Schistosomiasis

Parasitic disease screening among HIV patients from endemic countries in a Toronto clinic

BACKGROUND

Many North American-based HIV patients originate from parasitic disease-endemic regions. Strongyloidiasis, schistosomiasis and filariasis are important due to their wide distribution and potential for severe morbidity.

OBJECTIVES

To determine the prevalence, as determined by serological screening, of strongyloidiasis, schistosomiasis and filariasis among patients in an HIV-focused, primary care practice in Toronto, Ontario. A secondary objective was to determine factors associated with positive serological screens.

METHODS

A retrospective review of electronic patient records was conducted. Results of serological screens for parasites and relevant laboratory data were collected.

RESULTS

Ninety-seven patients were identified. The patients' mean CD4(+) count was 0.45×10(9)/L, median viral load was undetectable and 68% were on highly active antiretroviral therapy (HAART). Most originated from Africa (37%) and South America (35%). Of the 97 patients, 10.4% and 8.3% had positive or equivocal screening results for strongyloidiasis, respectively, 7.4% and 4.2% had positive or equivocal screening results for schistosomiasis and 5.5% and 6.8% had positive or equivocal screens for filariasis. Persons with positive parasitic serologies were more often female (28% versus 9%, P=0.03), younger in age (36 versus 43 years of age, P<0.01), had been in Canada for a shorter duration (5 versus 12 years, P<0.0001) and had a higher viral load (10,990 copies/mL versus <50 copies/mL, P <0.001). All patients were asymptomatic. Eosinophilia was not associated with positive screening results.

CONCLUSIONS

Using symptoms and eosinophilia to identify parasitic infection was not reliable. Screening for strongyloidiasis and schistosomiasis among patients with HIV from parasite-endemic countries is simple and benign, and may prevent future complications. The clinical benefits of screening for filariasis require further elucidation, but this practice appears to be the least warranted.

BACKGROUND

Many North American-based HIV patients originate from parasitic disease-endemic regions. Strongyloidiasis, schistosomiasis and filariasis are important due to their wide distribution and potential for severe morbidity.

OBJECTIVES

To determine the prevalence, as determined by serological screening, of strongyloidiasis, schistosomiasis and filariasis among patients in an HIV-focused, primary care practice in Toronto, Ontario. A secondary objective was to determine factors associated with positive serological screens.

METHODS

A retrospective review of electronic patient records was conducted. Results of serological screens for parasites and relevant laboratory data were collected.

RESULTS

Ninety-seven patients were identified. The patients’ mean CD4⁺ count was 0.45×10⁹/L, median viral load was undetectable and 68% were on highly active antiretroviral therapy (HAART). Most originated from Africa (37%) and South America (35%). Of the 97 patients, 10.4% and 8.3% had positive or equivocal screening results for strongyloidiasis, respectively, 7.4% and 4.2% had positive or equivocal screening results for schistosomiasis and 5.5% and 6.8% had positive or equivocal screens for filariasis. Persons with positive parasitic serologies were more often female (28% versus 9%, P=0.03), younger in age (36 versus 43 years of age, P<0.01), had been in Canada for a shorter duration (5 versus 12 years, P<0.0001) and had a higher viral load (10,990 copies/mL versus <50 copies/mL, P <0.001). All patients were asymptomatic. Eosinophilia was not associated with positive screening results.

CONCLUSIONS

Using symptoms and eosinophilia to identify parasitic infection was not reliable. Screening for strongyloidiasis and schistosomiasis among patients with HIV from parasite-endemic countries is simple and benign, and may prevent future complications. The clinical benefits of screening for filariasis require further elucidation, but this practice appears to be the least warranted.

A simple noninvasive index to predict significant liver fibrosis in patients with advanced schistosomiasis japonica

BACKGROUND

Schistosoma japonicum causes marked liver fibrosis, while lethal syndromes present in advanced schistosomiasis patients. Its management depends on the degree of fibrosis present.

PATIENTS AND METHODS

Fifty-two patients were recruited to assess the diagnostic value of bio-markers in patients with advanced schistosomiasis japonica. Fibrosis was assessed in liver biopsies using METAVIR system. The correlation between conventional parameters and significant fibrosis (F2-F4) was assessed using univariate analysis and logistic regression. The method of area under receiver operating characteristic curves (AUROCs) was used as a measurement of diagnostic efficacy.

RESULTS

White blood cell counts, platelet counts and albumin (all P<0.05) were significantly lower, while prothrombin time, international normalized ratio (INR), hyaluronic acid (HA), IV collagen and ultrasound fibrosis scores (all P<0.01) were significantly elevated in F2-F4 patients compared with F0-F1 patients. HA and INR were identified as independent predictors by multivariate analysis (P=0.023 and P=0.013, respectively). Of the routine laboratory tests for the diagnosis of significant fibrosis, HA gave the best AUROC of 0.875 (95% confidence interval (CI): 0.701-0.997). We constructed a new simple index (INR×HA/100) to discriminate between F2-F4 patients and F0-F1 patients. It showed the highest AUROC of 0.921 (95% CI: 0.828-1.000), and had better diagnostic values than APRI and FIB-4.

CONCLUSION

HA and INR were reliable markers for differentiating significant liver fibrosis in patients with advanced schistosomiasis japonica. And the new simple index can easily predict significant liver fibrosis with a high degree of accuracy.

New approaches with different types of circulating cathodic antigen for the diagnosis of patients with low Schistosoma mansoni load

BACKGROUND

Schistosomiasis mansoni is a debilitating and sometimes fatal disease. Accurate diagnosis plays a key role in patient management and infection control. However, currently available parasitological methods are laborious and lack sensitivity. The selection of target antigen candidates has turned out to be a promising tool for the development of more sensitive diagnostic methods. In our previous investigations, the use of crude antigens led to false-positive results. Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens.

