Are Members of the Triatoma brasiliensis (Hemiptera, Reduviidae) Species Complex Able to Alter the Biology and Virulence of a Trypanosoma cruzi Strain?

Trypanosoma cruzi is the causative agent of Chagas disease, transmitted to humans and mammals by blood-sucking hemipteran insects belonging to the Triatominae subfamily. The two main genotypes of T. cruzi (TcI and TcII) differ in many characteristics concerning their genetic profile. Despite the extensive literature on vectors and the etiologic agent, several interactive aspects between these two elements of Chagas disease are still waiting to be further clarified. Here, biological and histological features resulting from the interaction between Albino Swiss mice and T. cruzi isolate PB913 after passages through vectors of the Triatoma brasiliensis species complex were evaluated. Comparing the four members of the T. brasiliensis species complex-Triatoma brasiliensis brasiliensis Neiva, Triatoma brasiliensis macromelasoma Galvão, Triatoma melanica Neiva & Lent, and Triatoma juazeirensis Costa & Felix-no significant differences in parasitemia of the infected mice were observed. At 20 days post-infection, the highest number of parasites was observed in the group of mice that were infected with parasites obtained from T. b. macromelasoma. Tropism of the parasites to different organs such as heart, bladder, and skeletal muscles followed by inflammatory cell infiltrates was observed with quantitative and qualitative differences. Even though the four members of the T. brasiliensis species complex differ in their geographical distribution, morphology, biology, ecology, and genetics, no significant influence on the parasitemia of the T. cruzi PB913 isolate was detected. After evaluation of the tissue samples, a higher pathogenicity of parasites obtained from T. b. brasiliensis was noticeable.

Influence of specific treatment on the morbidity of Schistosomiasis mansoni in an endemic area of Minas Gerais, Brazil.

The authors describe the evolution of schistosomiasis mansoni in inhabitants of Capitão Andrade, Minas Gerais, Brazil, from 1973 to 1994. The prevalence of infection was 60.8% in 1973, 36.2% in 1984, and 27.3% in 1994. The evolution of the clinical forms of the disease in this group was as follows: unchanged in 76.7%, clinical progression in 8.4% and clinical regression in 14.9%. The reduction of the prevalence and severity of Schistosoma mansoni infection over the 21 years period, can be attributed to treatment of infected subjects performed in the area and to the installation of piped water in their dwellings.

Influence of specific treatment on the morbidity of schistosomiasis mansoni in an endemic area of Minas Gerais, Brazil

The authors describe the evolution of schistosomiasis mansoni in inhabitants of Capitäo Andrade, Minas Gerais, Brazil, from 1973 to 1994. The prevalence of infection was 60.8 percent in 1973, 36.2 percent in 1984, and 27.3 percent in 1994. The evolution of the clinical forms of the disease in this group was as follows: unchanged in 76.7 percent, clinical progression in 8.4 percent and clinical regression in 14.9 percent. The reduction of the prevalence and severity of Schistosoma mansoni infection over the 21 years period, can be attributed to treatment of infected subjects performed in the area and to the installation of piped water in their dwellings

[Sera levels of anti-Trypanosoma cruzi IgG in the course of chronic chagasic cardiopathy in 10 years]. / Níveis séricos de IgG anti-Trypanosoma cruzi na evolução da cardiopatia chagásica crônica, no período de 10 anos.

In order to investigate the relationship between T. cruzi specific antibodies (IgG) levels and the clinical course of chronic chagasic cardiopathy, the authors analyzed sera from 140 non-treated patients with specific drugs from Virgem da Lapa, Minas Gerais, during 10 years. Of these patients, 92 were women and 48 men, varying from 10 to 70 years old (mean = 38 +/-13.5 years). Antibody levels were estimated by the mean of titers obtained by an indirect immunofluorescence test, indirect hemagglutination assay and by the mean reactivity indexes (OD/cut-off) obtained by ELISA tests using a conventional antigens and recombinant proteins (CRA+FRA). During the study period, the course of the disease was as follows: 49 did not present cardiac alterations, 29 coursed to cardiopathy, 33 maintained initial cardiopathy, 25 evolved with aggravation of the cardiopathy and 4 with normalization of the electrocardiogram. Statistical analysis showed a significant increase in antibody levels among patients in the group with progressive cardiopathy, as well as in patients with age interval of 20 to 59 years, independent of sex. These findings indicated a direct association between T. cruzi specific antibodies (IgG) levels and the clinical course of chronic chagasic cardiopathy.

