Schistosomiasis is a parasitic infection caused by worms of the genus Schistosoma. It is a neglected tropical disease, affecting mainly populations living in poverty without adequate sanitation.... Show moreSchistosomiasis is a parasitic infection caused by worms of the genus Schistosoma. It is a neglected tropical disease, affecting mainly populations living in poverty without adequate sanitation. Treatment relies on one drug mainly, praziquantel, and its efficacy is dependent on the diagnostic tool used.Due to the parasite’s intravascular localisation, it is difficult to directly quantify them in infected humans. Thus, methods of detection like worm-derived circulating cathodic antigen (CCA) in urine or circulating anodic antigen (CAA) in urine and serum, have gained more attention. This thesis aims to explore and shed light on how to interpret schistosome-related circulating antigens CCA and CAA. We have addressed the interpretation of schistosome related assays in endemic and non-endemic regions, supported by data obtained from an animal study. Different diagnostic value can be attributed to different assays within different contexts. The results highlight the importance of a better understanding of antigen excretion patterns by different species to support optimalisation of antigen-based diagnostics of schistosomiasis. Show less
Availability of accurate tests to diagnose schistosomiasis, a neglected tropical disease caused by parasitic worms, is crucial for successful reduction of the burden of disease and eventually... Show moreAvailability of accurate tests to diagnose schistosomiasis, a neglected tropical disease caused by parasitic worms, is crucial for successful reduction of the burden of disease and eventually moving towards elimination. This thesis provides further evidence on the suitability of CAA detection for diagnosing Schistosoma infections and monitoring treatment efficacy by evaluating the UCP-LF CAA test in the context of various endemic and non-endemic settings. The UCP-LF CAA test is a lateral flow (LF) test for sensitive quantitative detection – using luminescent up-converting reporter particles (UCP) – of circulating anodic antigen (CAA). This antigen is regurgitated by live schistosome worms into the human circulation. The presence of CAA in blood or urine thus reflects an active Schistosoma infection. CAA-levels decrease rapidly after treatment of infected patients with anti-schistosomal drugs. In non-endemic settings (i.e. the absence of reinfection), CAA-levels became undetectable after treatment, indicating clearance of infection. This is in contrast to endemic settings of continuous exposure and ongoing transmission. Here, CAA-levels significantly decreased post-treatment but often remained detectable. Although alternative procedures such as antibody and DNA detection methods remain crucial for certain context-specific purposes, this thesis shows that CAA is the most favorable diagnostic marker currently available for diagnosis of active Schistosoma infections. Show less
Background:The long-term effects of schistosomiasis on the glomerulus may contribute to the development of chronic kidney disease. This study aimed to investigate baseline Schistosoma mansoni-Circu... Show moreBackground:The long-term effects of schistosomiasis on the glomerulus may contribute to the development of chronic kidney disease. This study aimed to investigate baseline Schistosoma mansoni-Circulating Anodic Antigen (CAA) levels and their association with kidney biomarkers related to podocyte injury and inflammation in long-term follow-up after praziquantel (PZQ) treatment.Methods:Schistosoma infection was diagnosed by detecting CAA in urine using a quantitative assay based on lateral flow using luminescent up-converting phosphor reporter particles. A cutoff threshold of 0.1 pg/mL CAA was used to diagnose Schistosoma infection (baseline) in a low-prevalence area in Ceará, Northeast, Brazil. Two groups were included: CAA-positive and CAA-negative individuals, both of which received a single dose of PZQ at baseline. Urinary samples from 55 individuals were evaluated before (baseline) and at 1, 2, and 3 years after PZQ treatment. At all time points, kidney biomarkers were quantified in urine and adjusted for urinary creatinine levels.Results:CAA-positive patients had increased baseline albuminuria and proteinuria and showed greater associations between kidney biomarkers. CAA levels correlated only with Vascular Endothelial Growth Factor (VEGF) (podocyte injury) levels. Increasing trends were observed for malondialdehyde (oxidative stress), monocyte chemoattractant protein-1 (inflammation marker), and VEGF. In the follow-up analysis, no relevant differences were observed in kidney biomarkers between the groups and different periods.Conclusions:S. mansoni-infected individuals presented subclinical signs of glomerular damage that may reflect podocyte injury. However, no causal effect on long-term renal function was observed after PZQ treatment. Show less
