Evaluation of Chagas' disease transmission through breast-feeding

On hundred milk or colostrum samples from 78 mothers with chronic Chagas' disease were parasitologically studied for Trypanosoma cruzi infection by means of direct examination and inoculation of mice. The mice were submitted to direct bllod examination three times a week. At the end of 45 days, xenodiagnosis and indirect immunofluorescent test (IFAT) for T. cruzi antibodies were carried out in the animals. No parasitized sample was observed even though five mothers had parasitemia at milk collection. In addition, 97 breast-fed children of chronic chagasic mothers, born free of infection, were tested for IgG antibodies to T. cruzi using IFAT. No case of T. cruzi infection was detected. The authors conclude that breast-feeding should not be avoided for children for chronic chagasic women. However, as these mothers had intermittent parasitemia, they should avoid nursing when there is nipple bleeding.

Aspergillus fumigatus fungus ball in hospitalized patients with chronic pulmonary disease: usefulness of double immunodiffusion test as a screening procedure

Double immunodiffusion (DID) was used as a screening test for the diagnosis of aspergillosis. Three hundred and fifty patients were tested, all of them referred from a specialized chest disease hospital and without a definitive etiological diagnosis. When DID was positive addtional information such as clinical history and radiographic findings were requested and also surgical specimens were obtained whenever possible. Specific precipitin hamds for Aspergillus fumigatus antigen were found in 29 (8.3%) of 350 patients sera. Nineteen (65.5%) of the 29 patients with positive serology were recognized as having a fungus ball by X-rays signs in 17 or by pathological examination in 2 or by both in 8 patients. This two-year prospective study has shown that pulmonary aspergillos is a considerable problem among patiens admitted to a Chest Diseases Hospital, especially in those with pulmonary cavities or bronchiectasis.

Serum uric acid levels in Chagas' disease

Uricemia was studied in a sample of 192 individuals from a highly endemic site for Chagas' disease (Bambuí, State of Minas Gerais, Brazil). The sample had serologically negative individuals (controls) and the positive ones were classified on the basis of the presence of electrocardiographic alterations (63), altered esophageal emptying (16), or without any sign on sympton of the disease (76). Only the individuals with the digestive form of chronic Chagas' disease showed hyperuricemia, when compared with the appropriate controls. Family data suggest that hyperuricemia is an effect of the digestive pathology, rather than a cause, since the non-infected sibs of the megaesophagous patients did not show elevated levesl of serum uric acid. Possible mechanisms responsible for these findings are postulated.

A cost-benefit analisys of chagas disease control

Chagas disease transmission can be effetively interrupted by insecticidal control of its triatomine bug vectors. We present here a simple model comparing the costs and benefits of such a programme, designed to eliminate domestic populations of Triatoma infestans throughout its known area of distribution over the seven southernmost countries of Latin America. The model has been simplified to require only four financial estimates relating to the unit cost of housing spraying and benefits due to avoidance of premature death in the acute phase of the disease, avoidance of supportive treatment and care in the chronic phase of the disease, and avoidance of corrective digestive and cardiac surgery. Exceptfor these direct medical costs, al other potential benefits have been ignored. Nevertheless, the model shows that the direct financial benefits of such a programme would far outweigh the costs, and the project would support a remarkably high internal rate of return under the least optimistic estimates.

Antigenic differences among Leishmania amazonensis isolates and their relationship with distinct clinical forms of the disease

Immunoblot analysis was used to investigate antigenic differences among clinical isolates of Leishmania amazonensis and their role in the etiology of the diseases. Western blots of promastigote homogenates were analyzed with either monoclonal antibodies (MAbs) specific for the L. mexicana complex (M-4, M-6, M-9 and M-11) or polyclonal sera from L. amazonensis infected patients with the various forms of clinical disease. In the case of the MAbs, no significant variation was observed among the strains of L. amazonensis, isolated from cases of cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), diffuse cutaneous leishmaniasis (DCL), visceral leishmaniasis (VL) or post kala-azar dermal leishmaniasis (PKDL), in either the relative morbility (Mr) or the quantitative amount (intensity) of the antigenic determinats. In the case of the sera of the infected patients, the patterns of antigenic reactivity of these strains revealed that, despite showing the presence of shared antigens, differences were observed between some of the antigenic components of the various isolates of L. amazonensis that were recognized by a single serum. Differences were also demonstrated between the antigenic determinants of a single isolate of L. amazonensis that were recognized by the different patient's sera. No apparent association was consistently found, however, between the Mr components identified in these isolates and clinical form of the disease or the geographical area of isolation. In addition, the spectrum of antigens recognized by the sera from patients with the same clinical form were not identical; although in some instances, similar Mr antigens were shared. These results indicate that isolates of L. amazonensis are not antigenically identical (homogeneous) and that the immune responses (antibodies) observed among infected patients are heterogeneous.

