Multimodality imaging in connective tissue disease-related interstitial lung disease.

Interstitial lung disease is a well-recognised manifestation and a major cause of morbidity and mortality in patients with connective tissue diseases. Interstitial lung disease may arise in the context of an established connective tissue disease or be the initial manifestation of an otherwise occult autoimmune disorder. Early detection and characterisation are paramount for adequate patient management and require a multidisciplinary approach, in which imaging plays a vital role. Computed tomography is currently the imaging method of choice; however, other imaging techniques have recently been investigated, namely ultrasound, magnetic resonance imaging, and positron-emission tomography, with promising results. The aim of this review is to describe the imaging findings of connective tissue disease-related interstitial lung disease and explain the role of each imaging technique in diagnosis and disease characterisation.

Fisetin as a promising antifungal agent against Cryptocococcus neoformans species complex.

AIMS: The aim of this study was to investigate the mechanisms of action of fisetin, a flavonol with antifungal activity previously evaluated against the Cryptococcus neoformans species complex. METHODS AND RESULTS: Ergosterol content and flow cytometry analysis were determined for the C. neoformans species complex in the presence of fisetin and ultrastructural analysis of morphology was performed on Cryptococcus gattii and C. neoformans. Decrease in the total cellular ergosterol content after exposure to fisetin ranged from 25·4% after exposure to 128 µg ml(-1) to 21·6% after exposure to 64 µg ml(-1) of fisetin compared with the control (without fisetin). The fisetin effects obtained with flow cytometry showed metabolic impairment, and alterations in its normal morphology caused by fisetin in C. neoformans cells were verified using scanning electron microscopy. CONCLUSIONS: Fisetin is a compound that acts in the biosynthesis of ergosterol. Flow cytometry showed that fisetin reduced viability of the metabolically active cells of C. gattii, while morphological changes explain the action of fisetin in inhibiting growth of these fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: This study supports the idea that fisetin may represent a good starting point for the development of future therapeutic substances for cryptococcosis.

Effects of eccentric overload bout on change of direction and performance in soccer players.

The aims of this study were to analyse the effects of eccentric overload training (EOT) on kinetic parameters during change of direction (COD) and performance related to sprinting and jumping abilities. 20 male soccer players performed 2 different protocols: 1) 5-min cycling warm-up and 2) 5-min cycling warm-up+YoYo half-squat exercise. The outcome measured included vertical ground reaction force (vGRF) and propulsive force (PvGRF), time to vGRF (T_vGRF) and propulsive force (T_PvGRF), contact time (CT), eccentric (ECC_IMP), concentric (CONC_IMP) and total (TOT_IMP) impulses and moments (Mx, My and Mz) during 2 COD tasks. Additionally, subjects performed a counter-movement jump (CMJ) and 20 m sprint tests. Results showed a substantial better improvement (likely to almost certainly) in vGRF (ES: 0.84), vAGRF (ES: 0.72), CT (ES: 0.48), My (ES: 0.35), Mz (ES: 0.44) and ECC_IMP (ES: 0.45) during crossover cutting maneuver, whereas during side-step cutting maneuver Time_ECC (ES: 0.68), CT (ES: 0.64), vGRF (ES: 0.48) and My (ES: 0.47) were substantially enhanced (likely). Furthermore, substantial better performance was found in CMJ (ES: 0.47; very likely) and 20 m (ES: 0.20; possibly). In conclusion, EOT produced a better muscle activation during 2 different COD tasks and greater sprinting and jumping performance.

Recommendations for the implementation of a national lung cancer screening program in Portugal-A consensus statement.

Lung cancer (LC) is a leading cause of cancer-related mortality worldwide. Lung Cancer Screening (LCS) programs that use low-dose computed tomography (LDCT) have been shown to reduce LC mortality by up to 25 % and are considered cost-effective. The European Health Union has encouraged its Member States to explore the feasibility of LCS implementation in their respective countries. The task force conducted a comprehensive literature review and engaged in extensive discussions to provide recommendations. These recommendations encompass the essential components required to initiate pilot LCS programs following the guidelines established by the World Health Organization. They were tailored to align with the specific context of the Portuguese healthcare system. The document addresses critical aspects, including the eligible population, methods for issuing invitations, radiological prerequisites, procedures for reporting results, referral processes, diagnostic strategies, program implementation, and ongoing monitoring. Furthermore, the task force emphasized that pairing LCS with evidence-based smoking cessation should be the standard of care for a high-quality screening program. This document also identifies areas for further research. These recommendations aim to guarantee that the implementation of a Portuguese LCS program ensures high-quality standards, consistency, and uniformity across centres.

Bacillus thuringiensis Cry1Ia10 and Vip3Aa protein interactions and their toxicity in Spodoptera spp. (Lepidoptera).

