Schistosomiasis is a disease caused by parasitic flatworms of the Schistosoma spp., and is increasingly recognized to alter the immune system, and the potential to respond to vaccines. The impact... Show moreSchistosomiasis is a disease caused by parasitic flatworms of the Schistosoma spp., and is increasingly recognized to alter the immune system, and the potential to respond to vaccines. The impact of endemic infections on protective immunity is critical to inform vaccination strategies globally. We assessed the influence of Schistosoma mansoni worm burden on multiple host vaccine-related immune parameters in a Ugandan fishing cohort (n = 75) given three doses of a Hepatitis B (HepB) vaccine at baseline and multiple timepoints post-vaccination. We observed distinct differences in immune responses in instances of higher worm burden, compared to low worm burden or non-infected. Concentrations of pre-vaccination serum schistosome-specific circulating anodic antigen (CAA), linked to worm burden, showed a significant bimodal distribution associated with HepB titers, which was lower in individuals with higher CAA values at month 7 post-vaccination (M7). Comparative chemokine/cytokine responses revealed significant upregulation of CCL19, CXCL9 and CCL17 known to be involved in T cell activation and recruitment, in higher CAA individuals, and CCL17 correlated negatively with HepB titers at month 12 post-vaccination. We show that HepB-specific CD4(+) T cell memory responses correlated positively with HepB titers at M7. We further established that those participants with high CAA had significantly lower frequencies of circulating T follicular helper (cTfh) subpopulations pre- and post-vaccination, but higher regulatory T cells (Tregs) post-vaccination, suggesting changes in the immune microenvironment in high CAA could favor Treg recruitment and activation. Additionally, we found that changes in the levels of innate-related cytokines/chemokines CXCL10, IL-1 & beta;, and CCL26, involved in driving T helper responses, were associated with increasing CAA concentration. This study provides further insight on pre-vaccination host responses to Schistosoma worm burden which will support our understanding of vaccine responses altered by pathogenic host immune mechanisms and memory function and explain abrogated vaccine responses in communities with endemic infections.Author summarySchistosomiasis drives host immune responses for optimal pathogen survival, potentially altering host responses to vaccine-related antigen. Chronic schistosomiasis and co-infection with hepatotropic viruses are common in countries where schistosomiasis is endemic. We explored the impact of Schistosoma mansoni (S. mansoni) worm burden on Hepatitis B (HepB) vaccination of individuals from a fishing community in Uganda. We demonstrate that higher schistosome-specific antigen (circulating anodic antigen, CAA) concentration pre-vaccination, is associated with lower HepB antibody titers post-vaccination at month 7. We show higher pre-vaccination levels of CCL17 in instances of high CAA that negatively associate with HepB antibody titers month 12 post-vaccination and coincided with lower frequencies of circulating T follicular helper cell populations (cTfh), proliferating antibody secreting cells (ASCs), and higher frequencies of regulatory T cells (Tregs). We also show that monocyte function is important in HepB vaccine responses, and high CAA is associated with alterations in the early innate cytokine/chemokine microenvironment. Our findings suggest that in individuals with high CAA and likely high worm burden, schistosomiasis can create an environment that is polarized against optimal host immune responses to the vaccine, which puts many endemic communities at risk for infection against HepB and other diseases that are preventable by vaccines. Show less
During chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role.... Show moreDuring chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role. Schistosoma mansoni soluble egg antigens (SEA) are bound and internalized by B cells and induce both human and mouse IL-10 producing Breg cells. To identify Breg-inducing proteins in SEA, we fractionated SEA by size exclusion chromatography and found 6 fractions able to induce IL-10 production by B cells (out of 18) in the high, medium and low molecular weight (MW) range. The high MW fractions were rich in heavily glycosylated molecules, including multi-fucosylated proteins. Using SEA glycoproteins purified by affinity chromatography and synthetic glycans coupled to gold nanoparticles, we investigated the role of these glycan structures in inducing IL-10 production by B cells. Then, we performed proteomics analysis on active low MW fractions and identified a number of proteins with putative immunomodulatory properties, notably thioredoxin (SmTrx1) and the fatty acid binding protein Sm14. Subsequent splenic murine B cell stimulations and hock immunizations with recombinant SmTrx1 and Sm14 showed their ability to dose-dependently induce IL-10 production by B cells both in vitro and in vivo. Identification of unique Breg cells-inducing molecules may pave the way to innovative therapeutic strategies for inflammatory and auto-immune diseases.Author summaryWorm parasites, such as schistosomes, are master regulators of the human immune system, manipulating the host response in order to prolong their survival in their host. As a bystander effect, they also reduce immune responses to allergens and/or auto antigens, thus protecting their host against inflammatory and auto-immune diseases. One of the immune cells involved in immune regulation is the IL-10-producing regulatory B (Breg) cells. Schistosome eggs release various molecules that induce the development of Breg cells, but the identity of these molecules is not yet fully known. In this study, the authors aimed to identify some of these molecules. They investigated both the involvement of glycans on high molecular weight schistosomal egg molecules, as well as dissected the role of proteins with a lower molecular weight coming from schistosomal eggs. Using proteomics, they targeted various interesting molecules, which they recombinantly expressed and confirmed the IL-10 inducing capacity in B cells in vitro and in vivo for 2 molecules. This new knowledge may explain the hyporesponsiveness found in chronic schistosome-infected people and may pave the way to new innovative therapies for inflammatory and auto-immune diseases. Show less
During chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role.... Show moreDuring chronic schistosome infections, a complex regulatory network is induced to regulate the host immune system, in which IL-10-producing regulatory B (Breg) cells play a significant role. Schistosoma mansoni soluble egg antigens (SEA) are bound and internalized by B cells and induce both human and mouse IL-10 producing Breg cells. To identify Breg-inducing proteins in SEA, we fractionated SEA by size exclusion chromatography and found 6 fractions able to induce IL-10 production by B cells (out of 18) in the high, medium and low molecular weight (MW) range. The high MW fractions were rich in heavily glycosylated molecules, including multi-fucosylated proteins. Using SEA glycoproteins purified by affinity chromatography and synthetic glycans coupled to gold nanoparticles, we investigated the role of these glycan structures in inducing IL-10 production by B cells. Then, we performed proteomics analysis on active low MW fractions and identified a number of proteins with putative immunomodulatory properties, notably thioredoxin (SmTrx1) and the fatty acid binding protein Sm14. Subsequent splenic murine B cell stimulations and hock immunizations with recombinant SmTrx1 and Sm14 showed their ability to dose-dependently induce IL-10 production by B cells both in vitro and in vivo. Identification of unique Breg cells-inducing molecules may pave the way to innovative therapeutic strategies for inflammatory and auto-immune diseases.Author summaryWorm parasites, such as schistosomes, are master regulators of the human immune system, manipulating the host response in order to prolong their survival in their host. As a bystander effect, they also reduce immune responses to allergens and/or auto antigens, thus protecting their host against inflammatory and auto-immune diseases. One of the immune cells involved in immune regulation is the IL-10-producing regulatory B (Breg) cells. Schistosome eggs release various molecules that induce the development of Breg cells, but the identity of these molecules is not yet fully known. In this study, the authors aimed to identify some of these molecules. They investigated both the involvement of glycans on high molecular weight schistosomal egg molecules, as well as dissected the role of proteins with a lower molecular weight coming from schistosomal eggs. Using proteomics, they targeted various interesting molecules, which they recombinantly expressed and confirmed the IL-10 inducing capacity in B cells in vitro and in vivo for 2 molecules. This new knowledge may explain the hyporesponsiveness found in chronic schistosome-infected people and may pave the way to new innovative therapies for inflammatory and auto-immune diseases. Show less
Schistosomiasis is a major neglected tropical disease (NTD) affecting both humans and animals. The morbidity and mortality inflicted upon livestock in the Afrotropical region has been largely... Show moreSchistosomiasis is a major neglected tropical disease (NTD) affecting both humans and animals. The morbidity and mortality inflicted upon livestock in the Afrotropical region has been largely overlooked, in part due to a lack of validated sensitive and specific tests, which do not require specialist training or equipment to deliver and interpret. As stressed within the recent WHO NTD 2021–2030 Roadmap and Revised Guideline for schistosomiasis, inexpensive, non-invasive, and sensitive diagnostic tests for livestock-use would also facilitate both prevalence mapping and appropriate intervention programmes. The aim of this study was to assess the sensitivity and specificity of the currently available point-of-care circulating cathodic antigen test (POC-CCA), designed for Schistosoma mansoni detection in humans, for the detection of intestinal livestock schistosomiasis caused by Schistosoma bovis and Schistosoma curassoni. POC-CCA, together with the circulating anodic antigen (CAA) test, miracidial hatching technique (MHT), Kato-Katz (KK) and organ and mesentery inspection (for animals from abattoirs only), were applied to samples collected from 195 animals (56 cattle and 139 small ruminants (goats and sheep) from abattoirs and living populations) from Senegal. POC-CCA sensitivity was greater in the S. curassoni-dominated Barkedji livestock, both for cattle (median 81%; 95% credible interval (CrI): 55%-98%) and small ruminants (49%; CrI: 29%-87%), than in the S. bovis-dominated Richard Toll ruminants (cattle: 62%; CrI: 41%-84%; small ruminants: 12%, CrI: 1%-37%). Overall, sensitivity was greater in cattle than in small ruminants. Small ruminants POC-CCA specificity was similar in both locations (91%; CrI: 77%-99%), whilst cattle POC-CCA specificity could not be assessed owing to the low number of uninfected cattle surveyed. Our results indicate that, whilst the current POC-CCA does represent a potential diagnostic tool for cattle and possibly for predominantly S. curassoni-infected livestock, future work is needed to develop parasite- and/or livestock-specific affordable and field-applicable diagnostic tests to enable determination of the true extent of livestock schistosomiasis. Show less
Hoekstra, P.T.; Casacuberta-Parta, M.; Lieshout, L. van; Corstjens, P.L.A.M.; Tsonaka, R.; Assare, R.K.; ... ; Dam, G.J. van 2022
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
