Schistosome feeding and regurgitation.

Schistosomes are parasitic flatworms that infect >200 million people worldwide, causing the chronic, debilitating disease schistosomiasis. Unusual among parasitic helminths, the long-lived adult worms, continuously bathed in blood, take up nutrients directly across the body surface and also by ingestion of blood into the gut. Recent proteomic analyses of the body surface revealed the presence of hydrolytic enzymes, solute, and ion transporters, thus emphasising its metabolic credentials. Furthermore, definition of the molecular mechanisms for the uptake of selected metabolites (glucose, certain amino acids, and water) establishes it as a vital site of nutrient acquisition. Nevertheless, the amount of blood ingested into the gut per day is considerable: for males ∼100 nl; for the more actively feeding females ∼900 nl, >4 times body volume. Ingested erythrocytes are lysed as they pass through the specialized esophagus, while leucocytes become tethered and disabled there. Proteomics and transcriptomics have revealed, in addition to gut proteases, an amino acid transporter in gut tissue and other hydrolases, ion, and lipid transporters in the lumen, implicating the gut as the site for acquisition of essential lipids and inorganic ions. The surface is the principal entry route for glucose, whereas the gut dominates amino acid acquisition, especially in females. Heme, a potentially toxic hemoglobin degradation product, accumulates in the gut and, since schistosomes lack an anus, must be expelled by the poorly understood process of regurgitation. Here we place the new observations on the proteome of body surface and gut, and the entry of different nutrient classes into schistosomes, into the context of older studies on worm composition and metabolism. We suggest that the balance between surface and gut in nutrition is determined by the constraints of solute diffusion imposed by differences in male and female worm morphology. Our conclusions have major implications for worm survival under immunological or pharmacological pressure.

Pulmonary arterial hypertension in schistosomiasis.

PURPOSE OF REVIEW: Schistosomiasis is one of the most prevalent parasitic diseases in the world, being present in more than 70 countries. Pulmonary hypertension is one of the several chronic complications of schistosomiasis; particularly in developing countries, schistosomiasis-associated pulmonary arterial hypertension might represent one of the most prevalent causes of pulmonary arterial hypertension. RECENT FINDINGS: New epidemiological data reinforce the importance of schistosomiasis in the context of pulmonary hypertension; furthermore, the inflammatory components of the pathophysiology of pulmonary hypertension associated with schistosomiasis have been recently explored, opening the perspective of new targets to be explored. Clinical and hemodynamic features of this particular complication of schistosomiasis, and the role of targeted therapies in this setting, have been better described in recent years. SUMMARY: The importance of schistosomiasis-associated pulmonary hypertension is now recognized with better knowledge about its pathophysiology and management. Nevertheless, there is a need for better understanding the predisposal factors (genetic, environmental and so on) for the development of pulmonary hypertension in schistosomiasis as a way to prevent it from occurring. Furthermore, better control programs to decrease disease transmission are still missing, ensuring that we will have to face this devastating complication of schistosomiasis for a long future.

Hepatic Shunting of Eggs and Pulmonary Vascular Remodeling in Bmpr2(+/-) Mice with Schistosomiasis.

