Background: Most studies assessing praziquantel (PZQ) efficacy have used relatively insensitive diagnostic methods, thereby overestimating cure rate (CR) and intensity reduction rate (IRR). To... Show moreBackground: Most studies assessing praziquantel (PZQ) efficacy have used relatively insensitive diagnostic methods, thereby overestimating cure rate (CR) and intensity reduction rate (IRR). To determine accurately PZQ efficacy, we employed more sensitive DNA and circulating antigen detection methods. Methodology: A sub-analysis was performed based on a previously published trial conducted in children from Cote d'Ivoire with a confirmed Schistosoma mansoni infection, who were randomly assigned to a standard (single dose of PZQ) or intense treatment group (4 repeated doses of PZQ at 2-week intervals). CR and IRR were estimated based on PCR detecting DNA in a single stool sample and the up-converting particle lateral flow (UCP-LF) test detecting circulating anodic antigen (CAA) in a single urine sample, and compared with traditional KatoKatz (KK) and point-of-care circulating cathodic antigen (POC-CCA). Principal findings: Individuals positive by all diagnostic methods (i.e., KK, POC-CCA, PCR, and UCP-LF CAA) at baseline were included in the statistical analysis (n = 125). PCR showed a CR of 45% (95% confidence interval (CI) 32-59%) in the standard and 78% (95% CI 66-87%) in the intense treatment group, which is lower compared to the KK results (64%, 95% CI 52-75%) and 88%, 95% CI 78-93%). UCP-LF CAA showed a significantly lower CR in both groups, 16% (95% CI 11-24%) and 18% (95% CI 12-26%), even lower than observed by POCCCA (31%, 95% CI 17-35% and 36%, 95% CI 26-47%). A substantial reduction in DNA and CAA-levels was observed after the first treatment, with no further decrease after additional treatment and no significant difference in IRR between treatment groups. Conclusion/Significance:The efficacy of (repeated) PZQ treatment was overestimated when using egg-based diagnostics (i.e. KK and PCR). Quantitative worm-based diagnostics (i.e. POC-CCA and UCPLF CAA) revealed that active Schistosoma infections are still present despite multiple treatments. These results stress the need for using accurate diagnostic tools to monitor different PZQ treatment strategies, in particular when moving toward elimination of schistosomiasis.Author summaryEfficacy of praziquantel (PZQ) for the treatment of schistosomiasis is usually assessed by classical microscopic detection of parasite eggs in stool or urine. Due to low sensitivity, especially in case of low-intensity infections, the prevalence of infection is underestimated leading to an overestimated cure rate (CR) when using these methods. In a repeated treatment trial, the efficacy of one versus four repeated PZQ treatments, given at 2-week intervals, was investigated in school-aged children from Cote d'Ivoire by applying a range of diagnostic methods, including traditional microscopy as well as more sensitive DNA and circulating antigen detection methods. Our results demonstrate that PZQ efficacy measurements vary based on the diagnostic method used: while egg-based diagnostics (stool microscopy and DNA detection methods) show an improved CR after repeated treatment, the CR determined by worm-based diagnostics (urine circulating antigen detection methods) remained poor over time. Although all four diagnostic methods showed a significant reduction in intensity of infection already after a single treatment, more accurate antigen diagnostics revealed that, in most cases, worms remain present even after multiple treatments. Hence, using accurate diagnostic tools is essential to determine the true infection status and to monitor and evaluate treatment programs. Show less
Hoekstra, P.T.; Casacuberta Partal, M.; Lieshout, L. van; Corstjens, P.L.A.M.; Tsonaka, R.; Assare, R.K.; ... ; Dam, G.J. van 2020
BackgroundPreventive chemotherapy with praziquantel (PZQ) is the cornerstone of schistosomiasis control. However, a single dose of PZQ (40 mg/kg) does not cure all infections. Repeated doses of PZQ... Show moreBackgroundPreventive chemotherapy with praziquantel (PZQ) is the cornerstone of schistosomiasis control. However, a single dose of PZQ (40 mg/kg) does not cure all infections. Repeated doses of PZQ at short intervals might increase efficacy in terms of cure rate (CR) and intensity reduction rate (IRR). Here, we determined the efficacy of a single versus four repeated treatments with PZQ on Schistosoma mansoni infection in school-aged children from Cote d'Ivoire, using two different diagnostic tests.MethodsAn open-label, randomized controlled trial was conducted from October 2018 to January 2019. School-aged children with a confirmed S. mansoni infection based on Kato-Katz (KK) and point-of-care circulating cathodic antigen (POC-CCA) urine cassette test were randomly assigned to receive either a single or four repeated doses of PZQ, administered at two-week intervals. The primary outcome was the difference in CR between the