BackgroundSchistosomiasis control relies mainly on mass drug administration of Praziquantel (PZQ) to school aged children (SAC). Although precision mapping has recently guided decision making, the... Show moreBackgroundSchistosomiasis control relies mainly on mass drug administration of Praziquantel (PZQ) to school aged children (SAC). Although precision mapping has recently guided decision making, the sub-districts and the epidemiological differences existing between bio-ecological settings in which infected children come from were not taken into consideration. This study was designed to fill this gap by using POC-CCA and KK to comparatively determine the prevalence and infection intensities of Schistosoma mansoni (S. mansoni) and to perform fine-scale mapping of S. mansoni infections and its infection intensities with the overarching goal of identifying sub-districts presenting high transmission risk where control operations must be boosted to achieve schistosomiasis elimination.MethodologyDuring a cross- sectional study conducted in Makenene, 1773 stool and 2253 urine samples were collected from SAC of ten primary schools. S. mansoni infections were identified using the point of care circulating cathodic antigen (POC-CCA) and Kato-Katz (KK) test respectively on urine and stool samples. Geographical coordinates of houses of infected SAC were recorded using a global position system device. Schistosome infections and infection intensities were map using QGIS software.ResultsThe prevalence of S. mansoni inferred from POC-CCA and KK were 51.3% and 7.3% respectively. Most infected SAC and those bearing heavy infections intensities were clustered in sub-districts of Baloua, Mock-sud and Carriere. Houses with heavily-infected SAC were close to risky biotopes.ConclusionThis study confirms the low sensitivity of KK test compared to POC-CCA to accurately identify children with schistosome infection and bearing different schistosome burden. Fine-scale mapping of schistosome infections and infection intensities enabled to identify high transmission sub-districts where control measures must be boosted to reach schistosomiasis elimination. Show less
BackgroundKnowing the prevalence of schistosomiasis is key to informing programmes to control and eliminate the disease as a public health problem. It is also important to understand the impact of... Show moreBackgroundKnowing the prevalence of schistosomiasis is key to informing programmes to control and eliminate the disease as a public health problem. It is also important to understand the impact of infection on child growth and development in order to allocate appropriate resources and effort to the control of the disease.MethodsWe conducted a survey to estimate the prevalence of schistosomiasis among school aged children in villages along the Albert-Nile shore line in the district of Pakwach, North Western Uganda. A total of 914 children aged between 10-15 years were screened for Schistosoma mansoni using the POC-CCA and Kato Katz (KK) techniques. The infection intensities were assessed by POC-CCA and KK as well as CAA tests. The KK intensities were also correlated with POC-CCA and with CAA intensity. Anthropometric measurements were also taken and multivariate analysis was carried out to investigate their association with infection status.ResultsThe prevalence of schistosomiasis using the POC-CCA diagnostic test was estimated at 85% (95% CI: 83-87), being highest amongst children living closer to the Albert-Nile shoreline. Visual scoring of the POC-CCA results was more sensitive than the Kato Katz test and was positively correlated with the quantified infection intensities by the CAA test. The majority of the children were underweight (BMI< 18.5), and most notably, boys had significantly lower height for age (stunting) than girls in the same age range (p < 0.0001), but this was not directly associated with S. mansoni infection.ConclusionHigh prevalence of S. mansoni infection in the region calls for more frequent mass drug administration with praziquantel. We observed high levels of stunting which was not associated with schistosomiasis. There is a need for improved nutrition among the children in the area.Author summarySchistosomiasis is a neglected but frequent disease that is caused by schistosomes, with over 290 million people worldwide at risk of infection. The major mode of transmission is through contact with fresh water sources infested with infected snails (the intermediate host). In this study, using the point of care test (POC-CCA), we screened 914 school aged children (10-15 years) living in the rural communities along the Lake Albert- River Nile shores of Pakwach district in Northern Uganda. We observed a very high prevalence of S. mansoni infections (over 80%) although the prevalence dropped to 40% in communities that were further from the lake shores. This high prevalence was also coupled with Kato Katz light schistosome infection intensities as categorised by WHO guidelines. We further compared the POC-CCA and Kato Katz tests to the more sensitive CAA assay and this revealed that even though both tests gave good probability of positive prediction, the POC-CCA had higher sensitivity in screening for S. mansoni infections than Kato Katz assay. The study also revealed high levels of stunting within the children, more so amongst boys. Frequent screening and mass treatment of these communities with praziquantel will reduce on the infection rates. But in addition, improved hygiene and sanitation will be required for a sustainable reduction in the prevalence and morbidity of schistosomiasis in the Albert-Nile communities along with dietary intervention for optimal child health. Show less
Background: Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries.... Show moreBackground: Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure. Methodology: We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference. Principal findings: IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed. Conclusions: We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens. Show less
Braet, S.M.; Hooij, A. van; Hasker, E.; Fransen, E.; Wirdane, A.; Baco, A.; ... ; Jong, B.C. de 2021
Author summaryLeprosy is the oldest infectious disease known to humankind. We still do not succeed in curbing its transmission, with more than 200,000 new patients detected worldwide each year.... Show moreAuthor summaryLeprosy is the oldest infectious disease known to humankind. We still do not succeed in curbing its transmission, with more than 200,000 new patients detected worldwide each year. Identifying persons with a high burden of bacteria is key to curb transmission. To identify these persons, bacteria are counted in invasive and painful samples like slit skin smears and skin biopsies. We evaluated whether we can use less invasive samples, like fingerstick blood or nasal swabs, to determine the bacterial load. We found that the level of antibodies against M. leprae (alpha PGL-I IgM) in fingerstick blood correlates well with the bacterial load determined in skin biopsies from the same leprosy patient. Therefore, a high level of antibodies against M. leprae in fingerstick blood might identify persons who pose a potential risk for transmission of leprosy and could be