. tani was found among the populations. Pupae with unique structural characters at the highest elevation showed a tendency to form their own haplotype cluster, as revealed by the COII gene. Tajima's D, Fu's Fs, and mismatch distribution tests revealed population expansion of S. tani in Cameron Highlands. A strong correlation was found between nucleotide diversity and the levels of dissolved oxygen in the streams where S. tani was collected.
  5. First molecular genotyping of voltage gated sodium channel alleles in Culex quinquefasciatus populations in Malaysia
    Low VL, Chen CD, Lim PE, Lee HL, Tan TK, Lim YA, et al.
    Pestic Biochem Physiol, 2013 Sep;107(1):127-31.
    PMID: 25149246 DOI: 10.1016/j.pestbp.2013.06.004
    A nationwide investigation was performed to detect the presence of 1014 mutation(s) in voltage gated sodium channel (kdr) gene of Culex quinquefasciatus from 14 residential areas across 13 states and a federal territory in Malaysia. Molecular genotyping of kdr mutation was performed via a modified three tubes allele-specific-polymerase chain reaction (AS-PCR) and direct sequencing of kdr gene. Based on the results of AS-PCR, homozygous susceptible (SS) genotype was found in nine out of 14 populations with 38 individuals from a total sample size of 140. Heterozygous (RS) genotype was most predominant (99 individuals) and distributed across all study sites. Homozygous resistance (RR) genotype was detected in Perak (one individual) and Selangor (two individuals). The resistance kdr allele frequencies ranged from 0.1 to 0.55, with the highest being detected in Cx. quinquefasciatus population from Selangor. This study has documented the first field-evolved instance of 1014F mutation in Malaysian mosquitoes and the findings of this study could be utilized in the implementation of strategic measures in vector control programs in Malaysia.
  6. Use of COI, CytB and ND5 genes for intra- and inter-specific differentiation of Haematobia irritans and Haematobia exigua
    Low VL, Tan TK, Lim PE, Domingues LN, Tay ST, Lim YA, et al.
    Vet Parasitol, 2014 Aug 29;204(3-4):439-42.
    PMID: 24912955 DOI: 10.1016/j.vetpar.2014.05.036
    A multilocus sequence analysis using mitochondria-encoded cytochrome c oxidase subunit I (COI), cytochrome B (CytB), NADH dehydrogenase subunit 5 (ND5); nuclear encoded 18S ribosomal RNA (18S) and 28S ribosomal RNA (28S) genes was performed to determine the levels of genetic variation between the closely related species Haematobia irritans Linnaeus and Haematobia exigua de Meijere. Among these five genes, ND5 and CytB genes were found to be more variable and informative in resolving the interspecific relationships of both species. In contrast, the COI gene was more valuable in inferring the intraspecific relationships. The ribosomal 18S and 28S sequences of H. irritans and H. exigua were highly conserved with limited intra- and inter-specific variation. Molecular evidence presented in this study demonstrated that both flies are genetically distinct and could be differentiated based on sequence analysis of mitochondrial genes.
  7. Fulltext Enzymatic characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus say (Diptera: Culicidae)
    Low VL, Chen CD, Lee HL, Tan TK, Chen CF, Leong CS, et al.
    PLoS One, 2013;8(11):e79928.
    PMID: 24278220 DOI: 10.1371/journal.pone.0079928
    There has been no comprehensive study on biochemical characterization of insecticide resistance mechanisms in field populations of Malaysian Culex quinquefasciatus. To fill this void in the literature, a nationwide investigation was performed to quantify the enzyme activities, thereby attempting to characterize the potential resistance mechanisms in Cx. quinquefasciatus in residential areas in Malaysia.
  8. Fulltext Molecular characterisation of the tick Rhipicephalus microplus in Malaysia: new insights into the cryptic diversity and distinct genetic assemblages throughout the world
    Low VL, Tay ST, Kho KL, Koh FX, Tan TK, Lim YA, et al.
    Parasit Vectors, 2015;8:341.