[Chagas' disease in a urban population of the health district of Rio Verde, Mato Grosso do Sul State, Brazil]. / Doença de Chagas na população urbana do distrito sanitário de Rio Verde, Mato Grosso do Sul, Brasil.

In order to evaluate some aspects of the Chagas' disease on urban population of the 12 municipalities of the sanitarian district of Rio Verde, Mato Grosso do Sul state, on 1998 we carried out a serological survey investigating anti-T. cruzi IgG by indirect immunofluorescence on blood samples collected on filter paper of 14,709 resident persons, confirmed by indirect hemagglutination and ELISA in serum. The parasitaemia was evaluated by indirect xenodiagnosis on 134 chagasic patients and the morbidity evaluated by anamnesis, physical exam and electrocardiogram in 191 pairs of chagasic/non-chagasic patients. The seropositivity was 1.83% (0.93% in autochtonous, 5.01% in alochtonous), xenodiagnosis was positive in 17.2% of the individuals (12.3% in autochtonous, 20.8% in alochtonous) and 24.6% of the seropositive patients presented chronic chagasic cardiopathy (19.1% in autochtonous, 27.8 in alochtonous). The analysis of the dates showed that alochtonous population is the main responsible for presence of the infection and morbidity of Chagas disease in the studied area.

A recombinant peptide antigen line immunoassay optimized for the confirmation of Chagas' disease.

BACKGROUND: The transfusion of contaminated blood has become the major route of transmission for Chagas' disease in Brazil. Current screening tests are insensitive and yield conflicting results, while confirmatory assays do not exist. A line immunoassay (INNO-LIA Chagas Ab [INNO-LIA]) combining relevant, immunodominant recombinant and synthetic antigens on a single nylon membrane strip was evaluated for the serologic confirmation of Chagas' disease. STUDY DESIGN AND METHODS: Sera from 1062 patients and healthy residents of four Brazilian regions endemic for Chagas' disease were used for test optimization. The established confirmation algorithm was evaluated with an independent set of positive (n = 75) and negative (n = 148) samples. RESULTS: In the optimization phase, without an established comparative gold standard, the results with the INNO-LIA were compared with those obtained in four other screening assays. In the validation phase, the INNO-LIA showed a sensitivity of 100 percent (95% CI, 95.21-100) and a specificity of 99.32 percent (95% CI, 96.29-99.98) for well-characterized sera. Moreover, its specificity reached 100 percent with a set of 40 sera obtained from patients with documented leishmaniasis. The interpretation criteria defined in this study indicated that the INNO-LIA accurately detected the presence of antibodies to various specific antigens of Trypanosoma cruzi. CONCLUSION: The INNO-LIA Chagas Ab assay may become the first commercial assay to reliably confirm the presence of antibodies to T. cruzi.

[Chagas disease in Virgem da Lapa, Minas Gerais, Brazil. IV. Clinical and epidemiological aspects of left ventricular aneurism]. / Doença de Chagas em virgem da Lapa, Minas Gerais, Brasil. IV. Aspectos clínicos e epidemiológicos do aneurisma ventricular esquerdo.