RATIONALE: Schistosomiasis is a major cause of pulmonary arterial hypertension (PAH). Mutations in the bone morphogenetic protein type-II receptor (BMPR-II) are the commonest genetic cause of PAH. OBJECTIVES: To determine whether Bmpr2(+/-) mice are more susceptible to schistosomiasis-induced pulmonary vascular remodeling. METHODS: Wild-type (WT) and Bmpr2(+/-) mice were infected percutaneously with Schistosoma mansoni. At 17 weeks postinfection, right ventricular systolic pressure and liver and lung egg counts were measured. Serum, lung and liver cytokine, pulmonary vascular remodeling, and liver histology were assessed. MEASUREMENTS AND MAIN RESULTS: By 17 weeks postinfection, there was a significant increase in pulmonary vascular remodeling in infected mice. This was greater in Bmpr2(+/-) mice and was associated with an increase in egg deposition and cytokine expression, which induced pulmonary arterial smooth muscle cell proliferation, in the lungs of these mice. Interestingly, Bmpr2(+/-) mice demonstrated dilatation of the hepatic central vein at baseline and postinfection, compared with WT. Bmpr2(+/-) mice also showed significant dilatation of the liver sinusoids and an increase in inflammatory cells surrounding the central hepatic vein, compared with WT. This is consistent with an increase in the transhepatic passage of eggs. CONCLUSIONS: This study has shown that levels of BMPR-II expression modify the pulmonary vascular response to chronic schistosomiasis. The likely mechanism involves the increased passage of eggs to the lungs, caused by altered diameter of the hepatic veins and sinusoids in Bmpr2(+/-) mice. Genetically determined differences in the remodeling of hepatic vessels may represent a new risk factor for PAH associated with schistosomiasis.

The Impact of Nurses on Neglected Tropical Disease Management.

Although Neglected Tropical Diseases (NTDs) are largely endemic in the developing nations of Africa, Asia, and South and Central America, they are reemerging with increasing frequency in developed countries. Their diagnosis, treatment, and control are an increasing public health concern that requires a different awareness by health care providers. Neglected tropical diseases (NTDs) are chronic infectious diseases which disproportionately burden poor, rural, and marginalized populations with significant mortality and high morbidity (disability, disfigurement, impaired childhood growth and cognitive development, increased vulnerability to coinfection) that reinforces their poverty. What can we learn from the nurses in developing countries already battling NTD's that could be useful in the developed world? This article provides an overview of distribution, pathophysiology, symptoms, and management of 13 NTDs, with particular attention to the role of nurses in delivering cost-effective integrated interventions. Case studies of schistosomiasis, Chagas disease, and leishmaniasis address recognition and treatment of infected individuals in developed nations where NTD infection is limited primarily to immigrants and travelers.

Monocyte subsets in schistosomiasis patients with periportal fibrosis.

A major issue with Schistosoma mansoni infection is the development of periportal fibrosis, which is predominantly caused by the host immune response to egg antigens. Experimental studies have pointed to the participation of monocytes in the pathogenesis of liver fibrosis. The aim of this study was to characterize the subsets of monocytes in individuals with different degrees of periportal fibrosis secondary to schistosomiasis. Monocytes were classified into classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)), and nonclassical (CD14(+)CD16(++)). The expressions of monocyte markers and cytokines were assessed using flow cytometry. The frequency of classical monocytes was higher than the other subsets. The expression of HLA-DR, IL-6, TNF-α, and TGF-ß was higher in monocytes from individuals with moderate to severe fibrosis as compared to other groups. Although no differences were observed in receptors expression (IL-4R and IL-10R) between groups of patients, the expression of IL-12 was lower in monocytes from individuals with moderate to severe fibrosis, suggesting a protective role of this cytokine in the development of fibrosis. Our data support the hypothesis that the three different monocyte populations participate in the immunopathogenesis of periportal fibrosis, since they express high levels of proinflammatory and profibrotic cytokines and low levels of regulatory markers.

[Urinary disorders associated with bilharziasis. Urodynamic evaluation. Findings in 10 cases]. / Troubles vésico-sphinctériens des bilharzioses. Etude urodynamique. A propos de 10 cas.

UNLABELLED: Bilharziasis urinary disorders are characterized by recurent hematuria, overactive bladder symptoms (urgency, frequency and urge incontinence) and sometimes weak stream with or without urinary retention. We report 10 cases of urodynamic assessment. RESULTS: The main urodynamic symptom was overactive detrusor with uninhibited detrusor contraction during the filling phase. Only 1 patient had underactive detrusor leading to urinary retention. Urinary symptoms were secondary to a neurogenic abnormality (spinal lesion) in 2 cases, and to a specific lesion of bladder mucosa in 8 cases. CONCLUSION: Urodynamic investigations are usefull in bilharziasis urinary disorders in order to specify the pathophysiology of urinary symptoms and to point a specific neurogenic (spinal) alteration in the genesis of the urinary symptoms.

