Serological proteomic screening and evaluation of a recombinant egg antigen for the diagnosis of low-intensity Schistosoma mansoni infections in endemic area in Brazil

Background

Despite decades of use of control programs, schistosomiasis remains a global public health problem. To further reduce prevalence and intensity of infection, or to achieve the goal of elimination in low-endemic areas, there needs to be better diagnostic tools to detect low-intensity infections in low-endemic areas in Brazil. The rationale for development of new diagnostic tools is that the current standard test Kato-Katz (KK) is not sensitive enough to detect low-intensity infections in low-endemic areas. In order to develop new diagnostic tools, we employed a proteomics approach to identify biomarkers associated with schistosome-specific immune responses in hopes of developing sensitive and specific new methods for immunodiagnosis.

Methods and findings

Immunoproteomic analyses were performed on egg extracts of Schistosoma mansoni using pooled sera from infected or non-infected individuals from a low-endemic area of Brazil. Cross reactivity with other soil-transmitted helminths (STH) was determined using pooled sera from individuals uniquely infected with different helminths. Using this approach, we identified 23 targets recognized by schistosome acute and chronic sera samples. To identify immunoreactive targets that were likely glycan epitopes, we compared these targets to the immunoreactivity of spots treated with sodium metaperiodate oxidation of egg extract. This treatment yielded 12/23 spots maintaining immunoreactivity, suggesting that they were protein epitopes. From these 12 spots, 11 spots cross-reacted with sera from individuals infected with other STH and 10 spots cross-reacted with the negative control group. Spot number 5 was exclusively immunoreactive with sera from S. mansoni-infected groups in native and deglycosylated conditions and corresponds to Major Egg Antigen (MEA). We expressed MEA as a recombinant protein and showed a similar recognition pattern to that of the native protein via western blot. IgG-ELISA gave a sensitivity of 87.10% and specificity of 89.09% represented by area under the ROC curve of 0.95. IgG-ELISA performed better than the conventional KK (2 slides), identifying 56/64 cases harboring 1–10 eggs per gram of feces that were undiagnosed by KK parasitological technique.

Conclusions

The serological proteome approach was able to identify a new diagnostic candidate. The recombinant egg antigen provided good performance in IgG-ELISA to detect individuals with extreme low-intensity infections (1 egg per gram of feces). Therefore, the IgG-ELISA using this newly identified recombinant MEA can be a useful tool combined with other techniques in low-endemic areas to determine the true prevalence of schistosome infection that is underestimated by the KK method. Further, to overcome the complexity of ELISA in the field, a second generation of antibody-based rapid diagnostic tests (RDT) can be developed.

Schistosomiasis remains a serious global public health problem. Detecting parasite eggs in patient stool samples using the KK method is the standard diagnostic recommended by the World Health Organization (WHO) for infection by S. mansoni. As a result of intensive control strategies, many previously high-endemic areas are now considered low-endemic areas and the KK method does not function well in low-endemic areas and therefore cannot be considered the gold standard. Thus, a new emphasis on strategies to accurately diagnose low-intensity infections was outlined in a plan from the WHO focusing on elimination of disease as a public health problem. Successful diagnoses and treatment of infected individuals may result in eradication of low-burden transmitters and consequently contribute to interruption of disease transmission. In this regard, immunological techniques have proven to be more sensitive and promising for identifying low-intensity infections where KK may be negative. The identification of antigens is the initial step for developing new immunodiagnostic assays. In this study, we used sets of pooled human sera samples from controls with acute and chronic infections to identify new target antigens via proteomic screening. Using these approaches, we initially identified 12 different egg proteins in S. mansoni-infected individuals (acute and chronic phase). A single antigen, identified as MEA, was shown to be highly specific as this antigen was not recognized by sera from negative patients or patients infected with other STH. The recombinant MEA protein functioned in an ELISA as a highly sensitive and specific antigen to detect patient IgG-antibodies. Recombinant MEA performed significantly better to detect low-intensity infections (1 egg per gram of feces) than the KK method using 2 slides. Therefore, we were able to use a proteomic screening approach to identify a potential new candidate antigen for development of far more sensitive diagnostic assays. Further diagnostic assays employing the MEA could be useful tools on their own or in combination with other methods for diagnosis of schistosome infection in populations living in extreme low-intensity endemic areas of Brazil.

