Imported schistosomiasis in Europe: sentinel surveillance data from TropNetEurop

Chronic schistosomiasis imported in France: A retrospective multicentre analysis of 532 patients, calling for international recommendations

BACKGROUND

Schistosomiasis is a major public health issue for migrants. This study aims to describe the clinical presentation and management of imported schistosomiasis in France.

METHODS

We included all new cases of schistosomiasis in patients aged ≥18 years, defined by a positive specific Western blot and/or a positive parasitological analysis of urine, stool or biopsy, between January 1, 2016, and December 31, 2019, in 4 laboratories in Paris and Western France.

RESULTS

Over the study period, 532 patients were included. Mean age was 37 years (18-91), and 461/532 (87 %) were men. Among 476/532 (89 %) patients born in an endemic area, 433 (91 %) were born in sub-Saharan Africa. Most of the patients (405/532, 76 %) had only a positive serology, and 127/532 (24 %) had ova on microscopic examination. Among 361/532 (68 %) who had at least one urine, stool or biopsy analysis, microscopic analysis was positive in 127 (35 %). Imaging showed lesions compatible with schistosomiasis in 88/164 (54 %) patients with clinical symptoms and 13/29 (45 %) patients without (p = 0.5). Patients who arrived in France less than one year before diagnosis were more likely to have clinical symptoms than those who arrived in France 1-5 years and >5 years prior to diagnosis (52 %, 41 % and 43 %, respectively, p = 0.03). Two-hundred and seventeen patients (40.8 %) were left untreated.

CONCLUSION

Approximately 50 % of patients with imported chronic schistosomiasis have radiological abnormalities, whether they are symptomatic or not, and management is heterogeneous. Multidisciplinary international guidelines are requested to clarify the management of this neglected disease.

Clinical Spectrum of Schistosomiasis: An Update

Schistosomiasis is a helminthic infection and one of the neglected tropical diseases (NTDs). It is caused by blood flukes of the genus Schistosoma. It is an important public health problem, particularly in poverty-stricken areas, especially those within the tropics and subtropics. It is estimated that at least 236 million people worldwide are infected, 90% of them in sub-Saharan Africa, and that this disease causes approximately 300,000 deaths annually. The clinical manifestations are varied and affect practically all organs. There are substantial differences in the clinical presentation, depending on the phase and clinical form of schistosomiasis in which it occurs. Schistosomiasis can remain undiagnosed for a long period of time, with secondary clinical lesion. Here, we review the clinical profile of schistosomiasis. This information may aid in the development of more efficacious treatments and improved disease prognosis.

Molecular approach to the epidemiology of urinary schistosomiasis in France

BACKGROUND

The diagnosis of urogenital schistosomiasis is based on the complementarity of serological technique and microscopic examination (ME). Between 2015 and 2019, the number of urinary schistosomiasis tests received in our laboratory increased sharply from 300 to 900 per year. Therefore, we wanted to evaluate the reliability of urine microscopic examination (ME, reference and routine technique) from urine sample by comparing it to other techniques (antigenic technique and PCR). To this end, we optimized two real-time PCRs targeting respectively Schistosoma haematobium (Sh) and Schistosoma mansoni (Sm).

METHODOLOGY/PRINCIPAL FINDINGS

914 urine samples from 846 patients suspected of urogenital schistosomiasis were prescribed and analyzed by PCR and also by antigenic technique for the first 143 samples. The antigenic technique evaluated was Schisto POC-CCA, Rapid Medical Diagnostics. These results (antigenic technique and PCR) were compared to ME which was performed from all urines. The percentage of 14% (128/914) positive cases with the PCR technique and the percentage of 6.0% (54/914) positive cases with ME is significantly different (Chi 2 test, p<0.001). These 128 positive PCRs correspond to 120 different patients, 88.3% (106/120) of them were young migrants and 11.7% (14/120) were French patients returning from travel. Among these migrants, more than 75% (80/106) came from French-speaking West Africa. In addition, the Schisto POC-CCA showed a specificity of 39% (46/117), too poor to be used as a screening tool in low or non-endemic areas.

CONCLUSION/SIGNIFICANCE

Targeted Sh and Sm PCRs in urine are reliable techniques compared to ME (reference technique). In view of our results, we decided to screen urinary schistosomiasis by direct ME always coupled by the PCR technique, which has shown better reliability criteria.

Delay in schistosomiasis diagnosis and treatment: a multicenter cohort study in Italy

BACKGROUND

Barriers to access to care, different diagnostic strategies and low awareness remain challenging issues in the fight against schistosomiasis.Our study aims to examine management of schistosomiasis in migrants attending large tertiary hospitals in Italy, in order to call for a comprehensive approach.

METHODS

A retrospective review of schistosomiasis cases was carried out between January 1, 2016, and December 31, 2017, in five large Infectious Disease Centers in Italy. We included all patients diagnosed with schistosomiasis. We differentiated among (i) asymptomatic patients diagnosed by serology either as healthy 'migrant evaluation' or as 'late evaluation' in patients followed because of a different infection and (ii) patients tested because of a suggestive clinical presentation. Patients characteristics and clinical data were recorded.

RESULTS

One hundred forty-nine patients were included, 137 (91.9%) were male, the median age was 26 years and 70% of them came from Sub-Saharan Africa.Thirty-eight asymptomatic patients (25.5%) were diagnosed by serology [15, (10.1%) among 'migrant evaluation' and 23 (15.4%) among 'late evaluation' group], and 111 (74.5%) presented with signs/symptoms.The median diagnostic delay from arrival in Italy was 31 months: 110 for asymptomatic group and 16 months for symptomatic patients. Among the 111 symptomatic patients, 41 individuals were already followed in our clinics, and they never underwent screening before appearance of evident disease. Among patients with positive serology who were tested by microscopy, 32/86 (37.2%) had confirmed diagnosis. Forty-five (37.8%) patients presented radiologic abnormalities. Praziquantel was the treatment of choice (70.1% for 3 days and 29.9% in a single-day dose), and 77 (51.7%) were lost to follow-up.

CONCLUSIONS

In our centers, a high proportion of patients were tested late after arrival, and most of them presented with clinical apparent disease. Well-defined strategies and implementation of recent guidelines are needed to improve early diagnosis and to overcome heterogeneity of practice.

Schistosomal extracellular vesicle-enclosed miRNAs modulate host T helper cell differentiation

During the chronic stage of Schistosoma infection, the female lays fertile eggs, triggering a strong anti-parasitic type 2 helper T-cell (Th2) immune response. It is unclear how this Th2 response gradually declines even though the worms live for years and continue to produce eggs. Here, we show that Schistosoma mansoni downregulates Th2 differentiation in an antigen-presenting cell-independent manner, by modulating the Th2-specific transcriptional program. Adult schistosomes secrete miRNA-harboring extracellular vesicles that are internalized by Th cells in vitro. Schistosomal miRNAs are found also in T helper cells isolated from Peyer's patches and mesenteric lymph nodes of infected mice. In T helper cells, the schistosomal miR-10 targets MAP3K7 and consequently downmodulates NF-κB activity, a critical transcription factor for Th2 differentiation and function. Our results explain, at least partially, how schistosomes tune down the Th2 response, and provide further insight into the reciprocal geographic distribution between high prevalence of parasitic infections and immune disorders such as allergy. Furthermore, this worm-host crosstalk mechanism can be harnessed to develop diagnostic and therapeutic approaches for human schistosomiasis and Th2-associated diseases.

