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

Evaluation of isotype-based serology for diagnosis of Schistosoma mansoni infection in individuals living in endemic areas with low parasite burden

Intestinal schistosomiasis is a chronic and debilitating disease that affects public health systems worldwide. Control interventions to reduce morbidity primarily involve the diagnosis and treatment of infected individuals. However, the recommended Kato-Katz (KK) parasitological method shows low sensitivity in individuals with low parasite loads and is not useful for monitoring elimination of parasite transmission at later stages. In the current study, we evaluated the accuracy of serum reactivity levels of different immunoglobulin isotypes in an enzyme-linked immunosorbent assay (ELISA), utilizing Schistosoma mansoni crude extracts, with the aim to improve the diagnosis of infected individuals with low parasite loads. The serum reactivity of IgM and IgG subclass antibodies (IgG1, IgG3, and IgG4) against soluble adult worm and egg antigen preparations was evaluated in residents from a schistosomiasis-endemic area in northern Minas Gerais, Brazil. The parasitological status of the study population was determined through fecal examination with multiple parasitological tests to create a consolidated reference standard (CRS) plus a fecal DNA detection test (q-PCR). Twelve months after praziquantel treatment, a second serum sample was obtained from the population for reexamination. A two-graph receiver operating characteristic curve (TG-ROC) analysis was performed using the serum reactivity of non-infected endemic controls and egg-positive individuals, and the cut-off value was established based on the intersection point of the sensibility and specificity curves in TG-ROC analyses. The diagnostic accuracy of each serological test was evaluated in relation to the parasitological CRS and to the combination of CRS plus qPCR results. The data revealed that serum reactivity of IgM and IgG3 against S. mansoni antigens did not allow identification of infected individuals from the endemic area. In contrast, serum IgG1 and IgG4-reactivity against schistosome antigens could distinguish between infected and non-infected individuals, with AUC values ranging between 0.728-0.925. The reactivity of IgG4 anti-soluble egg antigen - SEA (sensitivity 79 %, specificity 69 %, kappa = 0.49) had the best diagnostic accuracy, showing positive reactivity in more than 75 % of the infected individuals who eliminated less than 12 eggs per gram of feces. Moreover, serum IgG4 reactivity against SEA and against soluble worm antigen preparation (SWAP) was significantly reduced in the serum of infected individuals after 12 months of confirmed parasitological cure and in the absence of re-infection. These results reinforce that the described IgG4 anti-SEA ELISA assay is a sensitive alternative for the diagnosis of active intestinal schistosomiasis in individuals from endemic areas, including in those with a very low parasite load.

Respiratory morbidity in Schistosoma mansoni infection: a rapid review of literature

Background

Schistosomiasis contributes to 2.5 million disability-adjusted life years globally. Acute and chronic respiratory morbidity of Schistosoma mansoni (S. mansoni) is poorly documented in the literature. We conducted a rapid literature review of the burden of respiratory symptoms and lung function abnormalities among patients with S. mansoni. We also report the immunologic and lung imaging findings from the studies reviewed.

Methods

We carried out a comprehensive literature search in Embase and MEDLINE from the inception of the databases to 13th March 2023.

Results

A total of 2243 patients with S. mansoni were reported from 24 case reports, 11 cross-sectional studies, 7 case series, 2 cohort studies and 2 randomized controlled trials. The prevalence of any respiratory symptom was 13.3-63.3% (total number of patients studied, n = 149). The prevalence of the individual symptoms among patients with S. mansoni in whom respiratory symptoms were sought for was as follows: cough (8.3-80.6%, n = 338), dyspnea (1.7-100.0%, n = 200), chest pain (9.0-57.1%, n = 86), sputum production (20.0-23.3%, n = 30) and wheezing (0.0 - 20.0%, n = 1396). The frequency of the symptoms tended to be higher in acute schistosomiasis. Restrictive lung disease was prevalent in 29.0% (9/31). The commonest chest imaging findings reported were nodules (20-90%, n = 103) and interstitial infiltrates (12.5-23.0%, n = 89). Peripheral blood eosinophilia was prevalent in 72.0-100.0% of patients (n = 130) with acute schistosomiasis and correlated with symptoms and imaging abnormalities. Three case reports in chronic S. mansoni reported elevated C-reactive protein, leucocyte, neutrophil and absolute eosinophil counts, eosinophil percentage, IgE and IgG4.

