184 research outputs found
Development of a novel diagnostic technique and geospatial database for soil-transmitted helminthiasis in Malaysia / Romano Ngui
Get PDFThe main objectives of this thesis are two pronged which include the development of a novel diagnostic technique and the creation a geospatial database for soil-transmitted helminthiasis in Malaysia. These aims have been successfully accomplished and the outcomes are detailed out in Chapters 5 and 7. Nonetheless in order to achieve these good outcomes, prior work in getting appropriate samples for high resolution melting (HRM) analysis and current data for geographical information system (GIS) had to be conducted in some epidemiological studies in the human and animal populations and these are illustrated in Chapters 3, 4 and 6. Therefore, this abstract will summarize our main findings relevant to the two main objectives.
In the present study, we have successfully developed a cost-effective and practical diagnostic tool based on real-time PCR coupled with HRM analysis which can serve as a reliable alternative technique for rapid and accurate identification of the five major hookworm species, namely Necator americanus, Ancylostoma duodenale, Ancylostoma ceylanicum, Ancylostoma caninum and Ancylostoma braziliense that are known to be endemic in Malaysia. These five hookworm species can be easily distinguished from one another based on their unique and distinct melting characteristic HRM curves. Each species has their own curve profiles and characterized by different melting temperature (Tm) peaks (i.e., N. americanus: 79.24 ± 0.05°C and 83.00 ± 0.04°C; A. duodenale 79.12 ± 0.10°C; A. ceylanicum: 79.40 ± 0.10°C; A. caninum: 79.63 ± 0.05°C; A. braziliense: 79.70 ± 0.14°C). The present real-time PCR-HRM assay (100%) also has higher sensitivity compared to conventional semi-nested PCR (84.1%). However both techniques gave similar sensitivity (100%). The establishment of this new alternative diagnostic tool in this study has allowed accurate determination of
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parasite prevalence, increased the understanding of transmission dynamics and provided important information particularly on the zoonotic potential of hookworm in high risk communities (i.e., Orang Asli communities). In these socioeconomically disadvantaged communities, the poor levels of hygiene and overcrowding, along with a lack of veterinary attention and zoonotic awareness coupled with uncontrolled population of stray and semi-domesticated dogs or cats exist in close proximity with humans, exacerbating the risk of zoonotic transmission. Our findings shown that N. americanus (89.6%) was the most common hookworm species found in human fecal samples, followed by A. ceylanicum (19.0%) while no A. duodenale infection was detected in this study. This result indicated that almost a quarter of hookworm-positive individuals are infected with A. ceylanicum, a zoonotic hookworm species that utilizes dogs and cats as definitive hosts. In fact, our study among dogs and cats inhabiting the same locations showed that hookworm infections (61.9%) were significantly higher in both animals compared to other parasite species. Of these hookworm-positive samples, 47.1% of the infected dogs and cats were also harboring A. ceylanicum. It is especially evident in these poor and deprived communities as uncontrolled populations of dogs and cats co-exist with the Orang Asli communities as demonstrated in our earlier epidemiological analysis which showed that close contact with dogs and cats were significantly associated with hookworm infections in the Orang Asli communities. Furthermore, our analysis via molecular tool on these A. ceylanicum positive isolates indicated that some of the A. ceylanicum strains from both human and animal host within the same geographical location were clustered together within the same group based on phylogenetic analysis. This provided evidence to show that dogs and humans may share genetically similar genotypes of A. ceylanicum within the same geographical location. Thus, the present study highlighted that it is essential to recognize that accurate
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diagnosis through practical, sensitive and specific analytical tools are crucial factors to address key epidemiology and population genetic questions to support surveillance, treatment and control program of STH infections.
