High-throughput simultaneous quantitation of multi-analytes in tobacco by flow injection coupled to high-resolution mass spectrometry

The high-throughput screening by flow injection coupled to high-resolution mass spectrometry (HTS-FIA-HRMS) is a powerful technique that enables the identification of several types of samples in a short period of time, either with qualitative or quantitative purposes. Sensory attributes of tobacco are affected by its chemical composition, and it is very important to quantify multi-analytes in a high-throughput methodology. HTS-FIA-HRMS coupled to multivariate analysis was used to create calibration models for 27 analytes, or group of compounds, of tobacco sensory interest. The models were validated by different approaches, including permutation test to avoid overfitting, evaluation of the equipment repeatability by control samples, reproducibility comparison of results from two different equipment and analysts, and with a blind test analysis. All tests demonstrated a good response to the proposed method. No statistical difference between the errors of both equipment was observed, with less than 7% error from the control samples, and a blind test error between 5.96% and 20.10%. The partial least squares (O-PLS) regression models were applied to 815 samples, and a principal component analysis (PCA) was performed from the predicted concentration values, aiming at the non-supervised classification based on tobacco type. We expect that this proposed methodology shows not only the applicability in tobacco samples, but also demonstrates a guideline to an efficient performance of multi-analytes target analysis using the flow injection mass spectrometry with reliable and robust validation steps.

Innovative Approaches for Estimating the Levels of Tobacco-Specific Nitrosamines in Cured Tobacco Samples

Tobacco-specific nitrosamines (TSNAs), mainly the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are known carcinogens. Part of the NNK found in smoke is provided from matrix-bound NNK, and its determination is extremely relevant. However, the reference extraction procedure of matrix-bound NNK is time-consuming and labor-intensive and has a limited analytical capacity. Three different methodologies were proposed to predict matrix-bound NNK: simple linear regression (LR) with soluble NNK; multiple linear regression (MLR) considering soluble NNK and characteristic parameters of the samples; and orthogonal partial least-squares (O-PLS) regression using high-throughput screening by flow injection analysis coupled to high-resolution mass spectrometry (HTS-FIA-HRMS) data. Simple linear regression showed a high influence of matrix and leaf origin. Although an existing linearity trend has been observed ( R2 = 0.62) for the global model, higher correlation values were achieved for matrix and country segregation models. Multiple linear regression predicted matrix-bound NNK with more satisfactory efficiency than simple linear regression models. The coefficients of determination were 0.87 and 0.94 for flue-cured Virginia and air-cured Burley, respectively. However, this method has a limited application, since previous information about the sample is required. The proposed method based on HTS-FIA-HRMS and O-PLS has shown the most suitable performance in the prediction of matrix-bound NNK, with errors comparable to the reference method, and a higher throughput. In addition, this approach allows to determine other soluble nitrosamines, namely N'-nitrosoanatabine, N'-nitrosoanabasine, and N-nitrosonornicotine, with relative percentage errors between 5.25 and 11.98%. Therefore, the third approach is the best method for a large number of cured tobacco for accuracy in determination of TSNAs.

Modulation of gut microbiota by antibiotics improves insulin signalling in high-fat fed mice

AIMS/HYPOTHESIS

A high-fat dietary intake induces obesity and subclinical inflammation, which play important roles in insulin resistance. Recent studies have suggested that increased concentrations of circulating lipopolysaccharide (LPS), promoted by changes in intestinal permeability, may have a pivotal role in insulin resistance. Thus, we investigated the effect of gut microbiota modulation on insulin resistance and macrophage infiltration.

METHODS

Swiss mice were submitted to a high-fat diet with antibiotics or pair-feeding for 8 weeks. Metagenome analyses were performed on DNA samples from mouse faeces. Blood was collected to determine levels of glucose, insulin, LPS, cytokines and acetate. Liver, muscle and adipose tissue proteins were analysed by western blotting. In addition, liver and adipose tissue were analysed, blinded, using histology and immunohistochemistry.

RESULTS

Antibiotic treatment greatly modified the gut microbiota, reducing levels of Bacteroidetes and Firmicutes, overall bacterial count and circulating LPS levels. This modulation reduced levels of fasting glucose, insulin, TNF-α and IL-6; reduced activation of toll-like receptor 4 (TLR4), c-Jun N-terminal kinase (JNK), inhibitor of κ light polypeptide gene enhancer in B cells, kinase β (IKKβ) and phosphorylated IRS-1 Ser307; and consequently improved glucose tolerance and insulin tolerance and action in metabolically active tissues. In addition, there was an increase in portal levels of circulating acetate, which probably contributed to an increase in 5'-AMP-activated protein kinase (AMPK) phosphorylation in mice. We observed a striking reduction in crown-like structures (CLS) and F4/80(+) macrophage cells in the adipose tissue of antibiotic-treated mice.

CONCLUSIONS/INTERPRETATION

These results suggest that modulation of gut microbiota in obesity can improve insulin signalling and glucose tolerance by reducing circulating LPS levels and inflammatory signalling. Modulation also appears to increase levels of circulating acetate, which activates AMPK and finally leads to reduced macrophage infiltration.

