Browsing by Author "Verweij, J.J."
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Item Application of a circulating-cathodic-antigen (CCA) strip test and real-time PCR, in comparison with microscopy, for the detection of Schistosoma haematobium in urine samples from Ghana(Annals Tropical of Medicine and Parasitology 102(7): 625-33, 2008) Obeng, B.B.; Aryeetey, Y.A.; de Dood, C.J.; Amoah, A.S.; Larbi, I.A.; Deelder, A.M.; Yazdanbakhsh, M.; Hartgers, F.C.; Boakye, D.A.; Verweij, J.J.; van Dam, G.J.; van Lieshout, L.In the detection of parasitic infection, the traditional methods based on microscopy often have low sensitivity and/or specificity compared with the newer, molecular tests. An assay based on real-time PCR and a reagent strip test for detecting circulating cathodic antigen (CCA) have both now been compared with urine filtration and microscopy, in the detection of Schistosoma haematobium infections. Urine samples, obtained from 74 'cases' in areas of Ghana with endemic S. haematobium and 79 'controls' from non-endemic areas, were each checked using the three methods. With the results of the filtration and microscopy taken as the 'gold standard', real-time PCR was found to be 100% specific and 89% sensitive whereas the CCA strips were 91% specific and 41% sensitive. With the samples found to contain > or =50 eggs/10 ml (indicating relatively intense infections), the sensitivities of the PCR and CCA were higher, at 100% and 62%, respectively. As expected, egg counts were negatively correlated with the number of amplification cycles needed, in the PCR, to give a signal that exceeded the background (r=-0.38; P<0.01). Although the real-time PCR and CCA strip tests are very different, both show promise in the detection of S. haematobium infections. The PCR has optimal specificity and high sensitivity but the specificity of the CCA strips and the sensitivity of both tools could still be improved. A more thorough re-evaluation of the sensitivity and specificity of microscopy and these newer diagnostic methods, with an estimation of the cost-effectiveness of each technique, is recommended.Item Comparison of real-time pcr and kato smear microscopy for the detection of hookworm infections in three consecutive faecal samples from schoolchildren in ghana(Transactions of the Royal Society of Tropical Medicine and Hygiene, 2013-02) van Mens, S.P.; Aryeetey, Y.; Yazdanbakhshc, M.; van Lieshoutc, L.; Boakyec, D.; Verweij, J.J.Background: The classic technique used to detect hookworm infections in population-based surveys is microscopic examination of Kato thick smears of multiple faecal samples per person as variation in soil-transmitted helminth egg output is common. Methods: As an alternative to this time-consuming and logistically difficult procedure, a PCR-based method to detect hookworm infections was evaluated. Faecal samples collected from 65 Ghanaian school children during February-June 2006 were examined using both techniques. Results: Thirty-one children with ahookworm infection were detected by Kato examination of three faecal samples compared with 30 children detected by PCR of a single faecal sample and 39 detected by PCR of three faecal samples. Conclusion: PCR provides a sensitive alternative to the conventional microscopic detection of hookworm infections. © Royal Society of Tropical Medicine and Hygiene 2013. All rights reserved.Item Expanding molecular diagnostics of helminthiasis: Piloting use of the GPLN platform for surveillance of soil transmitted helminthiasis and schistosomiasis in Ghana(PLoS Neglected Tropical Diseases, 2018-01) Cunningham, L.J.; Odoom, J.; Pratt, D.; Boatemaa, L.; Asante-Ntim, N.; Attiku, K.; Banahene, B.; Osei-Atweneboana, M.; Verweij, J.J.; Molyneux, D.; Stothard, R.J.; Adams, E.R.The efforts to control and eradicate polio as a global health burden have been successful to the point where currently only three countries now report endemic polio, and the number of cases of polio continues to decrease. The success of the polio programme has been dependant on a well-developed network of laboratories termed the global polio laboratory network (GPLN). Here we explore collaborative opportunities with the GPLN to target two of the 18 diseases listed as a neglected tropical diseases (NTD) namely soil transmitted helminthiasis (STH) and Schistosomiasis (SCH). These were chosen based on prevalence and the use of faecal materials to identify both polio, STH and SCH. Our study screened 448 faecal samples from the Ghana GPLN using three triplex TaqMan assays to identify Ascaris lumbricoides, Necator americanus, Ancylostoma spp, Trichuris trchiura, Strongyloides stercoralis and Schistosoma spp. Our results found a combined helminth prevalence of 22%. The most common helminth infection was A. lumbricoides with a prevalence of 15% followed by N. americanus (5%), Ancylostoma spp. (2.5%), Schistosoma spp. (1.6%) and S. stercoralis (1%). These results show that it is possible to identify alternative pathogens to polio in the samples collected by the GPLN platform and to introduce new diagnostic assays to their laboratories. The diagnostic methods employed were also able to identify S. stercoralis positive samples, which are difficult to identify using parasitological methods such as Kato-Katz. This study raises the possibility of collaboration with the GPLN for the surveillance of a wider range of diseases which would both benefit the efforts to control the NTDs and also increase the scope of the GPLN as a diagnostic platform. © 2018 Cunningham et al.Item Molecular diagnosis of Schistosoma infections in urine samples of school children in Ghana(American Journal of Tropical Medicine and Hygiene, 2013-06) Aryeetey, Y.A.; Essien-Baidoo, S.; Larbi, I.A.; Ahmed, K.; Amoah, A.S.; Obeng, B.B.; Van Lieshout, L.; Yazdanbakhsh, M.; Boakye, D.A.; Verweij, J.J.Recent studies using an internal transcribed spacer (ITS)-based real-time polymerase chain reaction (PCR) for the detection of Schistosoma DNA in urine samples has shown high sensitivity and specificity when performed on controls and known microscopy-positive samples. In this study, using 730 urine samples collected from children in five primary schools from different communities in the Greater Accra region of Ghana, specific detection of Schistosoma DNA showed excellent sensitivity of 100% and 85.2% in urines with > 50 eggs/10 mL urine and ≤ 50 eggs/10 mL of urine, respectively. Additionally, Schistosoma-specific DNA was amplified in 102 of 673 samples in which Schistosoma eggs could not be detected with microscopy. Taking microscopy and/or PCR-positive samples as true positives, the negative predictive value calculated was 94.6-100% for each school sampled as compared with 54.3-95.7% using microscopy. This ITS-based real-time PCR proves to be a powerful tool in epidemiological surveys of schistosomiasis providing more precise and sensitive results than microscopy. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.