Currently Available Monitoring and Surveillance Systems for Taenia spp., Echinococcus spp., Schistosoma spp., and Soil-Transmitted Helminths at the Control/Elimination Stage: A Systematic Review

An increasing global focus on neglected tropical diseases (NTDs) has resulted in the set up of numerous control and elimination activities worldwide. This is partly true for Taenia solium taeniasis/cysticercosis, the most important foodborne parasitic infection. Despite substantial progress, adequate monitoring and surveillance (M&S) are required to sustain a status of control/elimination. This is often lacking, especially for T. solium. Therefore, the objective was to conduct a systematic literature review of the currently available M&S systems at the control/elimination stage of the four top-ranked helminth NTDs. Specifically, Taenia spp., Echinococcus spp., Schistosoma spp., and soil-transmitted helminths (STHs) were considered to determine if there are any similarities between their M&S systems and whether certain approaches can be adopted from each other. The systematic review demonstrated that rigorous M&S systems have been designed for the control/elimination stage of both STHs and schistosomiasis, particularly in China. On the other hand, a concept of M&S for Taenia spp. and Echinococcus spp. has not been fully developed yet, due to a lack of epidemiological data and the fact that many endemic countries are far away from reaching control/elimination. Moreover, accurate diagnostic tools for all four diseases are still imperfect, which complicates proper M&S. Finally, there is an urgent need to develop and harmonize/standardize M&S activities in order to reliably determine and compare the epidemiological situation worldwide.

Functional analysis of the Frzb2 gene in Schistosoma japonicum

Schistosomiasis is a globally important helminthic disease of humans and animals, and it is the second most common parasitic disease after malaria. Eggs produced by mature females are responsible for the disease’s occurrence and spread. Frzb2, a secreted frizzled-related protein, can inhibit Wnt signalling by competitive binding to the specific frizzled protein receptor. In this study, the complete gene sequence of SjFrzb2 was obtained by using 3′-rapid amplification of cDNA ends technology. SjFrzb2 transcript levels at different stages of S. japonicum maturation were evaluated by quantitative real-time RT-PCR analysis. SjFrzb2 was expressed at all developmental stages examined and exhibited the highest transcription level in 7-day-old worms, then gradually decreased during the growth and developmental stages to reach the lowest level at 18 days post-infection. SjFrzb2 gene expression was higher in female worms than in male worms and was significantly higher in female worms from a single-sex infection than in female worms from a bisexual infection. The functions of SjFrzb2 were explored via a small interfering RNA-based gene silencing approach and the soaking method. The results showed that SjFrzb2 gene knockdown impaired the growth and development of S. japonicum in mice, affecting not only the survival and morphological structure of the worms but also their reproductive ability and the viability of the produced eggs. Collectively, these observations imply that Frzb2 may be a novel target for the development of immuno- and/or small molecule-based therapeutics to control schistosomiasis fecundity and transmission.

Detection of Schistosoma mansoni-derived DNA in human urine samples by loop-mediated isothermal amplification (LAMP)

BACKGROUND

Schistosoma mansoni is the main species causing hepatic and intestinal schistosomiasis in Sub-Saharan Africa, and it is the only species in South America. Adult stages of the parasite reside in the mesenteric venous plexus of infected hosts, and eggs are shed in feces. Collecting patient stool samples for S. mansoni diagnostic purposes is difficult in large-scale field trials. Urine samples would be an alternative approach for molecular S. mansoni detection since they have several advantages over stool samples, including better handling, management and storage. Additionally, loop-mediated isothermal amplification (LAMP) technology is a powerful molecular diagnostic tool for infectious diseases, particularly under field conditions in developing countries. The present study aimed to assess the effectiveness of our previously developed LAMP assay (SmMIT-LAMP) for S. mansoni-specific detection in clinical urine samples.

METHODOLOGY/PRINCIPAL FINDINGS

The sensitivity of SmMIT-LAMP in urine was established in simulated fresh human urine samples artificially spiked with genomic DNA from S. mansoni. LAMP for 120 min instead of 60 min improved the sensitivity, reaching values of 0.01 fg/μL. A set of well-defined frozen stored human urine samples collected from Sub-Saharan immigrant patients was selected from a biobank to evaluate the diagnostic validity of SmMIT-LAMP. The set included urine samples from patients with microscopy-confirmed infections with S. mansoni, S. haematobium and other nonschistosome parasites, as well as urine samples from patients with microscopy-negative eosinophilia without a confirmed diagnosis. The SmMIT-LAMP was incubated for 60 and 120 min. A longer incubation time was shown to increase the LAMP-positive results in patient urine samples. We also tested urine samples from mice experimentally infected with S. mansoni, and LAMP-positive results were obtained from the third week after infection. A real-time LAMP assay was also performed with three individual urine samples.

CONCLUSIONS/SIGNIFICANCE

The SmMIT-LAMP could effectively detect S. mansoni DNA in mouse urine samples and produced promising results for human clinical samples. The detection of S. mansoni DNA in mouse urine samples from the third week after infection indicates that early diagnosis of active S. mansoni infection is possible using urine as a source of DNA. Further studies are still needed, but our method could be used as a promising molecular tool applicable to urine samples to diagnose human intestinal schistosomiasis caused by S. mansoni.

Exotic Tourist Destinations and Transmission of Infections by Swimming Pools and Hot Springs-A Literature Review

A growing number of people undertake international travel, and yet faster growth of such travel is expected in the tropics. Information on the hazards presented by pool and hot spring waters in tropical countries is very limited. This review aims to collate available information on pool water quality, alongside data on cases and outbreaks associated with swimming in pools in tropical regions affecting both local populations and travellers. Bacteria species commonly causing cases and outbreaks in the tropics as well as elsewhere in the world were excluded, and the review focuses on studies related to pathogens that, with the exception of Cryptosporidium, are unusual in more temperate climates. Studies concerning subtropical countries were included in the light of climate change. Diseases transmitted by vectors breeding in poorly maintained, neglected or abandoned pools were also included. 83 studies dealing with Microsporidia, Leptospira spp., Schistosomas spp., Cryptosporidium spp., Acanthamoeba spp., Naegleria spp., Clostridium trachomatis, viruses, and vectors breeding in swimming pool and hot tub waters, and fulfilling predefined criteria, have been included in our survey of the literature. In conclusion, prevention strategies for pool safety in the tropics are imperative. Public health authorities need to provide guidance to westerners travelling to exotic destinations on how to protect their health in swimming pools.

Schistosomiasis in a Scottish school group after freshwater swimming in Uganda: the need to raise awareness

Introduction

Schistosomiasis, a travel-related trematode infection, can cause a range of symptoms with potentially life-threatening complications. In this report, we describe an outbreak of schistosomiasis in a Scottish school group that had travelled to Uganda. We discuss the requirement for robust and accurate pre-travel advice, and the importance of raising awareness in travellers, particularly due to the asymptomatic nature of the disease. In addition, we highlight the need to submit a serum sample for laboratory testing on return from endemic regions where freshwater exposure has occurred.