Evaluation of spleen cell population and effect of splenectomy on granuloma modulation in BALB/c mice infected with Schistosoma mansoni

A kinetic study of the cells present in the spleen of BALB/c mice infected with Schistosoma mansoni was carried out. The lymphocytes were evaluated phenotypically with monoclonal antibodies and the effect of splenectomy on the modulation of periovular granuloma was also investigated. The infected mice had proportional increases in the numbers of neutophils, plasma cells, macrophages and eosinophils in the spleen. The largest number of neutrophil, plasma cells and macrophage were found between the 8th and the 12th week of infection, while the amount of eosinophils were higher later on, around the 20th week. The lymphocytes phenotipically characterized as Thy 1.2, Lyt 1.2 (CD4) increased mildly in proportional numbers. However, the percentage of lymphocytes with the Lyt 2.2 (CD8) phenotype, which is characteristic of supressor and cytotoxic T cells, increased significantly with the progress of the disease. The numbers of B lymphocytes, which comprise 50% of the mononuclear cells present in the spleen, increased significantly till the 16th week they began to decrease. The mean diameters of periovular granulomas were comparatively similar in both experimental groups (splenectomized and non-splenectomized mice). However, the evolutive types of granuloma (exudative, intermediate and fibrous) in splenectomized mice were proprtionally different from those of non splenectomized mice in the 16th and 24th week of infection. It is inferred that lymphonodes or other secondary lymphoide organs, in the abscence of the spleen, assume a modulating action on periovular granulomas, although the evolution of the granulomas is somehow delayed in splenectomized mice.

Factors influencing predation of the Waterbugs Sphaerodema annulatum (Fab.) and S. rusticum (Fab.) on the Disease Transmitting Snail Lymnaea (Radix) luteola (Lamarck)

Variations in the rate of predation of the waterbugs Sphaerodema annulatum and S. rusticum on the snails Lymnaea (Radix) luteola have been noted in respect to the morphs of the waterbugs, size of the prey individuals, densities of prey and predators, temperature and surface area of the waterbody concerned and the seasons. Consumption rate was highest (7.2 and 2.2 individuals per day per individual of S. annulatum and S. rusticum, respectively) in prereproductive ages of the waterbugs. This was followed by a gradual decline with the increase in age of the predators. The consumption rate was gradually higher with the increase of temperature from 20 °C to 35 °C. The bugs failed to survive beyond 35 days at 35 °C. Though the bugs prey upon the snails of all sizes preference for 6.5 ÷ 4.5 mm to 8 ÷ 5 mm individuals by S. annulatum and for 5 ÷ 3 mm to 6.5 ÷ 4.5 mm individuals belonged to 3 ÷ 2 - 4 ÷ 3 mm size group maximum when supplied separately. The rate of predation gradually declined with the rise of predator's desity irrespective of waterbug species. Predation rate increased with increasing prey density. This was level off when the prey snails were 1100 and 700 in number for S. annulatum and S. rusticum respectively. An adult S. annulatum and S. rusticum consumed 5.04, 3.7, 1.43 and 3.36, 2.49, 1.04 snails per day respectively in summer, monsoon and winter.

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.

Comparison of some behavioral and physiological feeding parameters of Triatoma infestans klug, 1834 and Mepraia spinolai porter, 1934, vectors of chagas disease in Chile

There are two vectors of Chagas disease in Chile: Triatoma infestans and Mepraia spinolai. We studied the feeding behavior of these species, looking for differences which could possibly explain the low impact of the latter species on Chagas disease. Both species used thermal cues to locate their feeding source and consumed a similar volume of blood which was inversely related to the body weight before the meal and directly related to the time between meals. The average time between bites were 6.24 and 10.74 days. The average bite of M. spinolai lasted 9.68 min, significantly shorter than the 19.46 min for T. infestans. Furthermore, while T. infestans always defecated on the host, this behavior was observed in M. spinolai in only one case of 27 (3.7%). The delay between the bites and defecation was very long in M. spinolai and short in T. infestans. These differences may affect the reduced efficiency of transmission of Chagas infection by M. spinolai.

Evolution of the clinical and epidemiological knowledge about Chagas disease 90 years after its discovery

Three different periods may be considered in the evolution of knowledge about the clinical and epidemiological aspects of Chagas disease since its discovery: (a) early period concerning the studies carried out by Carlos Chagas in Lassance with the collaboration of other investigators of the Manguinhos School. At that time the disease was described and the parasite, transmitters and reservoirs were studied. The coexistence of endemic goiter in the same region generated some confusion about the clinical forms of the disease; (b) second period involving uncertainty and the description of isolated cases, which lasted until the 1940 decade. Many acute cases were described during this period and the disease was recognized in many Latin American countries. Particularly important were the studies of the Argentine Mission of Regional Pathology Studies, which culminated with the description of the Romaña sign in the 1930 decade, facilitating the diagnosis of the early phase of the disease. However, the chronic phase, which was the most important, continued to be difficult to recognize; (c) period of consolidation of knowledge and recognition of the importance of Chagas disease. Studies conducted by Laranja, Dias and Nóbrega in Bambuí updated the description of Chagas heart disease made by Carlos Chagas and Eurico Villela. From then on, the disease was more easily recognized, especially with the emphasis on the use of a serologic diagnosis; (d) period of enlargement of knowledges on the disease. The studies on denervation conducted in Ribeirão Preto by Fritz Köberle starting in the 1950 decade led to a better understanding of the relations between Chagas disease and megaesophagus and other visceral megas detected in endemic areas.