The study aimed at the evaluation of the clinical and epidemiological characteristics of the aneurysm found in the left ventricle in chronic Chagas' disease patients. Three hundred, eighty eight people (298 chagasic patients and 90 randomly selected healthy individuals) were submitted to echocardiography. The ventricular function was assessed in the M mode by calculating the fraction of ejection, and in the bidimensional mode by analyzing he global systolic function. Segmental contractility was evaluated according to the method described by American Society of Echocardiography. Aneurysm of the left ventricle was diagnosed in 58 (18.8%) patients, all from the chagasic population. From these, 38 (12.7%) were found in the apical segment; 10 (3.4%) in the interventricular septum; and 2 (0.7%) each in the posterior wall; the inferior wall; apico-septal; and inferior-posterior. We could not observe any significant difference for the aneurysm frequencies in relation to age group, gender and race, and no association between aneurysm and arterial hypertension could be made. Of the 56 individuals presenting aneurysm, 55 (98.2%) were symptomatic with predominant palpitations; 53 (94.6%) showed an aberrant ECG with predominant ventricular extra-systoles followed by changes in conduction; and 34 (60.%) showed an impairment of the ventricular function, regardless of the affected segment. In view of these results we consider the apical aneurysm of the left ventricle as a marker of Chagas' disease and as an indicator of high morbidity of the human T. cruzi infection in Virgem da Lapa.

Doença de Chagas em virgem da Lapa, Minas Gerais, Brasil. IV. Aspectos clínicos e epidemiológicos do aneurisma ventricular esquerdo / Chagas disease in Virgem da Lapa, Minas Gerais, Brazil. IV. Clinical and epidemiological aspects of left ventricular aneurism

The study aimed at the evaluation of the clinical and epidemiological characteristics of the aneurysm found in the left ventricle in chronic Chagas' disease patients. Three hundred, eighty eight people (298 chagasic patients and 90 randomly selected healthy individuals) were submitted to echocardiography. The ventricular function was assessed in the M mode by calculating the fraction of ejection, and in the bidimensional mode by analyzing he global systolic function. Segmental contractility was evaluated according to the method described by American Society of Echocardiography. Aneurysm of the left ventricle was diagnosed in 58 (18.8%) patients, all from the chagasic population. From these, 38 (12.7%) were found in the apical segment; 10 (3.4%) in the interventricular septum; and 2 (0.7%) each in the posterior wall; the inferior wall; apico-septal; and inferior-posterior. We could not observe any significant difference for the aneurysm frequencies in relation to age group, gender and race, and no association between aneurysm and arterial hypertension could be made. Of the 56 individuals presenting aneurysm, 55 (98.2%) were symptomatic with predominant palpitations; 53 (94.6%) showed an aberrant ECG with predominant ventricular extra-systoles followed by changes in conduction; and 34 (60.%) showed an impairment of the ventricular function, regardless of the affected segment. In view of these results we consider the apical aneurysm of the left ventricle as a marker of Chagas' disease and as an indicator of high morbidity of the human T. cruzi infection in Virgem da Lapa.

Com o objetivo de avaliar as características clínicas e epidemiológicas do aneurisma ventricular esquerdo na doença de Chagas crônica, 388 indivíduos não selecionados: 298 chagásicos e 90 não-chagásicos, foram submetidos ao exame ecocardiográfico. A função ventricular foi avaliada ao modo M através do cálculo da fração de ejeção e ao bidimensional através da análise subjetiva da função sistólica global e a contratilidade regional foi avaliada pelo modelo da Sociedade Americana de Ecocardiografia. Foram diagnosticados 56 (18,8%) aneurismas do ventrículo esquerdo, todos entre os chagásicos, sendo 38 (12,7%) no segmento apical, 10 (3,4%) no septo interventricular, 2 (0,7%) ápico-septal, 2 (0,7%) na parede posterior, 2 (0,7%) na parede inferior e 2 (0,7%) no segmento ínfero-posterior. Não houve diferença significativa nas freqüências dos aneurismas em relação à faixa etária, ao sexo e à etnia. Não houve associação entre aneurismas e hipertensão arterial. Dos 56 indivíduos com aneurismas, 55 (98,2%) eram sintomáticos com predominância de palpitações, 53 (94,6,%) apresentaram ECG anormais, com predominância de extra-sístoles ventriculares, seguidas de alterações da condução e 34 (60,7%) apresentaram comprometimento da função ventricular, sem diferença quanto ao segmento acometido. Diante destes resultados podemos considerar o aneurisma ventricular esquerdo, principalmente apical, como um marcador de doença de Chagas e um indicador da alta morbidade da infecção humana pelo T. cruzi em Virgem da Lapa.