METHOD

Thus, our main goal was to test different types of circulating cathodic antigen glycoprotein (CCA), as "crude antigen," the protein chain of recombinant CCA and two individual peptides. These schistosome proteins/peptides were tested in a new diagnostic method employing immunomagnetic separation based on the improvement of antigen-antibody binding.

PRINCIPAL FINDINGS

Use of recombinant CCA as a diagnostic antigen allowed us to develop a diagnostic assay with high sensitivity and specificity with no false-negative results. Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment.

CONCLUSIONS/SIGNIFICANCE

Our new diagnostic method was superior to enzyme-linked immunosorbent assay in diagnosing low endemicity patients.

A Case of Squamous Cell Carcinoma of the Renal Pelvis in association with Schistosoma hematobium

A 72-year-old man presented with painless frank haematuria. Investigations included intravenous urogram and abdominal/pelvic CT which revealed a marked focal thickening of the wall of the inferior aspect of the left renal pelvis extending into the lower pole calyx and into the pelviureteric junction resulting in left hydronephrosis. Urine cytology demonstrated clusters of malignant keratinised squamous cells and schistosome ova. He underwent left laparoscopic radical nephroureterectomy and histology revealed moderately differentiated keratinising squamous cell carcinoma in the renal pelvis.

Nutritional status, intestinal parasite infection and allergy among school children in northwest Ethiopia

BACKGROUND

Parasitic infections have been shown to have deleterious effects on host nutritional status. In addition, although helmintic infection can modulate the host inflammatory response directed against the parasite, a causal association between helminths and allergy remains uncertain. The present study was therefore designed to evaluate the relationship between nutritional status, parasite infection and prevalence of allergy among school children.

METHODS

A cross sectional study was performed involving school children in two elementary schools in Gondar, Ethiopia. Nutritional status of these children was determined using anthropometric parameters (weight-for-age, height-for-age and BMI-for-age). Epi-Info software was used to calculate z-scores. Stool samples were examined using standard parasitological procedures. The serum IgE levels were quantified by total IgE ELISA kit following the manufacturer's instruction.

RESULT

A total of 405 children (with mean age of 12.09.1 ± 2.54 years) completed a self-administered allergy questionnaire and provided stool samples for analysis. Overall prevalence of underweight, stunting and thinness/wasting was 15.1%, 25.2%, 8.9%, respectively. Of the total, 22.7% were found to be positive for intestinal parasites. The most prevalent intestinal parasite detected was Ascaris lumbricoides (31/405, 7.6%). There was no statistically significant association between prevalence of malnutrition and the prevalence of parasitic infections. Median total serum IgE level was 344 IU/ml (IQR 117-2076, n=80) and 610 IU/ml (143-1833, n=20), respectively, in children without and with intestinal parasite infection (Z=-0.198, P>0.8). The prevalence of self reported allergy among the subset was 8%. IgE concentration was not associated either with the presence of parasitic infection or history of allergy.

CONCLUSION

The prevalence of malnutrition, intestinal parasitism and allergy was not negligible in this population. In addition, there was no significant association between the prevalence of allergy and their nutritional status, and parasite infection. Further research prospective observational and intervention studies are required to address the question of causality between nutritional factors, parasites, and allergy.

Schistosomiasis of the nervous system

Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma. Currently 200 million people worldwide are infected. Neurological manifestations are a result of the inflammatory response of the host to egg deposition in the brain and spinal cord and is usually seen in patients with recent infection with no evidence of systemic illness. Cerebral and cerebellar disease can result in headache, seizure, and increased intracranial pressure. Cerebral schistosomiasis is more common in Schistosoma japonicum, but increasing cases due to Schistosoma mansoni are being reported in the literature. Other complications of cerebral schistosomiasis include delirium, loss of consciousness, visual field impairment, focal motor deficits, and ataxia. Myelopathy is the most common neurological manifestation of Schistosoma mansoni and the conus medullaris and cauda equine are the most common sites of involvement. Severe disease can result in flaccid paraplegia with areflexia, sphincter dysfunction, and sensory disturbance. Early recognition and prompt treatment are essential when physicians are faced with schistosomiasis involving the central nervous system. Schistosomicidal drugs, such as praziquantel, steroids and surgery, are the mainstay of therapy for this severe form of schistosomiasis.

Preliminary Exploration on Anti-Fibrosis Effect of Kaempferol in Mice with Schistosoma Japonicum Infection

This study is to explore the effectiveness and mechanism of kaempferol on treatment of hepatic fibrosis induced by schistosoma egg. Thirty-six healthy male balb/c mice were randomly divided into 6 groups, including negative group, positive group, and 4 different dosages of kaempferol treatment groups. Each mouse was infected with 20 schistosoma Cercariae japonicum, except the ones in the negative group. Four weeks later, every infected mouse was administrated with 500mg/kg/day praziquantel for 2 days, and all kaempferol groups were followed by a 4-week administration of kaempferol with 5, 10, 15 and 20mg/kg/day respectively, while both control groups were administrated with normal saline. AH the mice were sacrificed on the 59th day after infection. The liver tissues were taken for Masson staining to detect collagen and real-time quantitative PCR to detect the mRNA expression of IL-13, collagen 1 and MMP-2. As a result, Masson stain showed that the optical density of the interested region in the positive group was significantly higher than that in the negative group (P<0.01), and the optical density in all kaempferol groups was significantly lower than that in the positive group (P<0.05 or P<0.01). Real-time PCR showed that the mRNA expression of IL-13 in the positive group was significantly higher than that in the negative group (P<0.01), and the expression of IL-13 in the 20mg/kg and 15mg/kg kaempferol groups was significantly lower than that in the positive group, respectively (P<0.05). The mRNA expression of collagen 1 in the positive group was significantly higher than that in the negative group (P<0.01), and mRNA expression of collagen 1 in the 20mg/kg kaempferol group was significantly lower than that in the positive group (P<0.05). There were no significant differences between the positive and negative groups on mRNA expression of MMP-2. The mRNA expression of MMP-2 in all kaempferol groups was significantly higher than that in the positive group (P<0.05 or P<0.01). In conclusion, kaempferol can ameliorate schistosoma egg-induced hepatic fibrosis via regulating the IL-13 signal pathway. Kaempferol is very likely to be an IL-13 targeted anti-fibrosis medicine.