prioritized for contact screening, which is essential for control of the disease.The World Health Organization (WHO) endorsed diagnosis of leprosy (also known as Hansen's disease) entirely based on clinical cardinal signs, without microbiological confirmation, which may lead to late or misdiagnosis. The use of slit skin smears is variable, but lacks sensitivity. In 2017-2018 during the ComLep study, on the island of Anjouan (Union of the Comoros; High priority country according to WHO, 310 patients were diagnosed with leprosy (paucibacillary = 159; multibacillary = 151), of whom 263 were sampled for a skin biopsy and fingerstick blood, and 260 for a minimally-invasive nasal swab. In 74.5% of all skin biopsies and in 15.4% of all nasal swabs, M. leprae DNA was detected. In 63.1% of fingerstick blood samples, M. leprae specific antibodies were detected with the quantitative alpha PGL-I test. Results show a strong correlation of alpha PGL-I IgM levels in fingerstick blood and RLEP-qPCR positivity of nasal swabs, with the M. leprae bacterial load measured by RLEP-qPCR of skin biopsies. Patients with a high bacterial load (>= 50,000 bacilli in a skin biopsy) can be identified with combination of counting lesions and the alpha PGL-I test. To our knowledge, this is the first study that compared alpha PGL-I IgM levels in fingerstick blood with the bacterial load determined by RLEP-qPCR in skin biopsies of leprosy patients. The demonstrated potential of minimally invasive sampling such as fingerstick blood samples to identify high bacterial load persons likely to be accountable for the ongoing transmission, merits further evaluation in follow-up studies. Show less
Troost-Kind, B.; Hemert, M.J. van; Pol, D. van de; Ende-Metselaar, H. van der; Merits, A.; Borggrewe, M.; ... ; Smit, J.M. 2021
Author summaryChikungunya fever is a debilitating disease caused by the mosquito-borne Chikungunya virus. Over the past two decades the geographical spread of the virus and its mosquito vector has... Show moreAuthor summaryChikungunya fever is a debilitating disease caused by the mosquito-borne Chikungunya virus. Over the past two decades the geographical spread of the virus and its mosquito vector has drastically increased thereby causing millions of infections. To date there is no antiviral drug and no vaccine available to treat/prevent Chikungunya virus infection. We recently showed that the natural steroidal alkaloid tomatidine has potent antiviral activity towards Chikungunya virus at submicromolar concentrations. In this study we dissected how tomatidine reduces the production of Chikungunya virus particles. We show that tomatidine lowers viral protein expression and we hypothesize that the effect of tomatidine on viral protein translation hampers the production of progeny viral RNA copies / number of infected cells thereby leading to a reduced production of secreted virus particles. Also, we show that Chikungunya virus does not readily become resistant to tomatidine. Collectively, we deciphered the mechanism by which tomatidine exerts antiviral activity to Chikungunya virus and our results strengthen the potential of tomatidine as an antiviral treatment strategy towards Chikungunya virus.Tomatidine, a natural steroidal alkaloid from unripe green tomatoes has been shown to exhibit many health benefits. We recently provided in vitro evidence that tomatidine reduces the infectivity of Dengue virus (DENV) and Chikungunya virus (CHIKV), two medically important arthropod-borne human infections for which no treatment options are available. We observed a potent antiviral effect with EC50 values of 0.82 mu M for DENV-2 and 1.3 mu M for CHIKV-LR. In this study, we investigated how tomatidine controls CHIKV infectivity. Using mass spectrometry, we identified that tomatidine induces the expression of p62, CD98, metallothionein and thioredoxin-related transmembrane protein 2 in Huh7 cells. The hits p62 and CD98 were validated, yet subsequent analysis revealed that they are not responsible for the observed antiviral effect. In parallel, we sought to identify at which step of the virus replication cycle tomatidine controls virus infectivity. A strong antiviral effect was seen when in vitro transcribed CHIKV RNA was transfected into Huh7 cells treated with tomatidine, thereby excluding a role for tomatidine during CHIKV cell entry. Subsequent determination of the number of intracellular viral RNA copies and viral protein expression levels during natural infection revealed that tomatidine reduces the RNA copy number and viral protein expression levels in infected cells. Once cells are infected, tomatidine is not able to interfere with active RNA replication yet it can reduce viral protein expression. Collectively, the results delineate that tomatidine controls viral protein expression to exert its antiviral activity. Lastly, sequential passaging of CHIKV in presence of tomatidine did not lead to viral resistance. Collectively, these results further emphasize the potential of tomatidine as an antiviral treatment towards CHIKV infection. Show less
Mouwenda, Y.D.; Ongwe, M.E.B.; Sonnet, F.; Stam, K.A.; Labuda, L.A.; Vries, S. de; ... ; Yazdanbakhsh, M. 2021
Two hookworm vaccine candidates, Na-GST-1 and Na-APR-1, formulated with Glucopyranosyl Lipid A (GLA-AF) adjuvant, have been shown to be safe, well tolerated, and to induce antibody responses in a... Show moreTwo hookworm vaccine candidates, Na-GST-1 and Na-APR-1, formulated with Glucopyranosyl Lipid A (GLA-AF) adjuvant, have been shown to be safe, well tolerated, and to induce antibody responses in a Phase 1 clinical trial (Clinicaltrials.gov NCT02126462) conducted in Gabon. Here, we characterized T cell responses in 24 Gabonese volunteers randomized to get vaccinated three times with Na-GST-1 and Na-APR-1 at doses of 30 mu g (n = 8) or 100 mu g (n = 10) and as control Hepatitis B (n = 6). Blood was collected pre- and post-vaccination on days 0, 28, and 180 as well as 2-weeks after each vaccine dose on days 14, 42, and 194 for PBMCs isolation. PBMCs were stimulated with recombinant Na-GST-1 or Na-APR-1, before (days 0, 28 and 180) and two weeks after (days 14, 42 and 194) each vaccination and used to characterize T cell responses by flow and mass cytometry. A significant increase in Na-GST-1 -specific CD4(+) T cells producing IL-2 and TNF, correlated with specific IgG antibody levels, after