Evaluation of three commercial enzyme-linked immunosorbent assays for diagnosis of Chagas' disease.

Chagas' disease is a common cause of morbidity in Latin American countries. In Brazil, naturally occurring transmission of its etiologic agent, Trypanosoma cruzi, has been almost completely abolished through effective control programs aimed at the triatomid insect vector. Thus, transfusion of blood from infected donors has become the major route for contracting Chagas' disease due to the socioeconomically motivated migration of residents from areas where the disease is endemic to the larger urban centers. Therefore, the employment of screening tests is mandatory for all blood banks throughout the country. We compared the diagnostic performances of three commercially available screening assays used in routine testing in Brazilian blood banks: the Abbott Chagas antibody enzyme immunoassay (Abbott Laboratórios do Brasil, São Paulo), the BIOELISACRUZI kit (Biolab-Mérieux, Rio de Janeiro, Brazil), and the BIOZIMA Chagas kit (Polychaco S.A.I.C., Buenos Aires, Argentina). The evaluation was performed with sera obtained from chagasic patients and healthy residents of four different areas in Brazil where Chagas' disease is either endemic or emergent and where clinical manifestations of the disease and circulating parasite strains vary. The results obtained with each kit were compared to matched in-house enzyme-linked immunosorbent assay and immunofluorescence assay data obtained for each sample. Depending on the area under investigation, the three commercial kits produced specificity values between 93.3 and 100.0%, sensitivity values between 97.7 and 100%, and accuracies ranging from 93.6 to 100.0%.

Immunoblot assay using excreted-secreted antigens of Trypanosoma cruzi in serodiagnosis of congenital, acute, and chronic Chagas' disease.

Immunoblotting with trypomastigote excreted-secreted antigens (TESA blot) of Trypanosoma cruzi was evaluated as a method for diagnosis of chronic and acute phases as well as congenital (in newborn children) Chagas' disease. Serum samples from acute-phase and congenital infections were considered to be positive when they reacted with ladder-like bands of 130- to 200-kDa antigens, recognized by immunoglobulin M (IgM) and IgG antibodies, while IgG from chronic-phase sera recognized a broad band antigen of 150 to 160 kDa. Nonchagasic sera were not reactive to these antigens. The study was carried out on 512 patients, 111 of whom were nonchagasic but included cases of leishmaniasis or other pathologies, and 401 chagasic patients. The latter group comprised 361 chronic cases, 36 acute cases, and 4 congenital cases in newborn children. Among the chronic cases, 256 were from areas in which T. cruzi is endemic but which differed widely in the pathogenic expression of T. cruzi infection and in parasitemia levels. These patients at the same time showed a broad range of low, medium, and high reactivity to conventional enzyme-linked immunosorbent assays and indirect immunofluorescence serotests for Chagas' disease. For these reasons they may better represent the universe of chagasic patients than would a sample of highly reactive sera obtained from chagasic patients in a single area endemic for T. cruzi. All acute and congenital cases showed positivity in the IgM and IgG TESA blots, while chronic cases were 100% positive for IgG antibodies. In nonchagasic sera, including 30 cases of visceral and muco-cutaneous leishmaniasis, the specificity index was 1.000, and no cross-reactions were observed. The TESA blot thus seems to be useful as a sensitive and specific diagnostic assay in cases of suspected acute or congenital T. cruzi infection and as a general confirmatory test for conventional Chagas' disease serology.

[Xenodiagnosis in chronic Chagas' disease. I. The sensitivity of Panstrongylus megistus and Triatoma infestans]. / Xenodiagnóstico na doença de Chagas crônica. I--Sensibilidade de Panstrongylus megistus e Triatoma infestans.

