Humoral and cellular immune response of adults from northeastern Brazil with chronic Trypanosoma cruzi infection: depressed cellular immune response to T. cruzi antigen among Chagas' disease patients with symptomatic versus indeterminate infection.

Infection with Trypanosoma cruzi can cause chronic Chagas' disease manifestations (cardiac, gastrointestinal), although most persons with chronic infection have no ill effects (indeterminate form). Cell-mediated immunity (CMI) responses are believed to be intrinsically important in the containment of T. cruzi and in the pathogenesis of Chagas' disease. Humoral and CMI responses were investigated in 70 T. cruzi-infected persons from an endemic area in northeastern Brazil and in 30 uninfected controls. An epidemiologic survey, physical examination, and blood evaluation were conducted for each subject. The 70 chronically infected persons were subclassified into three clinical groups: indeterminate, cardiac, and gastrointestinal. Serum was tested for antibodies to T. cruzi by hemagglutination assay, indirect immunofluorescent assay, and enzyme-linked immunosorbent assay, and for autoantibodies to tubulin. Serum levels of soluble interleukin-2 receptor (sIL-2R), albumin, and C-reactive protein (CRP) were also measured to assess one parameter each of immunosuppression, nutritional status, and inflammation. The proliferative response of peripheral blood mononuclear cells (PBMC) to T. cruzi antigens, mitogen (phytohemagglutinin), and antigen-free controls was also assessed. Our data did not reveal any significant differences in serum levels of antibodies to T. cruzi, antibodies to tubulin, albumin, CRP, or sIL-2R among the subgroups of infected individuals. The data demonstrate differences in CMI responses. Trypanosoma cruzi trypomastigote lysate stimulated proliferation of PBMC from infected persons, but not uninfected controls. Patients with symptomatic Chagas' disease (cardiac and gastrointestinal groups) had decreased cellular responses to T. cruzi lysate (median proliferation index [PI] = 3), compared with those in the indeterminate group (median PI = 9; P < 0.005). Further investigations of the mechanism of this reduced CMI response in those with chronic disease may yield insights into the pathogenesis of Chagas' disease.

Prevalence of HIV-1, HIV-2 and HTLV antibody, in Fortaleza, Ceara, Brazil, 1993-1994.

To evaluate the respective part of HIV-1, HIV-2, and human T lymphotropic virus (HTLV) infection in Fortaleza, the principal city of the Ceara state (Northeast of Brazil), a cross-sectional seroepidemiological survey was conducted from July 1993 to February 1994 in 6 selected groups: pregnant women, tuberculosis (Tb) patients, sexually transmitted disease (STD) patients, female and male commercial sex workers (CSWs) and prisoners. Sera were screened by Mixt HIV-1/HIV-2 commercial enzyme immunoassay and ELISA HTLV I/II. Each serum found positive by ELISA was confirmed by Western blot. A total of 2917 persons were interviewed, of whom 2754 (94.4%) agreed to participate and gave a blood sample. Twenty-eight were found to be HIV-1 antibody positive. The prevalence ranged from 0.25% in pregnant women to 2.9% in male CSWs. The prevalence was 1% in STD patients and 0.44% in Tb patients. None of the sera was found positive for HIV-2. The prevalence of antibodies to HTLV-1 varied from 0.12% in pregnant women to 1.21% in female CSWs. Five sera were positive for HTLV-II. These results confirm the hypothesis that the HIV epidemic in Northeastern Brazil is still limited to high risk groups. Repeated cross-sectional surveys of this type should be performed as a surveillance tool to study the dynamics of this epidemic in low prevalence areas. Defining risk factors should allow targeting of intervention strategies.

PIP: During July 1993 to February 1994, in Ceara state, Brazil, researchers conducted a cross-sectional seroepidemiological survey of 814 pregnant women, 451 tuberculosis patients, 395 sexually transmitted disease (STD) patients, 496 female and 171 male commercial sex workers (CSWs), and 427 prisoners. They aimed to determine the prevalence of HIV-1, HIV-2, and human T lymphotropic virus (HTLV). All subjects lived in Fortaleza, where the HIV epidemic is recent. They tended to be poorly educated, poor, and not married. 28 persons were positive for HIV-1. The HIV-1 prevalence rate ranged from 0.25% in pregnant women to 2.92% in male CSWs. It was 0.44% for tuberculosis patients, 1.01% for STD patients, 1.61% for female CSWs, and 1.64% for prisoners. Indeterminate results occurred in 0.4% of all subjects. They were more common in tuberculosis patients than in other groups (1.1% vs. 0.3%; p = 0.023). No one tested positive for HIV-2. The prevalence of HTLV-I ranged from 0.12% in pregnant women to 1.21% in female CSWs. It was 0.44% for tuberculosis patients, 0.51% for STD patients, 0.58% for male CSWs, and 0.47% for prisoners. Five people (1 pregnant woman, 1 tuberculosis patient, 1 female CSW, and 2 prisoners) tested positive for HTLV-II. A 45-year-old, homosexual CSW, intravenous drug user who had tuberculosis was coinfected with HIV-1 and HTLV-I. The most common risk factor for HIV-1 infection was never used condoms (48% for female CSWs to 89% for STD patients). These findings indicate that Fortaleza has a low endemicity for HIV-1 infection and that HIV-1 is still limited to high risk groups (e.g., CSWs). The authors recommend that periodic cross-sectional surveys be conducted to study the dynamics of HIV-1 infection in this low prevalence area.

Prevalence of GB virus C/hepatitis G virus among blood donors in north-eastern Brazil.

We tested 70 blood donors from Fortaleza (Ceara state, Brazil) for GB virus C/hepatitis G virus (GBV/HGV) infection by polymerase chain reaction and detection of antienvelope antibodies. Twenty-seven (38.6%) showed signs of an active or resolved infection. Sixty-four percent of those with indications of other blood-borne viral infections showed signs of GBV-C/HGV infection also.