the third vaccination (day 194) was observed. In contrast, no increase in Na-APR-1 specific T cell responses were induced by the vaccine. Mass cytometry revealed that, Na-GST-1 cytokine producing CD4(+) T cells were CD161(+) memory cells expressing CTLA-4 and CD40-L. Blocking CTLA-4 enhanced the cytokine response to Na-GST-1.In Gabonese volunteers, hookworm vaccine candidate, Na-GST-1, induces detectable CD4(+) T cell responses that correlate with specific antibody levels. As these CD4(+) T cells express CTLA-4, and blocking this inhibitory molecules resulted in enhanced cytokine production, the question arises whether this pathway can be targeted to enhance vaccine immunogenicity.Author summaryTwo hookworm vaccine candidate (Na-GST-1 and Na-APR-1) have been tested in Gabonese and found to be safe and to induce antibody response. We aimed to study the cellular immune responses among vaccinated and unvaccinated volunteers. We found that Na-GST-1 induced CD4(+) T cell responses (IL-2, TNF) among the vaccinated volunteers that received the high vaccine dose (100 ug). Furthermore Na-GST-1 specific memory T cells were found to express the inhibitory molecule CTLA-4. These responses was not observed in those who received the low dose of the Na-GST-1 vaccine, or those who received Na-APR-1 or HBV. By blocking CTLA-4, we observed an increase in TNF production. Our data suggest that an intervention involving blockage of the CTLA-4 molecule in the vaccinated could be beneficial in endemic settings where vaccine responses have been shown to be lower compared to non-endemic settings. Show less
Grau-Pujol, B.; Marti-Soler, H.; Escola, V.; Demontis, M.; Jamine, J.C.; Gandasegui, J.; ... ; Munoz, J. 2021
World Health Organization goals against soil-transmitted helminthiases (STH) are pointing towards seeking their elimination as a public health problem: reducing to less than 2% the proportion of... Show moreWorld Health Organization goals against soil-transmitted helminthiases (STH) are pointing towards seeking their elimination as a public health problem: reducing to less than 2% the proportion of moderate and heavy infections. Some regions are reaching WHO goals, but transmission could rebound if strategies are discontinued without an epidemiological evaluation. For that, sensitive diagnostic methods to detect low intensity infections and localization of ongoing transmission are crucial. In this work, we estimated and compared the STH infection as obtained by different diagnostic methods in a low intensity setting. We conducted a cross-sectional study enrolling 792 participants from a district in Mozambique. Two stool samples from two consecutive days were collected from each participant. Samples were analysed by Telemann, Kato-Katz and qPCR for STH detection. We evaluated diagnostic sensitivity using a composite reference standard. By geostatistical methods, we estimated neighbourhood prevalence of at least one STH infection for each diagnostic method. We used environmental, demographical and socioeconomical indicators to account for any existing spatial heterogeneity in infection. qPCR was the most sensitive technique compared to composite reference standard: 92% (CI: 83%-97%) for A. lumbricoides, 95% (CI: 88%-98%) for T. trichiura and 95% (CI: 91%-97%) for hookworm. qPCR also estimated the highest neighbourhood prevalences for at least one STH infection in a low intensity setting. While 10% of the neighbourhoods showed a prevalence above 20% when estimating with single Kato-Katz from one stool and Telemann from one stool, 86% of the neighbourhoods had a prevalence above 20% when estimating with qPCR. In low intensity settings, STH estimated prevalence of infection may be underestimated if based on Kato-Katz. qPCR diagnosis outperformed the microscopy methods. Thus, implementation of qPCR based predictive maps at STH control and elimination programmes would disclose hidden transmission and facilitate targeted interventions for transmission interruption. Show less
Pierneef, L.; Hooij, A. van; Taal, A.; Rumbaut, R.; Nobre, M.L.; Brakel, W. van; Geluk, A. 2021
Background Leprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients' households. As interruption of transmission is imminent in many countries,... Show moreBackground Leprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients' households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas. Methods and findings A literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels. Conclusions Quantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination.Author summary Leprosy, a chronic infectious disease caused by Mycobacterium leprae (M. leprae), targets the skin and nerves and often results in irreversible disabilities as well as social exclusion. Though the disease can be efficiently treated, leprosy elimination is hampered by ongoing transmission of M. leprae. Currently, elimination is monitored by the number of new cases. Since only a small percentage of individuals infected with M. leprae develops disease, this does not accommodate monitoring of transmission. Previous studies have shown that antibody levels against M. leprae in blood correspond to the bacterial load in an individual and can be used as a proxy for infection, although antibodies cannot distinguish between past and present infection. In young children, infection is recent by definition, which allows assessment of more current state of transmission in an area. Thus, this literature review investigated studies on leprosy serology in children without leprosy. Our findings underscore that young children are a fitting group for up-to-date monitoring of M. leprae transmission in an area as seropositivity is inversely related with age. Importantly, a standardized, field-friendly test quantitatively measuring anti-M. leprae antibodies should be applied for population screening to monitor the status of transmission and thereby elimination in an area. Show less