Discovery of platyhelminth-specific α/β-integrin families and evidence for their role in reproduction in Schistosoma mansoni

In all metazoa, the response of cells to molecular stimuli from their environment represents a fundamental principle of regulatory processes controlling cell growth and differentiation. Among the membrane-linked receptors mediating extracellular communication processes are integrin receptors. Besides managing adhesion to the extracellular matrix or to other cells, they arrange information flow into the cells by activating intracellular signaling pathways often acting synergistically through cooperation with growth factor receptors. Although a wealth of information exists on integrins in different model organisms, there is a big gap of knowledge for platyhelminths. Here we report on the in silico detection and reconstruction of α and β integrins from free-living and parasitic platyhelminths, which according to structural and phylogenetic analyses form specific clades separate from each other and from further metazoan integrins. As representative orthologs of parasitic platyhelminths we have cloned one beta-integrin (Smβ-Int1) and four alpha-integrins (Smα-Int1 - Smα-Int4) from Schistosoma mansoni; they were characterized by molecular and biochemical analyses. Evidence is provided that Smβ-Int1 interacts and co-localizes in the reproductive organs with known schistosome cellular tyrosine kinases (CTKs), of which the Syk kinase SmTK4 appeared to be the strongest interaction partner as shown by yeast two-hybrid analyses and coimmunoprecipitation experiments. By a novel RNAi approach with adult schistosomes in vitro we demonstrate for the first time multinucleated oocytes in treated females, indicating a decisive role Smβ-Int1 during oogenesis as phenotypically analyzed by confocal laser scanning microscopy (CLSM). Our findings provide a first comprehensive overview about platyhelminth integrins, of which the parasite group exhibits unique features allowing a clear distinction from the free-living groups. Furthermore, we shed first lights on the functions of integrins in a trematode model parasite, revealing the complexity of molecular processes involved in its reproductive biology, which may be representative for other platyhelminths.

Immunodiagnostic methods: what is their role in areas of low endemicity?

Worldwide Schistosomiasis mansoni continues to be a serious public health problem. Over the past decades, control programmes have made remarkable progress in reducing S. mansoni infections to a relatively low level in Brazil and African countries. Endemic regions are currently circumscribed in certain core areas where reinfection and repeated chemotherapy are frequent and, consequently, are related to residents with low parasite load. At present, diagnosis is predominately a key step for final disease control although low endemicity area residents are hardly detected by most of the available assays. In this paper, we review the current status and efforts made aiming at the improvement of diagnostic tools for S. mansoni in low endemicity infections. The establishment of diagnostic assays—simple, affordable, sensitive, and specific for field diagnosis of S. mansoni—is essential and should be given high priority.

Genitourinary schistosomiasis: life cycle and radiologic-pathologic findings

Genitourinary schistosomiasis is produced by Schistosoma haematobium, a species of fluke that is endemic to Africa and the Middle East, and causes substantial morbidity and mortality in those regions. It also may be seen elsewhere, as a result of travel or immigration. S haematobium, one of the five fluke species that account for most human cases of schistosomiasis, is the only species that infects the genitourinary system, where it may lead to a wide spectrum of clinical symptoms and signs. In the early stages, it primarily involves the bladder and ureters; later, the kidneys and genital organs are involved. It rarely infects the colon or lungs. A definitive diagnosis of genitourinary schistosomiasis is based on findings of parasite ova at microscopic urinalysis. Clinical manifestations and radiologic imaging features also may be suggestive of the disease, even at an early stage: Hematuria, dysuria, and hemospermia, early clinical signs of an established S haematobium infection, appear within 3 months after infection. At imaging, fine ureteral calcifications that appear as a line or parallel lines on abdominopelvic radiographs and as a circular pattern on axial images from computed tomography (CT) are considered pathognomonic of early-stage schistosomiasis. Ureteritis, pyelitis, and cystitis cystica, conditions that are characterized by air bubble-like filling defects representing ova deposited in the ureter, kidney, and bladder, respectively, may be seen at intravenous urography, intravenous ureteropyelography, and CT urography. Coarse calcification, fibrosis, and strictures are signs of chronic or late-stage schistosomiasis. Such changes may be especially severe in the bladder, creating a predisposition to squamous cell carcinoma. Genital involvement, which occurs more often in men than in women, predominantly affects the prostate and seminal vesicles.

CD36-related protein in Schistosoma japonicum: candidate mediator of selective cholesteryl ester uptake from high-density lipoprotein for egg maturation

Familial cholesteryl ester transfer protein (CETP) deficiency is more common in some East Asian populations than elsewhere, suggesting the possibility of a selective advantage of this genetic defect against regional infectious diseases. Historically, infection with the Asian blood fluke Schistosoma japonicum has been endemic in these regions, including Japan. We previously reported that eggs of S. japonicum require cholesteryl ester uptake from normal high-density lipoprotein (HDL) but not from CETP-deficient HDL for their maturation to miracidia, a critical step of the hepatic pathogenesis of schistosomiasis. Herein we show that cholesteryl ester uptake is selective from HDL, and identified CD36-related protein (CD36RP) as a candidate to mediate the reaction. CD36RP was cloned from the adult and the egg developmental stages of S. japonicum, with 1880 bp encoding 506 amino acid residues exhibiting the CD36 domains and two transmembrane regions. Using antibodies against recombinant peptides representing the potential extracellular domains of CD36RP, Western blotting detected a protein with a molecular mass of 82 kDa in the particulate fraction of the adult parasite cells, which was reduced to 62 kDa after N-glycanase treatment. The extracellular domain peptide bound human HDL, as established by immunoblots following nondenaturing gel electrophoresis. Antibodies against the extracellular domain suppressed HDL cholesteryl ester uptake and maturation of the eggs in vitro. CD36RP is a candidate receptor on eggs of S. japonicum that facilitates uptake of HDL cholesteryl ester necessary for egg embryonation and maturation.