    PMID: 26104478 DOI: 10.1186/s13071-015-0956-5
    The morphotaxonomy of Rhipicephalus microplus complex has been challenged in the last few years and prompted many biologists to adopt a DNA-based method for distinguishing the members of this group. In the present study, we used a mitochondrial DNA analysis to characterise the genetic assemblages, population structure and dispersal pattern of R. microplus from Southeast Asia, the region where the species originated.
  9. Detection of Anaplasmataceae agents and co-infection with other tick-borne protozoa in dogs and Rhipicephalus sanguineus sensu lato ticks
    Low VL, Prakash BK, Lim YA, Tan TK, Vinnie-Siow WY, Sofian-Azirun M, et al.
    Exp Appl Acarol, 2018 Aug;75(4):429-435.
    PMID: 30073430 DOI: 10.1007/s10493-018-0280-9
    Anaplasmosis and ehrlichiosis are of serious health concern worldwide for animals and humans. In the present study, we report the occurrence of Anaplasma platys and Ehrlichia canis in dogs and Rhipicephalus sanguineus sensu lato (s.l.) ticks from Peninsular Malaysia using a nested polymerase chain reaction assay based on amplification of the 16S rRNA gene. Anaplasma platys was detected from dogs and ticks with prevalence rates of 3.3% (8/240) and 2.9% (4/140), respectively. On the other hand, 12.9% (31/240) of the dogs and 0.7% (1/140) of the ticks were tested positive for E. canis. Additionally, co-infections of A. platys and E. canis with Babesia or Hepatozoon protozoa were also noted in this study. Double infection (E. canis + B. gibsoni) was observed in tick, whereas triple infections (E. canis + A. platys + B. vogeli and E. canis + A. platys + H. canis) were found in dogs. This study represents the first evidence of A. platys DNA in R. sanguineus s.l. in Malaysia.
  10. First molecular genotyping of insensitive acetylcholinesterase associated with malathion resistance in Culex quinquefasciatus Say populations in Malaysia
    Low VL, Chen CD, Lim PE, Lee HL, Lim YA, Tan TK, et al.
    Pest Manag Sci, 2013 Dec;69(12):1362-8.
    PMID: 23404830 DOI: 10.1002/ps.3512
    Given that there is limited available information on the insensitive acetylcholinesterase in insect species in Malaysia, the present study aims to detect the presence of G119S mutation in the acetylcholinesterase gene of Culex quinquefasciatus from 14 residential areas across 13 states and a federal territory in Malaysia.
  11. Mitochondrial DNA analyses reveal low genetic diversity in Culex quinquefasciatus from residential areas in Malaysia
    Low VL, Lim PE, Chen CD, Lim YA, Tan TK, Norma-Rashid Y, et al.
    Med Vet Entomol, 2014 Jun;28(2):157-68.
    PMID: 23848279 DOI: 10.1111/mve.12022
    The present study explored the intraspecific genetic diversity, dispersal patterns and phylogeographic relationships of Culex quinquefasciatus Say (Diptera: Culicidae) in Malaysia using reference data available in GenBank in order to reveal this species' phylogenetic relationships. A statistical parsimony network of 70 taxa aligned as 624 characters of the cytochrome c oxidase subunit I (COI) gene and 685 characters of the cytochrome c oxidase subunit II (COII) gene revealed three haplotypes (A1-A3) and four haplotypes (B1-B4), respectively. The concatenated sequences of both COI and COII genes with a total of 1309 characters revealed seven haplotypes (AB1-AB7). Analysis using tcs indicated that haplotype AB1 was the common ancestor and the most widespread haplotype in Malaysia. The genetic distance based on concatenated sequences of both COI and COII genes ranged from 0.00076 to 0.00229. Sequence alignment of Cx. quinquefasciatus from Malaysia and other countries revealed four haplotypes (AA1-AA4) by the COI gene and nine haplotypes (BB1-BB9) by the COII gene. Phylogenetic analyses demonstrated that Malaysian Cx. quinquefasciatus share the same genetic lineage as East African and Asian Cx. quinquefasciatus. This study has inferred the genetic lineages, dispersal patterns and hypothetical ancestral genotypes of Cx. quinquefasciatus.
  12. First molecular characterization of Giardia duodenalis from goats in Malaysia
    Lim YA, Mahdy MA, Tan TK, Goh XT, Jex AR, Nolan MJ, et al.