Reorientation effect and electrical current in a weakly anchored nematic cell

A nematic cell subjected to a large electric field undergoes a molecular reorientation that affects the electrical current flowing through it. To analytically establish the dependence of the current on the applied voltage, the cell is considered as parallel of resistance, R(t) , and capacitance, C(t) , that are connected with the nematic director profile. This profile is determined in the quasistatic regime in which the nematic orientation follows the time variation in the external field normal to the cell plates without delay. The analysis performed for a weakly anchored cell shows that the current presents a peak when the applied voltage overcomes the threshold voltage for the transition of Fréedericksz at a critical time t* as in the case of strong anchoring. For large voltages, R(t)-->R|| and C(t)-->C||, where parallel refers to the nematic director. We show that, for large enough time t>>t*, it is possible to connect the measured current with the extrapolation length characterizing the sample by means of simple analytical expressions. This connection can be used to experimentally estimate the anchoring energy by means of current measurements.

Long-time behavior of spreading solutions of Schrödinger and diffusion equations

We investigate the asymptotic time behavior of the solutions of a large class of linear differential equations that generalize the free-particle Schrödinger and diffusion equations, containing the standard ones as particular cases. We find general scalings that depend only on characteristic features of both the arbitrary initial condition and the Green function associated with the evolution equation. Basically, the amplitude of a long-time solution can be expressed in terms of low order moments of the initial condition (if finite) and low order spatial derivatives of the Green function. These derivatives can also be of the fractional type, which naturally arise when moments are divergent. We apply our results to a large class of differential equations that includes the fractional Schrödinger and Lévy diffusion equations. In particular, we show that, except for threshold cases, the amplitude of a packet may follow the asymptotic law t-alpha, with arbitrary positive alpha.

Metabolism of benzonitrile by Cryptococcus sp. UFMG-Y28

The yeast Cryptococcus sp. UFMG-Y28 can utilize benzonitrile as a nitrogen and possible additional carbon source. The kinetics of growth on Yeast Carbon Base (YCB) added of benzonitrile as sole nitrogen source showed that benzonitrile was metabolized to benzoic acid and ammonia. Liquid chromatography analysis indicated that Cryptococcus sp. UFMG-Y28 metabolized 12 mM benzonitrile to 10 mM benzoic acid. Resting cells cultivated on YCB-propionitrile medium showed nitrilase activity against benzonitrile. This strain appears to be promising for bioconversion of nitriles to high value acids and for bioremediation of sites contaminated with aliphatic and aromatic nitriles.

Bioconversion of nitriles by Candida guilliermondii CCT 7207 cells immobilized in barium alginate

Nitrile degradation by Candida guilliermondii CCT 7207 using free and immobilized cell systems was compared. Different specific growth rates were observed for immobilized (mumax=0.021 h(-1)) and the free cells (mumax=0.029 h(-1)). The maximum specific rate of acetic acid formation was 0.387 h(-1) and 0.266 h(-1) for free and immobilized cells, respectively. Cell adhesion to the support materials was confirmed by scanning electron microscopy. When immobilized, the yeast was able to use high nitrile and amide concentrations (aliphatic and aromatic) as nitrogen sources. The results suggest that C. guilliermondii CCT 7207 presents a physiological pattern potentially useful for the bioremediation of polluted environments or for the bioproduction of amides and organic acid of high commercial value.

[Chagas disease, environment, participation, and the state]

Human Chagas Disease (HCD) affects 16 million Latin Americans and is related to environmental and social questions like education, anthropogenic changes, housing, and migration. HCD requires domiciliation of the vector, which is introduced from sylvatic ecotopes or transported passively by humans. HCD is difficult to treat but possible to prevent. As a disease concentrating among poor individuals and regions, its control requires government intervention, involving education, community participation, and access to medical care. Public policies are required for HCD control, requiring participation by political parties and social control of public agencies to ensure program continuity. A consistent environmental policy is needed to prevent the spread of HCD to new areas such as the Amazon Region. Finally, partnerships among affected countries can help foster HCD control, raising self-esteem and helping promote a new political order in Latin America.

Morphometry of submucous and myenteric esophagic plexus of dogs experimentally reinfected with Trypanosoma cruzi

We carried out a morphometric study of the esophagus of cross-bred dogs experimentally infected or consecutively reinfected with Trypanosoma cruzi 147 and SC-1 strains, in order to verify denervation and/or neuronal hypertrophy in the intramural plexus. The animals were sacrificed in the chronic stage, 38 months after the initial infection. Neither nests of amastigotes, nor myositis or ganglionitis, were observed in all third inferior portions of esophageal rings analyzed. No nerve cell was identified in the submucous of this organ. There was no significant difference (p>0.05) between the number, maximum diameter, perimeter, or area and volume of the nerve cells of the myenteric plexus of infected and/or reinfected dogs and of the non-infected ones. In view of these results we may conclude that the 147 and SC-1 strains have little neurotropism and do not determine denervation and/or hypertrophy in the intramural esophageal plexuses in the animals studied, independent of the reinfections.

