The relevance of schistosomiasis

Diagnosis and Treatment of Five Parasites

General descriptions and monographs of the five parasites most likely to be seen in U.S. patients are presented. The appended monographs are designed to be a starting reference for answering drug information questions regarding these parasites. The drugs covered in the monographs are listed in the order of suggested use.

Schistosomiasis--an unusual cause of ureteral obstruction: a case history and perspective

A male, 32 years of age, presented with dysuria and abdominal pain, but no gross hematuria. He emigrated three years earlier from Somalia, East Africa, and was currently employed as a poultry processor in a rural Wisconsin community. The patient denied any trauma, sexual activity, or family history of significant illness. Abdominal and genitourinary exams were normal with negative tests for gonococcus and chlamydia. Urinalysis demonstrated microhematuria. A urogram and retrograde pyelogram revealed a mildly dilated right ureter down to the ureterovesical junction. Cystoscopy showed punctate white lesions on the bladder urothelium. Ureteroscopy was used to biopsy abnormal tissue in the distal ureter and bladder. Biopsy tissue demonstrated deposits of Schistosoma haematobium eggs. No ova were seen in collected urine specimens. The patient was successfully treated with praziquantel and will be monitored for sequelae of the disease. Schistosomiasis (Bilharziasis) can be expected to be seen with increasing frequency in the United States with the continuing influx of immigrants and refugees, as well as the return of travelers and soldiers from endemic areas. While no intermediate snail host exists for the transmission of Schistosoma sp. in the United States, the continued importation of exotic animals including snails from Africa, as well as the ability of schistosomes to shift host species warrants concern. Additionally, increasing disease associated with non-human bird schistosomes of the same genus seen in the midwestern United States is occurring throughout Europe. One should be aware that praziquantel may not always be available or effective in the treatment of schistosomiasis. It behooves the practicing clinician to remain updated on the status of this widespread zoonosis.

Splenic artery ligation and distal splenorenal shunt in schistosomiasis

BACKGROUND

A prospective study was carried out to evaluate the results of distal splenorenal shunt (DSRS) with or without splenic artery ligation (SAL) in patients with schistosomal portal hypertension.

MATERIALS AND METHODS

Thirty patients were divided into two groups: 15 were submitted to DSRS (Group I) and the other 15 were submitted to DSRS + SAL (Group II). They were observed for 24 months. Clinical and laboratory features were analyzed.

RESULTS

There was neither mortality nor clinical manifestation of portosystemic encephalopathy in both groups. Recurrent hemorrhage and thrombosis incidence had no statistical difference. Although patients in Group II presented higher levels of postoperative pain and fever, spleen size reduction was higher than in Group I. White blood cells and platelets were increased in patients who underwent DSRS + SAL, even though there was no statistically significant difference between the groups. An increase in bilirubin was observed on the first postoperative day. Arterial blood ammonia and liver function were similar in both groups. Endoscopic control showed reduction in size of varices or their disappearance in 80 and 93% of patients from Groups I and II, respectively.

CONCLUSIONS

Although SAL associated with DSRS was responsible for increasing postoperative morbidity, it did not increase the incidence of shunt thrombosis and improved white blood cells and platelets count as well as reduced the spleen size. Therefore, the authors believe that SAL associated with DSRS is an effective treatment for schistosomal portal hypertension. Besides, it should be performed when a large spleen and hypersplenism are present.

