Histological observations on Montenegro's reaction in man

The Montenegro skin test is widely used as a diagnostic method for American cutaneous leishmaniasis (ACL) but little is known about the histological changes that occur in the skin after administration of the antigen. This report is based on histological studies of biopsied material obtained, from inoculation sites, 48 hours after individuals had been given intradermal injections with a standardized Montenegro antigen. The material examined was obtained from four distinctly different test groups: naturally infected patients with parasitologically proved ACL and with positive Montenegro's reaction; individuals without previous history of ACL and not previously tested with Montenegro antigen; participants in anti-ACL vaccine trials who developed positive reactions to Montenegro antigen after vaccination; other participants in vaccine trials who had negative Montenegro responses after vaccination or had served as controls in the trials. The histological pictures of each group are described and discussed. Histologically, the reactions of vaccinated individuals were indistinguishable from those with naturally acquired infections.

Antibodies against non-structural c100/3 and structural core antigen of hepatitis C virus (HCV) in hemodialysis patients

Two groups of patients undergoing hemodialysis (HD) maintenance were evaluated for their antibody response to non-structural c100/3 protein and structural core protein of hepatitis C virus (HCV). Forty-six patients (Group 1) never presented liver abnormalities during HD treatment, while 52 patients (Group 2) had either current or prior liver enzyme elevations. Prevalence rates of 32.6% and 41.3% were found for anti-c100/3 and anti-HCV core antibodies, respectively, in patients with silent infections (Group 1). The rate of anti-c100/3 in patients of Group 2 was 71.15% and reached 86.5% for anti-HCV core antibodies. The recognition of anti-c100/3 and anti-core antibodies was significantly higher in Group 2 than in Group 1. A line immunoassay composed of structural and non-structural peptides was used as a confirmation assay. HBV infection, measured by the presence of anti-HBc antibodies, was observed in 39.8% of the patients. Six were HBsAg chronic carriers and 13 had naturally acquired anti-HBs antibodies. The duration of HD treatment was correlated with anti-HCV positivity. A high prevalence of 96.7% (Group 2) was found in patients who underwent more than 5 years of treatment. Our results suggest that anti-HCV core ELISA is more accurate for detecting HCV infection than anti-c100/3. Although the risk associated with the duration of HD treatment and blood transfusion was high, additional factors such as a significant non-transfusional spread of HCV seems to play a role as well. The identification of infective patients by more sensitive methods for HCV genome detection should help to control the transmission of HCV in the unit under study.

Schistosoma mansoni: protective immunity in mice cured by chemotherapy at the chronic phase of the disease

Aiming at demonstrating a decrease of acquired immunity after chemotherapeutic cure, a group of mice was infected with 25 Schistosoma mansoni cercariae (LE strain). A part of these animals was treated with 400 mg/kg oxamniquine, at 120 days after infection. Challenge infections were carried out at 45, 90 and 170-day-intervals after treatment (185, 210 and 290 days after primoinfection, respectively). Recovery of worms at 20 days after reinfections showed that a residual immunity remains up to 90 days after treatment, and disappears at 170 days after cure. Using the ELISA method, it was possible to detect a decrease of antibody levels (total IgG) in the treated group, when antigens from different evolutive stages of S. mansoni were used. The epidemiological implications of the present results, and the possible mechanisms involved in the decrease of acquired immunity after treatment are discussed.

Usefulness of the detection of Toxoplasma gondii antigens in AIDS patients

Toxoplasmic encephalitis (TE) is a mayor cause of central nervous system infection in patients with acquired immunodeficiency syndrome (AIDS). Toxoplasma antibodies were detected in 56 of 79 patients with AIDS (71%), in the present study. Fourteen out of 57 seropositive patients developed TF (25%) and had Toxoplasma gondii antigen detected in their urine. For this, most of them received an effective therapy, with the subsequent disappearance of the symptoms and discontinuity of excretion of the T. gondii antigens. Our results suggest that the monitoring of T. gondii antigen in the urine of AIDS patients may be useful to decide on the proper time for therapy, as well as to avoid the beginning of neurologic signs in these patients.

Mycobacterium avium complex (MAC): an unusual potential pathogen in cerebrospinal fluid of AIDS patients

Mycobacterium avium complex (MAC) is frequently isolated from patients with late complications of Acquired Immunodeficiency Syndrome (AIDS), especially in North America and Europe. However, its isolation from the central nervous system (CNS) has been seldom reported in these countries. MAC infections in AIDS patients in African and Latin American countries are believed to be uncommon. We report the isolation of MAC from cerebrospinal fluid (CSF) of 11 AIDS patients out of 1723 (0.63%) seen at "Centro de Referência e Treinamento - AIDS", São Paulo and discuss the significance of its isolation.

Mycobacterium avium complex (MAC) isolated from AIDS patients and the criteria required for its implication in disease

Before the AIDS pandemia, the Mycobacterium avium complex (MAC) was responsible in most cases for the pneumopathies that attack patients with basic chronic pulmonary diseases such as emphysema and chronic bronchitis36. In 1981, with the advent of the acquired immunodeficiency syndrome (AIDS), MAC started to represent one of the most frequent bacterial diseases among AIDS patients, with the disseminated form of the disease being the major clinical manifestation of the infection8. Between January 1989 and February 1991, the Section of Mycobacteria of the Adolfo Lutz Institute, São Paulo, isolated MAC from 103 patients by culturing different sterile and no-sterile processed specimens collected from 2304 patients seen at the AIDS Reference and Training Center and/or Emilio Ribas Infectology Institute. Disseminated disease was diagnosed in 29 of those patients on the basis of MAC isolation from blood and/or bone marrow aspirate. The other 74 patients were divided into categories highly (5), moderately (26) and little suggestive of disease (43) according to the criteria of DAVIDSON (1989)10. The various criteria for MAC isolation from sterile and non-sterile specimens are discussed.

Drug resistance of M. Tuberculosis isolated from patients with HIV infection seen at an AIDS Reference Center in São Paulo, Brazil

M. tuberculosis-positive cultures were obtained from 228 patients seen in our service and drug sensitivity assays were carried out from January 1992 to December 1994. A survey of the medical records of these patients showed resistance to one or more drugs in 47 (20.6%), 25 of whom (10.9%), who reported previous treatment, were considered to have acquired resistance. Among the antecedents investigated, only previous treatment and alcoholism were the factors independently associated with the occurrence of resistance. The survival of patients with resistant strains was lower than that of patients attacked by non-resistant M. tuberculosis. We conclude that in the present series M. tuberculosis resistance to tuberculostatic agents was predominantly of the acquired type.