Epidemiology and control of human schistosomiasis in Tanzania

In Tanzania, the first cases of schistosomiasis were reported in the early 19th century. Since then, various studies have reported prevalences of up to 100% in some areas. However, for many years, there have been no sustainable control programmes and systematic data from observational and control studies are very limited in the public domain. To cover that gap, the present article reviews the epidemiology, malacology, morbidity, and the milestones the country has made in efforts to control schistosomiasis and discusses future control approaches. The available evidence indicates that, both urinary and intestinal schistosomiasis are still highly endemic in Tanzania and cause significant morbidity.Mass drug administration using praziquantel, currently used as a key intervention measure, has not been successful in decreasing prevalence of infection. There is therefore an urgent need to revise the current approach for the successful control of the disease. Clearly, these need to be integrated control measures.

Study and implementation of urogenital schistosomiasis elimination in Zanzibar (Unguja and Pemba islands) using an integrated multidisciplinary approach

Background

Schistosomiasis is a parasitic infection that continues to be a major public health problem in many developing countries being responsible for an estimated burden of at least 1.4 million disability-adjusted life years (DALYs) in Africa alone. Importantly, morbidity due to schistosomiasis has been greatly reduced in some parts of the world, including Zanzibar. The Zanzibar government is now committed to eliminate urogenital schistosomiasis. Over the next 3–5 years, the whole at-risk population will be administered praziquantel (40 mg/kg) biannually. Additionally, snail control and behaviour change interventions will be implemented in selected communities and the outcomes and impact measured in a randomized intervention trial.

Methods/Design

In this 5-year research study, on both Unguja and Pemba islands, urogenital schistosomiasis will be assessed in 45 communities with urine filtration and reagent strips in 4,500 schoolchildren aged 9–12 years annually, and in 4,500 first-year schoolchildren and 2,250 adults in years 1 and 5. Additionally, from first-year schoolchildren, a finger-prick blood sample will be collected and examined for Schistosoma haematobium infection biomarkers. Changes in prevalence and infection intensity will be assessed annually. Among the 45 communities, 15 were randomized for biannual snail control with niclosamide, in concordance with preventive chemotherapy campaigns. The reduction of Bulinus globosus snail populations and S. haematobium-infected snails will be investigated. In 15 other communities, interventions triggering behaviour change have been designed and will be implemented in collaboration with the community. A change in knowledge, attitudes and practices will be assessed annually through focus group discussions and in-depth interviews with schoolchildren, teachers, parents and community leaders. In all 45 communities, changes in the health system, water and sanitation infrastructure will be annually tracked by standardized questionnaire-interviews with community leaders. Additional issues potentially impacting on study outcomes and all incurring costs will be recordedand monitored longitudinally.

Discussion

Elimination of schistosomiasis has become a priority on the agenda of the Zanzibar government and the international community. Our study will contribute to identifying what, in addition to preventive chemotherapy, needs to be done to prevent, control, and ultimately eliminate schistosomiasis, and to draw lessons for current and future schistosomiasis elimination programmes in Africa and elsewhere.

Trial registration

ISRCTN48837681

Neglected tropical diseases: survey and geometry of randomised evidence

OBJECTIVE

To assess the quantity and distribution of evidence from randomised controlled trials for the treatment of the major neglected tropical diseases and to identify gaps in the evidence with network analysis.

DESIGN

Systematic review and network analysis.

DATA SOURCES

Cochrane Central Register of Controlled Trials and PubMed from inception to 31 August 2011.

STUDY SELECTION

Randomised controlled trials that examined treatment of 16 neglected tropical diseases or complications thereof published in English, French, Spanish, Portuguese, German, or Dutch.

RESULTS

We identified 971 eligible randomised trials. Leishmaniasis (184 trials, 23,039 participants) and geohelminth infections; 160 trials, 46,887 participants) were the most studied, while dracunculiasis (nine trials, 798 participants) and Buruli ulcer (five trials, 337 participants) were least studied. Relative to its global burden of disease, lymphatic filariasis had the fewest trials and participants. Only 11% of trials were industry funded. Either a single trial or trials with fewer than 100 participants comprised the randomised evidence for first or second line treatments for Buruli ulcer, human African trypanosomiasis, American trypanosomiasis, cysticercosis, rabies, echinococcosis, New World cutaneous leishmaniasis, and each of the foodborne trematode infections. Among the 10 disease categories with more than 40 trials, five lacked sufficient head to head comparisons between first or second line treatments.

CONCLUSIONS

There is considerable variation in the amount of evidence from randomised controlled trials for each of the 16 major neglected tropical diseases. Even in diseases with substantial evidence, such as leishmaniasis and geohelminth infections, some recommended treatments have limited supporting data and lack head to head comparisons.

Intermittent fever, splenomegaly and eosinophilia in a recently resettled African refugee

We discuss a recently resettled African refugee child with acute schistosomiasis, who presented with fever, hepatosplenomegaly and marked eosinophilia. We outline the differential diagnoses of eosinophilia in the recently resettled refugee and returned traveller and outline the epidemiology and clinical spectrum of schistosomal infection, including controversies in management of acute schistosomiasis.