    Mol Cell Probes, 2013 Feb;27(1):28-31.
    PMID: 22971518 DOI: 10.1016/j.mcp.2012.08.006
    In the present study, 310 faecal samples from goats from eight different farms in Malaysia were tested for the presence of Giardia using a PCR-coupled approach. The nested PCR for SSU amplified products of the expected size (∼200 bp) from 21 of 310 (6.8%) samples. Sixteen of these 21 products could be sequenced successfully and represented six distinct sequence types. Phylogenetic analysis of the SSU sequence data using Bayesian Inference (BI) identified Giardia assemblages A, B and E. The identification of the 'zoonotic' assemblages A and B suggests that Giardia-infected goats represent a possible reservoir for human giardiasis in Malaysia.
  13. First genetic classification of Cryptosporidium and Giardia from HIV/AIDS patients in Malaysia
    Lim YA, Iqbal A, Surin J, Sim BL, Jex AR, Nolan MJ, et al.
    Infect Genet Evol, 2011 Jul;11(5):968-74.
    PMID: 21439404 DOI: 10.1016/j.meegid.2011.03.007
    Given the HIV epidemic in Malaysia, genetic information on opportunistic pathogens, such as Cryptosporidium and Giardia, in HIV/AIDS patients is pivotal to enhance our understanding of epidemiology, patient care, management and disease surveillance. In the present study, 122 faecal samples from HIV/AIDS patients were examined for the presence of Cryptosporidium oocysts and Giardia cysts using a conventional coproscopic approach. Such oocysts and cysts were detected in 22.1% and 5.7% of the 122 faecal samples, respectively. Genomic DNAs from selected samples were tested in a nested-PCR, targeting regions of the small subunit (SSU) of nuclear ribosomal RNA and the 60kDa glycoprotein (gp60) genes (for Cryptosporidium), and the triose-phosphate isomerase (tpi) gene (for Giardia), followed by direct sequencing. The sequencing of amplicons derived from SSU revealed that Cryptosporidium parvum was the most frequently detected species (64% of 25 samples tested), followed by C. hominis (24%), C. meleagridis (8%) and C. felis (4%). Sequencing of a region of gp60 identified C. parvum subgenotype IIdA15G2R1 and C. hominis subgenotypes IaA14R1, IbA10G2R2, IdA15R2, IeA11G2T3R1 and IfA11G1R2. Sequencing of amplicons derived from tpi revealed G. duodenalis assemblage A, which is of zoonotic importance. This is the first report of C. hominis, C. meleagridis and C. felis from Malaysian HIV/AIDS patients. Future work should focus on an extensive analysis of Cryptosporidium and Giardia in such patients as well as in domestic and wild animals, in order to improve the understanding of transmission patterns and dynamics in Malaysia. It would also be particularly interesting to establish the relationship among clinical manifestation, CD4 cell counts and genotypes/subgenotypes of Cryptosporidium and Giardia in HIV/AIDS patients. Such insights would assist in a better management of clinical disease in immuno-deficient patients as well as improved preventive and control strategies.
  14. Fulltext Plasmodium ovale infection in Malaysia: first imported case
    Lim YA, Mahmud R, Chew CH, T T, Chua KH
    Malar J, 2010;9:272.
    PMID: 20929588 DOI: 10.1186/1475-2875-9-272
    BACKGROUND:
    Plasmodium ovale infection is rarely reported in Malaysia. This is the first imported case of P. ovale infection in Malaysia which was initially misdiagnosed as Plasmodium vivax.

    METHODS:
    Peripheral blood sample was first examined by Giemsa-stained microscopy examination and further confirmed using a patented in-house multiplex PCR followed by sequencing.

    RESULTS AND DISCUSSION:
    Initial results from peripheral blood smear examination diagnosed P. vivax infection. However further analysis using a patented in-house multiplex PCR followed by sequencing confirmed the presence of P. ovale. Given that Anopheles maculatus and Anopheles dirus, vectors of P. ovale are found in Malaysia, this finding has significant implication on Malaysia's public health sector.