Besides advancement and improvement in diagnostic tools, it is also vital to understand the STH biology and epidemiology with regards to their environmental and ecological limits. Significantly, we have demonstrated how the utilization of GIS coupled with remote sensing (RS) technology can play an important role in providing basic information for the implementation of sustainable and effective control programs for STH infections. We believe that findings of this study will have direct beneficial implications to STH control programs in Malaysia. This is particularly relevant that an accurate estimation of the total disease burden has not been fully explained although STH infections in Malaysia are still highly prevalent especially in rural and remote communities such as the Orang Asli. Moreover, these data are rarely available in the public domain in a form that is accessible to policy maker or relevant authorities for control program intervention. The current study has successfully utilized GIS to collate and map the geographical distribution of STH infections from available empirical survey data in peninsular Malaysia and highlighted areas where such information is lacking. The current assembled database represents one of the largest and comprehensive survey coalitions of STH infections in the country, consisting 99 survey locations conducted between 1970 and 2012 through our combined search strategies. As illustrated in our prevalence maps, the geographical distribution of STH vary considerably with no clear pattern across the surveyed locations. Given that only few survey data is available for most regions in Malaysia as illustrated in our prevalence maps, thus it is important to generate predictive risk map of infection on the basis of their ecological limits such as climate and other environmental factors. In the present
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study, our correlation analysis between infection patterns and ecological factors indicated that Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) were significantly associated with the observed prevalence of A. lumbricoides. On the basis of these two significant variables, we have managed to extrapolate predictive risk map of A. lumbricoides particularly in areas for which no data are available. The predictive risk map can serve as a baseline data in the estimated number of population at risk, numbers requiring treatment and cost of delivering anthelminthic at broad scale by prioritizing areas and populations at greatest needs. Our A. lumbricoides predictive risk map showed that prevalence of infection is low along the west coast and southern part of the country, whilst the prevalence is high along the central plain and northern part. Based on our estimation according to the latest available national census in 2010, it is estimated that up to 3.5 million individuals would be infected with A. lumbricoides. Of these, we estimated that there are 587,482 school-aged children in 75 out of 81 districts corresponding to 359 out of 842 sub-districts in the country who warrant mass drug administration (MDA) treatment at least twice a year according to WHO recommendations. Thus, this study reinforces that the utilization of GIS and RS techniques can provide the way forward in developing and implementing sustainable national control programs at realistic scale by identifying key endemic areas, providing more accurate estimates of populations at risk and basic information on treatment intervention by reducing the costs involved at both upstream (e.g., survey and design) and downstream (e.g., targeting, monitoring and evaluation) particularly when the recourses for control program are limited
Soil-transmitted helminthiasis among indigenous communities in Malaysia: Is this the endless malady with no solution?
Get PDFSoil-transmitted helminths (STHs) are the most common intestinal parasitic infections of medical importance in human. The infections are widely distributed throughout the tropical and subtropical countries including Malaysia particularly among disadvantaged and underprivileged communities. This study was conducted to determine the prevalence and pattern of STH infections among Temuan indigenous subgroup. A cross sectional study was conducted among five villages in Peninsular Malaysia. Faecal samples and socioeconomic data were collected from each consented participant. Faecal samples were processed using formalin-ether sedimentation and examined under microscope. Data analysis was carried out using SPSS software programme for Windows version 24. A total of 411 participants voluntarily participated in this study. The overall prevalence of STH infections was 72.7% (95% CI = 68.2 – 77%). The most common STH species recorded was Trichuris trichiura (58.4%, 95% CI = 53.5 – 63.2%) followed by Ascaris lumbricoides (45.5%, 95% CI = 40.6 – 50.5%) and hookworm (23.1%, 95% CI = 19.1 – 27.5%). Multivariate analysis demonstrated that using untreated water was a significant predictor of STH infections in these communities. Our findings demonstrated that STH infections are still prevalent and co-exist with the low SES among this subgroup. Poverty and poor sanitation are the leading factors contributing to this malady. Hence, the reassessments of the existing control measures are needed
Toxoplasma gondii infection among selected indigenous community in Sarawak, East Malaysia
Get PDFToxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis in humans. To date, little is known about T. gondii infection among the
indigenous community, particularly in East Malaysia. This study was conducted to determine the status of T. gondii infection and to investigate associated risk factors among the indigenous community of Sarawak, East Malaysia. The sociodemographic data was obtained using a pretested questionnaire. A serological test was done to detect the presence of specific IgM and IgG antibodies against T. gondii in serum samples. A nested polymerase chain reaction (PCR) was used to determine acute infection among seropositive individuals. The overall seroprevalence of T. gondii infection was 50% (95% CI = 43.3 – 56.7). From this subset, 40.1%, 5.7%, and 4.2% were positive for anti-T. Gondii IgG antibodies, IgM, and both IgG and IgM,
respectively. Four seropositive samples were amplified through PCR. None of the pregnant women tested positive for T. gondii infection based on the serological and PCR assays. A significant association was found between age, low monthly household income, unemployment, usage of untreated water and close contact with T. gondii seropositive cats. These results provide basic information on T. gondii infection and may be useful for policymakers to initiate prevention and control programs, especially amongst pregnant women and women of childbearing age in the indigenous community
Microsporidia infection among various groups of the immunocompromised patients
