Adhesion and Co-stimulatory Molecules in the Pathogenesis of Hepatic and Intestinal Schistosomiasis Mansoni

Infection of a susceptible host with the blood fluke Schistosoma mansoni results in the formation of periovular granulomas and subsequent fibrosis in the target organs. Granulomogenesis and fibrogenesis are mediated by immunological events which require cell-cell and cell-matrix interactions. In this review, the role of adhesion and co-stimulatory molecules in the genesis of the schistosomal pathology (granulomogenesis and fibrogenesis) is outlined. These molecules provide essential immunological interactions not only for the initiation of granuloma formation but also for the maintenance and modulation of the schistosomal granuloma during chronic infection. Furthermore, the role of secreted soluble adhesion molecules in the different clinical forms and in the modulation of the schistosomal granuloma is discussed. Recent new insights into the role of adhesion molecules for the induction of pathology by other developmental stages of the parasite (other than eggs) will be presented.

Genital manifestations of schistosomiasis mansoni in women: important but neglected

Egg-induced lesions in the upper and the lower female reproductive tract are important complications of the infection with Schistosoma mansoni. The understanding of the pathophysiology and pathology of genital lesions is only rudimentary, simple and reliable diagnostic tools are not at hand, epidemiological data do not exist and how to treat best the women affected, is not known. In view of recent advances in the understanding of genital lesions induced by S. haematobium the existing literature is critically analysized and possible consequences of female genital schistosomiasis are outlined. We estimate that 6 to 27 % girls and women with intestinal schistosomiasis, at least temporarily, suffer from pathology induced by eggs sequestered somewhere in their genital organs. This is a mattern of concern and warrants more research into the epidemiology, pathology, diagnosis and therapy of this disease entity.

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.

Prognosis of schistosomiasis mansoni patients infected with hepatitis B virus

A clinical study on the evolution of patients with schistosomiasis mansoni has been conducted since 1983 at the outpatient clinic of the Infectious and Parasitic Disease Service in the Clementino Fraga Filho University Hospital in Rio de Janeiro, Brazil, comparing prevalence of positive tests for HBsAg, anti-HBsAg, and anti-HBc among patients infected with Schistosoma mansoni coming from various regions of Brazil and with different clinical forms of the disease. A non-significant predominance of HBsAg, anti-HBsAg, and anti-HBc was detected among patients with the hepatosplenic form of schistosomiasis, who presented a more severe clinical evolution with a higher frequency of hematemesis and/or melena, in addition to the development of macronodular cirrhosis and a worse prognosis as compared to patients with the toxemic form, schistosomiasis-infection and the hepatointestinal form.

Schistosomiasis mansoni is asssociated 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.

Freshwater snails and schistosomiasis mansoni in the State of Rio de Janeiro, Brazil: I - metropolitan mesoregion

In order to elaborate a planorbid chart of the State of Rio de Janeiro a survey of freshwater gastropods in the Metropolitan Mesoregion of this State was performed and revealed the occurrence of 20 species: Antillorbis nordestensis (Lucena, 1954); Biomphalaria glabrata (Say, 1818); Biomphalaria schrammi (Crosse, 1864); Biomphalaria straminea (Dunker, 1848); Biomphalaria tenagophila (Orbigny, 1835); Burnupia sp.; Drepanotrema anatinum (Orbigny, 1835); Drepanotrema cimex (Moricand, 1839); Drepanotrema lucidum (Pfeiffer, 1839); Ferrissia sp.; Gundlachia ticaga (Marcus & Marcus, 1962); Heleobia davisi Silva & Thomé, 1985; Lymnaea columella Say, 1817; Melanoides tuberculatus (Müller, 1774); Physa cubensis Pfeiffer, 1839; Physa marmorata Guilding, 1828; Pomacea sp.; Pomacea canaliculata (Lamarck, 1822); Pomacea lineata (Spix, 1827) and Pomacea sordida (Swainson, 1823). Among the planorbid species B. tenagophila was the most frequent, occurring in all municipalities surveyed. The present study extends the distribution of B. straminea in the State of Rio de Janeiro and reports new records for A. nordestensis, B. schrammi, G. ticaga, H. davisi and the genera Burnupia and Ferrissia. An account about the current transmission areas of schistosomiasis mansoni in this Mesoregion is presented as well.