[Chagas disease in Brazil]

This article presents the current situation for Chagas disease vectors in Brazil, based on data from the Brazilian National Health Foundation (FNS). Over the course of the last 20 years, continuous chemical control has resulted in a clear reduction of triatomine densities and Trypanosoma cruzi in Brazilian dwellings. Results have been particularly promising in relation to Triatoma infestans and Panstrongylus megistus, considered the most important species in the past. In parallel, data from school serological surveys, hospitalized patients, and mortality records show an important decrease in the disease. Nevertheless, some areas of the Brazilian Northeast and some residual foci of Triatoma infestans and Panstrongylus megistus remain as major challenges for public health authorities, requiring effective epidemiological surveillance. States and municipalities are required to assume this task at present, as the traditional Brazilian National Health Foundation is undergoing decentralization.

[Epidemiological surveillance of Chagas disease]

Chagas disease still constitutes an important medical problem in affected countries. In some, the extent of the disease is still unknown and control programs have not been implemented. In others the disease has been reduced due to regular control programs and other economic and social factors. Epidemiological surveillance with community participation to guard against disease transmission is now the basic challenge. Applied research and in-depth reformulation of health systems are required to establish efficient and sustainable Chagas disease surveillance programs, considering low density of peridomiciliary vectors as the most relevant factor. In addition, a large population of already infected, poor individuals require specific medical attention and social security. As a consequence of health care decentralization, Federal institutions such as the Brazilian National Health Foundation (FNS) are being progressively decommissioned, and new participants must be engaged in the process. Communities themselves, together with regional and local institutions, must take charge of surveillance in order to guarantee its efficiency and sustainability.

[Operational aspects of Triatoma brasiliensis control]

Vector control strategies against indigenous species is not easy, due to their capacity to reinvade treated premises from sylvatic ecotopes. Between August 1996 and December 1997 we conducted a study on reinfestation of houses after spraying in a county in the State of Ceará. Of 277 houses examined, 113 (40.8%) were infested (21.7% intradomiciliary and 35.4% peridomiciliary). Of the 433 Triatominae collected, 207 were Triatoma brasiliensis (49% of which intradomiciliary, with a mean of 1.8 insects/house) and 226 were Triatoma pseudomaculata (97% peridomiciliary). The age structure of the two indicated a univoltine development cycle for T. brasiliensis and two cycles per year for T. pseudomaculata. Four months after spraying with deltamethrin SC 25mg ia/m2, 9.7% of the houses were still positive, mainly with peridomestic infestations. Intradomiciliary wall bioassays showed persistence of the insecticide up to 9 months after spraying. Considering the high potential for recolonization of treated premises from sylvatic foci, we propose an operational strategy combining traditional evaluations and community-based surveillance with increased selective interventions and community education.

[General situation and perspectives of chagas disease in Northeastern Region, Brazil]

Primary and secondary data show the importance and distribution of human Chagas disease (HCD) in Northeast Brazil. Among the 27 detected vector species, Triatoma infestans, Panstrongylus megistus, Triatoma brasiliensis and Triatoma pseudomaculata are epidemiologically important. Major medical impact is attributed to T. infestans and P. megistus, the most domiciliated and vulnerable species, while the other two are native and more difficult to control. Regional differences in transmission and medical impact of HCD exist in the Northeast, where in general the disease appears to be less harmful than in other Brazilian regions like the Southeast and State of Goiás. There is a downward trend in HCD transmission and morbidity in the Northeast, its control in the region is a cause of concern because of the decommissioning of the National Health Foundation without a corresponding assimilation of its routine activities by regional and municipal institutions.

[Health care reform, decentralization, prevention and control of vector-borne diseases]

Economic policies are changing Latin American health programs, particularly promoting decentralization. Numerous difficulties thus arise for the control of endemic diseases, since such activities traditionally depend on vertical, and centralized structures. Theoretical arguments in favor of decentralization notwithstanding, no such tradition exists at the county level. The lack of program expertise at peripheral levels, intensive staff turnover, and even corruption are additional difficulties. Hence, the simple bureaucratic transfer of activities from the Federal to county level is often irresponsible. The loss of priority for control of endemic diseases in Latin America may mean the inexorable extinction of traditional control services. Malaria, dengue fever, and Chagas disease programs are examples of the loss of expertise and effectiveness in Latin America. A better strategy for responsible decentralization is required. In particular, a shared transition involving all governmental levels is desirable to effectively modernize programs. Maintenance of regional reference centers to ensure supervision, surveillance, and training is suggested.

[Epidemiological surveillance of Chagas disease]

Chagas disease still constitutes an important medical problem in affected countries. In some, the extent of the disease is still unknown and control programs have not been implemented. In others the disease has been reduced due to regular control programs and other economic and social factors. Epidemiological surveillance with community participation to guard against disease transmission is now the basic challenge. Applied research and in-depth reformulation of health systems are required to establish efficient and sustainable Chagas disease surveillance programs, considering low density of peridomiciliary vectors as the most relevant factor. In addition, a large population of already infected, poor individuals require specific medical attention and social security. As a consequence of health care decentralization, Federal institutions such as the Brazilian National Health Foundation (FNS) are being progressively decommissioned, and new participants must be engaged in the process. Communities themselves, together with regional and local institutions, must take charge of surveillance in order to guarantee its efficiency and sustainability.