The polyphagous pests belonging to the genus Spodoptera are considered to be among the most important causes of damage and are widely distributed throughout the Americas'. Due to the extensive use of genetically modified plants containing Bacillus thuringiensis genes that code for insecticidal proteins, resistant insects may arise. To prevent the development of resistance, pyramided plants, which express multiple insecticidal proteins that act through distinct mode of actions, can be used. This study analyzed the mechanisms of action for the proteins Cry1Ia10 and Vip3Aa on neonatal Spodoptera frugiperda, Spodoptera albula, Spodoptera eridania and Spodoptera cosmioides larvae. The interactions of these toxins with receptors on the intestinal epithelial membrane were also analyzed by binding biotinylated toxins to brush border membrane vesicles (BBMVs) from the intestines of these insects. A putative receptor of approximately 65 kDa was found by ligand blotting in all of these species. In vitro competition assays using biotinylated proteins have indicated that Vip3Aa and Cry1Ia10 do not compete for the same receptor for S. frugiperda, S. albula and S. cosmioides and that Vip3Aa was more efficient than Cry1Ia10 when tested individually, by bioassays. A synergistic effect of the toxins in S. frugiperda, S. albula and S. cosmioides was observed when they were combined. However, in S. eridania, Cry1Ia10 and Vip3Aa might compete for the same receptor and through bioassays Cry1Ia10 was more efficient than Vip3Aa and showed an antagonistic effect when the proteins were combined. These results suggest that using these genes to develop pyramided plants may not prove effective in preventing the development of resistance in S. eridiana.

Impact of ERAS in breast reconstruction with a latissimus dorsi flap, compared to conventional management.

BACKGROUND: Enhanced recovery after surgery (ERAS) programs are associated with improved management, reduced hospital stays, and lower complication rates. OBJECTIVE: To evaluate the impact of ERAS on mean length of stay (LOS) and postoperative morbidity in breast reconstruction with latissimus dorsi flap (LDF) compared with conventional recovery program. PATIENTS AND METHOD: All patients operated by LDF between December 2014 and October 2020: those managed before April 2018, when the ERAS protocol was introduced, were included in the "no ERAS" group, and beyond in the "ERAS" group. RESULTS: Out of 193 patients, 129 were included in the "ERAS" group and 64 in the "no ERAS" group. There was a significant difference between the two groups in LOS (4.2 ± 1.5 days in the "ERAS" group vs. 5.4 ± 1.9 days in the "no ERAS" group; p < 0.001), high-grade complications at 30 days (9.3% in the "ERAS" group vs. 25% in the "no ERAS" group; p = 0.01), reintervention rate (13.9% vs. 26.6%, respectively; p = 0.02), and 30-day rehospitalization rate (6.2% in the "ERAS" group vs. 15.6% in the "no ERAS" group; p = 0.03). CONCLUSION: The ERAS protocol has a positive impact on breast reconstruction with LDF without generating additional adverse effects. These results support the democratization of these programs for breast reconstruction surgery.

Antifungal susceptibility patterns of yeasts and filamentous fungi isolated from nail infection.

BACKGROUND: Onychomycosis is the nail infection caused by a wide spectrum of fungi species, including yeasts, dermatophytes and filamentous fungi non-dermatophytes (FFND). This fungal infection represents an important medical problem because it involves the patient's life quality. OBJECTIVE: The aim was to isolate and identify the fungal agents of onychomycosis, and to determine the in vitro susceptibility to antifungal agents. METHODS: During the period of March 2008 to March 2009, 114 patients clinically suspected of having onychomycosis were examined. Demographic data, mainly age and gender were obtained from each patient. The nail samples collected (136) were submitted to direct examination with potassium hydroxide 20% and grown on Sabouraud dextrose agar. The in vitro antifungal susceptibility testing was performed according to the method of broth microdilution, recommended by the Clinical Laboratory Standards Institute (CLSI). RESULTS: Onychomycosis was observed in 95 (83.3%) patients, including 16 men (16.8%) and 79 women (83.2%), with mean age of 48.1 years. Candida parapsilosis, Trichophyton rubrum and Fusarium spp were the fungi most frequently isolated. The most of the isolated yeasts showed susceptibility to antifungal agents studied. Among filamentous fungi, high MIC values to itraconazole were found for T. rubrum and T. mentagrophytes, while Fusarium spp showed decreased susceptibility to itraconazole and voriconazole. CONCLUSION: C. parapsilosis was the most common fungal species isolated from patients with onychomycosis. The different response obtained by in vitro susceptibility testing to drugs shows the importance of these methods to assist clinicians in choosing the best therapeutic option.

Epidemiological and mycological data of onychomycosis in Goiania, Brazil.