Background Leprosy is an infectious disease caused by Mycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas,... Show moreBackground Leprosy is an infectious disease caused by Mycobacterium leprae. As incidence begins to decline, the characteristics of new cases shifts away from those observed in highly endemic areas, revealing potentially important insights into possible ongoing sources of transmission. We aimed to investigate whether transmission is driven mainly by undiagnosed and untreated new leprosy cases in the community, or by incompletely treated or relapsing cases.Methodology/Principal findings A literature search of major electronic databases was conducted in January, 2020 with 134 articles retained out of a total 4318 records identified (PROSPERO ID: CRD42020178923). We presented quantitative data from leprosy case records with supporting evidence describing the decline in incidence across several contexts. BCG vaccination, active case finding, adherence to multidrug therapy and continued surveillance following treatment were the main strategies shared by countries who achieved a substantial reduction in incidence. From 3950 leprosy case records collected across 22 low endemic countries, 48.3% were suspected to be imported, originating from transmission outside of the country. Most cases were multibacillary (64.4%) and regularly confirmed through skin biopsy, with 122 cases of suspected relapse from previous leprosy treatment. Family history was reported in 18.7% of cases, while other suspected sources included travel to high endemic areas and direct contact with armadillos. None of the countries included in the analysis reported a distinct increase in leprosy incidence in recent years.Conclusions/Significance Together with socioeconomic improvement over time, several successful leprosy control programmes have been implemented in recent decades that led to a substantial decline in incidence. Most cases described in these contexts were multibacillary and numerous cases of suspected relapse were reported. Despite these observations, there was no indication that these cases led to a rise in new secondary cases, suggesting that they do not represent a large ongoing source of human-to-human transmission.Author summary Although leprosy remains a public health problem in many parts of the world, several countries have successfully controlled the Mycobacterium leprae transmission over recent decades and the case characteristics have been shown to change during periods of declining incidence. However, the potential for certain groups of individuals, such as untreated or relapsed leprosy patients with more severe forms of the disease, to act as sources of ongoing transmission remains unclear. In this systematic review, we aimed to evaluate leprosy case characteristics in low endemic settings, to identify possible sources of transmission and to describe the different control measures implemented. Together with socioeconomic improvement over time, the main strategies shared by many of the countries who achieved a substantial reduction in incidence over recent decades included BCG vaccination, active case finding, adherence to MDT and continued surveillance following treatment. By collecting information on cases in these settings, we found that the number of new cases reported remained low with no indication of a rise in new secondary cases, despite a high proportion of multibacillary disease and the presence of persistent cases of suspected relapse. This evidence suggests that such cases do not represent a large ongoing source of human-to-human transmission. Show less
Author summaryStrongyloidiasis is a poverty-related neglected tropical disease which can cause serious and potentially life-threatening symptoms, in particular in immunocompromised hosts. S.... Show moreAuthor summaryStrongyloidiasis is a poverty-related neglected tropical disease which can cause serious and potentially life-threatening symptoms, in particular in immunocompromised hosts. S. stercoralis is not yet included in the strategies coordinated by WHO for the control of STH, but there are plans for the establishment of a control strategy by 2030. Therefore, diagnostics and control tools to implement that strategy are needed. Different diagnostic approaches are used in different parts of the world and there is no standard diagnostic approach which can be used for routine diagnostic services and field studies. In this study, 437 stool samples from Northwest Ethiopia were analyzed using conventional Baermann, modified Baermann and modified Baermann with charcoal pre-incubation techniques. Using these procedures, we found high prevalence of S. stercoralis infection in the study area. The modified Baermann with charcoal pre-incubation technique worked significantly better than the others in recovering the S. stercoralis larvae, while the conventional Baermann, the most used in routine diagnostics, underestimates the true burden of the disease. The key findings in this study are important for future planning of intervention and control strategies against strongyloidiasis.BackgroundSoil-transmitted helminths (STH) are common in low and middle income countries where there is lack of access to clean water and sanitation. Effective diagnosis and treatment are essential for the control of STH infections. However, among STH parasites, Strongyloides stercoralis is the most neglected species, both in diagnostics and control strategies. Diagnostic methods cover different approaches, each with different sensitivities and specificities, such as serology, molecular techniques and microscopy based techniques. Of the later, the Baermann technique is the most commonly used procedure. In the literature, several ways have been described to perform the Baermann method, which illustrates the overall lack of a '(gold) reference standard' method for the diagnosis of S. stercoralis infection. In this study we have evaluated the performance of three Baermann techniques in order to improve the reference standard for the microscopic diagnosis of S. stercoralis infection thereby facilitating individual case detection, mapping of the disease and proper evaluation of treatment responses.Methods/Principal findingsA community based cross sectional study was conducted at Zenzelima, Bahir Dar Zuria Ethiopia. A total of 437 stool samples were collected and analyzed by the following procedures: conventional Baermann (CB), modified Baermann (MB), and modified Baermann with charcoal pre-incubation (MBCI). The diagnostic sensitivity and Negative Predictive Value (NPV) of each technique was calculated using the combination of all the three techniques as a composite reference standard. Our result indicated that larvae of S. stercoralis were detected in 151 (34.6%) stool samples. The prevalence of S. stercoralis