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INTRODUCTION: A descriptive, entomological and seroepidemiological study on Chagas disease was conducted in a place of recent occupation on the outskirts of Cochabamba, Bolivia: Avaroa/Primer de Mayo (population:3,000), where the socio-economic level is low and no control measures have been made available. METHODS: The immunofluorescent antibody test (IFAT) was used for IgG and IgM anti-Trypanosoma cruzi antibodies in filter paper bloodspot eluates from 128 subjects (73 females, 55 males) selected by systematic sampling. Concerning each subject age, gender, birthplace, occupation, duration of residence and building materials used in their houses were recorded. Vectors were captured both in domestic and peridomestic environments. RESULTS: Seropositive, 12.5% (16/128): females, 15.1% (11/73); males, 9.1% (5/55). Average time of residence: 6.1 years for the whole population sample and 7.4 years for the seropositive subjects. Most houses had adobe walls (76. 7%, n= 30), galvanized iron rooves (86.7%) and earthen floors (53. 4%) 80% of the walls had crevices. One hundred forty seven specimens of Triatoma infestans were captured, of which 104 (70.7%) were domestic, and 1 peridomestic Triatoma sordida. Precipitin host identification: birds, 67.5%; humans, 27.8%; rodents, 11.9%; dogs, 8. 7%; cats, 1.6%. House infestation and density indices were 53.3 and 493.0 respectively. We found 21 (14.3%) specimens of T. infestans infected with trypanosomes, 18 (85.7%) of which in domestic environments. DISCUSSION: The elements for the vector transmission of Chagas disease are present in Avaroa/Primer de Mayo and the ancient custom of keeping guinea pigs indoors adds to the risk of human infection. In neighboring Cochabamba, due to substandard quality control, contaminated blood transfusions are not infrequent, which further aggravates the spread of Chagas disease. Prompt action to check the transmission of this infection, involving additionally the congenital and transfusional modes of acquisition, is required.
Assuntos
Doença de Chagas/epidemiologia , Adolescente , Adulto , Animais , Anticorpos Antiprotozoários/sangue , Bolívia/epidemiologia , Gatos , Doença de Chagas/sangue , Doença de Chagas/transmissão , Criança , Pré-Escolar , Cães , Feminino , Técnica Indireta de Fluorescência para Anticorpo , Habitação , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Lactente , Insetos Vetores , Masculino , Pessoa de Meia-Idade , Roedores , Estudos Soroepidemiológicos , Triatoma , Trypanosoma cruzi/imunologia , População UrbanaRESUMO
The enzyme laccase was produced by the white-rot fungus Trametes versicolor in repeated batches cultures with immobilized mycelium. Two different culture conditions were used. Enzymes produced were evaluated regarding their stability at high temperatures (55 degrees C and 65 degrees C) and at alkaline conditions (pH 7.0 and pH 8.0) having in view the application of these enzymes in biobleaching of hardwood Kraft pulp. Biobleaching experiments were divided in two parts, enzymatic prebleaching followed by chemical bleaching. In the enzymatic prebleaching the enzyme laccase was used at two conditions of pH and temperature, whereas the reaction time was fixed at 1 h in all pretreatments. In the chemical bleaching the DEDED and DEpDED sequences were used. The enzyme action was evaluated by Kappa number, viscosity, and brightness at the end of bleaching sequences. There were obtained values of Kappa numbers lower than control assays, viscosities compatible with industrial pulps, and brightness higher than controls, when pulps were pretreated for 1 h with laccase at pH 8.0 and 55 degrees C.