Plasma levels of innate immune mediators are associated with liver fibrosis in low parasite burden Schistosoma mansoni-infected individuals

In the murine model, it was demonstrated that pro-inflammatory cytokines and chemokines are essential to the formation and modulation of Schistosoma-induced granulomatous inflammation. However, the relationship of these immune mediators and disease severity is hard to be established in naturally infected individuals. The current study evaluates the association between plasma concentrations of MIF, sTNF-R1, CCL3, CCL7 and CCL24 and schistosomiasis morbidity in Schistosoma mansoni-infected patients with a low parasite burden. For this propose, 97 S. mansoni-infected individuals were subjected to abdominal ultrasound analysis and clinical examination. Among them, 88 had plasma concentration of immune mediators estimated by ELISA assay. Multivariate linear regression models were used to evaluate the relationship between the plasma concentration of immune mediators and the variables investigated. Although most individuals presented low parasite burden, over 30% of them showed signs of fibrosis defined by ultrasound measurements and 2 patients had a severe form of schistosomiasis. No association between parasite burden and the plasma levels of chemokine/cytokines or disease severity was observed. There was a positive association between plasma concentration of CCL4, sTNF-R1, CCL3 and MIF with gall bladder thickness and/or with portal vein thickness that are liver fibrosis markers. In contrast, no association was found between CCL7 plasma concentrations with any of the schistosomiasis morbidity parameters evaluated. The data showed that CCL24, sTNFR1, MIF and CCL3 can be detected in plasma of S. mansoni-infected individuals and their concentration would be used as prognostic makers of Schistosoma-induced liver fibrosis, even in individuals with low parasite burden.

Predictors of the short- and long-term survival of HIV-infected patients admitted to a Brazilian intensive care unit

The outcomes of HIV-infected patients requiring critical care have improved. However, in developing countries, information about HIV-infected patients admitted to intensive care units (ICUs) is scarce. We describe the prognosis of HIV-infected patients admitted to a Brazilian ICU and the factors predictive of short- and long-term survival. A historical cohort study, including HIV-infected patients admitted to a Brazilian ICU at an HIV/AIDS reference hospital, was conducted. Survivors were followed up for 24 months after ICU discharge. Demographic, clinical and laboratory data, disease severity scores and mortality were evaluated. Data were analysed using survival and regression models. One hundred and twenty-five patients were studied. In-ICU and in-hospital mortality rates were 46.4% and 68.0%, respectively. Multivariate analysis showed that the in-ICU mortality was significantly associated with APACHE (Acute Physiology and Chronic Health Evaluation) II scores (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.03–1.11), mechanical ventilation (OR, 6.39; 95% CI, 1.29–31.76), tuberculosis treatment (OR, 2.62; 95% CI, 1.03–6.71), use of antiretroviral therapy (OR, 0.19; 95% CI, 0.05–0.77) and septic shock (OR, 4.38; 95% CI, 1.78–10.76). Septic shock was also associated with long-term survival (hazard ratio, 3.0; 95% CI, 1.31–6.90). In-hospital and in-ICU mortality were higher than those reported for developed countries. ICU admission mostly due to AIDS-related diseases may explain these differences.

Serum and cerebral spinal fluid levels of chemokines and Th2 cytokines in Schistosoma mansoni myeloradiculopathy

Schistosomal myeloradiculopathy (SMR) is the most common neurological form of Schistosoma mansoni infection. In this study we investigated the expression of chemokines and Th2 cytokines in serum and cerebral spinal fluid (CSF) of SMR patients. SMR patients presented increased serum levels of CCL11/eotaxin and CCL24/eotaxin-2 when compared to controls. SMR patients also had higher levels of IL-13 in CSF. Thus, SMR patients present enhancement of both IL-13 and CCR3 acting chemokines, both of which may facilitate the expression of a Th2 response and Th2-dependent damage to the spinal cord. As this cytokine is responsible for promoting Th2 responses, this finding is in accordance to the view that Th2 cells are important in the immunological process against the S. mansoni.

The immune dependence of chemotherapy

In this review, Mike Doenhoff and colleagues discuss the immune dependency of chemotherapy and the consequences for drug resistance. They also consider the implications for the control of infections that are relatively unresponsive to drugs, such as opportunistic infections in immunosuppressed patients.

Hepatosplenic schistosomiasis in field-based studies: a combined clinical and sonographic definition

A combined clinical and sonographic classification of hepatosplenic schistosomiasis mansoni to be used in field-based studies is proposed herein. Seven hundred forty one individuals out of 892 (83%), living in an area endemic for schistosomiasis in Brazil, have been submitted to clinical and ultrasound examinations. Based on two stool examinations the overall prevalence for schistosomiasis in this area was 73%. Abdominal palpation was performed with patients in dorsal decubit, during deep breath, by two experienced physicians and a portable ultrasound was used for the evaluation of liver fibrosis, portal collaterals and spleen size. Four groups of individuals were identified using data obtained by abdominal palpation and ultrasound examination: (1) palpable spleen and intense periportal thickening in 9 individuals (1.2%); (2) spleen not palpable and intense periportal thickening in 15 (2%); (3) palpable spleen with light to moderate periportal thickening in 32 (4.3%), and (4) palpable spleen with a normal liver on ultrasound in 30 (4%). The definition of hepatosplenic schistosomiasis in field-based studies as the finding of Schistosoma mansoni eggs in the stools in an individual with splenomegaly is not acceptable anymore. Abdominal ultrasound should be combined with clinical examination to accurately identify hepatosplenics in endemic areas for schistosomiasis.

