Cross-sectional and evolutive studies of schistosomiasis mansoni in untreated and mass treated endemic areas in the southeast and northeast of Brazil

Cross-sectional and evolutive studies on schistosomiasis mansoni were carried out before and after mass treatment in the endemic areas of Capitao Andrade and Padre Paraíso, state of Minas Gerais, Riachuelo, state of Sergipe, Alhandra, state of Paraíba, and Aliança, Alegre and Coroatá, lowland of the state of Maranhao, Brazil, in the last eighteen years. The studies included clinical and fecal examination by the Kato-Katz quantitative technique, skin testfor Schistosoma mansoni infection, evaluation of man-water contact and other epidemiological investigations such as infection rate and dynamic of the snail population. Results showed: (1) Higher prevalence of S. mansoni infection, greater egg load elimination and higher and earlier morbidity of the chronic froms of the disease in the southeast areas of Capitao Andrade and Padre Paraíso; (2) The incidence of hepatosplenic form is higher in some family clusters, in whites and mullattos in all the endemic areas but develop earlier in the southeast; (3) The prevalence and morbidity of schistosomiasis are decreasing both in the mass treated northeast and in the untreated southeast areas; (4) The mass treatment reduces rapidily the prevalence of the infection and the morbidity of the disease but can not control it because of the frequent reinfections due to the intensity of man-water contact.

Ecological studies on the intermediate host snails and the relevance to schistosomiasis control

A detailed knoledge of distribution patterns schistosome intermediate hsts and their populations dynamics and factors affecting these patterns will provide useful information about the possibilities and desirability of conducting snail control measures in various transmission situations. On the basis of various case studies the association between the occurence of human water contacts and the presence of schistosome intermediate hosts or infections in the intermediate hosts is illustrated. Other parameters affecting snail distribution patterns and density fluctuations are discussed. It is concluded that ecological studies on the intermediate host are extremely relevant, either to optimally apply existing control measures or to develop alternative measures of snail control, such as ecological or biological control.

Human schistosomiasis mansoni: studies on in vitro granuloma modulation

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to delayed hipersensitivity that results in granulomatous inflamatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflamatory disease is appsrently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor transactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We repport here on experiments wich extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the present of intact (F(ab')2 immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals. These data support the hypothesis that anti-SEA cross reactive idiotypes are important in regulating granulomatous hypersensitivy in chronic intestinal schistosomiasis patients and these cross-reactive idiotypes appear to play a major role in cell-cell interactions which result in the regulation of anti-SEA cellular immune responses.

Morphological and virological studies in six autopsies of children with adenovirus pneumonia

Pulmonary lesions compatible with adenovirus infection were detected by gross and microscopic examination of autopsy tissues children aged from 5 to 34 months. Hepatic lesions indicative of systemic infection were also found in four of the chisldren. The viral etiology was confirmed in three cases by in-situ hibridization, electro-microscopy and immunofluorescence performed in parafin-embedded tissues, and in one case by cell culture isolation of adenovirus type 2 from nasopharyngeal exudate. Routine testing by methods additional to conventional light microscopy would probably have revealed a larger number of adenovirus infections among the 1.103 autopsy records analyzed in this study.

Taxonomic studies of the subgenus Helcocyrtomyia: II. series Vexator (Diptera, Psychodidae, Phlebotominae)

Continuing to review the subgenus Helcocyrtomyia (Diptera, Psychodidae, Phlebotomiane) some specimens of sandflies from the vexator series were examined. Taxonomic remarks, geographic distribution and drawings of those species are presented.

Studies on the sandfly fauna of Samuel Ecological Station, Porto Velho Municipality, Rondônia State, Brazil

In a study of sandfly species in the Samuel Ecological Station, in Porto Velho, Rondônia State, the following species were identified: Lutzomyia brasiliensis, L. evangelistai, L. gomezi, L. anduzei, L. flaviscutellata, L. richardwardi, L. shawi, L. umbratilis, L. yuilli yuilli, L. dendrophyla, L. puctigeniculata, L. shannoni, L. amazonensis, L. ayrozai, L. carrerai carrerai, L. claustrei, L. davisi and L. lainsoni. L. richardwardi, L. umbratilis and L. c. carrerai were the predominant species captured of man forming 60.30% of the total catch. L. richarwardi was the most frequent at ground level (29.9%), while L. umbratilis predominated in the canopy (48.5%).

A simple and economic slide micro-immunoenzymatic (Micro-SIA) test for epidemiological studies of toxoplasmosis

A slide micro-immunoenzymatic assay (micro-SIA) to detectantibodies to non-particulate Toxoplasma gondii antigens is described. This assay allows the diagnosis of toxoplasmosis infection in about 1 hr. Twenty-four determinations can be performed per slide. Five hundred ng of antigen and 5 or 10 µl drop of each reactive are necessary per well. The clear contrast of colours obtained for negative and positive sera after the test is finished, allows direct discrimination of the results. However, it is possible to quantify the results of the reaction using a minireader. Sera dilution cutoff value, determined as themost frequent titre for the general population, is 1:100. The toxoplasma micro-SIA correlates well with indirect immunofluorescence (IIF), its sensitivity is atleast three times as much as IIF. The test has an intra and inter assay variation coefficient of 5.46 per cent and of 6.24 per cent respectively. Sera obtained at random from argentinian people were analyzed and a 56 per cent of infection was found. The main features of the Toxoplasma micro-SIA are its simplicity, sensitivity, reproducibility, and the virtual absence of background making it very suitable for screening tests.

