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" Comparing Different Diagnostic Methods and Detection Platforms for Schistosomiasis, Giardiasis and Malaria in Uganda and the Kingdom of Saudi Arabia "
Al-shehri, Hajri
Stothard, Russell
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1106862
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TLpq2417074481
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| Main Entry
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Al-shehri, Hajri
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Stothard, Russell
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| Title & Author
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Comparing Different Diagnostic Methods and Detection Platforms for Schistosomiasis, Giardiasis and Malaria in Uganda and the Kingdom of Saudi Arabia\ Al-shehri, HajriStothard, Russell
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| College
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The University of Liverpool (United Kingdom)
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| Date
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2019
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2019
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| Degree
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Ph.D.
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| Page No
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300
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| Abstract
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Introduction: Where access to sanitation is incomplete and environmental water contact high, water-borne diseases such as schistosomiasis can be common in children and occur alongside other parasitic diseases. Parasitological diagnosis based upon microscopy of parasite ova or larvae underestimates true infection prevalence, and as NCPs reduce the intensity of infection(s) with preventive chemotherapy, the diagnostic sensitivity also declines. In Uganda and the Kingdom of Saudi Arabia, for example, school-based disease control has been ongoing over the past decade, and there is a need to develop more sensitive methods of parasite detection and disease surveillance. Against this two-country backdrop, the application of novel diagnostics was investigated to reveal the current status of infections in school children. Parasitological- and serological-based methods were compared against the implementation of realtime PCR methods to detect DNA from faecal or dried blood spot specimens. Diagnostic performance was then compared, and its epidemiological significance discussed for each country setting. Method: In Uganda, Buliisa District, a total of 271 children were enrolled. Stool, urine and blood were collected and examined for schistosomiasis, giardiasis and malaria using a selection of commercially available RDTs in the field, then compared against real-time PCR methods with TaqMan® probes in the laboratory. In the Kingdom of Saudi Arabia, Al-Majardah District, a total of 163 children were enrolled for this study. As faecal samples could not be collected, blood and urine samples were inspected. Children were interviewed by questionnaire and collection of intermediate snail hosts made. In the following up, all children positive for schistosomiasis where re-examined one year later. Results: In Uganda, Buliisa District, the overall prevalence of S. mansoni was: 44.1% by microscopy of duplicate KK smears from two consecutive stools, 56.9% by urine-CCA dipstick, 67.4% by DNA-TaqMan® and 75.1% by antibodies to SEA- ELISA. Giardiasis was 41.6% by QUIK CHEK™ RDT, and up to 87.0% of children were excreting Giardia DNA. The prevalence of heavy infection by real-time PCR assay (Ct ≤ 19) was 19.5%. Notably, giardiasis was positively associated with egg-patent schistosomiasis and two Giardia assemblages, A and B, were found. Co-infections thereof varied by school and by age. A total of 138 (55.8%) cases of malaria were diagnosed for P. falciparum (PfHRP-2-detecting RDTs), and 45 samples (18.2%) were positive for pan-Plasmodium species (PfHRP-2 and pan-pLDH test lines). Upon analysis of dried blood spots with real-time PCR, a total of 198 (80.1 %) cases for any Plasmodium spp. was detected and compared to real-time PCR of faecal samples. In the Kingdom of Saudi Arabia, Al-Majardah District, using urine-CCA strip assessment and SEA-ELISA, the prevalence of S. mansoni was 15.3% and combined S.mansoni/haematobium was 34.3%, respectively. Molecular DNA analysis using the CO1 gene alongside morphological identification of collected snails demonstrated the presence of Bulinus forskalii in this area and the local absence of Biomphalaria at the time of the survey. Conclusion: Using a combination of diagnostic methods, vital contemporary epidemiological information on schistosomiasis, giardiasis and malaria was revealed and then compared across the two countries using the ASSURED criterion. Foremost, whilst real-time PCR methods with TaqMan® probes have the greatest potential in Uganda, in Saudi Arabia however, owing to the difficulties in obtaining a stool, this method is inappropriate. Nonetheless, DNA-based diagnostic platforms will be essential in future public health settings where prevalence and intensity of infections continue to fall, as improved sensitivity is required. Furthermore, the ability to simultaneously co-detect several infectious and parasitic diseases will boost disease surveillance efficiency and capacity.
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Epidemiology
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Health sciences
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Parasitology
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Public health
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