Schistosomiasis mansoni is associated with pyogenic liver abscesses in the state of Minas Gerais, Brazil

The association between pyogenic liver abscesses and schistosomiasis has been confirmed by clinical and experimental studies. In this retrospective study of 78 patients with pyogenic liver abscesses the association with schistosomiasis has been investigated. Pyodermitis, a known focus of bacteremia, was observed in 19 patients (24%). Blood eosinophilia was observed in 30 patients (39%). Staphylococcus aureus was cultured from abscesses in 17 out of 38 patients (45%). Forty-one out of 57 patients (53%) had stool examination. Schistosoma mansoni was the main parasite identified. Eggs of S. mansoni were also identified in liver biopsies in 7 out of 19 patients who did the exam. The large number of young patients with liver abscesses described here is different from what has been observed in developed countries. This clinical study provide support for the concept that granulomas of S. mansoni in the liver are foci for colonization with S. aureus, which in presence of staphylococcal bacteremia can form liver abscesses.

Schistosomal myeloradiculopathy due to Schistosoma mansoni: report on 23 cases

Schistosoma mansoni infection is likely to be responsible for a significant proportion of cases of myelopathy occurring in areas where schistosomiasis is endemic. The aim of this study is to describe the clinical, laboratory and therapeutic data of 23 patients with schistosomal myeloradiculopathy. The medical records of 23 patients with schistosomal myelopathy admitted to two general hospitals of Belo Horizonte (MG), in Brazil, from 1995 to 1999, were reviewed retrospectively. Seventeen patients were male (74%). The mean age for the whole group was 27 years. Lower limb weakness and associated lumbar and/or lower limb pain were reported by 20 patients (87%), and 16 (70%) were unable to walk. All individuals presented urinary retention and 19 (83%) complained of intestinal dysfunction. The treatment was based on the association of antischistosomal drugs and corticosteroids. Five patients (22%) presented a full response to treatment, 13 (57%) partial response without functional limitations and 4 (17%) partial improvement with limitations or no response. Three out of the 4 patients who stopped steroids before 45 days of treatment developed recurrence of the symptoms and signs of myelopathy. Our cases demonstrate the severe presentation of the disease and the data disclosed here suggest that treatment with steroids should be kept for months after clinical improvement.

Report of the second satellite symposium on ultrasound in schistosomiasis

A group of experts on schistosomiasis and ultrasonography discussed the experiences and results obtained with the Niamey-Belo Horizonte Protocol on Ultrasonography in Schistosomiasis. A series of recommendations about qualitative and quantitative data obtained by ultrasound in studies performed in Africa and Brazil are presented. Immunological, genetic and epidemiological studies must rely on ultrasound for the identification of patients with periportal thickening/fibrosis.

Pathogenic aspects of pyogenic liver abscess associated with experimental schistosomiasis

Schistosomiasis mansoni infection that occurs concurrently with Staphylococcus aureus bacteremia favors the formation of pyogenic liver abscess. The present experimental study in mice evaluated the following aspects of the relationship between infection with Schistosoma mansoni and liver abscess caused by S. aureus: a) the role of the eggs of S. mansoni in the genesis of the abscesses; b) the influence of different phases of schistosomiasis in the development of liver abscesses; and c) the effect of the treatment of schistosomiasis on the development of the abscesses. Macroscopic and histopathological study showed multiple liver abscesses around granulomas of S. mansoni in the acute and chronic phases of schistosomiasis. Treatment of acute schistosomiasis before experimentally-induced bacteremia did not prevent the formation of liver abscess. The study findings indicate that granulomas around S. mansoni eggs and worms lodged in the liver provide a focus and substrate for pyogenic abscesses caused by S. aureus.

Pyogenic abscesses and parasitic diseases

Parasitic diseases which during their course in the host switch the immune system from a T helper 1 to a T helper 2 response may be detrimental to the host, contributing to granuloma formation, eosinophilia, hyper-IgE, and increased susceptibility to bacterial and fungal infections. Patients and animals with acute schistosomiasis and hyper-IgE in their serum develop pyogenic liver abscess in the presence of bacteremia caused by Staphylococcus aureus. The Salmonella-S. mansoni association has also been well documented. The association of tropical pyomyositis (pyogenic muscle abscess) and pyogenic liver abscess with Toxocara infection has recently been described in the same context. In tropical countries that may be an interesting explanation for the great morbidity of bacterial diseases. If the association of parasitic infections and pyogenic abscesses and/or fungal diseases are confirmed, there will be a strong case in favor of universal treatment for parasitic diseases to prevent or decrease the morbidity of superinfection with bacteria and fungi.

Human toxocariasis and pyogenic liver abscess: a possible association

OBJECTIVES

To study the role of human toxocariasis in the pathogenesis of pyogenic liver abscess.