    CONCLUSIONS:
    The current finding should serve as an alert to epidemiologists, clinicians and laboratory technicians in the possibility of finding P. ovale in Malaysia. P. ovale should be considered in the differential diagnosis of imported malaria cases in Malaysia due to the exponential increase in the number of visitors from P. ovale endemic regions and the long latent period of P. ovale. It is also timely that conventional diagnosis of malaria via microscopy should be coupled with more advanced molecular tools for effective diagnosis.
  15. Molecular detection of Giardia contamination in water bodies in a zoo
    Lim YA, Lai MM, Mahdy MA, Mat Naim HR, Smith HV
    Environ Res, 2009 Oct;109(7):857-9.
    PMID: 19664767 DOI: 10.1016/j.envres.2009.07.007
    We used a combined microscopy-molecular approach to determine the occurrence and identities of waterborne Giardia sp. cysts isolated from 18 separate, 10l grab samples collected from a Malaysian zoo. Microscopy revealed that 17 of 18 samples were Giardia cyst positive with concentrations ranging from 1 to 120 cysts/l. Nine (52.9%) of the 17 cyst positive samples produced amplicons of which 7 (77.8%) could be sequenced. Giardia duodenalis assemblage A (6 of 7) and assemblage B (1 of 7), both infectious to humans, were identified at all sampling sites at the zoo. The presence of human infectious cysts raises public health issues, and their occurrence, abundance and sources should be investigated further. In this zoo setting, our data highlight the importance of incorporating environmental sampling (monitoring) in addition to routine faecal examinations to determine veterinary and public health risks, and water monitoring should be considered for inclusion as a separate element in hazard analysis, as it often has a historical (accumulative) connotation.
  16. Detection and molecular characterization of Giardia isolated from recreational lake water in Malaysia
    Lim YA, Ramasame SD, Mahdy MA, Sulaiman WY, Smith HV
    Parasitol Res, 2009 Dec;106(1):289-91.
    PMID: 19705155 DOI: 10.1007/s00436-009-1602-y
    Nine 50-l surface water samples from a Malaysian recreational lake were examined microscopically using an immunomagnetisable separation-immunofluorescent method. No Cryptosporidium oocysts were detected, but 77.8% of samples contained low numbers of Giardia cysts (range, 0.17-1.1 cysts/l), which were genetically characterised by SSU rRNA gene sequencing. Genotype analyses indicated the presence of Giardia duodenalis assemblage A suggesting potential risk to public health. The present study represents the first contribution to our knowledge of G. duodenalis assemblages in Malaysian recreational water.
  17. Intestinal parasites in various animals at a zoo in Malaysia
    Lim YA, Ngui R, Shukri J, Rohela M, Mat Naim HR
    Vet Parasitol, 2008 Oct 20;157(1-2):154-9.
    PMID: 18723289 DOI: 10.1016/j.vetpar.2008.07.015
    A survey was undertaken to investigate the prevalence of intestinal parasites from different groups of mammals housed in a zoological garden in Malaysia. A total of 197 faecal samples were collected randomly from various primates (99), hoofed mammals (70) and feline (28). It was discovered that 89.3% of feline, 54.5% of primates and 45.7% of hoofed mammals were infected with intestinal parasites. Intestinal parasites found in primates were Balantidium coli (19.2%), Cryptosporidium spp. (14.1%), hookworm (10.1%), Trichuris spp. (5.1%), Ascaris (4.0%) and Blastocystis spp. (2.0%). For hoofed mammals, hookworm had the highest prevalence (34.3%) followed by Trichuris spp. and Cryptosporidium spp. (5.7%). Meanwhile, for feline, Toxocara cati was the most prevalent (64.3%), followed by Cryptosporidium spp. (14.3%), Spirometra spp. (7.1%), and hookworm (3.6%). Animals that were infected were all asymptomatic with low parasite load. Routine monitoring of the presence of parasites in animals kept in the zoo is imperative in assisting zoo management in the formulation and implementation of preventive and control measures against the spread of infectious parasitic diseases among animals within the zoo or to humans.
  18. Current status and future trends in Cryptosporidium and Giardia epidemiology in Malaysia
    Lim YA, Ahmad RA, Smith HV
    J Water Health, 2008 Jun;6(2):239-54.