Systematic review and meta-analysis of artemisinin based therapies for the treatment and prevention of schistosomiasis

BACKGROUND

Chemotherapy based on repeated doses of praziquantel is still the most effective control strategy against Schistosomiasis, however artemisinin derivatives emerged as a family of compounds with schistomicide activity. The aim of the present work is to compare the efficacy of artemisinin-based therapies in the treatment and prophylaxis of human schistosomiasis. The design of this work involved a quantitative systematic review and meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

Retrieval of published studies was carried out through an electronic search of the PubMed (MEDLINE), EMBASE, Cochrane Library and CINAHL databases. This included reports comparing the therapeutic efficacy of artesunate alone, artesunate plus sulfadoxine-pyrimethamine and a combination of artemisinin derivatives plus praziquantel against praziquantel alone on different types of schistosomiasis. Moreover, studies on artesunate and artemether used as preventive drugs were also analyzed against placebo. The primary outcome measure for schistosomiasis treatment was "parasitological cure", whereas for the prophylaxis the outcome evaluated was "infection rate". Our results show that patients treated with artesunate alone have significantly lower cure rates than those treated with praziquantel (OR = 0.27 (95% C.I. 0.13-0.53; p<0.001)) and that the combined therapy of artesunate plus sulfadoxine-pyrimethamine is also significantly less effective than praziquantel treatment (OR = 0.14 (95% C.I. 0.02-0.92; p = 0.04)). However, the combination of an artemisinin derivatives plus praziquantel showed a higher cure rate than praziquantel monotherapy with OR = 2.07 (95% C.I. 1.27-3.36; p = 0.003). Finally, chemoprophylaxis with either artesunate (RR = 0.11 (95% C.I. 0.06-0.22; p<0.001)) or artemether (RR = 0.25 (95% C.I. 0.16-0.40; p<0.001)) was significantly better than a placebo in both cases.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis confirms that artemisinin derivatives used in combination with praziquantel have the potential to increase the cure rates in schistosomiasis treatment, but not artesunate alone. It is also confirmed that repeated doses of artemisinin derivatives play a prophylactic role, significantly reducing the incidence of Schistosoma japonicum infections compared with placebo.

Bladder cancer and schistosomiasis

Schistosoma-associated bladder cancer was believed, for several decades, to be a completely unique entity of disease, different from urothelial cancer. This was probably due to its distinct clinicopathologic and demographic features that varied from those of urothelial entity. The carcinogenesis is an extremely complex process resulting from the accumulation of many genetic and epigenetic changes leading to alterations in the cell proliferation regulation process. In bladder cancer, many of these carcinogenic cascades were not fully documented or somewhat conflicting. Inspite of the efforts performed, much is still needed to explore the presence or absence of the carcinogenic difference with a different etiology. The control of schistosomiasis in certain countries and the subsequent decrease in the intensity of infestation showed changing of features approaching that of urothelial tumors. However the schistosoma-associated bladder cancer presented in more advanced stages than schistosoma-non associated urothelial cancer. More recently, data are gathered that, upon applying the same treatment protocol and management care, stage by stage comparison of the treatment end-results were found to be similar in bladder cancer patients with a different etiology. All treatment options; including radical cystectomy with or without adjuvant or neoadjuvant chemo- or radiotherapy or trimodality bladder preserving treatment seem to lead to similar end-results regardless of etiologic factor(s) implicated in bladder cancer development.

Parasitic liver disease in travelers

Liver disease is an important source of morbidity among ill returning travelers. Jaundice is one of the most common and obvious symptoms of liver disease, the differential diagnosis of which is extensive, especially in travelers. Jaundice in travelers can arise from both infectious and noninfectious causes. We herein summarize the most common parasitic etiologies that may lead to jaundice in the returned traveler, visitors of friends and relatives, or new immigrants, and describe the etiology, epidemiology, and pathogenesis of clinical features of each.

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.

Pseudotumoral form of cerebral Schistosomiasis Mansoni

The authors report a case of 36-year-old woman presented with epileptic seizures and headaches. Magnetic resonance imaging (MRI) revealed an enhancing lesion with surrounding edema and mild mass effect in the left frontal lobe. Stereotactic brain biopsy demonstrated intraparenchymal granulomas surrounding S. mansoni eggs. Praziquantel was started (60mg/kg of body weight, in a single dose), followed by Prednisone (80mg/day) for seven days to treat the cerebral edema. The patient’s symptoms resolved following medical treatment and the follow-up MRI yielded normal findings.

Synthesis and biological evaluation of 1,4-naphthoquinones and quinoline-5,8-diones as antimalarial and schistosomicidal agents

Improving the solubility of polysubstituted 1,4-naphthoquinone derivatives was achieved by introducing nitrogen in two different positions of the naphthoquinone core, at C-5 and at C-8 of menadione through a two-step, straightforward synthesis based on the regioselective hetero-Diels-Alder reaction. The antimalarial and the antischistosomal activities of these polysubstituted aza-1,4-naphthoquinone derivatives were evaluated and led to the selection of distinct compounds for antimalarial versus antischistosomal action. The Ag(II)-assisted oxidative radical decarboxylation of the phenyl acetic acids using AgNO(3) and ammonium peroxodisulfate was modified to generate the 3-picolinyl-menadione with improved pharmacokinetic parameters, high antimalarial effects and capacity to inhibit the formation of β-hematin.

Haematobium eggs detection in human bladder cancer and sporocysts in snail vectors: Seven cases report and a review of the Burkina Faso literature

Schistosoma haematobium plays a central role in the development of bladder cancer in Burkina Faso. The objective of this study was to determine the presence of S. haematobium in the bladder cancer and in vector snails. For the first time, formalin-fixed tissues embedded in paraffin were analyzed by immunohistochemistry and PCR. Molecular detection has resulted in 7/7 positive bladder cancer. Finally, as the snail vectors were positive. We suggest the use of molecular methods in the snail vectors for the detection of cysts and in cancerous tissues in larger studies.