Case presentation

A Scottish school group consisting of 19 individuals visited Uganda during July 2016 with one positive symptomatic case identified on return to the UK. As three of the individuals were not Scottish residents, their data were excluded from this report. Freshwater exposure was noted from taking part in activities which included swimming in the Nile. The Scottish Parasite Diagnostic and Reference Laboratory performed serology testing using sera from 16 Scottish residents to detect IgG towards Schistosoma egg antigens. Thirteen were positive despite only one case being symptomatic.

Conclusion

The high positivity rate raised several issues. These included the lack of a robust risk assessment by the travel company organizing the trip, the lack of awareness of schistosomiasis by some individuals, the lack of appropriate and accurate pre-travel advice, and the asymptomatic nature of the infection. This report provides supportive evidence to strengthen the need for improvements to prevent largely asymptomatic cases being missed in future.

Schistosomiasis in immigrants, refugees and travellers in an Italian referral centre for tropical diseases

BACKGROUND

Schistosomiasis is one of the most important neglected tropical diseases. If unrecognised and untreated, the chronic infection can lead to irreversible complications.

METHODS

Retrospective observational study aimed at describing clinical history, laboratory findings and imaging presentation of imported schistosomiasis diagnosed at the Centre for Tropical Diseases, Sacro Cuore Don Calabria Hospital of Negrar, Verona, Italy from 2010 to 2014. The aim of our study was to assess differences in demographic characteristics, clinical presentation, laboratory data and ultrasound findings between immigrants/visiting friends and relatives (VFR) from endemic countries (endemic group) and expatriates/travellers (non-endemic group).

RESULTS

A total of 272 patients were retrieved: 234 in the endemic and 38 in the non-endemic group. Most of the patients acquired schistosomiasis in Africa (97.4%). Symptoms were reported by 52.9% of the patients; abdominal pain (36%), macroscopic hematuria (11.3%), and genito-urinary symptoms (7.4%) being the most frequently reported. Increased IgE and blood eosinophilia were observed in 169 (63.8%) and 130 (47.8%) patients, respectively. The proportion of positive serology was 250/272 (91.9%).The Circulating Cathodic Antigen CCA for Schistosoma mansoni was positive in 14/61 individuals (23%). At microscopy, infected subjects were 103/272 (37.9%). The species of Schistosoma found were S. haematobium (47.6%), S. mansoni (46.6%) or both (5.8%). Schistosomiasis was classified as confirmed in 103 (37.9%), probable in 165 (60.6%) and suspected in 4 (1.5%) cases using clinical presentation, laboratory data and ultrasound findings. The infection was further classified based on organ involvement: intestinal (17.9%), hepatosplenic (5.1%), urogenital (48.9%), and indeterminate (43.8%). The comparative analysis of endemic and non-endemic patients highlighted differences in sex and age. Endemic patients had more frequent ova identification (41.9% vs. 13.2%, P < 0.001) and increased IgE (70% vs. 26.3%, P < 0.001) when compared with non-endemic. Multivariate analyses showed that younger age, abnormal ultrasound findings and blood eosinophilia were significantly associated with positive microscopy (OR = 0.94, OR = 2.12, OR = 1.98, respectively).

CONCLUSIONS

Symptoms, eosinophilia and abnormal ultrasound findings were present in about half of patients, without differences between groups. Many patients had positive serology but negative microscopy, indicating that schistosomiasis might be misdiagnosed. A combination of diagnostic tools may facilitate the diagnosis.

Urinary Schistosomiasis in an Adolescent Refugee from Africa: An Uncommon Cause of Hematuria and an Emerging Infectious Disease in Europe

We report a case of urinary schistosomiasis in an adolescent refugee from Gambia (arrived to Italy illegally), who was brought to the Emergency Department of our hospital. The patient complained of gross hematuria and, in the absence of clinical evidence of bacterial urinary infection, was admitted to the pediatric ward, considering his provenience and social setting. An appropriate collection and microscopic analysis of urine samples led to the detection of bilharzia. Much attention should be paid to this emerging disease in Europe by physicians in order to recognize and treat it timely, which could prevent future and higher costs for public health systems and could reduce the potential risk of environmental spreading. In fact, there are some areas in Italy where the parasite can find its intermediate host to complete its lifecycle.

Kinases: Molecular Stage Directors for Schistosome Development and Differentiation

Understanding schistosome biology is still a challenging mission. The reproductive biology of this parasitic trematode is closely associated with the pathologic consequences of schistosomiasis, the devastating infectious disease caused by members of the family Schistosomatidae worldwide. Recent studies of signaling mechanisms confirmed the prominent roles of protein kinases (PKs) in directing schistosome biology, and first evidence was obtained for an additional contribution of kinases with substrates different from proteins (non-PKs). This review provides an overview of the Schistosoma mansoni kinome in the context of male-female interaction and summarizes recent studies of kinases controlling development and differentiation. Due to their importance for schistosome biology, kinases represent Achilles' heels and are therefore of high value also for translational research.

Schistosomiasis in European Travelers and Migrants: Analysis of 14 Years TropNet Surveillance Data

Schistosomiasis remains one of the most prevalent parasitic diseases worldwide and the infection is frequently found in travelers and migrants. The European Network for Tropical Medicine and Travel Health conducted a sentinel surveillance study on imported schistosomiasis between 1997 and 2010. This report summarizes epidemiological and clinical data from 1,465 cases of imported schistosomiasis. Direct pathogen detection and serology were the main diagnostic tools applied. Of these, 486 (33%) cases were identified among European travelers, 231 (16%) among long-term expatriates, and 748 (51%) among non-European immigrants. Overall, only 18.6% of travelers had received pretravel advice; 95% of infections were acquired in the African region. On species level, Schistosoma mansoni was identified in 570 (39%) and Schistosoma haematobium in 318 (22%) cases; 57.5% of patients were symptomatic. Acute symptoms were reported in 27% of patients leading to earlier presentation within 3 months. Praziquantel was used in all patients to treat schistosomiasis. Many infections were detected in asymptomatic patients. In 47.4% of asymptomatic patients infection was detected by microscopy and in 39% by serology or antigen testing. Schistosomiasis remains a frequent infection in travelers and migrants to Europe. Travelers should be made aware of the risk of schistosomiasis infection when traveling to sub-Saharan Africa. Posttravel consultations particularly for returning expatriates are useful given the high potential for detecting asymptomatic infections.

Derivatives of biarylalkyl carboxylic acid induce pleiotropic phenotypes in adult Schistosoma mansoni in vitro

Schistosomes and other parasitic platyhelminths cause infectious diseases of worldwide significance for humans and animals. Despite their medical and economic importance, vaccines are not available and the number of drugs is alarmingly limited. For most platyhelminths including schistosomes, Praziquantel (PZQ) is the commonly used drug. With respect to its regular application in mass treatment programs, however, there is increasing concern about resistance development.Previous studies demonstrated that inhibitors used to treat non-parasitic human diseases may be useful to be tested for their effects on parasites. To this end, we focused on biarylalkyl carboxylic acids (BACAs) as basis, which had been shown before to be interesting candidates in the context of finding alternative approaches to treat diabetes mellitus. We tested 32 chemically modified derivatives of these substances (biarylalkyl carboxylic acid derivatives (BACADs)) for their effects on adult Schistosoma mansoni in vitro. Treatment with 18 BACADs resulted in egg production-associated phenotypes and reduced pairing stability. In addition, 12 of these derivatives affected vitality and/or caused severe tegument damage, gut dilatation, or other forms of tissue disintegration which led to the death of worms. In most cases (10/12), one derivative caused more than one phenotype at a time. In vitro experiments in the presence of serum albumin (SA) and alpha-acidic glycoprotein (AGP) indicated a varying influence of these blood components on the effects of two selected derivatives. The variety of observed phenotypes suggested that different targets were hit. The results demonstrated that BACADs are interesting substances with respect to their anti-schistosomal effects.