METHODS

We compared the serology for toxocariasis and serum levels of IgE in 16 patients with pyogenic liver abscess to those in 32 matched (age and gender) controls to define the possible association between these two entities.

RESULTS

The serology for toxocariasis was positive in 10 of 16 patients compared with 4 of 32 controls. The relative odds and 95% confidence interval (conditional logistic regression), comparing cases and matched controls, was significant (1.4; 95% confidence interval, 1.1-1.7) for Toxocara serology. Regarding IgE serum levels, there was no difference between cases and controls.

CONCLUSIONS

Human toxocariasis can be one of the predisposing causes of pyogenic liver abscess, especially in tropical countries in which this parasitic disease is common. Treatment of human toxocariasis may prevent morbid complications like hepatic abscess and should be considered in patients with clinical and/or serological evidence of Toxocara infection.

Schistosoma mansoni: assessment of morbidity before and after control

The literature on the assessment of morbidity due to Schistosoma mansoni infection is updated. Imaging techniques such as ultrasonography, echodoppler cardiography, computerized tomography (CT scan) and magnetic resonance imaging (MRI) introduced a new perspective, and expanded our knowledge on morbidity. Three well-defined syndromes caused by schistosomiasis mansoni have been described: the stage of invasion, acute schistosomiasis (Katayama fever), and chronic schistosomiasis. Complications of the acute and chronic syndromes have also been reported: pulmonary hypertension, neuroschistosomiasis, association with Salmonella, association with Staphylococci, viral hepatitis B, glomerulonephritis. In most individuals with hepatosplenic schistosomiasis the spleen is increased in size. Hepatosplenic schistosomiasis can, however, occur without splenomegaly. The definition of hepatosplenic schistosomiasis in endemic areas as the finding of S. mansoni eggs in the stools in an individual with hepatosplenomegaly is not satisfactory anymore. Many aspects of morbidity are expected to change after schistosomiasis control. Some are expected to change quickly (worm burden, Salmonella bacteremia, hepatosplenic schistosomiasis in children) whereas others shall remain for years (pulmonary hypertension, glomerulonephritis, neuroschistosomiasis). Intestinal schistosomiasis in individuals with low worm burdens is very difficult to diagnose and therefore laborious to control.

[Dengue: a new approach]

Previous definition of classic dengue, with or without bleeding, and of dengue hemorrhagic fever (DHF) that may evolve without bleeding and with or without dengue shock syndrome (DSS) are reviewed here. The classical approach to the diagnosis and treatment of dengue, although useful in the past, nowadays breeds confusion and adds a burden to the physician's task of decision-making regarding the treatment of patients with severe forms of the disease. The classification of dengue proposed in this paper, and summarized in a diagram, incorporates new concepts about sepsis, systemic inflammatory response syndrome (SIRS), and acute respiratory distress syndrome (ARDS). This new approach, in our view, is a useful guide to initial evaluation and treatment of the disease. It also approximates the dengue syndrome to other protocols and medical procedures routinely used in intensive care units, making it easier to be followed by the health personnel working in areas subject to epidemic bursts.

HTLV-I associated infective dermatitis may be an indolent HTLV-I associated lymphoma

When present for a first time blood donation, a 28-year-old Brazilian white female reported a pruritic eczema of the scalp and retroauricular areas since childhood that had been frequently infected. Her mother had been diagnosed as having HTLV-I-associated myelopathy (HAM), and the patient was found to be a human T-lymphotropic virus type-I (HTLV-I) carrier. The patient had been breast-fed for 6 months. The patient had a complete examination, and a biopsy was taken from eczema in the retroauricular area. The biopsy indicated chronic lymphohistiocytic dermatitis with no abnormal lymphocytes. Eleven months later, the patient had an infiltration in the skin of the retroauricular area and a new biopsy revealed atypical lymphocytes. Nested polymerase chain reaction (PCR) was positive for HTLV-I and immunohistochemistry of the tissue at this time confirmed adult T-cell leukemia/lymphoma (ATLL). Retrospective immunohistochemistry showed that the first fragment submitted from the biopsy 11 months before was also compatible with the diagnosis of ATLL. This case fulfilled all major criteria for diagnosis of HTLV-I-associated infective dermatitis (HTLV-I-ID). We postulate that the patient had indolent ATLL associated with HTLV-I infective dermatitis since childhood. We recommend that tissue immunohistochemistry analysis be done in any patient with HTLV-associated infective dermatitis.