Antigens of worms and eggs showed a differentiated detection of specific IgG according to the time of Schistosoma mansoni infection in mice

INTRODUCTION: The correlation between the immunological assay and the antibody titer can offer a tool for the experimental analysis of different phases of the disease. METHODS: Two simple immunological assays for Schistosoma mansoni in mice sera samples based on specific IgG detection for worms soluble antigens and eggs soluble antigens were standardized and evaluated in our laboratory. Fifty mice were used in negative and positive groups and the results obtained by enzyme-linked immunosorbent assays (ELISA) assays were compared with the number of worms counted and the IgG titers at different times of infection. RESULTS: Data showed that ELISA using adult worm antigens (ELISA-SWAP) presented a satisfactory correlation between the absorbance value of IgG titers and the individual number of worms counted after perfusion technique (R²=0.62). In addition, ELISA-SWAP differentially detected positive samples with 30 and 60 days post infection (p=0.011 and 0.003, respectively), whereas ELISA using egg antigens (ELISA-SEA) detected samples after 140 days (p=0.03). CONCLUSIONS: These data show that the use of different antigens in immunological methods can be used as potential tools for the analysis of the chronological evolution of S. mansoni infection in murine schistosomiasis. Correlations with human schistosomiasis are discussed.

Comparative transcriptome analysis between planarian Dugesia japonica and other platyhelminth species

Background

Planarians are considered to be among the extant animals close to one of the earliest groups of organisms that acquired a central nervous system (CNS) during evolution. Planarians have a bilobed brain with nine lateral branches from which a variety of external signals are projected into different portions of the main lobes. Various interneurons process different signals to regulate behavior and learning/memory. Furthermore, planarians have robust regenerative ability and are attracting attention as a new model organism for the study of regeneration. Here we conducted large-scale EST analysis of the head region of the planarian Dugesia japonica to construct a database of the head-region transcriptome, and then performed comparative analyses among related species.

Results

A total of 54,752 high-quality EST reads were obtained from a head library of the planarian Dugesia japonica, and 13,167 unigene sequences were produced by de novo assembly. A new method devised here revealed that proteins related to metabolism and defense mechanisms have high flexibility of amino-acid substitutions within the planarian family. Eight-two CNS-development genes were found in the planarian (cf. C. elegans 3; chicken 129). Comparative analysis revealed that 91% of the planarian CNS-development genes could be mapped onto the schistosome genome, but one-third of these shared genes were not expressed in the schistosome.

Conclusions

We constructed a database that is a useful resource for comparative planarian transcriptome studies. Analysis comparing homologous genes between two planarian species showed that the potential of genes is important for accumulation of amino-acid substitutions. The presence of many CNS-development genes in our database supports the notion that the planarian has a fundamental brain with regard to evolution and development at not only the morphological/functional, but also the genomic, level. In addition, our results indicate that the planarian CNS-development genes already existed before the divergence of planarians and schistosomes from their common ancestor.

Effects of Cu/Zn superoxide dismutase (sod1) genotype and genetic background on growth, reproduction and defense in Biomphalaria glabrata

Resistance of the snail Biomphalaria glabrata to the trematode Schistosoma mansoni is correlated with allelic variation at copper-zinc superoxide dismutase (sod1). We tested whether there is a fitness cost associated with carrying the most resistant allele in three outbred laboratory populations of snails. These three populations were derived from the same base population, but differed in average resistance. Under controlled laboratory conditions we found no cost of carrying the most resistant allele in terms of fecundity, and a possible advantage in terms of growth and mortality. These results suggest that it might be possible to drive resistant alleles of sod1 into natural populations of the snail vector for the purpose of controlling transmission of S. mansoni. However, we did observe a strong effect of genetic background on the association between sod1 genotype and resistance. sod1 genotype explained substantial variance in resistance among individuals in the most resistant genetic background, but had little effect in the least resistant genetic background. Thus, epistatic interactions with other loci may be as important a consideration as costs of resistance in the use of sod1 for vector manipulation.

Driving resistance genes into vector populations remains a promising but underused method for reducing transmission of vector-borne diseases. Understanding the genetic mechanisms governing resistance and how resistance is maintained in vector populations is essential for the development of resistant vectors as a means of eradicating vector-borne diseases. We investigated the utility of one gene (cytosolic copper-zinc superoxide dismutase - sod1) for driving resistance associated alleles into populations of the snail Biomphalaria glabrata, a vector of the trematode parasite of humans, Schistosoma mansoni. Under controlled laboratory conditions we found no evidence for costs of resistance associated with carrying the most resistant allele at sod1 (in terms of growth, fecundity, or mortality). However, we did find a strong effect of genetic background on how strongly sod1 genotype influences resistance. Thus, epistatic interactions with other loci may be as important a consideration as costs of resistance in the use of sod1 for vector manipulation in the field.

CT presentations of colorectal cancer with chronic schistosomiasis: A comparative study with pathological findings

OBJECTIVE

To clarify pathological basis of computed tomography (CT) presentations of colorectal cancer (CRC) with schistosomiasis for the purpose of improving the accuracy of CT diagnosis and differential diagnosis of the condition.

MATERIALS AND METHODS

130 patients (87 male and 43 female; age range 49-86 years, mean 71.1) were selected whose diagnoses were pathologically confirmed as CRC with schistosomiasis. All the patients underwent abdominal plain CT and contrast enhanced scanning. The location, morphology, size, calcification features and enhancement modalities (patterns) were evaluated and compared with the pathological findings by two radiologists in a blind way.