infection based on the three diagnostic methods was 9.6%, 8.0%, and 31.3% by CB, MB, and MBCI respectively. The sensitivity and NPV for CB, MB, and MBCI were 26.7% and 70.8%, 22.1% and 69.6%, and 87.0% and 93.2%, respectively. The MBCI showed significant difference (P- value = <0.001) in the sensitivity and NPV values when compared with CB and MB values. The agreement between CB, MB, and MBCI with the composite reference standard was 31.8%, 26.7%, 89.6%, respectively.Conclusion/SignificanceOur results suggest the superior performance of MBCI. It is relatively easy to implement, simple to perform and comparatively cheaper. The CB is by far the commonly used method in routine diagnostic although this technique significantly underestimates the true burden of the disease and thereby contributing to the exclusion of S. stercoralis from the control strategies. Therefore, MBCI is recommended as a routine microscopy-based diagnostic test for S. stercoralis infection, particularly in settings where molecular procedures are not available. Show less
Cutaneous leishmaniasis (CL) is a chronic skin infection caused by Leishmania parasites, causing single or multiple skin nodules and ulcers on the exposed body locations. Healing of lesions is... Show moreCutaneous leishmaniasis (CL) is a chronic skin infection caused by Leishmania parasites, causing single or multiple skin nodules and ulcers on the exposed body locations. Healing of lesions is followed by scar formation. Active and healed CL lesions may affect patient's health related quality of life (HRQL). The aim of this study was to determine whether the body location of the leishmaniasis lesions affects the HRQL of localized CL patients in Suriname. The HRQL of 163 patients with CL was assessed by Skindex-29 and EQ-5D/VAS questionnaires. Forty-six patients out of the total study population also participated in a qualitative anthropological study involving in depth interviews. All patients were allocated in 4 groups in the following hierarchy: head and face, upper limbs, lower limbs and trunk. Patients with lesions on the lower limbs had significantly higher Skindex-29 scores, indicating worse HRQL, in the symptom scale compared to lesions on head/face and trunk. The lower limb group was more likely to report problems in the dimensions self-care, mobility, daily activities and pain/discomfort of the EQ-5D. Little to no social stigma was reported in the in-depth interviews. The findings of this study indicate that Surinamese patients with CL lesions located on the lower limbs had more impairment in HRQL than on other body locations. Stigma related to CL seems to be virtually absent in Suriname.Author summaryCutaneous leishmaniasis (CL) is a parasitic skin infection characterized by one or more skin lesions. Depending on the location of the lesions, patients may experience difficulties in their day-to-day life including stigma. The aim of this study was to evaluate the quality of life of CL patients with lesions. We collected the data among 163 CL patients with two different questionnaires assessing various parts of their quality of life; 46 patients provided additional information through in depth interviews. All patients were divided in four groups according to location of lesions on the body: head and face, upper limbs, lower limbs, and trunk. We found that patients experienced more difficulties when lesions were located on the lower limbs. Little to no social stigma was reported in the in-depth interviews. The study concluded that Surinamese patients with lesions on the lower limbs had a lower quality of life compared to other body locations. Show less
Background Given the potentially causal association of female genital schistosomiasis (FGS) with HIV-1 infection, improved diagnostics are urgently needed to scale-up FGS surveillance. The BILHIV ... Show moreBackground Given the potentially causal association of female genital schistosomiasis (FGS) with HIV-1 infection, improved diagnostics are urgently needed to scale-up FGS surveillance. The BILHIV (bilharzia and HIV) study assessed the performance of home-based self-collection methods (cervical and vaginal swabs) compared to cervicovaginal lavage (CVL) for the detection ofSchistosomaDNA by real-time polymerase chain reaction (PCR). Methods Between January and August 2018, a consecutive series of female participants from the Population-Cohort of the previous HIV prevention trial HPTN 071 (PopART), resident in Livingstone, Zambia were invited to take part in BILHIV if they were 18-31 years old, non-pregnant and sexually active. Genital self-collected swabs and a urine specimen were obtained and a questionnaire completed at home visits. CVL was obtained at clinic follow-up. Results 603 women self-collected genital swabs. Of these, 527 women had CVL performed by a mid-wife during clinic follow-up.SchistosomaDNA was more frequently detected in genital self-collected specimens (24/603, 4.0%) compared to CVL (14/527, 2.7%). Overall, 5.0% (30/603) women had female genital schistosomiasis, defined as a positive PCR by any genital sampling method (cervical swab PCR, vaginal swab PCR, or CVL PCR) and 95% (573/603) did not have a positive genital PCR. The sensitivity of any positive genital self-collected swab against CVL was 57.1% (95% CI 28.9-82.3%), specificity 97.3% (95.5-98.5%). In a subset of participants with active schistosome infection, determined by detectable urine Circulating Anodic Antigen (CAA) (15.1%, 91/601), positive PCR (4.3%, 26/601), or positive microscopy (5.5%, 33/603), the sensitivity of any positive self-collected specimen against CVL was 88.9% (51.8-99.7%). Conclusions Genital self-sampling increased the overall number of PCR-based FGS diagnoses in a field setting, compared with CVL. Home-based sampling may represent a scalable alternative method for FGS community-based diagnosis in endemic resource limited settings.Author summary Female Genital schistosomiasis (FGS) is a neglected and disabling disease that results when eggs from the waterborne parasiteSchistosoma haematobiumare trapped in the human reproductive tract. Current female genital schistosomiasis (FGS) diagnostic strategies are limited because they require expertise and equipment that may not be readily available in low income settings. Improved and accessible diagnostics are urgently needed to scale-up FGS surveillance. This is especially important as FGS has been associated with HIV-1 infection. The BILHIV (bilharzia and HIV) study assessed the performance of home-based self-collection methods (cervical and vaginal swabs) compared with a clinic-based cervicovaginal lavage (CVL) performed by a medical professional. Both methods used real-time polymerase chain reaction (PCR) to detectSchistosomaDNA. We found that, in a field setting, self-collected genital and cervical swabs increased the overall number of PCR-based FGS diagnoses, compared with clinically collected CVL. We report the sensitivity of self-collected swabs for the diagnosis of FGS, compared with CVL. We found that the sensitivity of self-collected genital swabs was high in a subset of women with active schistosome infection. We suggest that home-based self-sampling may represent a scalable community-based sampling platform for FGS community-based diagnosis in endemic resource limited settings. Show less