Freshwater snails and Schistosomiasis mansoni in the State of Rio de Janeiro, Brazil: II - Centro Fluminense Mesoregion

During the course of a survey carried out from 2000 to 2001 in the Centro Fluminense Mesoregion of the State of Rio de Janeiro 22 molluscan species were found. Many of the records are new due to the dearth of previous studies. Concerning the snail hosts of Schistosoma mansoni, the most frequently encountered species was Biomphalaria tenagophila, as it occurred in all the surveyed municipalities. There are new records of Biomphalaria straminea and Biomphalaria peregrina which is regarded as a potential intermediate host. Drepanotrema lucidum and Antillorbis nordestensis were found to be shedding echinostome cercariae and strigid cercariae respectively. An account about the current schistosomiasis transmission sites in this Mesoregion is presented as well.

Influence of specific treatment on the morbidity of schistosomiasis mansoni in an endemic area of Minas Gerais, Brazil

The authors describe the evolution of schistosomiasis mansoni in inhabitants of Capitão Andrade, Minas Gerais, Brazil, from 1973 to 1994. The prevalence of infection was 60.8% in 1973, 36.2% in 1984, and 27.3% in 1994. The evolution of the clinical forms of the disease in this group was as follows: unchanged in 76.7%, clinical progression in 8.4% and clinical regression in 14.9%. The reduction of the prevalence and severity of Schistosoma mansoni infection over the 21 years period, can be attributed to treatment of infected subjects performed in the area and to the installation of piped water in their dwellings.

Schistosomiasis mansoni in areas of low transmission: epidemiological characterization of Venezuelan foci

Severe schistosomiasis is a rare event in Venezuela nowadays, after a successful national campaign by the Schistosomiasis Control Program. Unfortunately, this program has practically disappeared, and snail surveillance in field is not a priority, anymore. Thus, schistosomiasis has become a neglected disease in this country. However, surveys in different populations from the endemic area have shown particular epidemiological features described herein. In five communities we evaluated 2,175 persons and searched for the presence of Biomphalaria glabrata snails. Some markers were used for classifying schistosomiasis foci: mean age of the persons with Schistosoma mansoni eggs in the stools, serological tests, presence of B. glabrata snails, and intensity of infection. Places without B. glabrata snails and with few schistosomiasis cases were defined as "past transmission sites"; a site with abundant snails but few cases was defined as "potential risk"; "new transmission" foci were characterized by the presence of infected snails and young people passing eggs in the stools. A "re-emergent" focus has shared these last features, showing in addition a place where schistosomiasis had been reported before. Recent evidences of active transmission with the increasing dispersion of B. glabrata snails, point out the necessity for the re-establishment of the Schistosomiasis Control Program in Venezuela.

Schistosomiasis mansoni in Bananal (State of São Paulo, Brazil): IV. Study on the public awareness of its risks in the Palha District

A rather high prevalence of mansoni schistosomiasis has been observed in some localities of Bananal, State of São Paulo, during the past decade. The highest prevalence of schistosomiasis was found in the Palha District; it was thus considered adequate for an evaluation of public awareness of the risks involved in acquiring schistosomiasis, a likely outcome of certain behavior patterns. We interviewed 542 district-dwellers. The 5-to-39 age-group constituted 65.5% of the whole sample. Concerning the infection, 69.2% had hearsay information; 46.1% know the infection; 69.6% know how it is acquired; 31.5% know about the symptoms and 57.1% know what can be done to avoid infection; 17.7% declared to have acquired the infection at least once in their lifetime; 62.3% reported total or partial immersion in collections of water of Bananal, once or twice a week, 53.9% of these for bathing or fishing. Although most (91.7%) households have treated running water, are connected to the sewage network or have septic tanks, 9% of the people interviewed use to defecate on the field. It became clear that the educational messages aimed at this population had not been adequate, having failed to fulfil any expectations. The local people received only piecemeal and subjective information about their problem. The control of schistosomiasis requires an integrated practice, which includes the analysis of macro-determinant factors, such as basic sanitation, habitation, education and health care. In short, we require a multidisciplinary vision of the mechanisms of transmission of the infection, which depends upon adequate planning and well trained personnel, intent on their educational work, to attain satisfactory results.