Differential effects of asymptomatic Ascaris lumbricoides, Schistosoma mansoni or hook worm infection on the frequency and TGF-beta-producing capacity of regulatory T cells during active tuberculosis.

Helminth induced expansion of regulatory T cells (Tregs) may take part in suppressing protective host responses during tuberculosis (TB), although Tregs functionality and link to TB disease severity remains unexplored. We investigated the species-specific effect of helminths on frequency and TGF-ß producing capacity of Tregs, and possible connection to TB disease severity. 89 pulmonary TB patients (PTB) and 69 community controls (CCs) from Gondar, Ethiopia, were included. Clinical disease severity was graded by TB score, and flow cytometry used to characterize Treg frequency and functionality measured as their TGF-ß-producing capacity. In helminth positive PTB patients (Helminth+PTB+) compared to helminth negative PTB or CCs, TGF-ß+ Tregs were significantly increased mainly in hookworm coinfection whereas S. mansoni increased TGF-ß+ Tregs in CCs. Treatment of TB and helminths decreased TGF-ß+ Tregs in Helminth+PTB+ at 2 months follow-up. There were no overall differences in the frequency of Tregs in CCs or PTB unless stratification on TB disease severity was performed. At inclusion Helminth+PTB+ had increased frequency of Tregs already at low disease severity, and TGF-ß+ Tregs correlated to intermediate-to-high disease severity. In conclusion, helminth specific increase of TGF-ß+ Tregs in PTB patients was correlated to TB disease severity and was restored following anti-helminth treatment.

Hepatic fibrosis in schistosomiasis: egg granulomas secrete fibroblast stimulating factor in vitro.

Cytosol extracts and culture supernatants of isolated egg granulomas obtained from livers of mice with Schistosoma mansoni infection stimulated fibroblasts to incorporate tritiated thymidine and to proliferate in vitro. This finding suggests that hepatic granulomas may play a role in regulating hepatic fibrosis in Schistosoma mansoni infections.

Immunopathogenesis of human schistosomiasis.

Schistosomiasis continues to be a significant cause of parasitic morbidity and mortality worldwide. This review considers the basic features of the pathology and clinical outcomes of hepatointestinal and genitourinary schistosomiasis, presents an overview of the numerous studies on animal models that have clarified many of the immunopathological features, and provides insight into our current understanding of the immunopathogenesis and genetic control of human schistosomiasis. In murine schistosomiasis, pathology is induced by a CD4(+) Th2 driven granulomatous response directed against schistosome eggs lodged in the host liver. The Th2 cytokines IL-4 and IL-13 drive this response, whereas IL-10, IL13Ralpha2, IFN-gamma and a subset of regulatory T-cells act to limit schistosome induced pathology. A variety of cell types including hepatic stellate cells, alternatively activated macrophages and regulatory T-cells have also been implicated in the pathogenesis of schistosomiasis. Current knowledge suggests the immunopathogenic mechanisms underlying human schistosomiasis are likely to be similar. The review also considers the future development of anti-pathology schistosome vaccines. As fibrosis is an important feature of many other diseases such as Crohn's disease and sarcoidosis, a comprehensive understanding of the cellular and molecular mechanisms involved in schistosomiasis may also ultimately contribute to the development an effective disease intervention strategy for other granulofibrotic diseases.

Other causes of PAH (schistosomiasis, porto-pulmonary hypertension and hemolysis-associated pulmonary hypertension).