Background Mass drug administration (MDA) of praziquantel is one of the main control measures against human schistosomiasis. Although there are claims for including pregnant women, infants and... Show moreBackground Mass drug administration (MDA) of praziquantel is one of the main control measures against human schistosomiasis. Although there are claims for including pregnant women, infants and children under the age of 5 years in high-endemic regions in MDA campaigns, they are usually not treated without a diagnosis. Diagnostic tools identifying infections at the primary health care centre (PHCC) level could therefore help to integrate these vulnerable groups into control programmes. freeBILy (fast and reliable easy-to-use-diagnostics for eliminating bilharzia in young children and mothers) is an international consortium focused on implementing and evaluating new schistosomiasis diagnostic strategies. In Madagascar, the study aims to determine the effectiveness of a test-based schistosomiasis treatment (TBST) strategy for pregnant women and their infants and children up until the age of 2 years. Methods A two-armed, cluster-randomized, controlled phase III trial including 5200 women and their offspring assesses the impact of TBST on child growth and maternal haemoglobin in areas of medium to high endemicity of Schistosoma mansoni. The participants are being tested with the point of care-circulating cathodic antigen (POC-CCA) test, a commercially available urine-based non-invasive rapid diagnostic test for schistosomiasis. In the intervention arm, a POC-CCA-TBST strategy is offered to women during pregnancy and 9 months after delivery, for their infants at 9 months of age. In the control arm, study visit procedures are the same, but without the POC-CCA-TBST procedure. All participants are being offered the POC-CCA-TBST 24 months after delivery. This trial is being integrated into the routine maternal and child primary health care programmes at 40 different PHCC in Madagascar's highlands. The purpose of the trial is to assess the effectiveness of the POC-CCA-TBST for controlling schistosomiasis in young children and mothers. Discussion This trial assesses a strategy to integrate pregnant women and their children under the age of 2 years into schistosomiasis control programmes using rapid diagnostic tests. It includes local capacity building for clinical trials and large-scale intervention research. Show less
Controlled human infection (CHI) models are an important research tool. Healthy volunteers are experimentally infected with a pathogen. In malaria research the model has been used for decades. Here... Show moreControlled human infection (CHI) models are an important research tool. Healthy volunteers are experimentally infected with a pathogen. In malaria research the model has been used for decades. Here, the model was used to test new Plasmodium falciparum strains, NF135.C10 an NF166.C8, and compare these with the commonly used strain NF54. In addition, a genetically modified malaria vaccine, PfSPZ-GA1, was tested. Unfortunately only few volunteers were protected against malaria.For schistosomiasis, a controlled human schistosomiasis infection (CoHSI) model was developed and hereafter a dose finding study with single-sex male only cercariae was performed. This study showed that in 80% of volunteers 20 cercariae were effective to induce an infection. Although the use of 30 cercariae resulted in 100% infection rate two out of three volunteers developed Katayama syndrome. These side effects were less after infection with 20 cercariae.At last suggestions were made to further improve the CHI model by the use of historical controls. Although this study design can only be used in CHI’s with well-know outcomes these study will be safer by reducing the cumulative risks as less volunteers can be used for these trials. Show less
Background: An accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed. We assessed the performance of different laboratory parameters, including the... Show moreBackground: An accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed. We assessed the performance of different laboratory parameters, including the up-converting reporter particle technology lateral flow assay to detect circulating anodic antigen (UCP-LF CAA), for the post-treatment follow-up of schistosomiasis in migrants attending a dedicated outpatient clinic in a non-endemic country.Methods: Routine anti-Schistosoma serology results and eosinophil counts were obtained of patients with positive urine/stool microscopy and/or PCR (confirmed cases) or only positive serology (possible cases), and at least one follow-up visit at 6 (T6) or 12 (T12) months after praziquantel treatment. All sera samples were tested with the UCP-LF CAA assay.Results: Forty-eight patients were included, 23 confirmed and 25 possible cases. The percentage seropositivity and median antibody titers did not change significantly during follow-up. UCP-LF CAA was positive in 86.9% of confirmed and 20% of possible cases. The percentage positivity and median CAA levels decreased significantly post-treatment, with only two patients having positive CAA levels at T12.Conclusions: The UCP-LF CAA assay proved useful for the diagnosis of active infection with Schistosoma spp. and highly valuable for post-treatment monitoring in migrants, encouraging the development of a commercial test. Show less
Schistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV... Show moreSchistosome infection is recognized as a potentially modifiable risk factor for HIV in women by the World Health Organization. Alterations in cervicovaginal bacteria have been associated with HIV acquisition and have not been studied in schistosome infection. We collected cervical swabs from Tanzanian women with and without S. mansoni and S. haematobium to determine effects on cervicovaginal microbiota. Infected women were treated, and follow-up swabs were collected after 3 months. 16S rRNA sequencing was performed on DNA extracted from swabs. We compared 39 women with S. mansoni with 52 uninfected controls, and 16 with S. haematobium with 27 controls. S. mansoni-infected women had increased abundance of Peptostreptococcus (p = 0.026) and presence of Prevotella timonesis (p = 0.048) compared to controls. High-intensity S. haematobium infection was associated with more diverse cervicovaginal bacterial communities than uninfected controls (p = 0.0159). High-intensity S. mansoni infection showed a similar trend (p = 0.154). At follow-up, we observed increased alpha diversity in S. mansoni (2.53 vs. 1.72, p = 0.022) and S. haematobium (2.05 vs. 1.12, p = 0.066) infection groups compared to controls. Modifications in cervicovaginal microbiota, particularly increased diversity and abundance of taxa associated with bacterial vaginosis and HIV (Peptostreptococcus, Prevotella), were associated with schistosome infection. Show less
Schistosomiasis is an acute and chronic disease caused by blood dwelling parasitic trematodes of the genus Schistosoma, and it is classified as the second most socioeconomically devastating... Show moreSchistosomiasis is an acute and chronic disease caused by blood dwelling parasitic trematodes of the genus Schistosoma, and it is classified as the second most socioeconomically devastating parasitic disease, second only to malaria. Currently the wormload is determined by the Kato-Katz method, which is not always reliable. In order to prepare diagnostic tools able to capture specific anti-carbohydrate antibodies or develop conjugate vaccines targeting these carbohydrate structures, sufficient amounts of well-defined fragments are needed. This thesis describes the synthesis of several glycans of these glycans present on the S. mansoni parasite, focusing mainly on the Circulating Anodic Antigen (CAA) and glycans bearing the unique α-(1-2)-L-Fucose-α-(1-2)-L-Fucose motifs. These glycans have been attached to gold nanoparticles and these particles were screened against several monoclonal antibodies and sera of individuals suffering from schistosomiasis. Show less
Schistosoma antigen detection tests have a large potential for schistosomiasis control programs due to their ability to detect active and ongoing Schistosoma infections, their much higher... Show moreSchistosoma antigen detection tests have a large potential for schistosomiasis control programs due to their ability to detect active and ongoing Schistosoma infections, their much higher sensitivity compared to micro-scopical methods, and the possibility to use non-invasive urine samples. Pregnant women and young children could especially benefit from affordable and easy-to-use antigen tests as inclusion of these vulnerable groups in mass drug administration campaigns will always require higher justification hurdles, especially in low to middle endemic regions with a higher proportion of individuals who are not infected and thus unnecessarily exposed to praziquantel.The overall objective of the 'fast and reliable easy-to-use diagnostics for eliminating bilharzia in young children and mothers' (freeBILy, www.freeBILy.eu) project is to thoroughly evaluate the point-of-care circulating cathodic antigen (POC-CCA) and the up-converting phosphor reporter particle, lateral flow circulating anodic antigen (UCP-LF CAA) urine strip tests to diagnose Schistosoma infections in pregnant women and young children and to assess their potential as a schistosomiasis control tool in test-and-treat strategies. The freeBILy project will generate valuable, evidence-based findings on improved tools and test-and-treat strategies to reduce the burden of schistosomiasis in pregnant women and young children. Show less
BackgroundSchistosoma antigen detection in urine is a valuable diagnostic approach for schistosomiasis control programmes because of the higher sensitivity compared to parasitological methods and... Show moreBackgroundSchistosoma antigen detection in urine is a valuable diagnostic approach for schistosomiasis control programmes because of the higher sensitivity compared to parasitological methods and preferred sampling of urine over stool. Highly accurate diagnostics are important in low Schistosoma transmission areas. Pregnant women and young children could particularly benefit from antigen testing as praziquantel (PZQ) can be given to only confirmed Schistosoma cases. This prevents the unborn baby from unnecessary exposure to PZQ. We present here the protocol of a diagnostic study that forms part of the freeBILy project. The aim is to evaluate the accuracy of circulating anodic antigen (CAA) detection for diagnosis of Schistosoma haematobium infections in pregnant women and to validate CAA as an endpoint measure for anti-Schistosoma drug efficacy. The study will also investigate Schistosoma infections in infants.MethodsA set of three interlinked prospective, observational studies is conducted in Gabon. The upconverting phosphor lateral flow (UCP-LF) CAA test is the index diagnostic test that will be evaluated. The core trial, sub-study A, comprehensively evaluates the accuracy of the UCP-LF CAA urine test against a set of other Schistosoma diagnostics in a cross-sectional trial design. Women positive for S. haematobium will proceed with sub-study B and will be randomised to receive PZQ treatment immediately or after delivery followed by weekly