Geographical distribution of Biomphalaria snails in the State of Minas Gerais, Brazil.

Published and unpublished observations on geographical distribution of Biomphalaria snails in the State of Minas Gerais, Brazil, were compiled. This work is aimed at knowing the present occurrence of Biomphalaria species in this region, and at contributing to the elaboration of the planorbid chart of Minas Gerais. In malacological surveys, performed by several researchers, the presence of seven species of this genus was recorded. Those planorbids were found in 12 mesoregions, in 283 (33.1%) municipalities out of 853 with the following distribution: B. glabrata (185 municipalities), B. straminea (125), B. tenagophila (58), B. peregrina (57), B. schrammi (26), B. intermedia (20) and B. occidentalis (2). B. glabrata and B. tenagophila are found naturally infected by Schistosoma mansoni in Minas Gerais. In 24 municipalities the three snail hosts of S. mansoni in Brazil, B. glabrata, B. tenagophila and B. straminea, are present.

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.

IL-10 plays a role in the modulation of human granulomatous hypersensitivity against Schistosoma mansoni eggs induced by immune complexes.

It has been demonstrated that the chronic intestinal form of schistosomiasis is associated with the establishment and maintenance of a variety of immunoregulatory mechanisms that lead to a diminished granulomatous reaction to parasite eggs. Using an in vitro model of granuloma reaction we showed that immune complexes (IC) isolated from the sera of chronic intestinal schistosomiasis patients were able to reduce the granulomatous hypersensitivity (developed by peripheral blood mononuclear cells (PBMC) from schistosomiasis patients) to soluble egg antigen (SEA)-conjugated polyacrylamide beads (PB-SEA). This inhibitory activity, mediated by IC, was also observed in the proliferative response of PBMC stimulated with SEA and soluble worm antigen preparation (SWAP). Furthermore, we observed a decrease in TNF-alpha and an increase in IL-10 production by PBMC treated with IC in an in vitro granuloma reaction. This phenomenon was also seen in a cell proliferation assay when PBMC were treated with IC and stimulated with S. mansoni antigens. These results demonstrate that circulating IC may down-regulate PBMC reactivity to S. mansoni antigens by changing the cytokine pattern produced by these cells.

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.

[The Queixadinha Project: morbidity and control of schistosomiasis in an endemic area in the northeast of Minas Gerais, Brazil]. / O Projeto Queixadinha: a morbidade e o controle da esquistossomose em área endêmica no nordeste de Minas Gerais, Brasil.

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.