Ocular pathological changes in hamsters experimentally infected with Schistosoma mansoni

Ocular lesions have been reported in patients with schistosomiasis; however, the problem with studying schistosomal infection of the human eye is that biopsies are almost impossible to take, and histopathological examination of suspicious lesions can only be undertaken post-mortem or after enucleation. This work aimed to study the possible effects and pathogenesis of schistosomiasis on the eye. This study involved 55 hamsters; five hamsters remained non-infected and the remaining 50 hamsters were infected with Schistosoma mansoni cercariae. Infected hamsters were sacrificed on weeks 8, 12, 16 and 20 post-infection (pi). Eye sections were prepared and stained for histopathological and immunohistochemical studies. Histopathological changes detected in hamsters infected after 16 and 20 weeks included looseness and oedema of the innermost retinal layers together with hyperplastic polypoid growth. Neither eggs nor granulomata were detected in eye sections throughout the experimental period. Deposition of S. mansoni antigen was revealed in 35% of infected hamsters. Later, on weeks 16 and 20 pi, moderate subepithelial conjuctival deposits and marked subchoroidal and scleral deposition were detected. In conclusion, the deposition of schistosomal antigen and immune complexes may play a pivotal role in the ocular changes that occur in schistosomiasis, even in the absence of detectable Schistosoma eggs. Schistosomiasis should be suspected in cases with unexplained ophthalmological findings, especially in endemic areas.

The Rapid-Heat LAMPellet Method: A Potential Diagnostic Method for Human Urogenital Schistosomiasis

Background

Urogenital schistosomiasis due to Schistosoma haematobium is a serious underestimated public health problem affecting 112 million people - particularly in sub-Saharan Africa. Microscopic examination of urine samples to detect parasite eggs still remains as definitive diagnosis. This work was focussed on developing a novel loop-mediated isothermal amplification (LAMP) assay for detection of S. haematobium DNA in human urine samples as a high-throughput, simple, accurate and affordable diagnostic tool to use in diagnosis of urogenital schistosomiasis.

Methodology/Principal Findings

A LAMP assay targeting a species specific sequence of S. haematobium ribosomal intergenic spacer was designed. The effectiveness of our LAMP was assessed in a number of patients´ urine samples with microscopy confirmed S. haematobium infection. For potentially large-scale application in field conditions, different DNA extraction methods, including a commercial kit, a modified NaOH extraction method and a rapid heating method were tested using small volumes of urine fractions (whole urine, supernatants and pellets). The heating of pellets from clinical samples was the most efficient method to obtain good-quality DNA detectable by LAMP. The detection limit of our LAMP was 1 fg/µL of S. haematobium DNA in urine samples. When testing all patients´ urine samples included in our study, diagnostic parameters for sensitivity and specificity were calculated for LAMP assay, 100% sensitivity (95% CI: 81.32%-100%) and 86.67% specificity (95% CI: 75.40%-94.05%), and also for microscopy detection of eggs in urine samples, 69.23% sensitivity (95% CI: 48.21% -85.63%) and 100% specificity (95% CI: 93.08%-100%).

Conclusions/Significance

We have developed and evaluated, for the first time, a LAMP assay for detection of S. haematobium DNA in heated pellets from patients´ urine samples using no complicated requirement procedure for DNA extraction. The procedure has been named the Rapid-Heat LAMPellet method and has the potential to be developed further as a field diagnostic tool for use in urogenital schistosomiasis-endemic areas.

Human schistosomiasis is a disease caused by several species of parasitic worms of the genus Schistosoma that is affecting 200 million people, especially in sub-Saharan Africa. Most people are infected with Schistosoma haematobium, the species that causes urogenital schistosomiasis and also bladder cancer in many chronic infections. The definitive diagnostic test is based on microscopic examination of urine samples to detect parasite eggs. This method has low sensitivity, high day-to-day variability and cannot be carried out in the acute phase of the disease since the parasite has not started yet to lay eggs. New high-throughput diagnostic tools would be desirable, permitting early treatment and preventing the pathology associated with chronic infections. An interesting approach is the loop-mediated isothermal amplification (LAMP) technique because of its simplicity in operation and potential use in clinical diagnosis and surveillance of infectious diseases. In this study, we developed and evaluated a LAMP assay for detection of S. haematobium DNA in patients´ urine samples using heated pellets with no complicated requirement procedure for DNA extraction, namely the Rapid-Heat LAMPellet method. This is a new, easy, rapid and cost-effective LAMP method that should prove useful for mass screening in limited-resource settings in urogenital schistosomiasis-endemic areas.

The first step toward diagnosing female genital schistosomiasis by computer image analysis

Schistosoma haematobium causes female genital schistosomiasis (FGS), which is a poverty-related disease in sub-Saharan Africa. Furthermore, it is co-endemic with human immunodeficiency virus (HIV), and biopsies from genital lesions may expose the individual to increased risk of HIV infection. However, microscopy of urine and hematuria are nonspecific and insensitive predictors of FGS and gynecological investigation requires extensive training. Safe and affordable diagnostic methods are needed. We explore a novel method of diagnosing FGS using computer color analysis of colposcopic images. In a cross-sectional study on young women in an endemic area, we found strong associations between the output from the computer color analysis and both clinical diagnosis (odds ratio [OR] = 5.97, P < 0.001) and urine microscopy for schistosomiasis (OR = 3.52, P = 0.004). Finally, using latent class statistics, we estimate that the computer color analysis yields a sensitivity of 80.5% and a specificity of 66.2% for the diagnosis of FGS.

Acute schistosomiasis: a risk underestimated by travelers and a diagnosis frequently missed by general practitioners-a cluster analysis of 42 travelers

BACKGROUND

In 2011, a patient was admitted to our hospital with acute schistosomiasis after having returned from Madagascar and having bathed at the Lily waterfalls. On the basis of this patient's indication, infection was suspected in 41 other subjects. This study investigated (1) the knowledge of the travelers about the risks of schistosomiasis and their related behavior to evaluate the appropriateness of prevention messages and (2) the diagnostic workup of symptomatic travelers by general practitioners to evaluate medical care of travelers with a history of freshwater exposure in tropical areas.

METHODS

A questionnaire was sent to the 42 travelers with potential exposure to schistosomiasis. It focused on pre-travel knowledge of the disease, bathing conditions, clinical presentation, first suspected diagnosis, and treatment.