RESULTS

CT showed that in 130 patients, the tumors occurred in the large intestine, among which 109 (83.9%) were solitary and 21 (16.1%) were multifocal. The intestinal wall was irregularly thickened in 123 patients, with soft tissue masses in 7 patients. Linear, spotty and small patchy calcifications were seen in 104 (80.0%) patients, with unclear margins in 96 patients. The tumors were markedly unevenly enhanced in 92 patients. Pathological examination revealed adenocarcinoma in 114 patients and in 104 patients, calcified Shistosoma japonicum (S. japonicum) ova inside the tumors, 15 patients were mucinous adenocarcinoma, and one patient was that of adenosquamous carcinoma.

CONCLUSION

Irregular thickening of the intestinal wall, soft tissue masses, multiple S. japonicum ova calcifications inside the tumor with obscured margins and multiple intestinal masses in some patients are important CT features of CRC with schistosomiasis.

Three-dimensional structure of a schistosome serpin revealing an unusual configuration of the helical subdomain

Parasitic organisms are constantly challenged by the defence mechanisms of their respective hosts, which often depend on serine protease activities. Consequently, protease inhibitors such as those belonging to the serpin superfamily have emerged as protective elements that support the survival of the parasites. This report describes the crystal structure of ShSPI, a serpin from the trematode Schistosoma haematobium. The protein is exposed on the surface of invading cercaria as well as of adult worms, suggesting its involvement in the parasite-host interaction. While generally conforming to the well established serpin fold, the structure reveals several distinctive features, mostly concerning the helical subdomain of the protein. It is proposed that these peculiarities are related to the unique biological properties of a small serpin subfamily which is conserved among pathogenic schistosomes.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Molecular mechanisms underlying occult hepatitis B virus infection

Chronic hepatitis B virus (HBV) infection is a complex clinical entity frequently associated with cirrhosis and hepatocellular carcinoma (HCC). The persistence of HBV genomes in the absence of detectable surface antigenemia is termed occult HBV infection. Mutations in the surface gene rendering HBsAg undetectable by commercial assays and inhibition of HBV by suppression of viral replication and viral proteins represent two fundamentally different mechanisms that lead to occult HBV infections. The molecular mechanisms underlying occult HBV infections, including recently identified mechanisms associated with the suppression of HBV replication and inhibition of HBV proteins, are reviewed in detail. The availability of highly sensitive molecular methods has led to increased detection of occult HBV infections in various clinical settings. The clinical relevance of occult HBV infection and the utility of appropriate diagnostic methods to detect occult HBV infection are discussed. The need for specific guidelines on the diagnosis and management of occult HBV infection is being increasingly recognized; the aspects of mechanistic studies that warrant further investigation are discussed in the final section.

Schistosomiasis: a case of severe infection with fatal outcome

Schistosomiasis is one of the most common parasitic diseases, still considered of public health significance. Acute schistosomiasis is of difficult diagnosis and therefore has been overlooked, misdiagnosed, underestimated and underreported in endemic areas. The delay between the exposure to contaminated water and the initial symptoms may explain this challenging diagnosis. Acute schistosomiasis is frequently reported in non-immune individuals while reinfection cases occurring in endemic areas is scarcely documented. The later usually shows a benign course but fatal cases do exist. The authors report a case of a young female patient, in the late puerperium, with a three-month history of weight loss, intermittent fever, cough, thoracic and abdominal pain and increased abdominal girth. Physical examination showed a tachycardia, tachypnea and hypotension. Laboratory tests showed a mild anemia, eosinophilia, and a slightly elevation of liver enzymes. Thorax and abdominal multidetector computed tomography evidenced a diffuse and bilateral pulmonary micronodules and peritoneal and intestinal wall thickening. The patient progressed rapidly to hepatic insufficiency, and death after respiratory insufficiency. An autopsy was performed and the findings were compatible with acute Schistosomiasis in a patient previously exposed to Schistosoma mansoni.

Sensitive and specific target sequences selected from retrotransposons of Schistosoma japonicum for the diagnosis of schistosomiasis

BACKGROUND

Schistosomiasis japonica is a serious debilitating and sometimes fatal disease. Accurate diagnostic tests play a key role in patient management and control of the disease. However, currently available diagnostic methods are not ideal, and the detection of the parasite DNA in blood samples has turned out to be one of the most promising tools for the diagnosis of schistosomiasis. In our previous investigations, a 230-bp sequence from the highly repetitive retrotransposon SjR2 was identified and it showed high sensitivity and specificity for detecting Schistosoma japonicum DNA in the sera of rabbit model and patients. Recently, 29 retrotransposons were found in S. japonicum genome by our group. The present study highlighted the key factors for selecting a new perspective sensitive target DNA sequence for the diagnosis of schistosomiasis, which can serve as example for other parasitic pathogens.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we demonstrated that the key factors based on the bioinformatic analysis for selecting target sequence are the higher genome proportion, repetitive complete copies and partial copies, and active ESTs than the others in the chromosome genome. New primers based on 25 novel retrotransposons and SjR2 were designed and their sensitivity and specificity for detecting S. japonicum DNA were compared. The results showed that a new 303-bp sequence from non-long terminal repeat (LTR) retrotransposon (SjCHGCS19) had high sensitivity and specificity. The 303-bp target sequence was amplified from the sera of rabbit model at 3 d post-infection by nested-PCR and it became negative at 17 weeks post-treatment. Furthermore, the percentage sensitivity of the nested-PCR was 97.67% in 43 serum samples of S. japonicum-infected patients.

CONCLUSIONS/SIGNIFICANCE

Our findings highlighted the key factors based on the bioinformatic analysis for selecting target sequence from S. japonicum genome, which provide basis for establishing powerful molecular diagnostic techniques that can be used for monitoring early infection and therapy efficacy to support schistosomiasis control programs.