Abdominal ultrasound in acute schistosomiasis mansoni

Reports on abdominal ultrasound studies in patients with acute schistosomiasis are still scarce and limited data are available on structural changes of the liver parenchyma in this stage of the disease. 26 patients with acute schistosomiasis mansoni were submitted to clinical and ultrasound examination. For ultrasound comparison, each acute patient was paired by age, gender, weight and height to a non-infected individual. Ultrasound showed a non-specific homogeneous size increase of the liver, and spleen in all acute patients, and easily identified intraabdominal lymph nodes in the periportal region in most cases. Three out of the five patients with periportal thickening underwent percutaneous liver biopsy. Periportal thickening disappeared 6 months after treatment for schistosomiasis. 24 months after successful treatment there was involution of the liver and spleen; lymph nodes, although reduced in size, were still easily recognized. Liver biopsy showed dense inflammatory infiltration of neutrophils, macrophages and eosinophils in the portal tracts associated with discrete fibrous tissue formation.

Visceral larva migrans syndrome complicated by liver abscess

We describe a case of visceral larva migrans syndrome complicated by liver abscess, pericardial effusion and ascites. To our knowledge, these findings have not been reported previously. The structural and immunological alterations caused by visceral larva migrans are thought to lead to the development of visceral abscesses.

[The association between human toxocariasis and pyogenic abscesses]

The association between hepatic abscesses and schistosomiasis mansoni was confirmed by clinical and experimental studies. Other parasites may cause systemic immunologic changes and local structural alterations in the affected organs that can facilitate the seeding of these areas by bacteria. Tropical pyomyositis, pyogenic liver and renal abscesses are frequent diseases in tropical areas. The visceral larva migrans syndrome is caused by the presence, in the human body, of larvae of worms that have other animals as their definitive host, most commonly being caused by Toxocara canis. The larvae migrate to various body organs leading to many inflammatory reactions in the form of granuloma and tissue necrosis. In this review we discuss the possible host-parasite-bacteria interactions that would favour the formation of abscesses in the organs involved by the larva of T. canis and present preliminary results of a clinical and experimental study undertaken during the last four years to define the role of this parasite in the pathogenesis of the abscesses.

Phenotype and cytokine profile of Schistosoma mansoni specific T cell lines and clones derived from schistosomiasis patients with distinct clinical forms

It is essential to distinguish the role of T lymphocytes on the physiopathology associated to more severe forms of schistosomiasis and on the immunomodulation that evolves in the majority of infected people. In this study, we generated Schistosoma mansoni-specific T cell lines and clones from patients with the acute and chronic (intestinal and hepatosplenic forms) phases of disease, from former ones, and from uninfected individuals sensitized to parasite soluble antigens. T cell lines derived from nontreated acute infected donors were capable of producing IL-4 and IL-5, while cells from treated patients secreted IFN-gamma. Lines from intestinal chronic and antigen-sensitized donors preferentially produced IFN-gamma, while those from hepatosplenic patients secreted all three cytokines. The cytokine analysis of CD4+ T cell clones revealed a Th2/Th0 pattern (clones producing IL-4 and IL-5 and clones producing all three cytokines) for those derived from infected patients, while cells from antigen-sensitized donors exhibited an opposite Th1/Th0 pattern (clones producing IFN-gamma and clones producing all three cytokines). The possible role of these T cell populations on human schistosomiasis mansoni is discussed.

Clinical forms of human Schistosoma mansoni infection are associated with differential activation of T-cell subsets and costimulatory molecules

The current study has compared the activation status and the expression of the CD28 molecule on circulating CD4+ and CD8+ lymphocytes from patients with different clinical forms of schistosomiasis. The data show that patients with acute schistosomiasis have an increase on the mean percentage of CD4+ HLA-DR+ cells, whereas chronic asymptomatic patients exhibit an increased mean percentage of CD8+ HLA-DR+ cells. Patients with the hepatosplenic disease showed an increase in both CD4+ HLA-DR+ and CD8+ HLA-DR+ cells. Despite the high levels of CD8+ HLA-DR+ cells in hepatosplenic patients, they presented a decreased ratio of CD8+ CD28+/CD8+ cells. These findings of a different percentage of circulating CD8+ CD28+ cells might explain the different in vitro cellular reactivity of asymptomatic and hepatosplenic patients and the defects in the cytokine secretion patterns reported in individuals with hepatosplenic schistosomiasis.

Schistosomiasis and associated infections

In hospital-based series viral hepatitis B has been frequently described in association with schistosomiasis whilst in field-based studies the association has not been confirmed. The association between schistosomiasis and Salmonella bacteraemia has been well documented. More recently, acute schistosomiasis has been shown to be a facilitating factor in the genesis of pyogenic liver abscesses caused by Staphylococcus aureus. New evidences indicate an interaction between the acquired immunodeficiency syndrome (AIDS) and schistosomiasis. In this paper, data on the association of schistosomiasis with other infections are updated.