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A critical role has been proposed for the switch from non-cytophilic IgG2 to cytophilic antibodies of IgG1 and IgG3 subclasses observed in the humoral immune responses to Plasmodium falciparum of some Africans. These Africans have acquired clinically immunity naturally, after several years of exposure to holo-endemic malaria. In the present study, the possibility that life-long exposure to low levels of malarial endemicity may be associated with changes in the IgG-subclass composition of antibodies to P. falciparum was investigated in a native Amazonian community. The subjects were 138 malaria-exposed but non-infected Karitiana Indians. In a separate investigation, the concentrations of IgG-subclass antibodies in acutely ill patients with severe malaria (N = 22) were compared with those in age- and sex-matched controls who had uncomplicated malaria (N = 44). Plasma concentrations of IgG against a detergent-soluble extract of P. falciparum schizonts were measured by quantitative ELISA, using indirect standardization. Among the Karitiana, the concentrations of anti-parasite antibodies of all subclasses increased with age, and there was no correlation between age and the proportion of such antibodies which was cytophilic. The predominance of cytophilic IgG1 and non-cytophilic IgG2 antibodies in all age-groups of the Karitiana provides an example of an intermediate pattern of immune responses to P. falciparum which contrasts with those previously described in both clinically immune and non-immune populations. Although mean concentrations of cytophilic IgG1 against P. falciparum were significantly higher in the controls than in the patients with severe malaria, there were no significant differences in other IgG subclasses. Lack of exposure to malaria in the past was associated with disease severity (odds ratio = 4.75; 95% confidence interval = 1.31-17.42), and may explain, at least partially, the occurrence of defective, low-IgG1 antibody responses to P. falciparum in those subjects who had severe malaria.
Assuntos
Anticorpos Antiprotozoários/sangue , Imunoglobulina G/sangue , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Doença Aguda , Adolescente , Adulto , Idoso , Envelhecimento/imunologia , Animais , Brasil , Criança , Pré-Escolar , Estudos Transversais , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Indígenas Sul-Americanos , Lactente , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de DoençaRESUMO
The production of lignin peroxidase from Phanerochaete chrysosporium was studied using immobilized mycelia in nylon-web cubes in semicontinuous fermentation using glucose pulses or ammonium tartrate pulses. Consistent enzyme production was achieved when glucose pulses were used, leading to an average activity of 253 U/L. The crude enzyme was added to eucalyptus kraft pulp before conventional and ECF bleaching sequences. Optimization of the enzymatic pretreatment led to the following operational conditions: enzyme load of 2 U/g of pulp, hydrogen peroxide addition rate of 10 ppm/h, and reaction time of 60 min. Pulp final characteristics were dependent on the chemical treatment sequence that followed enzymatic pretreatment. The chief advantage of enzymatic pretreatment was pulp viscosity preservation, which was observed in most of the experiments carried out with seven different chemical treatment sequences.
RESUMO
Kraft pulp was delignified using laccase produced by the white rot fungus Trametes versicolor immobilized in solid support under specific conditions. The stability tests showed that this enzyme was stable for 6 h at 55 degrees C and pH 8.0, allowing its use under pH and temperature conditions very close to those used in industrial bleaching. In this work, unbleached hardwood Kraft pulp was submitted to prebleaching using 2 U laccase/g pulp basis. Reaction time, temperature, and pH of the enzymatic treatment were investigated. Good results regarding Kappa number reduction, selectivities, and high viscosities were obtained when prebleaching was performed for 1 h at temperature of 55 degrees C and pH 8.0 followed by alkaline extraction and ECF bleaching sequences.
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We estimated the proportion of seropositivity for infection with Trypanosoma cruzi (Chagas' disease) in a sample of the rural population of the Province of Nasca, Department of Ica, southwestern Peru. Although Triatoma infestans, the only vector species identified in the Department of Ica, is often found in domestic environments, data of the extent of human infection with T. cruzi are scant. This study comprised 446 houses, known to be infested with triatomines, distributed in 19 rural localities. While visiting those houses we collected filter paper bloodspots from 864 occupants (of both sexes, aged one year or over). By means of the indirect fluorescent antibody test (IFAT), we detected anti-T. cruzi IgG antibodies in samples from 178 individuals (20.6%). Seropositivity was significantly more frequent in females (23.8%) than in males (17.5%). Among the 410 individuals in the 1- to 10-year-old age group (47.5% of the population sample), 85 (20.7%) were found seropositive, which is indicative of an early acquisition of the infection. Within this group no significant differences in seropositivity were associated with sex.