Studies on the replication of Mayaro virus grown in interferon treated cells

Mayaro virus grown in interferon treated infected cells has been characterized with regard to its ability to replicate in vertebrate (TC7) and invertebrate (Aedes albopictus) cells. Virus purified from interferon treated TC7 cells adsorbs and penetrates to the same extent as the control virus. During infection, these virus particles caused inhibition of host protein synthesis and synthesized the same spectrum of viral proteins as normal virus. This population however, was apparently more sensitive to interferon treatment. Electron microscopy of TC7 cells showed the presence of numerous aberrant virus particles budding from the plasma membrane.

Hemagglutinating and fusogenic activities of Newcastle disease virus: studies on receptor binding specificity and pH-induced conformational changes

Vaccinal and wild strains of Newcastle Disease virus (NDV) were analyzed for cell receptor binding and fusogenic biological properties associated with their HN (hemagglutinin-neuraminidase) and F (fusion protein) surface structures respectively. The evaluation of the biological activities of HN and F was carried out respectively by determination of hemagglutinating titers and hemolysis percentages, using erythrocytes from various animal origins at different pH values. Significant differences in hemagglutination titers for some strains of NDV were detected, when interacting with goose, sheep, guinea-pip and human "O" group erythrocytes at neutral pH. Diversity of hemolysis percentagens was observed between different NDV strains at acid pH. These analysis were developed to evaluate particular aspects of the actual influence of the receptor specifity and pH on the receptor binding and fusogenic processes of Newcastle Disease viruses.

Low occurrence of arthritic manifestations in patients with pulmonary tuberculosis: T cell subsets and humoral studies

Given the suspected role of mycobacteria in the establishment of disorders with an autoimmune background and joint damage, a study was conducted to analize whether rheumatic symptoms were likely to be present in tuberculosis (TB) patients. To this end, 330 patients with a bacteriologic confirmation of tuberculosis were investigated for the presence of arthritic complaints. The latter were recorded in five of them with rheumatic symptoms mostly involving interphalangeal and metacarpophalanged joints, and preceding the clinical manifestations of the TB illness. Three out of these five patients remained arthritic by the time of the bacteriologic conversion and fulfilled the criteria for the diagnosis of rheumatoid arthritis. In the two remaining patients sputum negativization was accompanied by a disappearance of rheumatic manifestations. These patients were also assessed for their peripheral levels of major T cell subsets as well as for the presence of autoantibodies. Comparisons with a series of non-arthritic TB cases, rheumatoid arthritis patients, and controls revealed that presence of rheumatic manifestations was associated with a different profile of autoantibody formation and T cell subset changes. Evidence recorded in the present study indicates that joint affectation in TB is a rare event, being rather the exception than the rule.

Evaluation of the rabbit as a model for Chagas disease - II: histopathologic studies of the heart, digestive tract and skeletal muscle

In order to investigate the value of the rabbit as an experimental model for Chagas' disease, seventy one animals were inoculated with different Trypanosoma cruzi strains and routes. The rabbits were submitted to necropsy in acute (earlier than three months of infection), recent chronic (three to six months) and late chronic (later than six months) phases. Myocarditis, generally focal and endomysial, occurred in 94.1%, 66.7% and 70.8% of the infected rabbits respectively in the acute, recent chronic and late chronic phases. The myocardial inflammatory exudate was composed by mononuclear cells, and also polymorphonuclear cells in the acute phase. In most cases of the late chronic phase, the myocarditis was similar to that described in the indeterminate form of human chagasic patients. Initial fibrosis occurred in the three phases but was more severe and frequent in the early chronic. Advanced fibrosis occurred only in the late chronic phase. Tissue parasites occurred only in the acute phase. The digestive tract and skeletal muscles showed mild and occasional lesions. Our data indicate that experimentally infected chagasic rabbits repeat some lesions similar to that of humans chagasic patients, specially that of the indeterminate form. So, it may be a useful, however not an ideal, model.

Biological comparison between three clones of Trypanosoma cruzi and the strain of origin (Bolivia) with reference to clonal evolution studies

After isolating three clones of Trypanasoma cruzi (Bolivia), we first characterized them according to parasitaemia, pleomorphism and virulence, and then histopathologically. The study's interest lies on the hypothesis that clonal evolution of T. cruzi has a major impact on biologically relevant properties of this parasite. Data obtained from the studies of parasitaemia, pleomorphism and virulence showed no differences between the groups studied. As a final point, the histopathological study shows us a muscular tissue tropism both in clones and in their mother strain (Bolivia). In this paper, we conclude that Bolivia strain and clones isolated from it, pertaining to the same major clone share similar biological properties.

Seroepidemiological Studies of Cutaneous Leishmaniasis in the Campeche State of México

Seroepidemiological studies of cutaneous leishmaniasis were carried out on 169 individuals in a rural area of the Campeche state of México. Fifty showed cutaneous lesions suggestive of leishmaniasis, 70% were parasite positive and 96% skin test positive. An overall 40% positivity to skin test with Montenegro's antigen was found. Most of the affected individuals were males from 11 to 30 years-old. Antibodies were determined by immunofluorescent antibody test (IFA) and by Western blot. Two antigen preparations were used, one from a Leishmania mexicana strain which produced localized cutaneous leishmaniasis (LCL) and the other from a diffuse cutaneous leishmaniasis (DCL). In the general population from the area of study 19% gave positive IFA tests with DCL antigen and 20% with LCL antigen while for the patients 67% gave positive IFA tests with DCL and 71% with LCL. By Western blot analysis most of the patients recognized more antigens in the DCL than in the LCL strain. In the DCL strain 78% of patients recognized a 105 kDa, 34% a 139 kDa, 28% a 117 kDa and 26% a 205 kDa MW antigen. In the LCL strain 40% of patients recognized a 205 kDa and 22% a 175 kDa antigens