The noble enigma: Chagas' nominations for the Nobel prize

Carlos Chagas, a Brazilian physician, discovered the American trypanosomiasis in 1909. Like other remarkable discoveries of those days, his work helped to articulate the insect-vector theory and other theoretical guidelines in tropical medicine. Unlike all other discoveries, all the stages of this work were accomplished in a few months and by a single man. Chagas' discovery was widely recognized at home and abroad. He was twice nominated for the Nobel Prize - in 1913 and in 1921-, but never received the award. Evidence suggests that the reasons for this failure are related to the violent opposition that Chagas faced in Brazil. The contentions towards Chagas were related to a rejection of the meritocratic procedures that gave him prominence, as well as to local petty politics.

Enzymatic degradation of nitriles by a Candida guilliermondii UFMG-Y65

Candida guilliermondii UFMG-Y65, isolated from a gold mine, was able to utilize different nitriles and the corresponding amides as sole source of nitrogen, at concentrations up to 2 M. Resting cells cultivated on YCB-acetonitrile medium showed nitrile hydrolyzing enzyme activities against acrylonitrile and benzonitrile. These enzymes were inducible and intracellular; the optimum pH was 7.0-8.0, and the optimum temperature 25 degrees C-30 degrees C. Liquid chromatographic analysis indicated that C. guilliermondii UFMG-Y65 metabolized 12 mM benzonitrile to 11 mM benzoic acid and 10 mM acrylonitrile to 7.9 mM acrylic acid. The results suggest that C. guilliermondii UFMG-Y65 may be useful for the bioproduction of amides and acids, and for the bioremediation of environments contaminated with nitriles.

The Southern Cone Initiative against Chagas disease

Chagas disease (also known as American trypanosomiasis) is now ranked as the most serious parasitic disease of the Americas, with an economic impact far outranking the combined effects of other parasitic diseases such as malaria, schistosomiasis and leishmaniasis. Although the chronic infection remains virtually incurable, transmission can be halted by eliminating the domestic insect vectors and screening blood donors to avoid transfusional transmission. In line with this strategy, governments of the six Southern Cone countries (Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay) launched in 1991 an ambitious initiative to control Chagas disease through elimination of the main vector, Triatoma infestans, and large-scale screening of blood donors. Now at its mid-point, the programme has achieved remarkable success, with transmission halted over vast areas of the previously endemic regions. Well over 2 million rural houses have been sprayed to eliminate T. infestans, and the programme has already shown significant economic rates of return in addition to the medical and social benefits.

[Community participation and control of endemic diseases in Brazil: problems and possibilities]

Community participation (CP) is considered one of the most important elements for the control of endemic diseases in poor countries, particularly for prevention and epidemiological surveillance. Mainly affecting the poorest segments of the population, endemic diseases are costly and require specific government action aimed at efficient, egalitarian, universal health system, where CP acts in a guardian, monitoring capacity and entails other specific tasks. Despite its rationality, CP has not been encouraged in countries like Brazil, due to the highly centralized nature of political power and activity. Several examples and situations of CP in Brazilian endemic diseases are described and discussed in the article. CP for endemic disease control should be seen as an ongoing social process, a profound social exercise, and a great challenge for the country as a whole and the new Unified Health System now being implemented in Brazil.

[The control of the transmission by transfusion of Chagas' disease in the Southern Cone Initiative]

The Southern Cone Initiative against Chagas' disease, was launched in 1991. The aim was to interrupt the transmission of Chagas disease by elimination of domestic populations of the major vector, Triatoma infestans, and by improved screening of blood donors. As a result of these activities, a marked reduction in the risk of transfusional transmission can now be seen throughout the programme area. In addition to specific legislation concerning the quality of transfused blood, a series of national and regional reference laboratories have been set up with the help of PAHO in order to improve the quality of pre-transfusional serodiagnosis. Results indicate a progressive reduction in the overall infection prevalence of blood donors, and show that the age-prevalence curve has shifted towards older age-groups. In this paper we analyse the changes in infection prevalence in the Southern Cone countries, drawing attention to the situation in Bolivia which has the highest indices of infection and lowest levels of coverage by the control programme. In this situation chemoprophylaxis of blood prior to transfusion may be recommended in accordance with PAHO criteria. In the medium term however, interruption of human Chagas disease transmission may be expected over most of the Southern Cone region, as long as the control activities are continued and consolidated through effective epidemiological surveillance.

IFN-gamma in human Chagas' disease: protection or pathology?

An apparently paradoxical role for IFN-gamma in human Chagas' disease was observed when studying the pattern of cytokine production by peripheral blood mononuclear cells (PBMC) obtained from two groups of chagasic patients after specific stimulation with Trypanosoma cruzi-derived antigens. The groups studied were 1) patients treated with benznidazole during the acute phase of Trypanosoma cruzi infection and 2) chronically infected untreated patients. In the treated group, higher levels of IFN-gamma were produced by PBMC from individuals cured after treatment when compared to non-cured patients. In contrast, in the chronically infected group (not treated) higher levels of IFN-gamma were produced by PBMC from cardiac patients in comparison with asymptomatic (indeterminate) patients. This apparently paradoxical role for IFN-gamma in human Chagas' disease is discussed in terms of the possibility of a temporal difference in IFN-gamma production during the initial stages of the infection (acute phase) in the presence or absence of chemotherapy. The maintenance of an immune response with high levels of IFN-gamma production during the chronic phase of the infection may favor cure or influence the development of the cardiac form of the disease.