RESULTS

Of the 42 questionnaires, 40 (95%) were returned, among which 37 travelers (92%) reported an exposure to freshwater, and 18 (45%) were aware of the risk of schistosomiasis. Among these latter subjects, 16 (89%) still reported an exposure to freshwater. Serology was positive in 28 (78%) of 36 exposed subjects at least 3 months after exposure. Of the 28 infected travelers, 23 (82%) exhibited symptoms and 16 (70%) consulted their general practitioner before the information about the outbreak had spread, but none of these patients had a serology for schistosomiasis done during the first consultation.

CONCLUSIONS

The usual prevention message of avoiding freshwater contact when traveling in tropical regions had no impact on the behavior of these travelers, who still went swimming at the Lily waterfalls. This prevention message should, therefore, be either modified or abandoned. The clinical presentation of acute schistosomiasis is often misleading. General practitioners should at least request an eosinophil count, when confronted with a returning traveler with fever. If eosinophilia is detected, it should prompt the search for a parasitic disease.

Re-positioning protein-kinase inhibitors against schistosomiasis

For decades, Praziquantel (PZQ) is the drug of choice against one of the most afflicting helminthic diseases worldwide, schistosomiasis. With respect to the fear of upcoming PZQ resistance, efforts are needed to find new chemotherapeutic options. Protein kinases (PKs) are essential molecules in signaling processes and indispensable to life. Aberrant PK functions take distinctive roles in human diseases and represent targets in chemotherapies. In schistosomes, conserved PKs were found to possess similar pivotal roles contributing not only to reproduction processes, but also to the pathology of schistosomiasis, which is closely associated to egg production. Exploiting the similarity of PKs of humans and schistosomes, PK inhibitors designed to treat human diseases may serve as lead compounds for new drugs against schistosomiasis.

Placental Schistosoma haematobium infection in a German returnee from Malawi

Schistosomiasis is a widespread helminthic infection which sometimes may affect travelers to endemic areas. We report on a case of urogenital and placental schistosomiasis in a 28-year-old German woman who had been exposed to schistosomiasis in Lake Malawi one year earlier. She experienced painless macrohaematuria in her 21st week of pregnancy. Cystoscopy revealed vesical lesions typical for urogenital schistosomiasis. Histopathology confirmed ova of Schistosoma (S.) haematobium. The patient was treated with praziquantel 40 mg/kg/body weight/day for 3 days. After 285 days of gestation and 18 weeks post treatment, the patient delivered a healthy girl. Histopathology of placenta revealed eggs of S. haematobium in placental stroma. The infant proved negative for anti-Schistosoma spp. antibodies at the age of 15 months. This is the first report on placental schistosomiasis since 1980 and the first case occurring in a traveler.

A loop-mediated isothermal amplification (LAMP) assay for early detection of Schistosoma mansoni in stool samples: a diagnostic approach in a murine model

BACKGROUND

Human schistosomiasis, mainly due to Schistosoma mansoni species, is one of the most prevalent parasitic diseases worldwide. To overcome the drawbacks of classical parasitological and serological methods in detecting S. mansoni infections, especially in acute stage of the disease, development of cost-effective, simple and rapid molecular methods is still needed for the diagnosis of schistosomiasis. A promising approach is the loop-mediated isothermal amplification (LAMP) technology. Compared to PCR-based assays, LAMP has the advantages of reaction simplicity, rapidity, specificity, cost-effectiveness and higher amplification efficiency. Additionally, as results can be inspected by the naked eye, the technique has great potential for use in low-income countries.

METHODOLOGY/PRINCIPAL FINDINGS

A sequence corresponding to a mitochondrial S. mansoni minisatellite DNA region was selected as a target for designing a LAMP-based method to detect S. mansoni DNA in stool samples. We used a S. mansoni murine model to obtain well defined stool and sera samples from infected mice with S. mansoni cercariae. Samples were taken weekly from week 0 to 8 post-infection and the Kato-Katz and ELISA techniques were used for monitoring the infection. Primer set designed were tested using a commercial reaction mixture for LAMP assay and an in house mixture to compare results. Specificity of LAMP was tested using 16 DNA samples from different parasites, including several Schistosoma species, and no cross-reactions were found. The detection limit of our LAMP assay (SmMIT-LAMP) was 1 fg of S. mansoni DNA. When testing stool samples from infected mice the SmMIT-LAMP detected S. mansoni DNA as soon as 1 week post-infection.

CONCLUSIONS/SIGNIFICANCE

We have developed, for the first time, a cost-effective, easy to perform, specific and sensitive LAMP assay for early detection of S. mansoni in stool samples. The method is potentially and readily adaptable for field diagnosis and disease surveillance in schistosomiasis-endemic areas.

Acute schistosomiasis in European students returning from fieldwork at Lake Tanganyika, Tanzania

BACKGROUND

Schistosomiasis is common in many African regions and poses a risk for travelers and the local population. So far, schistosomiasis in travelers or expatriates returning from the Tanzanian bank of Lake Tanganyika has not been reported.

METHODS

We report a group of students who sought treatment with signs of acute schistosomiasis after having returned from Lake Tanganyika, Tanzania. Information as to travel and exposure as well as clinical and laboratory data were collected.

RESULTS

Schistosomiasis was diagnosed in 8 of 16 students from Berlin, Germany, who had returned from a 2- to 3-month stay of fieldwork in Kigoma District at Lake Tanganyika, Tanzania. All 16 students reported frequent freshwater exposure at the lake. Six patients showed signs of acute schistosomiasis and had fever, and some of them also had cough, weakness, headache, or abdominal pain. Eosinophilia was present in five of the six symptomatic individuals. Notably, two serologically enzyme-linked immunosorbent assay (ELISA)-positive individuals did not report or present with symptoms or abnormal laboratory parameters. Schistosoma mansoni eggs were found in one symptomatic and one asymptomatic individual each. Blood and stool samples from the other eight individuals who were equally exposed to freshwater yielded negative results.

CONCLUSIONS

This is the first report of an outbreak of acute schistosomiasis imported from the Tanzanian shore of Lake Tanganyika and highlights the risk for travelers and the local population of acquiring the infection in that part of Tanzania. It provides arguments for routine serological screening for schistosomiasis in individuals who had prior freshwater contact in endemic areas, irrespective of symptoms or other laboratory findings.

Asymptomatic Schistosoma haematobium infection in a traveler with negative urine microscopy and late seroconversion presumably linked to artemisinin

We describe a Schistosoma haematobium infection with asymptomatic eosinophilia, persistently negative urine microscopy, and late seroconversion (7.5 months) in a traveler returning from Mali. After initial negative parasitological tests, travel history led to diagnostic cystoscopy, allowing final diagnosis with urine microscopy after the bladder biopsy. The patient was successfully treated with praziquantel. Difficulties in making the diagnosis of schistosomiasis in asymptomatic returning travelers are discussed; we propose a trial treatment in these cases.

A Schistosoma haematobium-specific real-time PCR for diagnosis of urogenital schistosomiasis in serum samples of international travelers and migrants

BACKGROUND

Diagnosis of urogenital schistosomiasis by microscopy and serological tests may be elusive in travelers due to low egg load and the absence of seroconversion upon arrival. There is need for a more sensitive diagnostic test. Therefore, we developed a real-time PCR targeting the Schistosoma haematobium-specific Dra1 sequence.