Recent years have witnessed a significant increase in the knowledge about the pathophysiology of pulmonary arterial hypertension (PAH) and the availability of multiple drugs specifically aimed at pulmonary circulation. Although most of this is related to the idiopathic form of PAH, this development has also turned attention to other forms of pulmonary hypertension such as schistosomiasis-associated PAH (Sch-PAH), portopulmonary hypertension (POPH), and hemolysis-associated pulmonary hypertension. The importance of these different forms of pulmonary hypertension spans their epidemiology and the multiple pathophysiological mechanisms associated with their development and complications. Taken together, Sch-PAH and hemolysis-associated pulmonary hypertension may represent the most prevalent forms of PAH worldwide. Portopulmonary hypertension is particularly important if the morbidity and mortality that it adds to patients with liver disease is considered. Although clear progress has been reached in these various forms of PAH, there are many different aspects yet to be addressed that may contribute to the basis of specific treatment applied to these subgroups of patients.

[Tropical Medicine in an Age of High Global Mobility - Schistosomiasis in a School Class after Travel to Rwanda]. / Tropenmedizin im Zeitalter hoher globaler Mobilität.

INTRODUCTION: Schistosomiasis is one of the most common parasitic diseases worldwide. If left untreated, intestinal (Schistosoma mansoni, S. japonicum, S. mekongi) and urogenital (S. haematobium) chronic disease manifestations occur depending on the parasite load. The early phase however is characterized by fever and an immune-complex-mediated illness. Long-distance travel to tropical regions is on the rise, academic partnerships and humanitarian missions take even young people to developing countries. METHODS: 12 students from a German secondary school had fresh water exposure during a 14-day school trip to Rwanda in Lake Kivu in the west of the country. After returning to Germany, one of the students fell ill with acute schistosomiasis (Katayama syndrome), which led to examination of the other students. WBC, differential blood count, serology for schistosomal antibodies and ova detection in urine and stool were performed on first presentation and 6 and 12 months after therapy. RESULTS: Positive antibody results indicated infection in all students, eosinophilia was found in 9 patients, ova of S. mansoni were detected in 3 cases. At presentation in our outpatient department 11 of the 12 students were asymptomatic. All patients received therapy with praziquantel. DISCUSSION: Tropical diseases will further increase due to high global mobility. For their prevention and diagnosis physicians need to be sensitized beyond subject specific units. We describe an outbreak of schistosomiasis in a school class to sensitize physicians outside endemic areas. Since the disease is often asymptomatic a high number of unrecognized infections and illnesses can be assumed. When suspecting or treating schistosomiasis, a specialized center should always be consulted.

Does physical exercise influence in the development of neuroeschistosomiasis?

Neuroschistosomiasis is a severe form of presentation of schistosomiasis in which Schistosoma spp. affects the central nervous system. This is the first study performed to analyze whether there is any relationship between physical effort and the appearance of neuroschistosomiasis, through clinical, molecular and immunological evaluations. An experimental controlled study using 64 male Balb/c inbred mice divided into four groups according to presence or absence of S. mansoni infection and submitted to physical effort or resting was conducted. Thirteen weeks after exercise training, S. mansoni DNA was detected in the brain or spinal cord in about 30% of the infected animals moreover, only S. mansoni-positive samples showed positive labeling for S. mansoni antigens in the brain or spinal cord, with a striking reaction inside the microglia. However, the behavioral tests did not show any clinical symptoms of neuroschistosomiasis in animals submitted to physical effort or in resting. In animals with S. mansoni-positive DNA, immunohistochemical data revealed astrogliosis and microgliosis, elevated IL-10 levels and decreased TNF-α expression. This study demonstrated that isometric exercise does not promote neuroschistosomiasis, furthermore, ectopic forms of schistosomiasis in the central nervous system were largely asymptomatic and exhibited a Th2 immune response profile. More experimental studies are necessary in order to characterize the pathological process of experimental neuroschistosomiasis.

Maternal malaria but not schistosomiasis is associated with a higher risk of febrile infection in infant during the first 3 months of life: A mother-child cohort in Benin.