    PMID: 18209286 DOI: 10.2166/wh.2008.023
    Cryptosporidium and Giardia are major causes of diarrhoeal diseases of humans worldwide, and are included in the World Health Organisation's 'Neglected Diseases Initiative'. Cryptosporidium and Giardia occur commonly in Malaysian human and non-human populations, but their impact on disease, morbidity and cost of illness is not known. The commonness of contributions from human (STW effluents, indiscriminate defaecation) and non-human (calving, lambing, muck spreading, slurry spraying, pasturing/grazing of domestic animals, infected wild animals) hosts indicate that many Malaysian environments, particularly water and soil, are sufficiently contaminated to act as potential vehicles for the transmission of disease. To gain insight into the morbidity and mortality caused by human cryptosporidiosis and giardiasis, they should be included into differential diagnoses, and routine laboratory testing should be performed and (as for many infectious diseases) reported to a centralised public health agency. To understand transmission routes and the significance of environmental contamination better will require further multidisciplinary approaches and shared resources, including raising national perceptions of the parasitological quality of drinking water. Here, the detection of Cryptosporidium and Giardia should be an integral part of the water quality requirement. A multidisciplinary approach among public health professionals in the water industry and other relevant health- and environment-associated agencies is also required in order to determine the significance of Cryptosporidium and Giardia contamination of Malaysian drinking water. Lastly, adoption of validated methods to determine the species, genotype and subgenotype of Cryptosporidium and Giardia present in Malaysia will assist in developing effective risk assessment, management and communication models.
  19. Prevalence of cryptosporidiosis in HIV-infected patients in Kajang Hospital, Selangor
    Lim YA, Rohela M, Sim BL, Jamaiah I, Nurbayah M
    Southeast Asian J. Trop. Med. Public Health, 2005;36 Suppl 4:30-3.
    PMID: 16438176
    A total of 66 fecal specimens obtained from patients infected with human immunodeficiency virus (HIV) from Kajang Hospital were screened for Cryptosporidium oocysts. The fecal specimens were concentrated using the formalin ethyl acetate concentration technique, stained with modified Ziehl-Neelsen and confirmed with immunofluorescence stain. It was established that 2 (3.0%) were positive for Cryptosporidium. The two cases involved a Chinese local man (with diarrhea) and an Indonesian foreigner (without diarrhea). A higher index of suspicion for clinical cryptosporidiosis in HIV patients, including those with chronic weight loss with or without diarrhea, is recommended. In addition, laboratory testing for Cryptosporidium in HIV-infected patients is highly recommended in order to have a better understanding of the epidemiology and management of the disease in Malaysia.
  20. Occurrence of Giardia cysts and Cryptosporidium oocysts in the Temuan Orang Asli (aborigine) River System
    Lim YA, Aahmad RA
    Southeast Asian J. Trop. Med. Public Health, 2004 Dec;35(4):801-10.
    PMID: 15916072
    A survey of the river water frequently used by the Temuan Orang Asli (aborigine) indicated that 66.7% of the river water samples were Giardia cyst positive and 5.6% were Cryptosporidium oocyst positive. Although Giardia cysts were detected in samples from all the sites (e.g. upstream, midstream, and downstream), Cryptosporidium was only present in one river water sample taken from downstream from a village. The only sample of upstream water which contained Giardia cysts had a concentration of 0.7 cysts/l. All samples taken from midstream contained cysts with a mean concentration of 9.8 +/- 6.6 cysts/l (range = 1-20 cysts/l). Eighty-three point three percent of the samples collected from downstream contained cysts and 16.7% had oocysts. The average concentration of cysts was 12.9 +/- 16.4 cysts/l (range = 0-44 cysts/l), whereas the oocyst concentration was 0.4 oocysts/l. All river samples tested positive for the presence of E. coli, indicating fecal contamination. The results of this study imply that the river system is contaminated with fecal-oral transmitted parasites. The river water, used by the Orang Asli, is a probable route for Giardia and Cryptosporidium transmission in this community. Long term strategies, incorporating health education regarding personal hygiene, and provision of toilets and the importance of their proper usage, need to be embraced by this community in order to control the spread of these parasites.
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