METHODOLOGY/PRINCIPAL FINDINGS

The PCR was evaluated on urine (n = 111), stool (n = 84) and serum samples (n = 135), and one biopsy from travelers and migrants with confirmed or suspected schistosomiasis. PCR revealed a positive result in 7/7 urine samples, 11/11 stool samples and 1/1 biopsy containing S. haematobium eggs as demonstrated by microscopy and in 22/23 serum samples from patients with a parasitological confirmed S. haematobium infection. S. haematobium DNA was additionally detected by PCR in 7 urine, 3 stool and 5 serum samples of patients suspected of having schistosomiasis without egg excretion in urine and feces. None of these suspected patients demonstrated other parasitic infections except one with Blastocystis hominis and Entamoeba cyst in a fecal sample. The PCR was negative in all stool samples containing S. mansoni eggs (n = 21) and in all serum samples of patients with a microscopically confirmed S. mansoni (n = 22), Ascaris lumbricoides (n = 1), Ancylostomidae (n = 1), Strongyloides stercoralis (n = 1) or Trichuris trichuria infection (n = 1). The PCR demonstrated a high specificity, reproducibility and analytical sensitivity (0.5 eggs per gram of feces).

CONCLUSION/SIGNIFICANCE

The real-time PCR targeting the Dra1 sequence for S. haematobium-specific detection in urine, feces, and particularly serum, is a promising tool to confirm the diagnosis, also during the acute phase of urogenital schistosomiasis.

Acute schistosomiasis in travelers: 14 years' experience at the Hospital for Tropical Diseases, London

We report 79 cases of acute schistosomiasis. Most of these cases were young, male travelers who acquired their infection in Lake Malawi. Twelve had a normal eosinophil count at presentation and 11 had negative serology, although two had neither eosinophilia nor positive serology when first seen. Acute schistosomiasis should be considered in any febrile traveler with a history of fresh water exposure in an endemic area once malaria has been excluded.

A foreign invader or a reclusive native? DNA bar coding reveals a distinct European lineage of the zoonotic parasite Schistosoma turkestanicum (syn. Orientobilharzia turkestanicum ())

Natural foci of Schistosoma turkestanicum (syn. Orientobilharzia turkestanicum) has been identified in the Gemenc Forest regions of Hungary utilising red deer as the definitive host. In order to identify the origins of this parasite in Europe standard DNA bar coding techniques were employed to sequence fragments of the cytochrome oxidase 1 (cox1) and the nuclear ribosomal internal transcribed region (ITS) from 10 individual adult male worms. Phylogenetic reconstruction using maximum likelihood phylogenetic reconstruction and haplotype networks of the cox1 showed all the worms to be of a distinct unique Hungarian lineage although some ITS haplotypes were shared with worms from populations in China and Iran. Molecular clock analysis suggests an early divergence event around 270,000years before present (YBP) between all S. turkestanicum populations giving rise to the Chinese, Iranian and Hungarian lineages. However, divergence of the sequences within the Hungarian population appears to have occurred approximately 63,000 YBP suggesting a long established population of S. turkestanicum in Europe. This suggests that the Hungarian population of S. turkestanicum has been native since the Ice Age and probably established itself during the last interglacial period as red deer moved into Europe from North Africa and the Middle East. This may also indicate that the parasite may have unknown populations established in several other countries in Eastern, Central and Southern Europe.

Acute pulmonary schistosomiasis in travelers: case report and review of the literature

We report the case of an American traveler who developed acute pulmonary schistosomiasis after swimming in a lake in Madagascar, and we review the literature on acute pulmonary schistosomiasis. Schistosomiasis is one of the world's most prevalent parasitic diseases, with three species (Schistosoma mansoni, Schistosoma haematobium and Schistosoma japonicum) causing the greatest burden of disease. Pulmonary manifestations may develop in infected travelers from non-endemic areas after their first exposure. The pathophysiology of acute pulmonary disease is not well-understood, but is related to immune response, particularly via inflammatory cytokines. Diagnosis of schistosomiasis may be either through identification of characteristic ova in urine or stool or through serology. Anti-inflammatory drugs can provide symptomatic relief; praziquantel, the mainstay of chronic schistosomiasis treatment, is likely not effective against acute disease; the only reliable prevention remains avoidance of contaminated freshwater in endemic areas, as there is no vaccine. Travelers who have been exposed to potentially contaminated freshwater in endemic areas should seek testing and, if infected, treatment, in order to avoid severe manifestations of acute schistosomiasis and prevent complications of chronic disease. Clinicians are reminded to elicit a detailed travel and exposure history from their patients.

Schistosoma real-time PCR as diagnostic tool for international travellers and migrants

OBJECTIVE

To evaluate the use of a genus-specific PCR that combines high sensitivity with the detection of different Schistosoma species for diagnosis in international travellers and migrants in comparison to standard microscopy.

METHODS AND RESULTS

The genus-specific real-time PCR was developed to target the 28S ribosomal RNA gene of the major human Schistosoma species. It was validated for analytical specificity and reproducibility and demonstrated an analytical sensitivity of 0.2 eggs per gram of faeces. Its diagnostic performance was further evaluated on 152 faecal, 32 urine and 38 serum samples from patients presenting at the outpatient clinic of the Institute of Tropical Medicine in Antwerp (Belgium). We detected Schistosoma DNA in 76 faecal (50.0%) and five urine (15.6%) samples of which, respectively, nine and one were not detected by standard microscopy. Only two of the 38 serum samples of patients with confirmed schistosomiasis were positive with the presently developed PCR. Sequence analysis on positive faecal samples allowed identification of the Schistosoma species complex.

CONCLUSION

The real-time PCR is highly sensitive and may offer added value in diagnosing imported schistosomiasis. The genus-specific PCR can detect all schistosome species that are infectious to humans and performs very well with faeces and urine, but not in serum.

Intestinal schistosomiasis as unusual aetiology for acute appendicitis, nowadays a rising disease in Western countries

Intestinal schistosomiasis as unusual aetiology for acute appendicitis, nowadays a rising disease in western countries. Recent changes in global migration has led to an immigration growth in our scenario, upsurging people coming from endemic areas of schistosomiasis. Schistosomal appendicitis, seldom reported in developed countries, is now an expected incrising entity in our hospitals during the near future. Due to this circumstances, we believe that schistosomiasis should be consider as a rising source for acute appendicitis in western countries. In order to illustrate this point, we present a case of a 45-years-old black man, from Africa, was admitted via A&E because of acute abdominal pain, located in right lower quadrant. Acute appendicitis was suspected, and he underwent laparotomy and appendectomy. Pathological study by microscope revealed a gangrenous appendix with abscesses and parasitic ova into the submucosal layer of the appendix, suggesting Schistosomiasis.

