BackgroundSchistosomiasis remains one of the most prevalent parasitic infections in the world and has significant economic and public health consequences, particularly in poor communities. Reliable and accurate diagnosis plays a key role in surveillance, prevention and control of schistosomiasis. Currently, the microscopic Kato Katz (KK) stool thick smear technique is the most commonly used method to diagnose Schistosoma mansoni infections in epidemiological surveys. It is well-known that the sensitivity of this parasitological method decreases when infection intensities are moderate to low, however. The urine-based Point-of Care Circulating Cathodic Antigen (POC-CCA) test has been extensively evaluated as a further diagnostic tool. Several studies have shown that the POC-CCA test is more sensitive but less specific than the KK method. However, to clarify the meaning of inconsistent results between KK and POC-CCA tests in clinical routine, this study compares the accuracy of microscopy and POC-CCA versus real-time polymerase chain reaction (real-time PCR) results of urine and faecal samples from African school children participants.MethodologyThis was a school-based cross-sectional study conducted in 2015 among 305 school children aged 7–16 years from two primary schools located in Ilemela and Magu Districts, north-western Tanzania. Single stool and urine samples were collected from each participant and examined for the presence of Schistosoma mansoni eggs, parasite antigen, and parasite DNA using KK thick smears, POC-CCA tests, and real-time PCR, respectively.Principal findingsThe prevalence of S. mansoni infection, calculated by KK was 85.2%, by real-time PCR 92.9% and by POC-CCA 94.9%. In comparison to KK, the POC-CCA and real-time PCR tests had sensitivities of 89.7% and 99.5% and specificities of 22.73% and 29.55%, respectively. However, due to the known limitations of the KK assay, we also used latent class analysis (LCA) that included POC-CCA, KK, and schistosome-specific real-time PCR results to determine their sensitivities and specificities. The POC-CCA test had the highest sensitivity (99.5%) and a specificity of 63.4% by LCA and the real-time PCR test had a sensitivity of 98.7% and the highest specificity (81.2%).ConclusionIn moderate and high prevalence areas, the POC-CCA cassette test is more sensitive than the KK method and can be used for screening and geographical mapping of S. mansoni infections. Real-time PCR is highly sensitive and also shows the highest specificity among the 3 investigated diagnostic procedures. It can offer added value in diagnosing schistosomiasis.

Background Intestinal schistosomiasis is highly endemic in Tanzania and mass drug administration (MDA) using praziquantel is the mainstay of the control program. However, the MDA program covers only school aged children and does not include neither adult individuals nor other public health measures. The Ijinga schistosomiasis project examines the impact of an intensified treatment protocol with praziquantel MDA in combination with additional public health interventions. It aims to investigate the feasibility of eliminating intestinal schistosomiasis in a highly endemic African setting using an integrated community-based approach. In preparation of this project, we report about baseline data on S.mansoni prevalence, intensity of infection, related hepatosplenic morbidities and their associated factors. Methods A cross sectional study was conducted among 930 individuals aged 1–95 years living at Ijinga Island, north-western Tanzania in September 2016. Single stool and urine samples were collected from each study participant and processed using Kato Katz (KK) technique and point-of-care Circulating Cathodic (POC-CCA) antigen test for detection of S.mansoni eggs and antigen respectively. Ultrasonographical examination for S.mansoni hepatosplenic morbidities was done to all participants. For statistical analyses Fisher’s exact test, chi-square test, student-t-test, ANOVA and linear regression were used where applicable. Results Overall based on KK technique and POC-CCA test, 68.9% (95%CI: 65.8–71.8) and 94.5% (95%CI: 92.8–95.8) were infected with S.mansoni. The overall geometrical mean eggs per gram (GMepg) of faeces was 85.7epg (95%CI: 77.5–94.8). A total of 27.1, 31.2 and 51.9% of the study participants had periportal fibrosis (PPF-grade C-F), splenomegaly and hepatomegaly. Risk factors for PPF were being male (aRR = 1.08, 95%CI: 1.02–1.16, P < 0.01), belong to the age group 16–25 years (aRR = 1.23, 95%CI: 105–1.44, P < 0.01), 26–35 years (aRR = 1.42, 95%CI: 1.21–1.67, P < 0.001), 36–45 years (aRR = 1.56, 95%CI:1.31–1.84, P < 0.001) and ≥ 46 years (aRR = 1.64, 95%CI:1.41–1.92, P < 0.001). The length of the left liver lobe was associated with being female (P < 0.03), belong to the age group 1–5 years (P < 0.013), 6–15 years (P < 0.04) and S.mansoni intensity of infection (P < 0.034). Male sex (aRR = 1.15, 95%CI:1.06–1.24, P < 0.001) and belonging to the age groups 16–25 years (aRR = 1.27, 95%CI:1.05–1.54, P < 0.02) or 26–35 years (aRR = 1.32, 95%CI:108–1.61, P < 0.01) were associated with splenomegaly. Conclusion Schistosoma mansoni infection and its related morbidities (hepatomegaly, splenomegaly, periportal fibrosis) are common in the study area. Age, sex and intensity of infection were associated with periportal fibrosis. The prevalence of S.mansoni was above 50% in each age group and based on the observed prevalence, we recommend MDA to the entire community.

Background: To detect acute schistosomiasis, low-intensity infections, or to verify the success of treatment with praziquantel, highly sensitive test methods are required. The aim of this study was therefore to demonstrate the performance of Schistosoma mansoni specific DNA detection in serum and urine using real-time polymerase chain reaction (PCR) in an endemic area before and after treatment. Methods: The study pursued a 1-week and 20-weeks longitudinal design with a treatment intervention among 36 study participants aged 18 to 70 years in the community of Kayenze, a fishing village in Ilemela district on the southern shore of Lake Victoria in northwestern Tanzania between February and June 2018. Blood, urine and stool samples were collected from each participant to diagnose Schistosoma mansoni infection before and two times after treatment with praziquantel using serum-and urine based real-time PCR, point-of-care circulating cathodic antigen (POC-CCA) rapid diagnostic test and the microscopic Kato-Katz (KK) method. Kappa coefficient (κ) was used to estimate the agreement between these diagnostic tests compared to a combined "gold standard" of positive results by serum-based real-time PCR and/or positive egg counts determined by KK. Kendall's Tau rank correlation was used to examine the relationship between cycle threshold (Ct)-values and egg counts and the Wilcoxon signed-rank test was used to compare the median Ct-values of the different examination time points. Results: By using the combined "gold standard" of the parasitological Kato-Katz test and/or serum-based real-time PCR, a S. mansoni prevalence of 77.1% could be determined at baseline. In terms of sensitivity, serum-based realtime PCR (96.3%) and POC-CCA assay (77.8%) showed the highest results. The detection of DNA from urine samples showed the lowest sensitivity (33.3%). Treatment with praziquantel resulted in a significantly reduced prevalence of S. mansoni. No infection could be detected by Kato-Katz, with the POC-CCA test only 33.3%. The analysis of the median Ct values over time (which were determined by the serum-based real-time PCR) showed that the Ct decreases significantly shortly after treatment (from 30.3 to 28) and increases above baseline level (34.9) three months later. Conclusions: The data presented here show that the serum-based real-time PCR exhibits excellent diagnostic accuracy, in contrast to the use of urine as sample material for S. mansoni DNA detection. However, as circulating DNA does not necessarily reflect the persistence of living worms in schistosomiasis, this method is less well suited to verify the success of treatment with praziquantel.

No abstract

No abstract