Splenic palpation for the evaluation of morbidity due to schistosomiasis mansoni

This study was undertaken to determine the accuracy of splenic palpation for the diagnosis of splenomegaly, and to determine whether the frequency of individuals with a palpable spleen in an endemic area can be considered as an index of morbidity of schistosomiasis. For the clinical diagnosis of splenomegaly, two criteria have been tested: (A) presence of a palpable spleen and (B) presence of a palpable spleen whose border could be felt more than 4 cm below the costal margin. In an area of high prevalence of the disease (66.3%) 285 individuals aged 18 years or more have been submitted to abdominal ultrasonography and physical examination. Splenomegaly was defined as a splenic length greater than 120 mm by ultrasound and the sensitivity, specificity, positive and negative predictive values of criterion A were 72.2%, 90.5%, 35.1% and 97.8%. The values for criterion B were 27.8%, 98%, 50% and 95%, respectively. In an non endemic area, 517 individuals were submitted to the same protocol and 22 individuals had a palpable spleen, but no patient fulfilled criterion B for splenomegaly, and only one met the ultrasonographic criterion for splenomegaly. The authors concluded that abdominal palpation is a poor method for the diagnosis of splenomegaly.

Chronic carriers of hepatitis B surface antigen in an endemic area for schistosomiasis mansoni in Brazil

Data on the association of schistosomiasis and hepatitis B in field-based studies are scarce. Two areas have been selected for this study: i) Queixadinha, endemic for schistosomiasis, with a population of 693 individuals, and ii) Capão, a control non-endemic area, with 515 inhabitants. Sera of all individuals in both areas were tested for hepatitis B infection, yearly, from 1994 to 1997. In the first area hepatitis B was found in 32.1% of children up to one year old and reached a peak of 68.7% in the age range of 15 to 19 years. In the control area the prevalence of hepatitis B was under 5% up to 19 years of age and the highest prevalence was observed in adults over 45. HBsAg was detected in 9.4% of the individuals living in the endemic area for schistosomiasis and in 1.4% of the controls (OR = 4.98; 95% CI = 3.7-6.7). The index of chronicity of HBsAg was not statistically different in the studied areas (8.1% x 7.3%; OR = 1.09; 95% CI = 0.42-3.03), nor was it different for people with and without schistosomiasis in Queixadinha (8.7% x 7.0%). We conclude that the Schistosoma mansoni infection has not altered the course of hepatitis B in the studied area.

Fever of undetermined origin in patients with the acquired immunodeficiency syndrome in Brazil: report on 55 cases

The medical records of patients with AIDS admitted to a general hospital in Brazil from 1989 to 1997 were reviewed retrospectively with the aim at defining the frequency and etiology of fever of undetermined origin (FUO) in HIV-infected patients of a tropical country and to evaluate the usefulness of the main diagnostic procedures. 188 (58.4%) out of 322 patients reported fever at admission to hospital and 55 (17.1%) had FUO. Those with FUO had a mean CD4+ cell count of 98/ml. A cause of fever was identified for 45 patients (81.8%). Tuberculosis (32.7%), Pneumocystis carinii pneumonia (10.9%), and Mycobacterium avium complex (9.1%) were the most frequent diagnoses. Other infectious diseases are also of note, such as cryptococcal meningitis (5.5%), sinusitis (3.6%), Salmonella-S. mansoni association (3.6%), disseminated histoplasmosis (3.6%), neurosyphilis (1.8%), and isosporiasis (1.8%). Four patients had non-Hodgkin's lymphoma (7.3%). We conclude that an initial aggressive diagnostic approach should be always considered because biopsies (lymph node, liver and bone marrow) produced the highest yield in the diagnosis of FUO and the majority of the diagnosed diseases are treatable. The association of diseases is common and have contributed to delay the final diagnosis of FUO in most cases. In our study area the routine request of hemocultures for Salmonella infection and the investigation of cryptococcal antigen in the serum should be considered.

Visceral larva migrans and tropical pyomyositis: a case report

We report a case of tropical pyomyositis in a boy who presented with a severe febrile illness associated with diffuse erythema, and swelling in many areas of the body which revealed on operation extensive necrotic areas of various muscles that required repeated débridement. The patient gave a history of contact with dogs, and an ELISA test for Toxocara canis was positive. He also presented eosinophilia and high serum IgE levels. Staphylococcus aureus was the sole bacteria isolated from the muscles affected. We suggest that tropical pyomyositis may be caused by the presence of migrating larvae of this or other parasites in the muscles. The immunologic and structural alterations caused by the larvae, in the presence of concomitant bacteremia, would favour seeding of the bacteria and the development of pyomyositis.

Salmonella-S. mansoni association in patients with acquired immunodeficiency syndrome

Two young men with Salmonella bacteraemia, active schistosomiasis and the acquired immunodeficiency syndrome are reported. The clinical presentation comprised nonspecific signs and symptoms, such as fatigue, malaise, weight loss, diarrhoea, prolonged fever, and hepatosplenomegaly. In one patient, liver biopsy showed poorly formed granulomata around Schistosoma mansoni eggs and hepatitis. Treatment of schistosomiasis alone induced consistent clinical improvement with eventual cure of both Salmonella and S. mansoni infections. Recognition of the Salmonella-S. mansoni association in patients with AIDS is important because treatment of schistosomiasis makes a difference, improving the prognosis of this otherwise, recurrent, potentially fatal bacteraemia.