Evaluation of eight serological tests for diagnosis of imported schistosomiasis

The diagnosis of schistosomiasis in individuals from countries where the disease is not endemic is challenging, and few data are available on the accuracy of serological diagnosis in those patients. We evaluated the performance of eight serological assays, including four commercial kits, in the diagnosis of imported schistosomiasis in individuals from areas where the disease is not endemic, including six enzyme-linked immunosorbent assays using three different antigens, an indirect hemagglutination assay, and an indirect immunofluorescent-antibody test. To analyze the assays, we used a total of 141 serum samples, with 121 derived from patients with various parasitic infections (among which were 37 cases of schistosomiasis) and 20 taken from healthy volunteers. The sensitivity values for detection of schistosomiasis cases ranged from 41% to 78% and were higher for Schistosoma mansoni than for S. haematobium infections. Specificity values ranged from 76% to 100%; false-positive results were most frequent for samples from patients with cestode infections. By combining two or more tests, sensitivity improved markedly and specificity decreased only moderately. Serological tests are useful instruments for diagnosing imported schistosomiasis in countries where the disease is not endemic, but due to limitations in test sensitivities, we recommend the use of two or more assays in parallel.

Acute schistosomiasis in a cluster of travelers from Rwanda: diagnostic contribution of schistosome DNA detection in serum compared to parasitology and serology

BACKGROUND

Diagnosis of acute schistosomiasis is often elusive in travelers. Serum schistosome DNA detection is a promising new diagnostic tool. Its performance is compared with current diagnostic procedures in a cluster of travelers recently infected in Rwanda.

METHODS

Recent infection with schistosomiasis was suspected in 13 Belgian children and adults, within 2 months after swimming in the Muhazi Lake, Rwanda. All were subjected to clinical examination, eosinophil count, feces parasite detection, schistosome antibody tests [enzyme-linked immunosorbent assay (ELISA) and hemagglutination inhibition assay (HAI)], and schistosome DNA detection in serum by real-time polymerase chain reaction.

RESULTS

All 13 patients, between 6 and 29 years old, had a high eosinophil count (median 2,120 µL(-1) ; range 1,150-14,270). Seven of nine persons exposed for the first time developed symptoms compatible with acute schistosomiasis. Eggs of Schistosoma mansoni were found in a concentrated feces sample of 9/13 (69%), with low egg counts (median 20 eggs per gram; range 10-120). Antischistosome antibodies (ELISA and/or HAI) were present in serum of 10/13 (77%) patients. Combining schistosome antibody tests and fecal microscopy demonstrated schistosomiasis in 11/13 (85%) patients. Schistosome-specific DNA was isolated in all 13 (100%) serum samples.

CONCLUSION

In this cluster of travelers with acute schistosomiasis, schistosome DNA detection in serum was able to confirm infection in all exposed persons. It clearly outperformed antibody tests and microscopic parasite detection methods as a qualitative diagnostic test.

Travel-related schistosomiasis, strongyloidiasis, filariasis, and toxocariasis: the risk of infection and the diagnostic relevance of blood eosinophilia

BACKGROUND

This study prospectively assessed the occurrence of clinical and subclinical schistosomiasis, strongyloidiasis, filariasis, and toxocariasis, and the screening value of eosinophilia in adult short-term travelers to helminth-endemic countries.

METHODS

Visitors of a pre-travel health advice centre donated blood samples for serology and blood cell count before and after travel. Samples were tested for eosinophilia, and for antibodies against schistosomiasis, strongyloidiasis, filariasis, and toxocariasis. Previous infection was defined as seropositivity in pre- and post-travel samples. Recent infection was defined as a seroconversion. Symptoms of parasitic disease were recorded in a structured diary.

RESULTS

Previous infection was found in 112 of 1207 subjects: schistosomiasis in 2.7%, strongyloidiasis in 2.4%, filariasis in 3.4%, and toxocariasis in 1.8%. Recent schistosomiasis was found in 0.51% of susceptible subjects at risk, strongyloidiasis in 0.25%, filariasis in 0.09%, and toxocariasis in 0.08%. The incidence rate per 1000 person-months was 6.4, 3.2, 1.1, and 1.1, respectively. Recent infections were largely contracted in Asia. The positive predictive value of eosinophilia for diagnosis was 15% for previous infection and 0% for recent infection. None of the symptoms studied had any positive predictive value.

CONCLUSION

The chance of infection with schistosomiasis, strongyloidiasis, filariasis, and toxocariasis during one short-term journey to an endemic area is low. However, previous stay leads to a cumulative risk of infection. Testing for eosinophilia appeared to be of no value in routine screening of asymptomatic travelers for the four helminthic infections. Findings need to be replicated in larger prospective studies.

Travelers as a sentinel population: use of sentinel networks to inform pretravel and posttravel evaluation

The establishment of collaborative sentinel surveillance networks specifically to monitor disease trends among travelers offers new options for evaluating travel health issues. These networks can inform pre- and posttravel patient management by providing complementary surveillance information, facilitating communication and collaboration between participating network sites, and enabling new analytical options for travel-related research. The two major multinational sentinel networks are TropNetEurop and GeoSentinel. Practical examples demonstrating their significant contributions to improved travel health information are discussed. Data obtained from studying health problems among travelers may also have significant benefits for local populations in resource-limited countries. However, there are limitations of data collected by sentinel networks, so they should be considered as complementary tools and not relied on as an exclusive basis for evaluating health risks among travelers.

High rate of failure in treatment of imported schistosomiasis

BACKGROUND

There is an increasing number of imported cases of schistosomiasis in Europe, but there are only few studies on the efficacy of praziquantel for the treatment of schistosomiasis in non-endemic settings.

METHODS

Patients treated for schistosomiasis in 2003 to 2008 were offered reexamination with serology, eosinophil count, IgE, microscopy of 24 h urine samples and/or rectal biopsies >3 months after treatment. All patients had been treated with at least one dose of praziquantel 40 to 60 mg/kg >12 weeks after exposure and had not been reexposed to schistosomiasis after treatment.

RESULTS

Twenty-eight traveler (15 tourists and 13 expatriates) and two immigrants were reexamined after treatment. Viable ova were detected in six traveler (20%). Ova were found in 5/23 (22%) rectal biopsies and in 2/12 (17%) urine samples. Treatment failure was suspected in a symptomatic patient who 2 years after treatment had eightfold rise in antibody titer and elevated IgE but no detectable ova in urine or rectal biopsies. Additional 13 patients had one or more parameters, which could indicate persistent infection. There were no significant differences in eosinophil count, IgE or, change in antibody titer between patients with versus without detectable ova after treatment.

CONCLUSIONS

In traveler with a low parasite burden, assessment of treatment results can be difficult because of the low sensitivity of microscopy and persistence of antibodies for several years after treatment. We found a high rate of treatment failure among traveler, indicating that nonimmune patients may need more than the recommended single day of treatment for eradication of parasites. Until more sensitive and specific methods for detection of persistent, active infection are available, repeated treatment should be considered in patients with continuous symptoms or other indications of treatment failure even when viable ova cannot be detected by microscopy.

Defining infections in international travellers through the GeoSentinel surveillance network

International travellers are often exposed to a wide range of infections, most of which are a reflection of common diseases in the destination country. The consequences of acquiring such infections are serious and can be associated with substantial morbidity and mortality. Attempting to define the range of infections and the risk factors that are associated with acquiring them during travel to different regions worldwide will provide an evidence base for the development and implementation of effective preventative interventions. This Science and Society article focuses on the valuable function served by the GeoSentinel surveillance network in defining the range of infections in travellers.