[Cecílio Romaña, Romaña's sign and Chagas' disease]

Cecílio Romaña was an important Argentinean researcher dedicated to tropical diseases in the period 1930-1960, recently died in Barcelona. Working mainly on the epidemiological, clinical and pathological aspects of American trypanosomiasis, Romaña became very famous in 1935 when he accurately described the most typical portal recognized in all the endemic area with the cognomen of "Romaña sign". This description caused an enormous polemic with Romaña's then director, the great Salvador Mazza, who never accepted the specificity of the sign and, much less, its popular name (which was proposed by the Brazilian researchers Emmanuel Dias and Evandro Chagas). This history is briefly summarized in the present article, as well as the great impact of Romaña's discovery in the recognition of the acute Chagas' disease in all the endemic area.

Utilization of acetonitrile and other aliphatic nitriles by a Candida famata strain

A variant of a yeast strain identified as Candida famata isolated from gold mine effluent was able to grow on acetonitrile, acrylonitrile, butyronitrile, isobutyronitrile, methacrylnitrile, propionitrile, succinonitrile, valeronitrile, acetamide, isobutyamide, and succinamide as sole nitrogen source, after acclimatization. The yeast grew on acetonitrile and acetamide at concentrations up to 4%. The utilisation of acetonitrile and acetamide by the C. famata strain probably involves hydrolysis in a two-step reaction mediated by both inducible and intracellular nitrile hydratase and amidase.

Anti-Trypanosoma cruzi antibody isotype profiles in patients with different clinical manifestations of Chagas' disease

Chagas' disease results from infection with the protozoan hemoflagellate Trypanosoma cruzi. Patients in the chronic phase of infection can be categorized into four groups based on the presence of cardiac abnormalities (CARD), gastrointestinal involvement (DIGEST), a combination of both presentations (BOTH), or indeterminate (IND) if Chagas' related pathology is not apparent. Previous studies have indicated that parasite-specific antibody production is important in both resistance to and pathogenesis of disease. The anti-T. cruzi epimastigote stage antibody isotype profiles in the sera of Brazilian patients from each clinical category, as well as from uninfected individuals (UNINF) from the same endemic area were analyzed. Anti-epimastigote immunoglobulin G (IgG)1 and IgG3 levels were strikingly high with titers > or = 1:100,000. Sera from patients in the CARD group had higher levels of IgM than either UNINF or IND individuals, which is consistent with the theory that autoimmunity may contribute to chagasic cardiomyopathy. The IgA levels were higher in sera from patients with gastrointestinal involvement when compared with individuals from any of the other clinical categories as well as from uninfected controls. Interestingly, patients with both digestive and cardiac involvement did not express high serum levels of IgA. However, like patients with cardiac involvement alone, persons with both clinical manifestations produced elevated levels of IgG2 compared with the IND or UNINF groups. These data suggest the presence of complex immunoregulatory processes, most likely related to differential cytokine involvement, which can influence the expression of antibody isotypes and possibly the course of disease.

[Feeding and defecation dynamics of Triatoma sordida]

Today, Triatoma sordida is the most frequently captured triatomine in Brazil. For a better understanding of its vectorial potential, its feeding dynamics and dejections behaviour were studied in comparison with Triatoma infestans and P. megistus. The proportion of T. sordida and T. infestans that blood fed on anaesthetized rats did not differ significantly. There was no significant difference in the time elapse between release of the bugs and the initiation of blood feeding. The mean time between completion of a blood meal and the first dejection was significantly lower in T. infestans than in T. sordida. The numbers of insects that defecated during the blood meal or immediately afterwards was similar for both species. Approximately 80 specimens of each of T. sordida, T. infestans and Panstrongylus megistus were offered daily blood meals for 30 minutes, over a period of 30 days. T. sordida bit more frequently than did P. megistus and T. infestans. These data could indicate that T. sordida may not be completely adapted to its host and might have difficulty in complete its blood meal.

Inter-relation of sylvatic and domestic transmission of Trypanosoma cruzi in areas with and without domestic vectorial transmission in Minas Gerais, Brazil

During the period 1980-1986, we captured triatomine bugs and mammalian reservoir hosts from sylvatic and domestic situations in different municipalities of the State of Minas Gerais. Trypanosoma cruzi was isolated from captured bugs, mammals and patients. After cultivation in LIT medium, the electrophoretic enzyme profiles were determined. We obtained a total of 32 parasite isolates from regions with active domestic transmission, and 24 isolates from areas under control. For the first areas the results suggest introduction of T. cruzi from sylvatic habitats, through incursion of infected opossums and/or sylvatic T. sordida, which appears to have given rise to at least one acute human infection. Of particular interest is the finding of sylvatic opossums and a T. sordida nymph infected with ZB, that could indicate return of parasites from chronic human infections to sylvatic transmission cycles. For the areas under control we also interpret the results as interaction between sylvatic and domestic cycles of transmission, here through the invasion of houses by bugs carrying the Z1 zymodeme from the sylvatic environment. The Multivariate Correspondence Analysis gives a spatial description between the different parasite isolates and confirms the existence of a bridge in the opposite direction in the region with active vectorial transmission including the exporting of Z2 through the peridomestic environment into the sylvatic cycle. For the other areas this bridge corresponds especially to Panstrongylus megistus, importing Z1 into the domestic environment.