Conclusion

There is a high prevalence of respiratory morbidity among patients with S. mansoni, particularly in the acute stage of the infection, although the studies are relatively small. Larger studies are needed to characterize respiratory morbidity in chronic schistosomiasis and determine the underlying clinical and immunological mechanisms.

Case Report: Diagnosis and Assessment of Cure Approaches for Acute Schistosomiasis in Pre-School Children

Acute schistosomiasis (AS) manifests with a broad spectrum of clinical features in pediatric populations. Diagnosis may be difficult in the absence of detectable numbers of eggs. As a result, new approaches may be required to achieve an accurate diagnosis. Optimal praziquantel (PZQ) treatment regimen for young children is debatable. Also, the post-treatment response is still poorly evaluated due to the lack of reliable markers. A group of 6 children (a toddler and 5 pre-school children) and one pre-adolescent were investigated for AS clinical manifestations and followed-up for two years after treatment. Ova detection was performed by Kato-Katz (KK) and presence of Schistosoma mansoni DNA was assessed by real-time PCR (rt-PCR) in stool samples. IgG and IgE anti-Schistosoma levels and urinary antigen were detected by ELISA and point-of-care circulating cathodic antigen (POC-CCA) testing in serum and urine, respectively. AS clinical symptoms were present in 5/7 (71.4%) of the infected children, and hypereosinophilia was detected in all of them. Ova detection and serology were positive in only 3/7 (44.9%) and 4/7 (57.1%), respectively. However, real-time PCR (rt-PCR) showed the presence of Schistosoma DNA in 6/7 (85.7%) of the cases, and urinary antigen was detected in all infected children. The long-term follow-up after treatment with three doses of PZQ (80mg/kg/dose), showed high cure rates (CR) as demonstrated by the DNA-based assay as well as reduced levels of side effects. CR based on urinary antigen detection ranged from 28.6 to 100%, being the highest CR due to double testing the 2-year post-treatment samples. The results suggest that high dose and repeated treatment with PZQ might be effective for AS in young children. Also, new laboratory markers should be considered to diagnosis and monitor the drug response.

Prevalence, infection intensity and geographical distribution of schistosomiasis among pre-school and school aged children in villages surrounding Lake Nyasa, Tanzania

Planning and implementation of schistosomiasis control activities requires an understanding of the prevalence, intensity of infection and geographical distribution of the disease in different epidemiological settings. Although, Tanzania is known to be highly endemic to schistosomiasis, there is paucity of data on the geographical distribution of schistosomiasis in potential large water bodies in the country. Thus, the present study was conducted to determine the prevalence, infection intensities and geographical distribution of schistosomiasis along villages located on the shoreline of Lake Nyasa, southern Tanzania. A cross-sectional study was conducted among 1560 children aged 1–13 years old living in villages located along the shoreline of Lake Nyasa. A single urine and stool sample was obtained from each participating child and screened for S.mansoni using Kato Katz (KK) technique to detect eggs and using point-of-care circulating Cathodic Antigen (POC-CCA) test to detect antigen in urine. Urine filtration technique was used to screen for S.haematobium eggs in urine samples. Villages/primary school were mapped using geographical information system and prevalence map was generated using ArcView GIS software. The overall prevalence of S.mansoni based on KK technique and POC-CCA test was 15.1% (95%CI: 13.4–16.9) and 21.8% (95%CI: 18.5–25.3) respectively. The prevalence S.haematobium was 0.83% (95%CI: 0.5–1.4) and that of haematuria was 0.9%. The arithmetic mean egg intensities for S.haematobium and S.mansoni were 18.5 mean eggs/10 ml (95%CI: 5.9–57.6) of urine and 34.7 mean epg (95%CI: 27.7–41.7) respectively. Villages located on the southern end of the lake had significantly high prevalence of S.mansoni than those located on the northern part (χ² = 178.7838, P = 0.001). Cases of S.haematobium were detected only in three villages. Both S.mansoni and S.haematobium infections occur in villages located along the shoreline of Lake Nyasa at varying prevalence. These finding provide insights that can provide guidance in planning and implementation of MDA approach and other recommended measures such as improvement in sanitation, provision of clean water and behaviour changes through public health education.