BACKGROUND: Malaria and schistosomiasis represent two of the most prevalent and disabling parasitic infections in developing countries. Few studies have evaluated the effect of maternal schistosomiasis and malaria in the peri-conceptional period on infant's risk of infection. METHODS: In Benin, women were followed from the preconception period until delivery. Subsequently, their children were followed from birth to 3 months of age. Pre-pregnancy malaria, malaria in pregnancy (MiP)-determined monthly using a thick blood smear-and urinary schistosomiasis-determined once before pregnancy and once at delivery using urine filtration-were the main maternal exposures. Infant's febrile infection (fever with respiratory, gastrointestinal and/or cutaneous clinical signs anytime during follow-up) was the main outcome. In a secondary analysis, we checked the relation of malaria and schistosomiasis with infant's hemoglobin (Hb) concentration. Both effects were separately assessed using logistic/mixed linear regression models. RESULTS: The prevalence of MiP was 35.7% with 10.8% occurring during the 1st trimester, and the prevalence of schistosomiasis was 21.8%. From birth to 3 months, 25.3% of infants had at least one episode of febrile infection. In multivariate analysis, MiP, particularly malaria in the 1st trimester, was significantly associated with a higher risk of infant's febrile infection (aOR = 4.99 [1.1; 22.6], p = 0.03). In secondary results, pre-pregnancy malaria and schistosomiasis were significantly associated with a lower infant's Hb concentration during the first 3 months. CONCLUSION: We evidenced the deleterious effect of maternal parasitic infections on infant's health. Our results argue in favor of the implementation of preventive strategies as early as in the peri-conception.

Restaging Pulmonary Schistosomiasis.

Schistosomiasis is traditionally classified into an acute and a chronic phase, although a precise temporal distinction between the two phases has not been established. Lung involvement can be observed in both phases. We previously reported seven cases of pulmonary lesions due to chronic schistosomiasis in African immigrants. All cases were documented with CT scans and demonstrated complete resolution after treatment with praziquantel. Moreover, another case showed spontaneous disappearance of the nodule before treatment with praziquantel. These findings are similar to those observed in the acute phase of schistosomiasis, with well-defined or ground glass nodules that resolve spontaneously. According to these findings, we postulate the presence of an "intermediate" phase of schistosomiasis involving the lungs that can be defined as an "early chronic phase," and presents analogies to the acute phase. We also hypothesize that in the "early chronic phase," the female worms transit through the lungs where they may lay eggs. These passages not only cause transient, but also radiologically visible alterations. The pathophysiology of lung lesions in the late chronic phase is probably different: the adult worms settled in the mesenteric plexuses produce eggs for years. The eggs repeatedly migrate to the perialveolar capillary beds via portal-caval shunting. Thus, in this case it is the eggs and not the adult worms that reach the lungs in a scattered way. Based on our findings, we suggest the alternative hypothesis that the pulmonary involvement is a phase of the natural evolution of the infection, both from Schistosoma mansoni and Schistosoma haematobium.

Prevalence and factors associated with renal dysfunction among children with sickle cell disease attending the sickle cell disease clinic at a tertiary hospital in Northwestern Tanzania.

BACKGROUND: Little is known on how the interaction between Sickle Cell Disease (SCD) and renal insults caused by other coexisting conditions in Sub Saharan Africa such as urinary schistosomiasis, malnutrition and HIV affect the prevalence of renal dysfunction in children with SCD. OBJECTIVES: To determine the prevalence and factors associated with renal dysfunction among children with SCD aged 6 months to 12 years attended at a tertiary hospital in Northwestern Tanzania. METHODS: A cross sectional hospital-based study with a short follow up component of 3 months for 153 children with SCD was done to document demographics, clinical characteristics and features of renal dysfunction including urine dipstick albuminuria (>20mg/l) and eGFR (<60ml/ml/min/1.73m2). Other potential renal insults such as HIV infection and Schistosomiasis were also evaluated. RESULTS: At enrollment, 48/153(31.37%) children had renal dysfunction declining to 31(20.3%) at 3 months follow up. Acute chest syndrome (OR 3.04, 95% CI [1.08-8.96], p = 0.044), severe anemia (OR 0.44, 95% CI [0.26-0.76],p = 0.003), urinary schistosomiasis (OR 7.43, 95% CI [2.10-26.32] p<0.002) and acute malnutrition (OR 4.92, 95% CI [1.29-18.84], p = 0.020). were associated with renal dysfunction. CONCLUSION: Where prevalent, urinary schistosomiasis and acute malnutrition increase the risk for renal dysfunction in children with SCD. We recommend albuminuria routine screening in children with SCD especially those presenting with acute chest syndrome, severe anemia and features of acute malnutrition for early detection of renal dysfunction among children with SCD.