From January 1986 to February 1994, 563 xenodiagnosis (XD) were applied in 563 chronic chagasic patients from different areas of Brazil; 292 were women and 271 were men between 6 and 89 years (average: 41.4 +/- 14.7 years). To each XD 40 nymphs on the 4th stage were used: 20 from Panstrongylus megistus (Pm) and 20 from Triatoma infestans (Ti) in fast, during at least 14 days. The exam in each nymph was made 45 days after being applied on the patient, by observation in optical microscopy of the drugs and/or the grinded from the digestive tube. The results are: a) 205 (36.4%) positive XD, including 85 (15.1%) due only nymphs of Pm, 44 (7.8%) Ti and 76 (13.5%) Pm and Ti; b) positively in 4.9% of the nymphs from Pm and in 3.0% of the Ti nymphs examined. These results' analysis showed that the Pm nymphs were more sensitive that Ti's ones to the infection by Trypanosoma cruzi, increasing considerably the xenopositivity, independently from birthplace, sex or age of the patients. These results point out that to increase the efficacy of XD in chronic Chagas' disease, the exam must have more than a species of triatomine with different sensibilities to the T. cruzi infection, and in case of using one species on XD, Pm must substitute Ti.

[Morbidity of Chagas disease in areas of Sertão da Paraiba and Caatinga do Piauí]. / Morbidade da doença de Chagas em áreas do Sertão da Paraíba e da Caatinga do Piauí.

A clinical and electrocardiographic case control study was carried out with 186 pairs of persons with positive and negative serology for T. cruzi infection from the Sertão Paraíba and in 200 seropositive cases from the region of Caatinga in the State of Piauí, North-eastern Brazil. The predominant clinical manifestations in seropositive cases in both areas were: palpitations, dyspnea on effort, precordial pain, dysphagia, odynophagia, pyrosis and intestinal constipation. The EKG abnormalities rates suggestive of chronic chagasic cardiopathy were respectively in Paraíba and Piauí: AV block 3.8% and 2%, RBBB III 6.4% and 7%, RBBB III+ LAB 10.7% and 10.5%, and multifocal extrasystoles 2.7% and 3%. Xenodiagnosis in a sample of 54 seropositive individuals in the Sert-ao of Para-iba and in 120 in the Caatinga of Piauí was revealed 13% and 34% positive; PCR tests in a sample of 47 seropositives in Paraíba and 101 in Piauí revealed positives in 44.6% and 59.5% respectively. Blood culture in LIT media of 101 seropositive cases from the Caatinga of Piauí was positive for T. cruzi in 25.7%. A triatomine survey carried out in a sample of 132 domiciles and peridomiciles in the Sertão of Paraíba and in a sample of 159 in the Caatinga of Piauí showed the following results: In Paraíba, 16 specimens of T. brasiliensis, not infected with T. cruzi, were captured. In Piauí, 750 triatomines were captured, of these 625 were examined: 49 were T. pseudomaculata, not infected with T. cruzi (19 in peridomiciles and 30 in the domiciles), and 576 were T. brasiliensis (371 in the domiciles and 205 in the peridomiciles) and of this latter specie 32 (5.5%) were infected with T. cruzi (31 in the domiciles and one in the peridomicile).

Development and evaluation of an enzyme linked immunotransfer blot technique for serodiagnosis of Chagas' disease.

An enzyme linked immunoelectrotransfer blot technique (EITB) was developed and evaluated for the serodiagnosis of Chagas' disease. EITB strips were prepared using Trypansoma cruzi (Y strain) epimastigotes lysate. Evaluation was performed with 235 serum samples collected from individuals living in an endemic area for Chagas' disease. Among those samples, 160 were serological positive in three conventional tests for T. cruzi and 75 were negative. The specificity was determined using 37 serum samples from patients with other infectious diseases. The EITB test showed sensitivity of 99.3% and specificity of 100% when a positive reaction was defined as the presence of 3 bands from a group of 7 (14, 19, 27, 30, 34, 37 and 75), a negative reaction was defined as the absence of 6 of the 7 bands, and an indeterminate reaction as the presence of two of the 7 bands.