Illness among US resident student travellers after return to the USA: a GeoSentinel analysis, 2007-17

Background

The number of US students studying abroad more than tripled during the past 20 years. As study abroad programmes' destinations diversify, students increasingly travel to resource-limited countries, placing them at risk for infectious diseases. Data describing infections acquired by US students while travelling internationally are limited. We describe illnesses among students who returned from international travel and suggest how to prevent illness among these travellers.

Methods

GeoSentinel is a global surveillance network of travel and tropical medicine providers that monitors travel-related morbidity. This study included the records of US resident student international travellers, 17-24 years old, who returned to the USA, had a confirmed travel-related illness at one of 15 US GeoSentinel sites during 2007-17 and had a documented exposure region. Records were analysed to describe demographic and travel characteristics and diagnoses.

Results

The study included 432 students. The median age was 21 years; 69% were female. More than 70% had a pre-travel consultation with a healthcare provider. The most common exposure region was sub-Saharan Africa (112; 26%). Students were most commonly exposed in India (44; 11%), Ecuador (28; 7%), Ghana (25; 6%) and China (24; 6%). The median duration of travel abroad was 40 days (range: 1-469) and presented to a GeoSentinel site a median of 8 days (range: 0-181) after travel; 98% were outpatients. Of 581 confirmed diagnoses, the most common diagnosis category was gastrointestinal (45%). Acute diarrhoea was the most common gastrointestinal diagnosis (113 of 261; 43%). Thirty-one (7%) students had vector-borne diseases [14 (41%) malaria and 11 (32%) dengue]. Three had vaccine-preventable diseases (two typhoid; one hepatitis A); two had acute human immunodeficiency virus infection.

Conclusions

Students experienced travel-related infections, despite the majority having a pre-travel consultation. US students should receive pre-travel advice, vaccinations and chemoprophylaxis to prevent gastrointestinal, vector-borne, sexually transmitted and vaccine-preventable infections.

Distribution and current infection status of Biomphalaria straminea in Hong Kong

Background

Schistosomiasis, also generally known as snail fever, is a parasitic disease caused by trematode flatworms of the genus Schistosoma. In Hong Kong and mainland China, the freshwater snail Biomphalaria straminea has been introduced and has the potential to transmit intestinal schistosomiasis caused by S. mansoni, a parasite of man which has a wide distribution in Africa and parts of the New World, especially Brazil. The first identification of B. straminea in Hong Kong dates back to the 1970s, and its geographical distribution, phylogenetic relationships, and infection status have not been updated for more than 30 years. Thus, this study aims to reveal the distribution and current infection status of B. straminea in contemporary Hong Kong.

Methods

Snails were collected from different parts of Hong Kong from July 2016 to January 2017. Both anatomical and molecular methods were applied to identify B. straminea. Cytochrome c oxidase subunit 1 (cox1), internal transcribed spacer 1 (ITS1), 5.8S rDNA, internal transcribed spacer 2 (ITS2), and 16S ribosomal DNA (rDNA) were sequenced from individual snails and analyzed. To detect the presence of S. mansoni, both biopsy and PCR analyses were carried out.

Results

Using both anatomical and molecular analyses, this study demonstrated the existence of black- and red-coloured shell B. straminea in different districts in the New Territories in Hong Kong, including places close to the mainland China border. None of the B. straminea (n = 87) investigated were found to be infected with S. mansoni when tested by biopsy and PCR. The Hong Kong B. straminea are genetically indistinguishable, based on the chosen molecular markers (cox1, ITS1-5.8S-ITS2, and 16S rDNA), and are similar to those obtained in mainland China and South America.