Schistosomiasis mansoni in Bananal (State of São Paulo, Brazil): III. Seroepidemiological studies in the Palha District

The Palha district, municipality of Bananal, State of São Paulo, Brazil, had 10.3% cases of Schistosoma mansoni diagnosed from 1994 to 2000 by coproscopy: about three times the municipality average. The immunofluorescent antibody test was used to assess gut-associated IgM antibody titers of samples from 452 inhabitants. It disclosed 129 (28.5%) positive cases. Subjects were classified according to age, sex, birthplace, and period of residence. Titers varied from 8 to 4,096 (geometric mean: 170.2). Seropositives were aged from 6 to 69 years (average: 24.5), 75% of them aged 34 or less, predominantly males (78 or 60.5%). Of all subjects, 65.7% were born and had been living in Bananal since; 24.2% came from neighboring municipalities and are residing in Bananal from two months to 89 years (average: 22.7 years). Further Kato-Katz coproscopy from 97 seropositives (geometric mean titer, 619) revealed S. mansoni eggs in 11 subjects (11.3%). Serology was deemed useful in screening subjects to be further investigated by coproscopy, considering that blood collection had better acceptance than supplying fecal samples. Higher than average serological titers may indicate new cases in endemic areas. Longitudinal studies associated with epidemiological investigation, including titer evolution are advised, as isolated data are difficult to interpret.

Schistosomiasis mansoni in Bananal (State of São Paulo, Brazil): II. Intermediate hosts

We conducted monthly snail captures in Bananal, State of São Paulo, Brazil, between March 1998 and February 2001, to identify Schistosoma mansoni vectors, estimate seasonal population changes, and delimit foci. We also evaluated the impact of improvements in city water supply and basic sanitation facilities. We identified 28,651 vector specimens, 28,438 as Biomphalaria tenagophila, 49 of them (0.2%) infected with S. mansoni, and 213 as B. straminea, none of the latter infected. Vectors predominated in water bodies having some vegetation along their banks. Neither population density nor local vegetation could be linked to vector infection. We found the first infected snails in 1998 (from March to May). Further captures of infected snails ocurred, without exception, from July to December, when rainfall was least. Irrespective of season, overall temperature ranged from 16.5ºC to 21ºC; pH values, from 6.0 to 6.8. Neither factor was associated with snail population density. Frequent contact of people with the river result from wading across it, extracting sand from its bottom, fishing, washing animals, etc. Despite a marked reduction in contamination, cercaria shedding persists. Whatever the location along its urban course, contact with river Bananal, particularly of the unprotected skin, entails risks of infection.

Freshwater snails and Schistosomiasis mansoni in the state of Rio de Janeiro, Brazil: III - Baixadas Mesoregion

In this paper, the third of a series dealing with the survey of freshwater gastropods of the state of Rio de Janeiro, the results of collections carried out in the Mesoregion Baixadas from 2000 to 2002 are presented. Twenty-two species, belonging to seven families, were found. As to the snail intermediate hosts of Schistosoma mansoni, the most frequent species was Biomphalaria tenagophila besides some new findings of Biomphalaria straminea. No specimens were found harboring larval forms of S. mansoni although different kinds of cercariae had been observed.

Schistosomiasis mansoni in low transmission areas: abdominal ultrasound

In endemic areas with low prevalence and low intensity of infection, the diagnosis of hepatic pathology due to the Schistosoma mansoni infection is very difficult. In order to establish the hepatic morbidity, a double-blind study was achieved in Venezuelan endemic areas, with one group of patients with schistosomiasis and the other one of non-infected people, that were evaluated clinically and by abdominal ultrasound using the Cairo classification. Schistosomiasis diagnosis was established based on parasitologic and serological tests. The increase of the hepatic size at midclavicular and midsternal lines (in hepatometry) and the hard liver consistency were the clinical parameters able to differentiate infected persons from non infected ones, as well as the presence of left lobe hepatomegaly detected by abdominal ultrasound. The periportal thickening, especially the mild form, was frequent in all age groups in both infected and uninfected patients. There was not correlation between the intensity of infection and ultrasound under the current circumstances. Our data suggest that in Venezuela, a low endemic area of transmission of schistosomiasis, the hepatic morbidity is mild and uncommon. The Cairo classification seems to overestimate the prevalence of periportal pathology. The specificity of the method must be improved, especially for the recognition of precocious pathology. Other causes of hepatopathies must be investigated.