Inter-relações entre os ciclos de transmissão do Trypanosoma cruzi no município de Bambuí, Minas Gerais, Brasil

Neste trabalho apresentamos um estudo das inter-relações recentes entre os ciclos de transmissão silvestre e doméstico do T. cruzi no município de Bambuí, Minas Gerais, Brasil. No final da década de 1930, o Panstrongylus megistus era encontrado em 75% das casas. Subseqüentemente, o Triatoma infestans tornou-se a espécie predominante, sendo encontrada em 20% das residências urbanas e em mais de 60% das periurbanas. Com as intensas campanhas de borrifação desenvolvidas entre 1956 e 1969, o T. infestans foi erradicado do município, e a transmissão da doença de Chagas ao homem, interrompida, com aparecimento de P. megistus em residências rurais. Amostras de T. cruzi isoladas via xenodiagnóstico e hemocultura de 43 gambás (Didelphis albiventris) capturados em ambiente peridomiciliar e silvestre foram caracterizadas isoenzimaticamente e, independentemente da via de isolamento, apresentaram perfil de zimodema Z1. Por meio do Programa de Vigilância Epidemiológica da doença de Chagas, no período de agosto de 1986 a dezembro de 1988, 154 exemplares de P. megistus foram capturados pela população no peridomicílio e intradomicílio rural, estando 9,8% infectados pelo T. cruzi. Na caracterização isoenzimática de 13 amostras de T. cruzi isoladas desses triatomíneos, seis pertenciam ao zimodema Z1 (ciclo de transmissão silvestre), e sete ao Z2 (ciclo de transmissão doméstico). A captura de exemplares de P. megistus no intradomicílio, naturalmente infectados com parasitas de ambos os ciclos, indica a superposição dos ciclos de transmissão da doença de Chagas no município de Bambuí. Outra evidência da inter-relação dos ciclos pôde ser observada no isolamento de T. cruzi Z2 de um gato e a participação do cão como reservatório de T. cruzi Z1. A presença do P. megistus no peridomicílio representa importante elo entre o ambiente silvestre e o intradomicílio, servindo como veiculador do T. cruzi Z1 e na manutenção de ciclos de transmissão do T. cruzi Z2 no peridomicílio e domicílio, propiciando de forma gradual a reinfestação do município caso a Vigilância Epidemiológica seja interrompida.

Evaluation of the Chagas' disease vector control program in Minas Gerais, Brazil, with special reference to Triatoma sordida

As of 1979, data gathered by the Chagas' Disease Control Program (CDCP) in the Brazilian state of Minas Gerais indicated that Triatoma infestans was the Chagas' disease vector most commonly found in and around human dwellings. A decade later, however, this picture had changed, presumably as a result of control efforts; few specimens of T. infestans were collected; and Triatoma sordida had become the most commonly collected vector insect. The aim of the work reported here was to assess the effectiveness of the CDCP in Minas Gerais in 1979-1989, with special reference to T. sordida. For this purpose, 1979-1989 triatomine collection data were reviewed for the two Minas Gerais health districts (Montes Claros and Uberaba) believed to have the heaviest T. sordida infestations. In addition, 1987 data from a serologic survey for human Trypanosoma cruzi infections in seven municipalities of these regions were compared with earlier (1978) serologic data from the same locales. In general, the triatomine collection data documented the precipitous decline of T. infestans in and around human dwellings. They also indicated that while the T. sordida collections had remained stable (in Uberaba) or increased markedly (in Montes Claros), there had been no great upsurge in the numbers of T. sordida collected inside dwellings. It was concluded that control measures were preventing extensive house reinfestations in both Montes Claros and Uberaba; that the situation in Uberaba was relatively stable; and that the marked increase in T. sordida populations around homes in Montes Claros was associated with forest clearing and changing settlement patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Ecological aspects of the vectorial control of Chagas' disease in Brazil

The feasibility and most important ecological aspects of vectorial Chagas' disease control are discussed. The spread and maintenance of this disease involve multiple ecological and sociopolitical factors that must be taken into account when control programs are planned, executed and evaluated. In spite of its complexity, Chagas disease can be controlled using methods that target specific mechanisms of transmission, the most important being vectorial and transfusional. Major ecological problems in Chagas' disease control do not exist, even in the case of the chemical control of triatomine vectors. The main challenges for the Brazilian Control Program at this moment are: its maintenance as a political priority; the threat of peridomestic vectors; and the consolidation of permanent horizontal and participative epidemiological surveillance systems against the vector.