Onychomycosis defined as fungal infection of the nail represents more than 50% of all onychopathies. Epidemiological studies have shown that this mycosis is worldwide in occurrence, but with geographical variation in distribution. The direct microscopy and culture of the nail samples were performed to identify the causative agent. Out of 2273 patients with nail infection examined between January 2000 and December 2004 in Goiania, state of Goias, Brazil, diagnosis of onychomycosis was confirmed in 1282 cases, with dermatophytes and Candida species being the most common aetiological agents isolated. Dermatophyte onychomycosis was more common in toenails than in fingernails, while onychomycosis caused by yeast had a similar frequency in both toenails and fingernails. Among the species identified, Candida albicans was responsible for 492 cases (38.4%) of onychomycosis, Trichophyton rubrum was found in 327 cases (25.6%) and Trichophyton mentagrophytes in 258 cases (20.1%). Other fungi isolated from nail infections included Aspergillus sp., Trichosporon sp., Geotrichum sp. and Fusarium sp. In our study, yeast of the genus Candida were the dominant cause of onychomycosis in women and dermatophytes were the principal cause of this condition in men.

Acute acquired toxoplasmosis: clinical-laboratorial aspects and ophthalmologic evaluation in a cohort of immunocompetent patients.

Most cases of acute acquired toxoplasmosis (AAT) are oligosymptomatic and self-limited. Therefore, these infections rarely indicate treatment. Prospective studies of AAT patients are rare in the medical literature. The frequency of systemic manifestations has not been sufficiently studied. In order to search for risks factors for systemic and ocular involvement, 37 patients were submitted to a diagnostic investigative protocol. The most frequent findings were lymph node enlargement (94.6%), asthenia (86.5%), headache (70.3%), fever (67.6%) and weight loss (62.2%). Hepatomegaly and/or splenomegaly were present in 21.6% of cases (8/37). Liver transaminases were elevated in 11 patients (29.7%) and lactic dehydrogenase in 17 patients (45.9%). Anaemia was found in four patients (10.8%), leucopoenia in six patients (16.2%), lymphocytosis in 14 patients (37.8%) and thrombocytopenia in one patient (2.7%). Fundoscopic examination revealed retinochoroiditis in four patients (10.8%). No statistical association was found between any one morbidity and retinochoroiditis. Nevertheless, a significant association was found between the presence of more than eight morbidity features at evaluation and long-lasting disease. An ideal diagnostic protocol for AAT would include evidence of systemic involvement. Such a protocol could be used when planning treatment.

A new consensus for Trypanosoma cruzi intraspecific nomenclature: second revision meeting recommends TcI to TcVI.

In an effort to unify the nomenclature of Trypanosoma cruzi, the causative agent of Chagas disease, an updated system was agreed upon at the Second Satellite Meeting. A consensus was reached that T. cruzi strains should be referred to by six discrete typing units (T. cruzi I-VI). The goal of a unified nomenclature is to improve communication within the scientific community involved in T. cruzi research. The justification and implications will be presented in a subsequent detailed report.

Creative dance can enhance proprioception in older adults.

AIM: It has been shown by many authors that proprioception declines with age. However, few studies have examined the effects of exercise interventions on proprioception. The purpose of this study was to investigate the effects of a creative dance program on proprioception of older adults. METHODS: Thirty-seven men and women between 55 and 80 years of age, who were not engaged in any exercise program for at least one year, were randomly assigned to an experimental (63.6 + or - 5.7 years) or a control group (65.3 + or - 7.6 years). The experimental group participated in a creative dance program for 12 weeks with a periodicity of 3 sessions of 90 minutes per week. Measures of knee kinesthesia, knee joint position sense and arm positioning were taken before and after the program. RESULTS: After 12 weeks, knee joint position sense (P = 0.005) knee kinesthesia (in flexion) (P = 0.04), and arm positioning (P = 0.008) significantly improved within the creative dance training group. At 12 weeks follow-up, arm positioning performance was significantly better for the creative dance group when compared with the control group (P = 0.043). The control group did not show any significant improvement in proprioception. CONCLUSIONS: This study showed that a creative dance program emphasising body awareness can improve proprioception in older adults.

Genotyping of Giardia duodenalis from Southern Brown Howler Monkeys (Alouatta clamitans) from Brazil.

Giardia duodenalis is a widespread intestinal protozoan that can infect humans and animals, both domestic and wild. Independent of host, infections present with the same symptoms. However, based on host specificity, Giardia isolates have been grouped into genotypes A to G. Parasites of assemblage A and B are known to infect humans, in addition to primates and a wide variety of mammals. In Brazil, hitherto Giardia genotypes were defined only for humans and domestic animals. To evaluate the genotypes of different Giardia present among other animals, fecal samples from 28 Southern Brown Howler Monkeys (Alouatta clamitans) kept in captivity from South Brazil were screened for G. duodenalis using parasitological methods. All of them were asymptomatic, but positive for Giardia. The genotype of the G. duodenalis circulating among these animals was ascertained by molecular typing, performed using amplification and sequencing of the beta-giardin gene. Sixteen of 28 samples were successfully amplified by PCR and sequencing of this gene s revealed that all of them were of the genotype A1. These findings suggest that A. clamitans represent a potential risk of environmental contamination of a G. duodenalis genotype that also infect humans, and therefore can be considered a potential reservoir for G. duodenalis of a genotype that can also infects humans. Therefore, these results highlight a potential public health problem due to the epidemiological and molecular evidence for anthropozoonotic transmission.