Get PDFWhile information with regards to the bacterial and viral infections are commonly available among clinicians, data on parasitic infection, particularly Microsporidia among immunocompromised patient is currently lacking in Malaysia. This study was conducted to determine the prevalence of Microsporidia among a various group of immunocompromised patient. Two hundred and eighty-eight archived stool samples were examined for the presence of Microsporidia with Gram-Chromotrope Kinyoun staining method. The overall prevalence of Microsporidia was 29.2 % (84/288; 95% CI=24.2-34.5). The end-stage renal failure (ESRF) patients (32.1%) recorded the highest infection rate, followed by cancer (26.2%), human immunodeficiency virus (HIV/AIDS) (22.6%) and acute gastroenteritis (AGE) (7.1%). Meanwhile, organ transplant recipients and autoimmune disease patients recorded the lowest prevalence rate (6.0%). Other intestinal parasites were Strongyloides stercoralis, Trichuris trichiura, Ascaris lumbricoides and Cryptosporidium species. Diarrhoea was the most common symptoms among patients with microsporidiosis. The present study showed that the prevalence of Microsporidia infection was relatively high among immunocompromised patients. This finding highlighted the importance to include detection of microsporidia infection as a routine differential diagnosis in immunocompromised patients, which serves the benefit of treatment to the patients
Hitting the floor: Understanding migration patterns following the first episode of psychosis
Get PDFRecent research published in Health and Place (Ngamini Ngui et al., 2013b) found that one third of people with first episode psychosis [FEP] will have made a large-scale migration six years after initial diagnosis. Here, I extend this discussion around three important observations. Namely, at first presentation the most disadvantaged communities already shoulder the burden of psychotic morbidity; people with FEP in more rural communities migrate less often, and; people with FEP exhibit both upwards and downwards social mobility after onset. Understanding the reasons for (non-)migration before and after psychosis onset is now required for effective public mental health and service provision
Prospects on the Application of DNA Barcoding on Soil-Transmitted Helminths in Children
Get PDFAbstractSince more than a decade, DNA barcoding has been widely used to examine biological samples and differentiate species, as well as employed in ecological and conservational studies. There is a growing interest of DNA barcoding, particularly in medical parasitology, but its potential utility in soil-transmitted helminths (STHs) remains unclear. Therefore, in this article, we review the studies using DNA barcoding and its applications in medical parasitology with special focus on STHs such as Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus, and Trichuris trichiura. DNA barcoding is reliable for identifying STH species as well as its cryptic species. In addition, epidemiological data and the impacts of STH infections on children are discussed. This article further discusses the paucity of STH DNA barcodes (partial cytochrome oxidase subunit 1 [COI] mitochondrial DNA [mtDNA] sequences) in two gene banks; National Center for Biotechnology Information (NCBI) and Barcode of Life Data (BOLD) Systems. It also highlights the future prospects of DNA barcoding including primer designing and reference library on STHs.</jats:p
Modelling the portfolio behaviour of the Australian authorised short-term money market
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Researchers can access this thesis by asking their local university, institution or public library to
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Rapid Detection and Identification of Human Hookworm Infections through High Resolution Melting (HRM) Analysis
Get PDFHookworm infections are still endemic in low and middle income tropical countries with greater impact on the socioeconomic and public health of the bottom billion of the world's poorest people. In this study, a real-time polymerase chain reaction (PCR) coupled with high resolution melting-curve (HRM) analysis was evaluated for an accurate, rapid and sensitive tool for species identification focusing on the five human hookworm species.. An evaluation of the method's sensitivity and specificity revealed that this assay was able to detect as low as 0.01 ng/µl hookworm DNA and amplification was only recorded for hookworm positive samples.The HRM assay developed in this study is a rapid and straightforward method for the diagnosis, identification and discrimination of five human hookworms. This assay is simple compared to other probe-based genotyping methods as it does not require multiplexing, DNA sequencing or post-PCR processing. Therefore, this method offers a new alternative for rapid detection of human hookworm species
Tongue necrosis secondary to mucormycosis in a diabetic patient: A first case report in Malaysia
No full textMucormycosis is a rare fungal infection and high mortality that commonly affects patients with the weakened immune system. We present an unusual case of tongue necrosis probably due to the healthcare-associated mucormycosis (HCM) in a diabetic patient. Although cannot be proved with certainty, we surmise that intubation as a risk factor in our case. The diagnosis was confirmed by histopathological examination (HPE) of the necrotic tissue specimen. The patient was responded well to lipid complex amphotericin B (250 mg) regime after surgery. Subsequent follow up revealed that no signs of recurrence. Early, recognition, diagnosis, prompt treatment and awareness among clinician are representing the most effective way of managing the disease
A Case of Zoonotic Ancylostoma ceylanicum Infection in a Suburban Area of Selangor, Malaysia
No full textIntroduction
The animal hookworm, Ancylostoma ceylanicum, is a dominant hookworm species of dogs and cats. However, it has increasingly been found infecting humans in Southeast Asia.
Purpose
We report an autochthonous case of A. ceylanicum in a suburban area of Selangor, Malaysia. A 66-year-old Indian lady who is an avid gardener presented with chronic diarrhea of 4 months’ duration.
Methods
The patient was examined clinically and colonoscopy was performed. Adult parasites obtained via colonoscopy were subjected to microscopy and molecular investigations.
Results
Clinical examinations were unremarkable, and blood investigation revealed normochromic normocytic anemia. Stool occult blood was positive but negative for ova, cyst and adult parasites. Colonoscopy performed showed multiple diverticulae and worm infestation from the terminal ileum to sigmoid colon. Morphological examination on the adult worms showed the specific characteristics of Ancylostoma species. Molecular investigations further confirmed the nematode as Ancylostoma ceylanicum. She was treated with albendazole 400 mg daily for 3 days with symptomatic improvements sustained 3 months later. It is suspected that the patient had ingested or contacted soil contaminated with filariform larvae while gardening.
Conclusion
Information on the A. ceylanicum infection in humans, especially in urban and suburban areas, is limited, necessitating further epidemiological and clinical studie
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