Schistosoma mansoni egg-induced hepatic granulomas in mice deficient for the interferon-gamma receptor have altered populations of macrophages, lymphocytes and connective tissue cells

Systemic production and mobilization of inflammatory cells and formation of hepatic periovular granulomas were studied in Schistosoma mansoni-infected mice with deficient interferon gamma (IFN-gamma) receptor (IFN-gammaR(o/o)). The impaired IFN-gamma signaling did not cause a significant modification of the overall kinetics of inflammatory cells, but mutant mice developed smaller hepatic periovular granulomas with a two-fold reduction in all the cell lineages. In granulomas of normal mice, the fully differentiated macrophages were progressively predominant, whilst in IFN-gammaR(o/o) mice, the granulomas contained a higher percentage of immature and proliferating monocytes. Granulomas of IFN-gammaR(o/o) mice had an enhanced and accelerated fibrotic reaction, corresponding to an increased content of proliferative and activated connective tissue cells. Simultaneously, their granulomas had an increased ratio of T over B cells, with an increase in CD8(+) and a reduction in CD4(+) T cells. The functional IFN-gamma receptor was not required for initial recruitment of monocytes and lymphocytes into granulomas, but it was necessary for the maturation of macrophages, upregulation of major histocompatibility class 2 (MHC-II) expression and consequent stimulation of lymphocyte subpopulations depending upon the MHC-II-mediated antigen presentation.

Histological assessment of tissue repair after treatment of human schistosomiasis

Schistosomiasis is one of the main health problems hindering socio-economic development in Egypt. It affects millions at an early age, diminishing productivity and exerting a significant socio-economic impact. Schistosomiasis endemicity in Egypt varies in different areas. Schistosoma mansoni, with a prevalence generally ranging between 20 to 40%, has replaced Schistosoma haematobium in the Nile Delta, and the latter is now localized to upper Egypt with low endemicity levels (5-10%). The pathology of schistosomiasis consists essentially of a series of chronic inflammatory lesions produced in and around blood vessels by eggs or their products and sometimes by dead adult worms. If the ova continued to be deposited in sufficient numbers and over several years, they would ultimately lead to progressive fibrosis of the portal tracts and urinary bladder, or may be carried in blood and become trapped in the lungs, gastro-intestinal and genital tracts with only occasional association with other organs. The etiology of human pipe-stem fibrosis is still not understood. The host immune response and frequency of exposure and the time of re-infection interval appear to be involved in the overall process of fibrosis. Additional factors are probably involved in the human disease as genetic host susceptibility, malnutrition, repeated infections and repeated treatment, mixed infections including hepatitis, tuberculosis and typhoid. Reversibility of the fibrosis might be related to the proportion of the collagen types present. Immuno-histopathological demonstration of various types of collagen confirms the importance of time for administration of the treatment and period of follow-up. According to previous studies, the timing for treatment affects the reversibility of liver fibrosis emphasizing the importance of early treatment of schistosomiasis to prevent complications.

Schistosoma mansoni: adhesion of mannan-binding lectin to surface glycoproteins of cercariae and adult worms

Schistosoma mansoni is a blood-dwelling trematode which can persist for several years in the vessels of the human host. The schistosomal surface has been extensively characterized by lectin binding studies, revealing the carbohydrate composition of the worm's tegument. Using fluorescent and scanning electron microscopy we demonstrate that the surface carbohydrates of cercariae and adult worms are the binding ligands for mannanbinding lectin (MBL), a serum protein that is part of the innate immune system. An in vitro complement activation assay with C1q-deficient complement suggests that MBL, in association with the serine proteases MASP-1 and MASP-2, is capable of fixing complement components on the schistosomal tegument and activating the complement cascade via the "MBL pathway." MBL is constitutively expressed by hepatocytes and present in the blood at a stable level. Since it is also a weak acute-phase protein and therefore upregulated in an acute-phase response we investigated the serum MBL levels in patients infected with Schistosoma sp. and in healthy control persons. An enzyme-linked immunosorbent assay indicated no differences between the two groups. Although our results suggest an involvement of MBL activated complement in vitro, its role in vivo remains to be clarified.