sample collection. This approach includes comparative monitoring of CAA levels following PZQ intake and will also contribute further data for safety of PZQ administration during pregnancy. Sub-study C is a longitudinal study to determine the incidence of S. haematobium infection as well as the age for first infection in life-time.DiscussionThe freeBILy trial in Gabon will generate a comprehensive set of data on the accuracy of the UCP-LF CAA test for the detection of S. haematobium infection in pregnant women and newborn babies and for the use of CAA as a marker to determine PZQ efficacy. Furthermore, incidence of Schistosoma infection in infants will be reported. Using the ultrasensitive diagnostics, this information will be highly relevant for Schistosoma prevalence monitoring by national control programs as well as for the development of medicaments and vaccines.Trial registrationThe registration number of this study is NCT03779347 (clinicaltrials.gov, date of registration: 19 December 2018). Show less
During a schistosome infection, the host generates a plethora of antibodies against schistosome glycans. This thesis looks into the anti-schistosome-glycan antibody dynamics in different hosts with... Show moreDuring a schistosome infection, the host generates a plethora of antibodies against schistosome glycans. This thesis looks into the anti-schistosome-glycan antibody dynamics in different hosts with the aim of identifying targets that are relevant in the context of infection and protection. Show less
Grootveld, R. van; Dam, G.J. van; Dood, C. de; Vries, J.J.C. de; Visser, L.G.; Corstjens, P.L.A.M.; Lieshout, L. van 2018
Schistosomiasis is a tropical disease affecting over 230 million people worldwide. Although effective drug treatment is available, reinfections are common, and development of immunity is slow. Most... Show moreSchistosomiasis is a tropical disease affecting over 230 million people worldwide. Although effective drug treatment is available, reinfections are common, and development of immunity is slow. Most antibodies raised during schistosome infection are directed against glycans, some of which are thought to be protective. Developing schistosomula are considered most vulnerable to immune attack, and better understanding of local antibody responses raised against glycans expressed by this life stage might reveal possible glycan vaccine candidates for future vaccine research. In this tehsis we adressed the spatial and temporal expression of glycans expressed during the critical larval stages of schistosome development and we studied the (protective) antibody responses against these glycans in animals and infected human populations. Together these studies thereby contribute to an important basis for the understanding of the anti-glycan antibody responses towards Schistosoma in general and towards the vulnerable schistosomulum in particular. Show less
The work presented in this thesis aimed at increasing our understanding of the effect of helminths on Plasmodium spp. immune response in co-infected individuals living in endemic countries. It... Show moreThe work presented in this thesis aimed at increasing our understanding of the effect of helminths on Plasmodium spp. immune response in co-infected individuals living in endemic countries. It presents data from studies conducted in rural and semi urban areas of Lambaréné (Gabon) where the burden of malaria and helminths is particularly important. Although scarce previous studies have indicated an effect of helminths on malaria outcomes and immune response to Plasmodium spp. parasite in co-infected subjects. However it is still debated how consistent is this effect across study sites and teams and what its immunological basis is. Show less
Low birth weight including preterm birth and intrauterine growth retardation, remains important in sub-Saharan Africa and particularly highly prevalent in Gabon. Among the risk factors of... Show more Low birth weight including preterm birth and intrauterine growth retardation, remains important in sub-Saharan Africa and particularly highly prevalent in Gabon. Among the risk factors of low birth weight in sub-Saharan Africa are very young maternal age, first pregnancy, poor gestational nutrition and small stature of the mother. In Gabon, besides malaria, the other two major parasitic infections namely urogenital schistosomiasis and the filarial infection Loa loa, are common in pregnant women. Maternal schistosomiasis like malaria showed to be associated with higher proportions of low birth weight babies. Mefloquine as an alternative preventive treatment, despite showing no difference with sulphadoxine – pyrimethamine in preventing low birth weight, was however more effective in preventing malaria infection and anaemia. Mefloquine administered for the prevention of malaria was effective against concomitant urogenital schistosomiasis, suggesting that mefloquine could seriously be considered as a combined intervention for both malaria and schistosomiasis during pregnancy, and an alternative to praziquantel. Maternal infection with L. loa was associated with expansion in the neonatal cord blood of functionally activate Tregs that kept Th1 and Th17 immune responses in check, providing some insights on the impact of in utero exposure on the offspring’s development and health. Show less
Downs, J.A.; Corstjens, P.L.A.M.; Mngara, J.; Lutonja, P.; Isingo, R.; Urassa, M.; ... ; Dam, G.J. van 2015