Cytokines as determinants of resistance and pathology in human Schistosoma mansoni infection

The role of different cytokines in the peripheral blood mononuclear cell (PBMC) proliferative response and in in vitro granuloma formation was evaluated in a cross-sectional study with patients with the different clinical forms and phases of Schistosoma mansoni infection, as well as a group of individuals "naturally" resistant to infection named normal endemic (NE). The blockage of IL-4 and IL-5 using anti-IL-4 and anti-IL-5 antibodies significantly reduced the PBMC proliferative response to soluble egg (SEA) and adult worm (SWAP) antigens in acute (ACT), chronic intestinal (INT) and hepatosplenic (HS) patients. Similar results were obtained in the in vitro granuloma formation. Blockage of IL-10 had no significant effect on either assay using PBMC from ACT or HS. In contrast, the addition of anti-IL-10 antibodies to PBMC cultures from INT patients significantly increased the proliferative response to SEA and SWAP as well as the in vitro granuloma formation. Interestingly, association of anti-IL-4 and anti-IL-10 antibodies did not increase the PBMC proliferative response of these patients, suggesting that IL-10 may act by modulating IL-4 and IL-5 secretion. Addition of recombinant IL-10 decreased the proliferative response to undetectable levels when PBMC from patients with the different clinical forms were used. Analysis of IFN-gamma in the supernatants showed that PBMC from INT patients secreted low levels of IFN-gamma upon antigenic stimulation. In contrast, PBMC from NE secreted high levels of IFN-gamma. These data suggest that IL-10 is an important cytokine in regulating the immune response and possibly controlling morbidity in human schistosomiasis mansoni, and that the production of IFN-gamma may be associated with resistance to infection.

Short report: endomyocardial fibrosis and cardiomyopathy in an area endemic for schistosomiasis

An association of schistosomiasis and endomyocardial fibrosis or cardiomyopathy has been suggested. Clinical, stool, abdominal ultrasound, electrocardiogram, and Doppler echocardiogram examinations were performed on 226 patients from an area endemic for schistosomiasis. The diagnosis of schistosomiasis was made in 152 patients (69%) but clinical, electrocardiographic, or Doppler echocardiographic evidence of a schistosome cardiomyopathy or endomyocardial fibrosis could not be detected in any patient.

Acute schistosomiasis: report on five singular cases

The cases of five patients with unusual manifestations of acute schistosomiasis mansoni are described in this paper. One patient developed skin lesions, three displayed diverse lung involvement, and one presented pyogenic liver abscesses caused by Staphylococcus aureus.

Role of immune complexes from patients with different clinical forms of schistosomiasis in the modulation of in vitro granuloma research

Schistosomiasis is a disease whose pathology is strongly related to the granulomatous reaction formed around parasite eggs trapped in host tissues. Studies have shown that the chronic intestinal form (INT) of this infection is associated with a variety of immunoregulatory mechanisms which lead to a diminished granulomatous reaction. Using an in vitro model of granuloma reaction, we show that immune complexes (IC) isolated from sera of INT patients are able to reduce granulomatous reaction developed by peripheral blood mononuclear cells (PBMC) from acute (AC), INT and hepatosplenic (HE) patients to soluble egg antigen (SEA)-conjugated polyacrylamide beads (PB-SEA). This inhibitory activity is also observed in cell proliferation assay of PBMC from INT and HE patients stimulated with SEA and adult worm antigen (SWAP). Furthermore, IC isolated from sera of patients with different clinical forms of the disease are also able to suppress INT patients PBMC reactivity. Therefore, our results show that circulating IC present in sera of patients with different clinical forms of schistosomiasis may downregulate PBMC reactivity to parasite antigens resulting in a diminished granuloma reaction to parasite eggs.

[Schistosomiasis and viral hepatitides: a review]

The papers published on the association of schistosomiasis with viral hepatitis (B, C and D) are reviewed. The shortcomings of each work are pointed out and suggestions are forwarded to try and direct the investigations on this probable interaction.

Ultrasonography of periportal fibrosis in schistosomiasis mansoni in Brazil

In patients with hepatosplenic schistosomiasis, characteristic thickening of the walls of the portal vein in the hilus and its central and peripheral branches is observed. In an area of high prevalence of the disease in Brazil, 424 individuals older than 5 years have been examined by abdominal ultrasonography and 146 presented fibrosis, classified as central in 31 (21%), peripheral in 56 (38%), and both central and peripheral in 59 (40%). The mean ages of the subjects in the 3 groups were 45.7, 24.1 and 31.9 years, respectively (P < 0.05). The presence of central fibrosis was associated with the presence of peripheral fibrosis (odds ratio 10.7, P < 0.000001). Splenomegaly was found in 16% and 15% of individuals with peripheral and both central and peripheral fibrosis, respectively. No subject with central but no peripheral fibrosis and splenomegaly was identified. We conclude that central fibrosis occurs among older subjects but should not be considered a criterion for advanced disease.

