Background: Given that helminth infections are thought to have strong immunomodulatory activity, the question whether helminth infections might affect responses to malaria antigens needs to be addressed. Different cross-sectional studies using diverse methodologies have reported that helminth infections might either exacerbate or reduce the severity of malaria attacks. The same discrepancies have been reported for parasitemia. Methods/Design: To determine the effect of geohelminth infections and their treatment on malaria infection and disease outcome, as well as on immunological parameters, the area of Nangapanda on Flores Island, Indonesia, where malaria and helminth parasites are co-endemic was selected for a longitudinal study. Here a Double-blind randomized trial will be performed, incorporating repeated treatment with albendazole (400 mg) or placebo at three monthly intervals. Household characteristic data, anthropometry, the presence of intestinal helminth and Plasmodium spp infections, and the incidence of malaria episodes are recorded. In vitro cultures of whole blood, stimulated with a number of antigens, mitogens and toll like receptor ligands provide relevant immunological parameters at baseline and following 1 and 2 years of treatment rounds. The primary outcome of the study is the prevalence of Plasmodium falciparum and P. vivax infection. The secondary outcome will be incidence and severity of malaria episodes detected via both passive and active follow-up. The tertiary outcome is the inflammatory cytokine profile in response to parasite antigens. The project also facilitates the transfer of state of the art methodologies and technologies, molecular diagnosis of parasitic diseases, immunology and epidemiology from Europe to Indonesia. Discussion: The study will provide data on the effect of helminth infections on malaria. It will also give information on anthelminthic treatment efficacy and effectiveness and could help develop evidence-based policymaking. Trial registration: This study was approved by The Ethical Committee of Faculty of Medicine, University of Indonesia, ref:194/PT02.FK/Etik/2006 and has been filed by ethics committee of the Leiden University Medical Center. Clinical trial number:ISRCTN83830814. The study is reported in accordance with the CONSORT guidelines for cluster-randomized studies.

Infection with filarial parasites is associated with T cell hyporesponsiveness, which is thought to be partly mediated by their ability to induce regulatory T cells (Tregs) during human infections. This study investigates the functional capacity of Tregs from different groups of filarial patients to suppress filaria-specific immune responses during human filariasis. Microfilaremic (MF), chronic pathology (CP) and uninfected endemic normal (EN) individuals were selected in an area endemic for Brugia timori in Flores island, Indonesia. PBMC were isolated, CD4CD25^hi cells were magnetically depleted and in vitro cytokine production and proliferation in response to B. malayi adult worm antigen (BmA) were determined in total and Treg-depleted PBMC. In MF subjects BmA-specific T and B lymphocyte proliferation as well as IFN-gamma, IL-13 and IL-17 responses were lower compared to EN and CP groups. Depletion of Tregs restored T cell as well as B cell proliferation in MF-positives, while proliferative responses in the other groups were not enhanced. BmA-induced IL-13 production was increased after Treg removal in MF-positives only. Thus, filaria-associated Tregs were demonstrated to be functional in suppressing proliferation and possibly Th2 cytokine responses to BmA. These suppressive effects were only observed in the MF group and not in EN or CP. These findings may be important when considering strategies for filarial treatment and the targeted prevention of filaria-induced lymphedema. Lymphatic filariasis is a neglected disease still prominent in low-resource settings and is very disabling when it progresses to chronic pathology caused by lymphedema. Until now, studies on the contribution of Tregs to lymphocyte hyporesponsiveness in human filariasis have focused on frequency and phenotypic characteristics of these cells. We have looked at the functional consequence of the presence of Tregs in filaria-specific immune responses during different stages of human lymphatic filariasis. Proliferation of not only T cells, but also B cells, was decreased in patients with microfilaremia compared to uninfected individuals and chronic pathology (lymphedema) patients. The suppressed lymphocyte proliferative responses were increased after in vitro removal of Tregs in the microfilaria-positive group only, indicating the presence of filaria-specific functional Tregs in microfilaremic patients which are not as active in subjects with chronic pathology or without infection. Th2 cytokine responses were specifically enhanced in microfilaremics as well after Treg depletion, suggesting Treg-associated suppression of filaria-specific Th2 responses. Taken together, filaria-specific Treg contribute to immune modulation during microfilaremia and might need to be considered in therapeutic strategies to prevent chronic pathology induced by filarial infection.

: The increasing number of refugees coming from or passing through Schistosoma-endemic areas and arriving in Europe highlights the importance of screening for schistosomiasis on arrival, and focuses attention on the choice of diagnostic test. We evaluate the diagnostic performance of circulating anodic antigen (CAA) detection in 92 asymptomatic refugees from Eritrea. Results were compared with already-available stool microscopy, serology, and urine point-of-care circulating cathodic antigen (POC-CCA) data. For a full diagnostic comparison, real-time polymerase chain reaction (PCR) and the POC-CCA were included. All outcomes were compared against a composite reference standard. Urine and serum samples were subjected to the ultra-sensitive and highly specific up-converting particle lateral flow CAA test, Schistosoma spp. real-time PCR was performed on urine and stool, and the POC-CCA was used on urine using the G-score method. CAA was detected in 43% of urine and in 40% of serum samples. Urine PCR was negative in all 92 individuals, whereas 25% showed Schistosoma DNA in stool. POC-CCA was positive in 30% of individuals. The CAA test confirmed all microscopy positives, except for two cases that were also negative by all other diagnostic procedures. Post-treatment, a significant reduction in the number of positives and infection intensity was observed, in particular regarding CAA levels. Our findings confirm that microscopy, serology, and POC-CCA lack the sensitivity to detect all active Schistosoma infections. Accuracy of stool PCR was similar to microscopy, indicating that this method also lacks sensitivity. The CAA test appeared to be the most accurate method for screening active Schistosoma infections and for monitoring treatment efficacy.