Infection with parasitic helminths has been reported to improve insulin sensitivity and glucose homeostasis, lowering the risk for type 2 diabetes. However, little is known about its impact on... Show moreInfection with parasitic helminths has been reported to improve insulin sensitivity and glucose homeostasis, lowering the risk for type 2 diabetes. However, little is known about its impact on whole-body lipid homeostasis, especially in obese individuals. For this purpose, a cross-sectional study was carried out in lean and overweight/obese adults residing in the Lambarene region of Gabon, an area endemic forSchistosoma haematobium. Helminth infection status, peripheral blood immune cell counts, and serum metabolic and lipid/lipoprotein levels were analyzed. We found that urineS.haematobiumegg-positive individuals exhibited lower serum total cholesterol (TC; 4.42vs4.01 mmol/L, adjusted mean difference [95%CI] -0.30 [-0.68,-0.06]; P = 0.109), high-density lipoprotein (HDL)-C (1.44vs1.12 mmol/L, -0.24 [-0.43,-0.06]; P = 0.009) and triglyceride (TG; 0.93vs0.72 mmol/L, -0.20 [-0.39,-0.03]; P = 0.022) levels than egg-negative individuals. However, when stratified according to body mass index, these effects were only observed in overweight/obese infected individuals. Similarly, significant negative correlations between the intensity of infection, assessed by serum circulating anodic antigen (CAA) concentrations, and TC (r = -0.555; P<0.001), HDL-C (r = -0.327; P = 0.068), LDL-C (r = -0.396; P = 0.025) and TG (r = -0.381; P = 0.032) levels were found in overweight/obese individuals but not in lean subjects. Quantitative lipidomic analysis showed that circulating levels of some lipid species associated with cholesterol-rich lipoprotein particles were also significantly reduced in overweight/obese infected individuals in an intensity-dependent manner. In conclusion, we reported that infection withS.haematobiumis associated with improved lipid profile in overweight/obese individuals, a feature that might contribute reducing the risk of cardiometabolic diseases in such population.Author summary Infection with parasitic helminths has been reported to be beneficial for metabolic homeostasis by improving insulin sensitivity and lowering the risk for developing type 2 diabetes. Elevated circulating cholesterol and triglyceride levels associated with obesity are also risk factors for cardiometabolic diseases. In the framework of a cross-sectional study conducted in an endemic rural area, we have investigated the impact of infection withSchistosoma hematobiumon serum lipid homeostasis in adult individuals with a broad range of body weight. We found that helminth infection is associated with a lower serum total cholesterol (TC), high-density lipoprotein (HDL)-C and triglyceride (TG) levels, especially in overweight/obese individuals. Furthermore, significant negative correlations between the intensity of infection and TC, HDL-C, LDL-C and TG levels were also found in overweight/obese individuals but not in lean subjects. Altogether our study show for the first time that infection withSchistosoma hematobiumis associated with an improved serum lipid profile in overweight/obese humans, a feature that may contribute to protection against cardiometabolic diseases in such population. Further investigation is however required to elucidate the underlying molecular mechanisms. Show less
Cools, P.; Lieshout, L. van; Koelewijn, R.; Addiss, D.; Ajjampur, S.S.R.; Ayana, M.; ... ; Levecke, B. 2020
Background Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs;Ascaris lumbricoides,Trichuris trichiura,Necator americanus... Show moreBackground Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs;Ascaris lumbricoides,Trichuris trichiura,Necator americanus,Ancylostoma duodenaleandA.ceylanicum),Strongyloides stercoralisandSchistosomain human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. Methods and principal findings A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris,Trichuris,N.americanus,Ancylostoma,StrongyloidesandSchistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. Conclusions/Significance We showed the technical feasibility of an international EQAS for the NAAT of STHs,StrongyloidesandSchistosoma. In addition, we documented that there are clear benefits for participating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs.Author summary Tests that detect parasite DNA in human stool are increasingly being used for the diagnosis of infections with intestinal worms, including schistosomiasis. To ensure the quality in diagnostic testing of these parasitic worms, it is important that laboratories evaluate the diagnostic performance of their DNA-based tests. This can best be achieved by participating in an external quality assessment scheme (EQAS). An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. Currently, such an EQAS for parasitic worms is lacking. We therefore piloted an international EQAS for the diagnosis of parasitic worms involving 15 laboratories in Africa, Asia, Australia, Europe, and North America. Although most laboratories performed well, we could clearly identify those laboratories that may need to improve their test protocol. We found that laboratories were using many different test protocols, and further research should aim to verify whether this has an impact on the performance of the diagnostic outcomes. 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