Acute schistosomiasis outbreak: clinical features and economic impact.

BACKGROUND: Acute schistosomiasis (AS) is a systemic hypersensitivity reaction that has been recognized mostly in nonimmune travelers. Although the condition is self-limited, it can be severe. We describe an outbreak of AS in a group of travelers returning from Tanzania and estimate the disease burden. METHODS: After we identified the index case, we initiated an epidemiological investigation of the entire group. Diagnosis was established on the basis of symptoms, serologic data, and ova detection. Relevant clinical information was documented with use of a structured questionnaire, and the patient's economic burden was recorded. Health-related quality of life was assessed during the illness and 3 months later. RESULTS: Of 34 group members, 27 had a single exposure to a fresh water pond, 22 (81%) of whom were infected. AS developed in 19 (86%) of the 22 infected travelers. Cough (78% of patients), fever (68%), and fatigue (58%) were the most common symptoms, with mean durations (+/- standard deviation) of 22 +/- 11, 11 +/- 7, and 37 +/- 16 days, respectively. The total number of medical encounters was 258 (mean no. of encounters per patient, 11), and 152 work and school days were missed (mean, 8 days per patient). During the acute phase of illness, there was a significant decline in health-related quality of life that returned to expected norms after 3 months. CONCLUSIONS: A single, short exposure of travelers to an infected pond led to a high infection rate. The illness had a significant impact on the patients' daily functions, and patients extensively used medical resources. Education to avoid exposure to fresh water remains the most effective method of schistosomiasis prevention.

Androgen profiles among Egyptian adults considering liver status.

BACKGROUND AND AIM: Hepatitis C virus (HCV) and environmental hepatotoxins may have an indirect influence on health by altering the synthesis and function of hormones, particularly reproductive hormones. We aimed to evaluate liver diseases and sex steroid hormones in Egypt, which has the highest prevalence of HCV worldwide. METHODS: We measured markers of hepatitis B virus (HBV), HCV and schistosomiasis infection as well as liver function in 159 apparently healthy subjects. We measured total testosterone (T), sex-hormone binding globulin (SHBG) and albumin, and calculated the free androgen index. RESULTS: Anti-HCV antibodies were detected in 51% of men and 42% of women. Based on HCV reverse transcription PCR (RT-PCR) of 44 men and 33 women, 11% of men and 21% of women showed HCV viremia. There was schistosomiasis in 25% of men and 9% of women, and mixed HCV viremia and schistosomiasis in 57% of men and 52% of women. Compared with men with schistosomiasis only (mean 593.3 +/- 73.4 ng/dL), T was higher in men with mixed HCV viremia and schistosomiasis (mean 854.5 +/- 47.9 ng/dL; P = 0.006) and men with mixed chronic HCV and schistosomiasis (mean 812.1 +/- 43.3 ng/dL; P = 0.001). Men with mixed chronic HCV and schistosomiasis had also significantly higher SHBG (mean 57.7 +/- 3.9 ng/dL) than males with schistosomiasis only (mean 34.8 +/- SE 4.5 ng/dL; P = 0.0003). CONCLUSION: Future investigations should consider that a high prevalence of asymptomatic liver disease may alter associations between hormone concentrations and chronic disease etiology.

Schistosomiasis.

Schistosomiasis is the second most prevalent tropical disease in the world and has a multitude of clinical manifestations.