T regulatory cell responses to immunization with a soluble egg antigen in Schistosoma mansoni-infected mice

The aim of the study is to characterize the phenotypes of CD4⁺ CD25⁺ T regulatory cells within the liver granulomas and association with both Foxp-3 gene expression and splenic cytokines. Naïve C57BL/6 mice were intravenously injected with multiple doses of the soluble egg antigen (SEA) 7 days before cercarial infection. The immunized and infected control groups were sacrificed 8 and 16 weeks post-infection (PI). Histopathology, parasitological parameters, splenic phenotypes for T regulatory cells, the FOXP-3 expression in hepatic granuloma using real-time PCR, and the associated splenic cytokines were studied. Histopathological examination of the liver revealed remarkable increase in degenerated ova within hepatic granuloma which decreased in diameter at weeks 8 and 16 PI (P<0.01). The percentage of T regulatory cells (CD4⁺ CD25⁺) increased significantly (P<0.01) in the immunized group compared to the infected control at weeks 8 and 16 PI. The FOXP-3 expression in hepatic granulomas increased from 10 at week 8 to 30 fold at week 16 PI in the infected control group. However, its expression in the immunized group showed an increase from 30 at week 8 to 70 fold at week 16 PI. The splenic cytokine levels of pro-inflammatory cytokines, IFN-γ, IL-4, and TNF-α, showed significant decreases (P<0.05) compared to the infected control group. In conclusion, the magnitude and phenotype of the egg-induced effects on T helper responses were found to be controlled by a parallel response within the T regulatory population which provides protection in worm parasite-induced immunopathology.

IL-10R blockade during chronic schistosomiasis mansoni results in the loss of B cells from the liver and the development of severe pulmonary disease

In schistosomiasis patients, parasite eggs trapped in hepatic sinusoids become foci for CD4+ T cell-orchestrated granulomatous cellular infiltrates. Since the immune response is unable to clear the infection, the liver is subjected to ongoing cycles of focal inflammation and healing that lead to vascular obstruction and tissue fibrosis. This is mitigated by regulatory mechanisms that develop over time and which minimize the inflammatory response to newly deposited eggs. Exploring changes in the hepatic inflammatory infiltrate over time in infected mice, we found an accumulation of schistosome egg antigen-specific IgG1-secreting plasma cells during chronic infection. This population was significantly diminished by blockade of the receptor for IL-10, a cytokine implicated in plasma cell development. Strikingly, IL-10R blockade precipitated the development of portal hypertension and the accumulation of parasite eggs in the lungs and heart. This did not reflect more aggressive Th2 cell responsiveness, increased hepatic fibrosis, or the emergence of Th1 or Th17 responses. Rather, a role for antibody in the prevention of severe disease was suggested by the finding that pulmonary involvement was also apparent in mice unable to secrete class switched antibody. A major effect of anti-IL-10R treatment was the loss of a myeloid population that stained positively for surface IgG1, and which exhibited characteristics of regulatory/anti-inflammatory macrophages. This finding suggests that antibody may promote protective effects within the liver through local interactions with macrophages. In summary, our data describe a role for IL-10-dependent B cell responses in the regulation of tissue damage during a chronic helminth infection.

Characterization of the Src/Abl hybrid kinase SmTK6 of Schistosoma mansoni

Cellular protein-tyrosine kinases play key roles in signal transduction processes in eukaryotes. SmTK4 was the first Syk kinase identified in a parasite and found to be tissue-specifically transcribed in the gonads of adult Schistosoma mansoni. Functional analyses confirmed its role in oogenesis and spermatogenesis. As an SmTK4 upstream binding partner, the cellular protein-tyrosine kinase SmTK6 was isolated from a yeast two-hybrid library. Phylogenetic analyses performed in this study confirmed the first suggestions of a hybrid character of SmTK6. Biochemical studies made in Xenopus oocytes using inhibitors against Src (herbimycin A) and Abl (imatinib) kinases exhibited a biochemical inhibition profile of SmTK6, which was intermediate of Src and Abl kinases. As SmTK6 upstream interaction partners, we identified among others the known Src kinase SmTK3 and the Venus kinase receptor SmVKR1 of S. mansoni by yeast two-hybrid analyses, all of which co-localized in the gonads. Co-immunoprecipitation experiments confirmed interactions between SmTK6 and SmTK3 or SmVKR1. In Xenopus oocytes, it was finally shown that SmVKR1 but also SmTK3 were able to activate SmTK6 enzymatic activity indicating its functions in a receptor tyrosine kinase signal transduction cascade. These results not only demonstrate an intermediate but Src-biased profile of the unusual kinase SmTK6. They also strongly substantiate previous indications for a kinase complex, consisting of a receptor tyrosine kinase, Syk and Src kinases, which has been hypothesized to be involved in proliferation and differentiation processes in the gonads of schistosomes.

Parasitic infections in HIV infected individuals: diagnostic & therapeutic challenges

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leishmaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection.

Gastrointestinal neoplasia associated with bowel parasitosis: real or imaginary?

Several parasitic species are well known to have carcinogenic properties, namely; Schistosoma hematobium (squamous cell carcinoma of the bladder) and the liver flukes Opisthorchis and Chlonorchis (cholangiocarcinoma). A large number of parasites are known to colonize the gastrointestinal tract. We sought to review the evidence that implicates these parasites in gastrointestinal neoplasia. Schistosoma japonicum, which is endemic primarily in east Asia, has been shown in multiple studies to convey a mildly increased risk of colorectal adenocarcinoma. The data supporting a causative role for Schistosoma mansoni in colorectal or other neoplastic processes are less convincing, limited primarily to small case-control studies and case series. Reports of possible associations between other gastrointestinal parasites (e.g., E. histolytica and A. lumbricoides) and neoplasia may be found in the literature but are limited to individual cases. We conclude that, other than S. japonicum and to a lesser extent S. mansoni, there is little evidence of an association between gastrointestinal parasites and neoplasia.