Conclusion

Biomphalaria straminea is now well established in freshwater habitats in Hong Kong. No evidence of infection with S. mansoni has been found. Surveillance should be continued to monitor and better understand this schistosomiasis intermediate host in mainland China and Hong Kong.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2285-3) contains supplementary material, which is available to authorized users.

Streptozotocin (STZ) and schistosomiasis mansoni change the biodistribution of radiopharmaceutical sodium (99m)Tc-pertechnetate in mice

INTRODUCTION

Technetium-99m ((99m)Tc) is a radionuclide commonly used in nuclear medicine to obtain (99m)Tc-radiopharmaceuticals, which can be used to evaluate either physiological processes or changes related to diseases. It is also used in some experimental studies. Streptozotocin (STZ) administration to rodents causes lesions in very early stages and induces severe and permanent diabetes. Most morbidity of schistosomiasis mansoni is attributed to a granulomatous inflammatory response and associated liver fibrosis. This study was designed to investigate whether STZ administration and schistosomiasis modify the biodistribution of the radiopharmaceutical sodium (99m)Tc-pertechnetate.

METHODS

Adult female mice were infected by exposure to 100Schistosoma mansoni cercariae (BH strain, Belo Horizonte, Brazil) and euthanized after nine weeks. STZ was administered by a single intraperitoneal injection of 100mg/kg body weight, 3 or 15days before euthanasia. Each animal received 100μl of sodium (Na) (99m)Tc-pertechnetate ((99m)TcO4(-)) (740kBq). The animals were divided into four groups: A, uninfected; B, infected; C, uninfected + STZ; and D, infected + STZ. Blood, brain, thyroid, heart, lungs, liver, spleen, pancreas and kidneys were removed. The radioactivity was counted and the percentage of the injected dose of Na(99m)TcO4 per gram of the organ (% ID/g) was determined.

RESULTS

Three days after the STZ injection, there was a decrease of Na(99m)TcO4 uptake by the liver, lungs, pancreas and kidneys (p<0.05) in group D when compared with group A. After 15days, the decrease of Na(99m)TcO4 uptake occurred also in the brain, thyroid, heart, spleen and blood (p<0.05) in group D.

CONCLUSION

We demonstrated modifications on the biodistribution of Na(99m)TcO4 due to STZ administration and schistosomiasis, possibly due to physiological alterations in some organs.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

The biodistribution of radiopharmaceutical Na(99m)TcO4 should be carefully evaluated in subjects with diabetes and/or schistosomiasis infection.

Outbreak of urogenital schistosomiasis in Corsica (France): an epidemiological case study

BACKGROUND

Schistosomiasis is a snail-borne parasitic disease endemic in several tropical and subtropical countries. However, in the summer of 2013, an unexpected outbreak of urogenital schistosomiasis occurred in Corsica, with more than 120 local people or tourists infected. We used a multidisciplinary approach to investigate the epidemiology of urogenital schistosomiasis in Corsica, aiming to elucidate the origin of the outbreak.

METHODS

We did parasitological and malacological surveys at nine potential sites of infection. With the snails found, we carried out snail-parasite compatibility experiments by exposing snails to schistosome larvae recovered from the urine of a locally infected Corsican patient. Genetic analysis of both mitochondrial (cox1) and nuclear (internal transcribed spacer) DNA data from the Schistosoma eggs or miracidia recovered from the infected patients was conducted to elucidate the epidemiology of this outbreak.

FINDINGS

We identified two main infection foci along the Cavu River, with many Bulinus truncatus snails found in both locations. Of the 3544 snails recovered across all sites, none were naturally infected, but laboratory-based experimental infections confirmed their compatibility with the schistosomes isolated from patients. Molecular characterisation of 73 eggs or miracidia isolated from 12 patients showed infection with Schistosoma haematobium, S haematobium-Schistosoma bovis hybrids, and S bovis. Further sequence data analysis also showed that the Corsican schistosomes were closely related to those from Senegal in west Africa.