Schistosomiasis: clinical relevance to surgeons in Australasia and diagnostic update

All surgeons working in Australasia should be prepared to encounter imported cases of schistosomiasis. The disease should be considered when typical symptoms are present, and there is evidence of skin exposure to fresh water in an endemic area. Whether or not signs of urinary or intestinal tract schistosomiasis are present, ectopic ova can involve and produce symptoms in almost any structure including the liver, the lungs, the reproductive system and the central nervous system, sometimes producing puzzling clinical abnormalities decades after primary infection. Recovery of ova from urine, stool or their detection in a biopsy confirms diagnosis but, when this is unsuccessful, immunological tests support diagnosis. Imaging techniques (e.g. ultrasonography, standard radiology, computed tomography or magnetic resonance imaging scans) may indicate and define involvement of various organs and structures. The surgeon often has an important role to play in the management of the protean complications of schistosomiasis.

Proteoglycans synthesized by the hepatic granulomas isolated from schistosome-infected mice and by the granuloma-derived connective tissue cell lines

Proteoglycans synthesized in vitro by periovular granulomas isolated from livers of schistosome-infected mice were compared with those produced by granuloma-derived cell lines: the primary cell line GR and the permanent cell line GRX. Proteoglycans were metabolically labelled with 35S-sulfate and extracted with 4 M guanidine-HCl containing 2.0% Triton X-100, in the presence of proteinase inhibitors. The radiolabelled proteoglycans were purified and characterized by anion-exchange, gel-filtration and affinity-column chromatography. Heparan sulfate proteoglycans (HS-PGs) and chondroitin sulfate/dermatan sulfate-containing proteoglycans (CS/DS-PGs) were detected in both the culture medium and the cell-associated fractions obtained from GR cells. More than 90% of the cell-associated HS-PG from these cells contained a hydrophobic portion, as evidenced by their ability to bind to octyl-Sepharose. In contrast, among the secreted proteoglycans, it was the CS/DS-PG and not the HS-PG that bound to this resin. The major fractions of cell-associated and secreted proteoglycans from GRX cells were HS-PGs. Similar to HS-PGs from GR cells, 50% of the cell-associated HS-PG bound to octyl-Sepharose, while only 20% of secreted proteoglycans (HS-PGs) bound to this resin. The proteoglycans purified from the whole granuloma were composed mainly of DS-PG, of a size and hydrophobicity similar to the CS/DS-PG from GR cells. Possible correlations among the structure, secretion, distribution and function of proteoglycans in granulomatous reactions are discussed.

Effect of praziquantel on certain immune responses of schistosomal Egyptian patients. II. Cell-mediated lymphoproliferative response

The lymphoproliferative blastogenic responses to mitogens, PHA and Con A, and to schistosome-derived antigens. S. mansoni worm and egg, were tested in 35 schistosomal patients and 10 healthy controls. Of the former group, 18 patients had intestinal mansoniasis and 17 had mansoniasis with hepatosplenomegaly. The test was repeated 2 weeks and 1 and 2 months after treatment with praziquantel. The delayed intradermal test for schistosomiasis was performed on 25 of the schistosomal patients and was repeated 1 month after treatment. Statistical analysis of results of lymphoproliferative blastogenic responses showed no significant differences between the control and the two schistosomal groups in response to mitogens. The group with intestinal mansoniasis responded significantly to both schistosomal antigens, compared to the control and hepatosplenic groups. Their proliferative responses showed a significant rise 2 weeks after treatment, then a gradual drop at 1 and 2 month intervals. The hepatosplenic group responded significantly to worm antigen before treatment; their proliferative responses to both schistosomal antigens showed a significant rise 2 weeks after treatment and remained raised thereafter. No relationship was established between either of the two schistosomal groups for age, intensity of infection or positive delayed intradermal reaction.