[Hemotherapy and transfusional Chagas' disease in Brazil]

With the increased presence of Chagas' disease in urban areas and the rising importance of transfusional transmission of Trypanosoma cruzi, a proper and realistic approach to hemotherapeutic treatment has become crucial in Brazil. Bringing together data from various institutions, this study analyzed hemotherapy and the problem of transfusional Chagas' disease in 850 Brazilian municipalities from 1988 to 1989. It was found that some type of hemotherapy was practiced in 68.8% of these municipalities at the time, this practice being qualitatively and quantitatively proportional to the population size of the municipality. The official blood bank system supplied the blood used in 13% of these services. In relation to prevention of the main diseases transmissible by transfusion, prior screening of donors was carried out by 75.2% of the services for syphilis, 65.4% for hepatitis, 53.8% for AIDS, and 66.9% for Chagas' disease. These percentages vary by region and by size of the municipality. The majority of donors are classified as voluntary, with only 2% categorized as paid donors. In the case of Chagas' disease, most services used only one serologic technique to screen donors, most commonly hemagglutination or immunofluorescence, while only 10.3% of services had previous experience with chemoprophylaxis using gentian violet. The proportion of potential donors with positive serology for anti-Trypanosoma cruzi antibodies was around 1%. These data were confirmed by information from blood banks and Brazilian hemotherapy professionals.

Community participation in vector control: lessons from Chagas' disease

As applied to vector-borne disease control, the term community participation has been broadly interpreted. Community-based vector control projects have been described as having both active and passive components. Recently, community participation in organized efforts to control Chagas' disease has become more dynamic, with increasingly active involvement by local community members. Chagas' disease is a particularly significant vector-borne disease problem in the South American countries of Brazil, Venezuela, and Bolivia, and health officials there are beginning to emphasize horizontal or decentralized approaches to control of triatomine vectors. Experience suggests that vector control programs using community participation have significant and sustainable impact on vector density, appear to be more cost-effective than purely vertically structured programs, are readily integrated with other health or development programs, promote an enduring sense of pride in home and community, and are politically viable vector control strategies. Community participation per se has inherent value because of its positive effect on social relationships and community solidarity. Moreover, it is a dynamic process that results in accrued benefits for public health that exceed most vector control program goals and persist well beyond program termination.

[Parasitologic and serological evaluation of caprines experimentally inoculated with Trypanosoma cruzi]

The experimental infection by Trypanosoma cruzi was studied in nine young goats. These animals were inoculated by intraperitoneal route with 10(3) trypomastigotes/Kg body weight with strains 147 (Group 1) and 229 (Group 2), isolated from chronic Chagasic patients proceeding from Bambuí, Minas Gerais, Brazil. The infected animals were submitted to fresh blood examinations, xenodiagnosis, hemoculture and serology (IFAT and ELISA). The follow up of T. cruzi infection ranged from 7 to 30 months and it was possible to note a markable difference concerning the course of infection between the two groups. The parasite was visualized, for the first time in experimentally infected goats in the acute period through fresh blood examinations and xenodiagnosis and through hemoculture and xenodiagnosis during the chronic period of the Chagasic infection. These results suggest that, under some epidemiological conditions, goats may be important in the sylvatic and peridomiciliar transmission cycles of T. cruzi specially young animals.

A doença de Chagas e seu controle na América Latina: uma análise de possibilidades

A doença de Chagas segue como importante agravo à saúde na maior parte da América Latina, afetando 16 milhões de pessoas e colocando sob risco outras dezenas de milhões de indivíduos, geralmente de origem rural, pobres e socialmente marginalizados. As estratégias e insumos ao controle da endemia concentram-se no controle do vetor e da transmissão transfusional, mostrando-se eficientes e estando disponíveis há pelo menos duas décadas. Sua implementação depende basicamente de vontade política e de disponibilidade técnica e orçamentária, como demonstrado no exemplo brasileiro. São discutidos aspectos epidemiológicos e operacionais da luta antichagásica, o que envolve um horizonte de reformulação e aprimoramento dos próprios sistemas de saúde dos países endêmicos. O controle da doença é viável, constituindo-se num desafio às autoridades sanitárias e à opção dos países pela esfera social. Em particular, a superação da doença de Chagas pode ser um importante fator de catálise para a almejada unidade latino-americana.

The ecology of Triatoma sordida in natural environments in two different regions of the state of Minas Gerais, Brazil

A study was undertaken about T. sordida in the natural environment in two different regions of the state of Minas Gerais: Itapagipe (Triângulo), an area of cerrado modified by the formation of fields of pasture and agriculture, and Mato Verde (north) an area of transition between caatinga and cerrado with profound deforestation in the last years due to the expansion of cotton cultivation. In both regions the principal ecotopes identified were hollow trees and the bark of live or dead trees, where the occurrence of a food source is not frequent. In this environment, the triatomines utilize various food sources; opposums appear to represent an important source of infection. In the north of Minas, a greater concentration of reservoirs and vectors was observed than in the Triângulo which could explain the higher level of infection of the triatomines in the north. Close attention to the process of domiciliation of T. sordida in the north of Minas is recommended where an extensive intervention by man in the natural environment has occurred and where a rise in the population of triatomines in the peridomestic environment has been observed in recent years.