Pulmonary hypertension in schistosomiasis mansoni

To evaluate cardiopulmonary involvement in schistosomiasis mansoni, 246 patients from an endemic area of Brazil were examined; 152 had been previously treated for schistosomiasis. Based on stool examination and/or abdominal ultrasonography, the patients were divided into those with schistosomiasis (69%) and those in whom the disease was not present (31%). M mode measurements were similar in the 2 groups. Pulmonary pressure was measured by Doppler echocardiography; 25% of the subjects had pulmonary hypertension. Those with pulmonary hypertension had a higher prevalence of schistosomiasis (80%) than those without (64%; P = 0.03). No case of cor pulmonale was diagnosed by electrocardiography or Doppler echocardiography. The prevalence of pulmonary hypertension correlated neither with periportal fibrosis nor with prior treatment for schistosomiasis.

Pyogenic liver abscesses and acute schistosomiasis mansoni: report on 3 cases and experimental study

Three children with acute schistosomiasis mansoni developed pyogenic liver abscesses. The abscesses were diagnosed by ultrasonography and confirmed during laparotomy. Staphylococcus aureus were the sole bacteria isolated from the abscesses. An experimental study was carried out in mice to establish whether schistosomiasis is a predisposing cause for pyogenic liver abscesses. Seventeen mice (group 1) were infected with 40 Schistosoma mansoni cercariae (LE strain) and 60 d later inoculated intravenously with a strain of Staph. aureus, isolated from a patient with bacteraemia; 17 mice infected with Sch. mansoni (group 2), 19 infected with bacteria alone (group 3), and 18 uninfected mice (group 4), served as controls. Thirteen group 1 mice (77%) developed multiple liver abscesses while none was observed in the controls. These results indicate that acute schistosomiasis mansoni concurrent with Staph. aureus bacteraemia favours the colonization of the liver by bacteria and the development of pyogenic hepatic abscesses.

Pathogenetic factors of acute schistosomiasis mansoni: correlation of worm burden, IgE, blood eosinophilia and intensity of clinical manifestations

A clinical study of 34 previously healthy young patients simultaneously infected in an endemic area of schistosomiasis mansoni is presented, emphasizing the initial phase of the infection. Its intensity was established according to the occurrence, intensity, and duration of the signs and symptoms in order to investigate the possible correlations between the worm burden (estimated by the number of eggs in faeces), the blood eosinophilia and specific levels of IgE (estimated by the area of immediate intradermal reaction), with the clinical manifestations. A significant but low-level association was found between the worm burden and morbidity, suggesting that multiple factors, besides worm burden itself, may contribute to the pathogenesis of the disease.

[The Queixadinha Project: morbidity and control of schistosomiasis in an endemic area in the northeast of Minas Gerais, Brazil]

In an endemic area for schistosomiasis in the northeast of the state of Minas Gerais in Brazil 516 individuals have been submitted to clinical and laboratory examination, ultrasonography of the abdomen and dopplerecocardiography in order to define the morbidity of schistosomiasis before and after treatment. A high prevalence of schistosomiasis (66.3%) and of severe disease (9.5% with palpable spleens) were recorded. Ultrasonography classified liver periportal fibrosis as light (19.4%), moderate (27.6%) and intense (6.8%), and 46.0% presented no periportal fibrosis. Twenty one out of the 53 individuals (39.6%) with palpable spleens did not present liver fibrosis on ultrasound. Periportal lymph nodes were described in 33.8% of the population and anti-KLH antibodies were found in the serum of 40.7%. Urinary alterations compatible with the glomerulopathy of schistosomiasis were observed in 4.5% of the population, and 11.7% of the individuals examined by dopplerecocardiography had pulmonary hypertension. Twelve months after treatment for schistosomiasis the prevalence of the disease dropped from 66.3% to 25.0%. In Queixadinha, a profile of the morbidity of schistosomiasis has just been established.

Secondary cutaneous manifestations of acute schistosomiasis mansoni

The secondary cutaneous manifestations of the initial phase of schistosomiasis mansoni were studied in 34 patients who had been infected simultaneously in the same location. Sixteen of the patients developed angioedema and/or urticaria, generally of short duration and of mild intensity and usually about 30 days post-infection. There was no apparent association between the occurrence of these skin manifestations and the patients' worm burdens, blood eosinophilias or areas of immediate reaction to an intradermal inoculation with worm antigen. Other factors, particularly host immunological reactivity, are thought to be important elements in the genesis of the manifestations.