Serum immunoreactive somatomedin-C levels in growth failure and delayed puberty associated with chronic hepatosplenic schistosomiasis

Eleven patients, five males, six females, aged 14-20 years with hepatosplenic schistosomiasis (HSS), growth failure and delayed puberty were submitted to endocrine evaluation. All patients had well preserved parenchymal liver function although several changes were present in the portal system, showing a poorly vascularized liver. Bone age was retarded, thyroid function was normal, the human growth hormone response to hypoglycaemia was within the normal limits and the prolactin response to TRH was normal. LH and FSH basal levels were normal and a normal rise was observed after a provocative test with LHRH. Gonadal function, expressed as serum testosterone or oestradiol levels, was abnormally low for the chronological age. Serum somatomedin-C levels were also low (range 0.11-2.10 U/ml) for the respective Tanner stage or bone age of each individual patient. One year after a splenorenal shunting in the three patients that returned for follow-up, it was observed that sexual maturation reached Tanner stage III, linear growth increment ranged from 9.0 to 11.5 cm and serum somatomedin-C levels increased to 4.3-5.6 U/ml. We concluded that a combination of undernutrition and marked vascular changes in the liver, present in HSS, are associated with decreased serum sex steroids and somatomedin-C concentrations, resulting in growth failure and delayed puberty in these patients.

Morphological, histochemical and biochemical observations on the connective tissue matrix of in situ and isolated hepatic granulomas in experimental murine schistosomiasis

The connective tissue matrix of hepatic granulomas from Swiss mice, each infected with 20 Schistosoma mansoni cercariae, was examined using morphological, histochemical and biochemical methods, during the evolution of the disease. Evidence was obtained by both light and electron microscopy that suggested the presence of two different collagen populations which appeared successively during granuloma evolution. Morphological features suggesting the occurrence of collagenolysis were observed at the final stage of granuloma development. The connective tissue matrix of schistosome granulomas was devoid of elastic system fibres. Schistosome egg granulomas contain dermatan sulphate-proteoglycan.

Ultrasonographical aspects of urinary schistosomiasis: assessment of morphological lesions in the upper and lower urinary tract

Ultrasonographic evaluation of 213 patients with urinary schistosomiasis in different age groups was performed in an endemic area of the Democratic Republic of Congo. The results were compared with 94 age matched controls without urinary schistosomiasis. In patients the bladder showed thickening of the wall, polypoid lesions of the mucosa and bladder wall, calcifications and urinary retention. Urinary tract obstruction, predominantly unilateral, was demonstrated. The lesions increased in severity with the intensity of infection, parallel to an increase in ova excretion. Children aged between 8 and 19 years were most severely affected. Pathological lesions of the upper urinary tract were rare in patients over 25 years of age. The combination of morphological abnormalities was interpreted as being specific for urinary schistosomiasis as they did not occur in the control group. It is suggested that real time ultrasonography may be used to identify morphological lesions in urinary schistosomiasis.

Network interactions in Schistosoma japonicum infection. Identification and characterization of a serologically distinct immunoregulatory auto-antiidiotypic antibody population

This study examined the role of naturally occurring anti-idiotypic antibody (anti-id), specific for epitopes on antibodies to schistosome egg antigens (SEA), in serosuppression during Schistosoma japonicum infection. Three anti-id preparations were obtained from pools of infected serum at 12, 16, and 30 wk of infection. Anti-id (12 wk) bound 36% of labeled anti-SEA antibodies, had an idiotype binding capacity (IBC) of 5 micrograms/ml, and did not suppress SEA-induced proliferation. Anti-id (16 wk) bound 17% of labeled anti-SEA antibodies, had 29 micrograms IBC/ml, and reduced 3H incorporation from 21.4 +/- 0.5 (10 micrograms/ml normal Ig) to 9.1 +/- 1.5 X 10(4) cpm (P less than 0.01). Anti-id (30 wk) bound 66% of labeled anti-SEA antibody, had 84 micrograms IBC/ml, and suppressed 3H incorporation by 88% (4.8 +/- 0.3 X 10(4) cpm, P less than 0.001). Analysis of the serologic reactivity of these three populations of anti-idiotypic antibodies revealed that anti-id (12 wk) described an idiotypic population of anti-SEA molecules containing a minor cross-reactive idiotype (SJ-CRIm). In contrast, anti-id (30 wk) described a serologically distinct, idiotypic population containing a major cross-reactive idiotype of anti-SEA molecules (SJ-CRIM). A monoclonal anti-id, which reacted with greater than 50% of the anti-SEA molecules describing SJ-CRIM, was profoundly suppressive in vitro and reduced granulomatous inflammation around parasite eggs in vivo from 113 X 10(3) micron2 to 23 X 10(3) micron2 (80% suppression, P less than 0.001). These observations suggest that immune network interactions modulate inflammation in chronic murine S. japonicum infection.