Sensitive and rapid detection of Schistosoma japonicum DNA by loop-mediated isothermal amplification (LAMP)

In this study, a loop-mediated isothermal amplification (LAMP) assay was established to detect Schistosoma japonicum DNA in faecal and serum samples of rabbits, and serum samples of humans infected with S. japonicum. This LAMP assay was based on the sequence of highly repetitive retrotransposon SjR2, and was able to detect 0.08 fg S. japonicum DNA, which is 10(4) times more sensitive than conventional PCR. The LAMP assay was also highly specific for S. japonicum and able to detect S. japonicum DNA in rabbit sera at 1 week p.i. Following administration of praziquantel, detection of S. japonicum DNA in rabbit sera became negative at 12 weeks post-treatment. These results demonstrated that LAMP was effective for early diagnosis of, and evaluation of therapy effectiveness for, S. japonicum infection. Both PCR and LAMP assays were then used to detect S. japonicum DNA in 30 serum samples from S. japonicum-infected patients and 20 serum samples from healthy persons. The percentage sensitivity of LAMP was 96.7%, whereas that of PCR was only 60%, indicating that LAMP was more sensitive than conventional PCR for clinical diagnosis of schistosomiasis cases in endemic areas. The established LAMP assay should provide a useful and practical tool for the routine diagnosis and therapeutic evaluation of human schistosomiasis.

Schistosomiasis in Swedish travellers to sub-Saharan Africa: can we rely on serology?

In the absence of egg excretion, laboratory diagnosis of recently acquired schistosomiasis is dependent on serology. 42 of 83 Swedish adventure tourists to sub-Saharan Africa had serum anti-schistosome antibodies indicating recent infection. There is little doubt regarding the specificity and sensitivity of serology for the demonstration of infection, but there is a need for alternative serological methods which could be more widely used than the standard immunofluorescence assay (IFA) for antibodies against gut-derived antigens (anti-GAA). We present results suggesting that 40/42 anti-GAA positive cases also react with keyhole limpet haemocyanin (KLH), a readily available commercial antigen. High anti-GAA titres were seen for more than 2 y despite treatment with praziquantel. Thus we are faced with several questions. How likely is it that positive serology means treatment failure? What is the risk involved in chronic infection? What is the prospect for monitoring treatment outcome by serology? We conclude that there is a need for better information on the risk of becoming infected, for improved methods for testing and for monitoring the therapeutic effects in adventure tourists.

Application of an ELISA test using Schistosoma bovis adult worm antigens in travellers and immigrants from a schistosomiasis endemic area and its correlation with clinical findings

We have recently evaluated an ELISA for the diagnosis of human schistosomiasis using S. bovis adult worm antigens (AWA Sb), showing a sensitivity of 94% and a specificity of 97% for patients diagnosed by egg detection. Nevertheless, the comparison of this AWA Sb ELISA with direct parasitological findings as the gold standard could introduce a selection bias, due to the well-known lack of sensitivity of direct methods in the detection of acute schistosomiasis and of low burden infections. The objective of the present work is to compare it with parasitological methods and commercial indirect haemagglutination test using S. mansoni antigens (WA Sm IHA) in 254 immigrants and travellers with different clinical settings; in addition, to find specific bands in the EITB of different phases of schistosomiasis. The AWA Sb ELISA showed 72% of seropositivity in patients with Katayama fever, while patients with eosinophilia and genito-urinary complaints showed 27% and 93%, respectively. The diagnosis yield was globally higher than direct egg detection or WA Sm IHA test with regard to the clinical setting. Finally, the utilization of EITB with S. bovis AWA permits the confirmation of diagnosis in chronic and acute phases of the disease.

Schistosoma japonicum: a PCR assay for the early detection and evaluation of treatment in a rabbit model

A specific PCR assay for the detection of Schistosoma japonicum DNA in rabbit fecal and serum samples was developed by amplifying a 230-bp fragment from the sequence information of the clone G55A of the highly repetitive retrotransposon SjR2. The minimum amount of DNA detectable using the PCR assay was 0.8pg, and the expected PCR product was amplified when DNA equivalent of 1.1 egg from feces was used as template. In the meantime, serum anti-worm IgG was examined by ELISA. ELISA gave positive results at 4-6 weeks post-infection depending on the cercarial doses. The parasite eggs were detected in feces at 7 weeks post-infection. In contrast, S. japonicum DNA was detected in sera at first week post-infection, and it became negative at 10 weeks post-treatment, whereas the anti-worm IgG was still at high levels at 23 weeks post-treatment. These data demonstrated that the PCR assay established provides a potential tool for the early diagnosis and therapy evaluation for S. japonicum infection in humans.

Eosinophilia during intestinal infection

Eosinophilia is a common finding in tropical developing countries, and is mainly caused by chronic helminth infections, predominantly of the gut. Although only a minority of infections is symptomatic, development during childhood can be impaired, and in some patients serious complications and sequelae may occur. Eosinophilia in helminth infection is typically associated with a strong Th2 immune response, and eosinophils can effectively kill or damage larvae and adult worms in vitro. However, in vivo, eosinophils are only partly effective in the control of helminth infection, and recent research has shown that eosinophils are involved in a range of immunomodulatory effects, such as increased production of the down-modulatory cytokines interleukin 10 and tumour growth factor beta, as well as stimulation of regulatory T cells and alternatively activated macrophages. Increasing evidence suggests that immunomodulation favours parasite survival and reduces immune pathology. On the other hand, immunomodulation induced by helminth infections may contribute to protection from allergic and autoimmune responses, as proposed by the 'hygiene hypothesis' to explain the increase in allergic diseases in the industrialised world. The predictive value of eosinophilia for the presence of helminth infections is limited and depends on the epidemiological background and the extent of the eosinophilia. It increases considerably in populations with a high prevalence of parasitic infections, as in developing tropical countries or in travellers to those areas.

Schistosomiasis among travelers: new aspects of an old disease

Schistosomiasis is increasingly encountered among travelers returning from the tropics; signs and symptoms of travelers may differ from those of local populations. During 1993–2005, schistosomiasis was diagnosed in 137 Israeli travelers, most of whom were infected while in sub-Saharan Africa. Clinical findings compatible with acute schistosomiasis were recorded for 75 (66.4%) patients and included fever (71.3%), respiratory symptoms (42.9%), and cutaneous symptoms (45.2%). At time of physical examination, 42 patients (37.1%) still had symptoms of acute schistosomiasis, chronic schistosomiasis had developed in 23 (20.4%), and 48 (42.5%) were asymptomatic. Of patients who were initially asymptomatic, chronic schistosomiasis developed in 26%. Diagnosis was confirmed by serologic testing for 87.6% of patients, but schistosome ova were found in only 25.6%. We conclude that acute schistosomiasis is a major clinical problem among travelers, diagnostic and therapeutic options for acute schistosomiasis are limited, and asymptomatic travelers returning from schistosomiasis-endemic areas should be screened and treated.

Helminth-related Eosinophilia in African immigrants, Gran Canaria

Of 788 recent African adult immigrants to Las Palmas de Gran Canaria, 213 (27.0%) had eosinophilia. The most frequent causes were filariasis (29.4%), schistosomiasis (17.2%), and hookworm infection (16.8%). Stool microscopy and filarial and schistosomal serologic tests gave the highest diagnostic yield. Country of origin and eosinophil count were associated with specific diagnoses.