INTERPRETATION

The freshwater swimming pools of the Cavu River harbour many B truncatus snails, which are capable of transmitting S haematobium-group schistosomes. Our molecular data suggest that the parasites were imported into Corsica by individuals infected in west Africa, specifically Senegal. Hybridisation between S haematobium and the cattle schistosome S bovis had a putative role in this outbreak, showing how easily and rapidly urogenital schistosomiasis can be introduced and spread into novel areas where Bulinus snails are endemic, and how hybridisation could increase the colonisation potential of schistosomes. Furthermore our results show the potential risk of schistosomiasis outbreaks in other European areas, warranting close monitoring and surveillance of all potential transmission foci.

FUNDING

WHO, ANSES, RICET, and the Ministry of Health and Consumption.

An update on travelers' diarrhea

PURPOSE OF REVIEW

Travelers' diarrhea, affecting millions of travelers every year globally, continues to be a leading cause of morbidity despite advances in vaccination, prevention, and treatment. Complications of travelers' diarrhea often present to gastroenterologists and some patients followed by gastroenterologists are at higher risk of developing travelers' diarrhea. This review will provide an update on recent progress made in the epidemiology, pathogenesis, diagnosis, prevention, and treatment of travelers' diarrhea.

RECENT FINDINGS

Most causes of travelers' diarrhea remain bacterial, but newly recognized pathogens are emerging. Patient-related and travel-related factors affect disease development risk and should guide prophylaxis and treatment. Although specific vaccines are being developed, they have not yet had a major impact on travelers' diarrhea, and understanding their roles and limitations is especially important. Prophylaxis and treatment of populations at risk (children, chronically ill patients, and those on immunosuppressive medications) remain challenging and require a tailored approach.

SUMMARY

Travelers' diarrhea will continue to challenge patients and physicians despite the use of sanitation advice, prophylactic vaccines, and treatment with antibiotics. Effects may extend beyond the time of travel, such as postinfectious complications and exacerbation of preexisting disease. Future research should focus on novel strategies for reducing exposure to pathogens, vaccine development, early detection, and targeted treatments.

Laboratory diagnosis of schistosomiasis and Katayama syndrome in returning travellers

The gold standard for laboratory diagnosis of schistosomiasis is the presence of typical eggs in stool or urine. The laboratory diagnosis of schistosomiasis and Katayama syndrome in returning travellers is difficult because the number of excreted eggs is often very limited. In early infections and in patients with only a few contacts with contaminated water, the total number of parasites, migrating larvae or schistosomulae, and adult worms, is very low. Eggs can only be found in faeces or urine when there is at least one pair of adult worms at the final location. The number of parasites increases as a function of the number of contacts with infected water. The exact latency between contamination and egg production is unknown. It is estimated that excretion of eggs starts after 40-50 days. The specific diagnosis of early schistosomiasis and Katayama fever relies essentially on serologic tests or preferably on PCR (if available). These assays are much more sensitive (up to four times) in the early phase of schistosomiasis than microscopic examination for typical eggs. Eosinophilia (sometimes exceeding 50%) is often present in patients with acute schistosomiasis (Katayama fever), but may be limited or absent in late fibrotic manifestations of the disease.

Biomarkers for schistosomiasis: towards an integrative view of the search for an effective diagnosis

Human schistosomiasis, caused mainly by Schistosoma mansoni, S. japonicum, and S. hematobium, remains a prevalent and serious parasitic disease worldwide. Although it is a debilitating disease, a lack of sensitive methods for the precise diagnosis of active infection cases is important to prevent morbidity. The optimization of new diagnostic approaches may be accomplished by the selection of specific markers. In that manner, markers can be satisfactorily used for detection of different phases of infection, as acute and chronic phases, pre-patent and post-patent phases and after chemotherapy, improving the efficiency of methods. For that purpose, proteomics and glycomics analyses have been performed in schistosomes, in particular S. mansoni, using powerful high-throughput methodologies. These investigations have not only chartered protein, o-glycan and n-glycan profiles across developmental stages within mammalian host, but are also leading to the characterization of features of the surface tegument, the eggshell and excretory-secretory proteomes of schistosomes.