Basement membrane proteins and type III procollagen in murine schistosomiasis

The livers of female CBA mice were examined 9 to 10 weeks after subcutaneous infection with Schistosoma mansoni. Cryostat liver sections and isolated liver cells were examined by indirect immunofluorescence using specific antibodies against basement membrane proteins (laminin, fibronectin and type IV collagen and type III collagen precursor. Liver cells were isolated by collagenase digestion, purification on Percoll density gradients and centrifugal elutriation to yield enriched fractions of hepatocytes, endothelial and Kupffer cells (Fractions I, II, III respectively). Infected animals yielded more than three times the control number of non-parenchymal cells; electron microscopy revealed that the increase in Fraction II was due mainly to eosinophilic leucocytes and in Fraction III due to Kupffer cells and macrophages from the schistosomal granulomata. Studies of cryostat liver sections showed that the schistosomal granulomata contained dense deposits of type III collagen precursor and fibronectin in the distribution of the reticulin fibres but laminin and type IV collagen were conspicuous only in new vessels in the periphery of the granuloma. Isolated liver cells showed fibronectin on their surface. Immunofluorescence studies could not be performed on Kupffer and endothelial cell fractions because of marked non-specific fluorescence. These experiments indicate that centrifugal elutriation is a useful method for isolating the constituent cells of murine schistosomal granulomata.

Changes in collagen and albumin mRNA in liver tissue of mice infected with Schistosoma mansoni as determined by in situ hybridization

We have employed in situ hybridization to evaluate the molecular mechanisms responsible for hypoalbuminemia and increased liver collagen content in murine schistosomiasis. Results were compared using a simplified method of hybridizing isolated hepatocytes from Schistosoma mansoni-infected and normal mouse liver with mouse albumin (pmalb-2) and chick pro-alpha 2(l) collagen (pCg45) probes. Whereas hepatocytes from infected mice showed significantly less albumin mRNA than hepatocytes from control, there were more grains of procollagen mRNA in hepatocytes from infected as compared with control liver. Hybridization of infected liver tissue sections with the collagen probe showed more grains per field in granulomas than in liver regions, whereas with the albumin probe there was more hybridization in liver tissue than in granulomas. These results suggest that in murine schistosomiasis a reduction in albumin mRNA sequence content may be associated with decreased albumin synthesis and ultimately leads to hypoalbuminemia. In addition, although the granuloma seems to be the primary source of type I collagen synthesis, hepatocytes are also capable of synthesizing collagen, especially under fibrogenic stimulation.

Alteration of granuloma angiotensin I-converting enzyme activity by regulatory T lymphocytes in murine schistosomiasis

Granulomatous inflammatory lesions in murine schistosomiasis mansoni undergo a spontaneous diminution at the chronic phase of the disease concurrent with an increase in angiotensin I-converting enzyme (ACE) activity. The objective of this investigation was to determine whether T cells influence ACE activity within the granulomas. Cyclophosphamide and cimetidine treatments of mice, which augment delayed-type hypersensitivity reactions, enhanced liver granuloma size and decreased granuloma ACE activity. The suppression of liver granuloma by the adoptive transfer of spleen cells from chronically infected, immunomodulated mice into recipients with acute infection increased ACE activity of granulomas and granuloma macrophages. The increased ACE activity was dependent upon the transfer of Thy 1.2+ splenic lymphocytes. The level of the ACE activity was proportionate to the number of administered spleen cells. Thus, the level of ACE activity within the egg-induced granuloma is dependent upon T lymphocytes present in the spleen and granulomas of infected animals.