Background: The prevalence of asthma and atopic disease has been reported to be low in low income countries, however helminth infections are likely to be high among these communities. The question of whether helminth infections play a role in allergic diseases can best be addressed by intervention studies. None of the studies so far have been based on a large scale placebo-controlled trial.Method/Design: This study was designed to assess how intestinal helminth infections can influence the immune response and atopic and allergic disorders in children in Indonesia. The relations between allergic outcomes and infection and lifestyle factors will be addressed. This study was set up among school-age children in semi urban and rural areas, located in Ende District of Flores Island, Indonesia. A randomized placebo-controlled anthelmintic treatment trial to elucidate the impact of helminth infections on the prevalence of skin prick test (SPT) reactivity and symptoms of allergic diseases will be performed. The children living in these semi-urban and rural areas will be assessed for SPT to allergens before and after 1 and 2 years of treatment as the primary outcome of the study; the secondary outcome is symptoms (asthma and atopic dermatitis); while the tertiary outcome is immune responses (both antibody levels to allergens and cellular immune responses).Discussion: The study will provide information on the influence of helminth infections and anthelmintic treatment on immune response, atopy and allergic disorders.Trial registration: Current Controlled Trials ISRCTN:ISRCTN83830814

BACKGROUND: Partial protective immunity to schistosomiasis develops over time, following repeated praziquantel (PZQ) treatment. Moreover, animals develop protective immunity after repeated immunization with irradiated cercariae. Here, we evaluated the development of natural immunity through consecutive exposure-treatment cycles with Schistosoma mansoni in healthy, Schistosoma -naive participants using single-sex, controlled human S. mansoni infection. METHODS: Twenty-four participants were randomized in a double-blinded (1:1) manner to either the reinfection group, which received 3 exposures (weeks 0, 9, and 18) to 20 male cercariae, or to the infection control group, which received 2 mock exposures with water (weeks 0 and 9) prior to cercariae exposure (week 18). Participants were treated with PZQ (or placebo) at weeks 8, 17, and 30. Attack rates (ARs) after the final exposure (weeks 19–30) using serum circulating anodic antigen (CAA) positivity were compared between groups. Adverse events (AEs) were collected for safety. RESULTS: Twenty-three participants completed the follow-up. No protective efficacy was observed, given an 82% (9 of 11) AR after the final exposure in the reinfection group and 92% (11 of 12) in the infection control group (protective efficacy 11%; 95% CI –24% to 35%; P = 0.5). Related AEs were higher after the first infection (45%) compared with the second (27%) and third (28%) infections. Severe acute schistosomiasis was observed after the first infections only (2 of 12 in the reinfection group and 2 of 12 in the infection control group). CONCLUSION: Repeated Schistosoma exposure and treatment cycles resulted in apparent clinical tolerance, with fewer symptoms reported following subsequent infections, but did not result in protection against reinfection. TRIAL REGISTRATION: ClinicalTrials.gov NCT05085470. FUNDING: European Research Council (ERC) Starting Grant (no. 101075876).

Background: The potential of schistosomiasis to spread across borders, coupled with the considerable delay by which infected travellers and migrants are diagnosed in Europe, calls for better surveillance of the distribution of this disease. This study explored the geographical origin and genetic profiles of Schistosoma infections imported into Europe and diagnosed in a network of 11 European centres specialized in traveller and migrant health. Methods: Genetic profiles were obtained from DNA extracted from concentrated Schistosoma eggs or Schistosoma -positive samples (faeces, urine, biopsy) collected during routine diagnostic procedures. The species-specific cytochrome oxidase sub-unit 1 ( cox1 ) diagnostic region and the standard complete internal transcribed spacer (ITS) 1 + ITS2 (ITS1 + 2) ribosomal DNA region were amplified and sequenced, together with a partial region of 18S ribosomal DNA in selected cases. Prevalences of the different genetic profiles within the whole patient cohort and by country/geographical area of possible infection were analysed. A phylogenetic analysis was performed using the larger cox1 (~ 956 base pairs) sequences dataset. Results: A total of 94 samples were available for analysis, 36 from patients with a diagnosis of intestinal schistosomiasis and 58 with urinary schistosomiasis, all acquired in a sub-Saharan African country. Mitochondrial (mt) cox1 , nuclear ITS1 + 2 and/or 18S (mt/nuclear) genotypes were successfully obtained from 51/94 (54%) samples; while for 43/94 (46%) samples, only a partial mt genotype was obtained. Infections with Schistosoma haematobium and Schistosoma mansoni were identified in the majority of cases (66/94; 70%), while mixed Schistosoma spp. genetic profiles, which were identified in 30% (28/94) of the samples, were almost exclusively (27/28; 96%) associated with cases of urinary schistosomiasis. Among the urinary infections, almost half (27/58; 47%) could be identified as having a mixed genetic profile. These mostly (26/28; 93%) included genetic traits of S. haematobium and Schistosoma bovis , and all were from patients probably infected in West Africa. Conclusions: Infections with S. haematobium and S. mansoni represent the majority of cases of schistosomiasis currently being diagnosed in Europe; however, mixed Schistosoma genetic profiles (mostly S. haematobium/S. bovis ) were identified in at least 30% of samples. Our results call for a coordinated effort encompassing prompt diagnosis and treatment of Schistosoma infections, together with monitoring of the possible introduction of species of Schistosoma and establishment of their autochthonous transmission under suitable conditions in Europe.