Assuntos
Doença de Chagas/epidemiologia , Adolescente , Adulto , Animais , Anticorpos Antiprotozoários/sangue , Doença de Chagas/sangue , Doença de Chagas/imunologia , Doença de Chagas/transmissão , Criança , Pré-Escolar , Feminino , Inquéritos Epidemiológicos , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Peru/epidemiologia , Estudos Soroepidemiológicos , Trypanosoma cruzi/imunologiaRESUMO
Antibodies of IgG and IgM isotypes reacting with Plasmodium falciparum and P. vivax thicksmear antigens were searched for by the indirect fluorescent antibody test (IFAT) in a random sample of 230 blood donors at the transfusion centre of Porto Velho (HEMERON), Rondônia State, western Brazilian Amazon. A high prevalence of IgG seropositivity (32% against P. falciparum, 24% against P. vivax and 37% against either P. falciparum or P. vivax antigens) was detected among them, despite the fact that candidates reporting recent (< 12 months) malaria attacks were not eligible. Only a small proportion of them had also detectable IgM antibodies to these antigens. These data suggest an intense, relatively recent exposure to malaria in such an urban population sample. However, parasitaemia (as detected by microscopical examination of Giemsa-stained thick smears) was patent in only one prospective donor. The antibody profile of blood donors was compared with that of healthy subjects of all age groups, living in a close endemic area (Candeias village, 21 km east of Porto Velho). The villagers were classified into two groups according to their history of a recent (< 12 months) or a remote (> 12 months) past malaria attack due to either P. falciparum or P. vivax. Extensive overlapping was observed when the distribution of antibody titres of healthy subjects from Candeias village with a recent and remote malaria history was compared. In conclusion, subjects with a recent or a remote malaria history could not be distinguished by serological criteria alone.
Assuntos
Anticorpos Antiprotozoários/análise , Doadores de Sangue , Imunoglobulina G/análise , Imunoglobulina M/análise , Plasmodium falciparum/imunologia , Plasmodium vivax/imunologia , Adolescente , Adulto , Animais , Antígenos de Protozoários/imunologia , Brasil , Feminino , Imunofluorescência , Humanos , Malária/transmissão , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
A system of surveillance for Chagas' disease aiming at a systematic investigation of the occurrence of triatominae in human dwellings in S. Paulo, Brazil was proposed. It included a serological survey of residents in house considered to be potential breeding places for blood-sucking triatomines. Serologically positive cases were observed to be distributed in age groups from 19 years of age upwards. Case-investigation revealed that the infection had been acquired either in S. Paulo in the past or recently in other States. A serologically positive (titre = 128 - IgG) case of an 8-year-old male child, was detected by the In direct Fluorescent Antibody Technique (IFAT). In S. Paulo State natural transmission is now of low probability. An epidemiological investigation disclosed the fact that this was a case of blood transfusion infection. The donor was found to be serologically positive (IFAT, titre = 1024 - IgG). His case-history was typical of vector transmitted infection. It is worthy of note that blood had been donated by this patient in four instances, without his condition having been diagnosed. The necessity of organizing an integrated Public Health Service to take more efficient care of such cases is stressed.
Assuntos
Doença de Chagas/transmissão , Vigilância da População , Reação Transfusional , Adulto , Brasil , Doença de Chagas/prevenção & controle , Criança , Humanos , Masculino , Desenvolvimento de ProgramasRESUMO
Blood sampling on filter paper is a current practice in malaria seroepidemiological studies by indirect fluorescent antibody test (IFAT). There is, however, scant comparative information about the use of bloodspot eluates for detection of malarial IgG antibodies simultaneously by IFAT and enzyme immunoassay (ELISA). Here we report data obtained by both serological methods done on 219 bloodspot eluate samples collected in a rural community in Brazilian Amazon Basin (Alto Paraíso, Ariquemes municipality) where malaria is endemic. Plasmodium falciparum and P. vivax thick smear antigens were used in the IFAT; a detergent-soluble P. falciparum antigen was prepared for ELISA. Substantial agreement of results (Kappa coefficient k = 0.686) was observed when P. falciparum antigen was used in both tests, and IFAT titers were found to be strongly correlated to ELISA antibody units (Spearman correlation coefficient rs = 0.818, p < 0.001). Only moderate agreement (k = 0.467) between IFAT with P. vivax antigen and ELISA with P. falciparum antigen was observed. Spearman correlation coefficient value between quantitative results (IFAT titers and ELISA antibody units) in this case was numerically lower (rs = 0.540, p < 0.0001). Our results suggest that, with P. falciparum antigen, both IFAT and ELISA performed on bloodspot eluates are equivalent for seroepidemiological purposes.