two treatment arms, measured by triplicate KK thick smears 10 weeks after the first treatment. Secondary outcomes included CR estimated by POC-CCA, IRR by KK and POC-CCA, and safety of repeated PZQ administration.Principal findingsDuring baseline screening, 1,022 children were assessed for eligibility of whom 153 (15%) had a detectable S. mansoni infection, and hence, were randomized to the standard treatment group (N = 70) and the intense treatment group (N = 83). Based on KK, the CR was 42% (95% confidence interval (CI) 31-52%) in the standard treatment group and 86% (95% CI 75-92%) in the intense treatment group. Observed IRR was 72% (95% CI 55-83%) in the standard treatment group and 95% (95% CI 85-98%) in the intense treatment group. The CR estimated by POC-CCA was 18% (95% CI 11-27%) and 36% (95% CI 26-46%) in the standard and intense treatment group, respectively. Repeated PZQ treatment did not result in a higher number of adverse events.Author summaryThe previously established efficacy of the widely used drug praziquantel (PZQ) against schistosomiasis might have been overestimated due to the use of inaccurate diagnostic methods. Repeated PZQ treatment at short intervals in areas with ongoing transmission could more effectively target non-susceptible schistosomula as they will have matured into drug susceptible worms within a few weeks. In the current study, we aimed to determine the cure rate (CR) of repeated PZQ, measured by the Kato-Katz (KK) technique and the point-of-care circulating cathodic antigen (POC-CCA) test, respectively. An open-label, randomized controlled trial was conducted assigning 153 school-aged children with a confirmed Schistosoma mansoni infection to two groups, one receiving a single PZQ treatment, while the second group received four repeated PZQ treatments, given at two-week intervals. Based on the KK test, the CR was significantly higher after four repeated treatments compared to a single treatment. When using POC-CCA, a diagnostic method that has not been utilized before in studies assessing the efficacy of four repeated PZQ treatments, the CR was much lower, even after four repeated PZQ treatments. Our results indicate that worms are still present after multiple PZQ treatments and that PZQ might be less efficacious than previously published. Show less
Hoekstra, P.T.; Partal, M.C.; Amoah, A.S.; Lieshout, L. van; Corstjens, P.L.A.M.; Tsonaka, S.; ... ; Dam, G.J. van 2018
BackgroundLarge scale administration of the anthelminthic drug praziquantel (PZQ) to at-risk populations is the cornerstone of schistosomiasis control, although persisting high prevalence of... Show moreBackgroundLarge scale administration of the anthelminthic drug praziquantel (PZQ) to at-risk populations is the cornerstone of schistosomiasis control, although persisting high prevalence of infections in some areas and growing concerns of PZQ resistance have revealed the limitations of this strategy. Most studies assessing PZQ efficacy have used relatively insensitive parasitological diagnostics, such as the Kato-Katz (KK) and urine-filtration methods, thereby overestimating cure rates (CRs). This study aims to determine the efficacy of repeated PZQ treatments against Schistosoma mansoni infection in school-aged children in Cote d'Ivoire using the traditional KK technique, as well as more sensitive antigen- and DNA-detection methods.MethodsAn open-label, randomised controlled trial will be conducted in school-aged children (5 to 18years) from the region of Taabo, Cote d'Ivoire, an area endemic for S. mansoni. This 8-week trial includes four two-weekly standard doses of PZQ in the intense treatment intervention group and one standard dose of PZQ in the standard treatment control group. The efficacy of PZQ will be evaluated in stool samples using the KK technique and real-time PCR as well as in urine using the point-of-care circulating cathodic antigen test and the up-converting phosphor, lateral flow, circulating anodic antigen assay. The primary outcome of the study will be the difference in CR of intense versus standard treatment with PZQ on individuals with a confirmed S. mansoni infection measured by KK. Secondary outcomes include the difference in CR and intensity reduction rate between the intense and standard treatment groups as measured by the other diagnostic tests, as well as the accuracy of the different diagnostic tests, and the safety of PZQ.DiscussionThis study will provide data on the efficacy of repeated PZQ treatment on the clearance of S. mansoni as measured by several diagnostic techniques. These findings will inform future mass drug administration policy and shed light on position of novel diagnostic tools to evaluate schistosomiasis control strategies.Trial registrationThe study is registered at EudraCT (2016-003017-10, date of registration: 22 July 2016) and (NCT02868385, date of registration: 16 August 2016). Show less
Hoekstra, P.T.; Partal, M.C.; Amoah, A.S.; Lieshout, L. van; Corstjens, P.L.A.M.; Tsonaka, S.; ... ; Dam, G.J. van 2018