[The clinical, social and occupational aspects of Chagas disease in an endemic area under the control of the state of Minas Gerais, Brazil]

Among 301 construction workers examined in Bambuí, Brasil, 11.6% presented positive serology for American trypanosomiasis, with a prevalence of 5.0% in the age group 17-29 years, 13.8% in the 30-39 and 39.4% in the 40-57. Electrocardiographic disturbances were detected in 31.3% of the seropositive and in 7.1% of the seronegative individuals, with a significant difference in the age group 40-57 years. Cardiac enlargement and esophagopathy were detected respectively in 8.6% and 8.6% of the positive and 1.5% and 0.8% of the negative group. Chagasic and non-Chagasic individuals came from the same region and social status, but the seropositive group was more associated with low scholarship and immediate antecedent of rural activities. The effectiveness of the programme of vector control installed in the Region in the years 1970 is once more confirmed by its positive impact on the prevalence and morbidity of human Chagas disease. Congenital and transfusional Chagas disease seem to play a very small epidemiologic role in the Region at the present time.

[Intracardial autonomous nervous system in a fatal case of acute Chagas disease]

An analysis of the intracardiac autonomic nervous system (ICANS) has been made in 150 histological sections obtained from atrial fragments of a 74 year-old man who died of cardiac failure, as a consequence of acute Chagas' disease (ACD), probably acquired via digestive tract. Small quantities of mononuclear infiltrate around ganglia and/or nerve branches without significant morphologic alterations of the neurons were found in 10 slides; another slide showed ganglionitis and periganglionitis of moderate intensity associated to neuronal alterations. Focal epicarditis, usually of slight degree, was observed in all slides. The findings suggest: a) that the inflammation of ganglia and fibers of the ICANS in the ACD occurs at least in part by expansion from adjacent epicarditis; b) that even in the fatal cases of the trypanosomiasis cruzi the pathologic lesions of the ICANS may be slight.

The threat of reintroduction of natural transmission of Chagas' disease in Bambuí, Minas Gerais State, Brazil, due to Panstrongylus megistus

In the Epidemiological Surveillance Program in the county of Bambuí, Minas Gerais, between August 1986 and December 1988, 154 Panstrongylus megistus were captured by the local population in both peridomicile and intradomicile environments. Fifteen (9.8%) of the P. megistus harboured Trypanosoma cruzi. Precipitin tests showed that the most frequent triatomine blood meal sources were birds, but other sources were dogs, men and cats. The isoenzyme characterization of 13 T. cruzi strains showed that six belonged to zymodeme Z1, corresponding to the wild cycle parasites, and seven belonged to zymodeme Z2, corresponding to parasites isolated from chronic chagasic patients (domestic cycle). As P. megistus were found to be naturally infected by parasites from both cycles. They are clearly able to transmit T. cruzi from the wild cycle to the domestic cycle. Furthermore the capacity of P. megistus in colonizing houses was observed in one residence, vacant for several years, in which 153 triatomines were captured. The data show the possibility of P. megistus reintroducing the natural transmission of Chagas' disease in the county if Epidemiological Surveillance is interrupted.

Possible oral transmission of acute Chagas' disease in Brazil

In October 1986, 7 to 22 days after a meeting at a farm in Paraíba state, 26 individuals presented with a febrile illness associated with bilateral eyelid and lower limb edema, mild hepatosplenomegaly, lymphadenopathy and, occasionally a skin rash. A 11-year-old boy exhibited atrial premature complexes and a 74-year-old patient developed acute heart failure. In two patients hospitalized in São Paulo city, acute Chagas' disease was diagnosed by the demonstration of circulating Trypanosoma cruzi. At autopsy in a fatal case, acute Chagas' cardiomyopathy was demonstrated. Xenodiagnosis were positive in 9 out of 14 tested patients. A specific IgG immune response was found in all patients and specific IgM antibodies were identified in 20 out of 22 tested patients. A epidemiological survey showed the existence of Triatoma brasiliensis in the outbuildings of this farm, but none in the house where most of the guests stayed. A high rate of infection with Trypanosoma cruzi was found in opossums. These observations together with those related to the food consumed by the patients, lead the authors to suggest that the human infections resulted from oral contamination probably originating from naturally infected marsupials in the area or crushed infected bugs.

[Epidemiologic study of the sources of blood feeding of the triatominae of the Aroeira farm (Catolé do Rocha, Paraìba) and neighboring localities]

We have analysed the blood feeding sources of 94 triatomine bugs (51 T. brasiliensis, 42 T. pseudomaculata and one R. neglectus) from Fazenda Aroeira, in Catolé do Rocha Municipality, Paraíba State, and four neighbouring localities. The positivity for marsupial, man and bird blood were, respectively, 39.7, 6.2 and 23.0%. Three insects from Fazenda Aroeira were positive both for T. cruzi and marsupial blood while only one of the three was positive for another mammal. Marsupials are the most important source of T. cruzi for the insects of the area, which have little contact with man.