Characterization and Comparison of Genetic Variation in Cotesia flavipes (Hymenoptera: Braconidae) Mass Reared for Biological Pest Control Using Microsatellite Markers.

The larval parasitoid Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) is an important biological control agent of the sugarcane borer, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae). This exotic parasitoid has been mass reared for field release since its introduction in the 1970s. Insects are exchanged between labs or introduced from the field, but without basic studies or criteria. Thus, the objective of this study was to evaluate the genetic variability of insects from six Brazilian States (São Paulo, Minas Gerais, Paraná, Goiás, Maranhão, and Alagoas) using microsatellites. Analysis of five loci using at least 22 females from each location was performed. The molecular analysis made possible to verify that four out of the five loci analyzed were polymorphic. The allele frequencies of three loci were in agreement with the Hardy-Weinberg Equilibrium for all insects of all regions. It was also observed that five alleles were exclusively presented in only two loci. The variation among and within populations was 24.65 and 75.34%, respectively. The estimated shared genotypes between the C. flavipes individuals showed that K = 2 was the most likely number of genetic groups causing the current variation, as well as high shared genotypes from these groups of the individuals. Considering all the analyzed loci, the genetic differentiation was at a moderate level. We suggest a possible mixture of biological materials based on genetic distances and the degree of structuring displayed.

Genotyping of Giardia duodenalis from human and animal samples from Brazil using beta-giardin gene: a phylogenetic analysis.

Giardia duodenalis is one of the major diarrhea agents in human and animals distributed worldwide, and present high levels of genetic diversity, showing seven genotypes: A, B, C, D, E, F, and G. Only Assemblages A and B have been detected in humans and in a wide range of other mammalians hosts, whereas the remaining Assemblages (C-G) are host-specific. Molecular characterization of cysts of human and animal origin are useful to address the co-circulate isolates between these host, and represents an objective means to evaluate zoonotic infection hypothesis. In the present work the G. duodenalis genotypes were characterized by restriction fragment length polymorphisms and DNA sequencing analysis of PCR products of the beta-giardin gene. The cysts were collected in the city of Rio de Janeiro, in Brazil, from a population composed by humans (n=366, 310 children and 56 adults), domestic animals (n=11) from a municipal daycare center in the surroundings of a slum and neighborhood medium-high class domestic animals (n=18). Parasitological exams were developed in human fecal samples. Parasites were found in 60% (186/310) and 66% (37/56) of the samples from children and adults, respectively. Among children's samples, 27.7% (86/310) were positive for G. duodenalis. Only 1.7% (1/56) of the adults was positive for this parasite. In general a total of 87 fecal samples (86 from children and 1 from adult) from all population studied were positive for G. duodenalis, and 62 of these were subjected to molecular analysis using a PCR that amplified a fragment of the beta-giardin gene. Sixty samples were typed as genotype A1, two as genotype A2 and genotype B was not encountered. Among domestic animals samples (n=29), eight (seven dogs and one cat) from the slum community were identified as genotype A1, and all control samples (n=18) were negative in the molecular assay. The host-specific genotypes C, D and, F were not found. In this study we described single case of G. duodenalis infection associated with a child and her dog and both isolates characterized as genotype A1. Despite the low incidence, this data suggest the putative existence of a zoonotic cycle of G. duodenalis in the studied population.

Mapping of the distribution of Trypanosoma cruzi infection among small wild mammals in a conservation unit and its surroundings (Northeast-Brazil).

Maps are a useful tool that permits correlation of landscapes with hotspots of parasite transmission. Here, they were used as a tool for geovisualization to evaluate variables involved in the transmission of Trypanosoma cruzi among small wild mammals in an area endemic for Chagas disease, the "Serra da Capivara" National Park (PARNA) and its surroundings in Piauí State, Northeast Brazil. The implementation of a Geographical Information System (GIS) allowed the observation that a previously noted aggregated distribution of Triatoma sordida and Triatoma brasiliensis, T. cruzi prevalence and infection pattern of small wild mammals was directly or indirectly influenced by the local relief and human action. Small mammalian species diversity was higher in mesic refugia inside the park and in its buffer zone and lower in the disturbed area by anthropic activities. Didelphis albiventris was more abundant in the areas affected by human action. Thrichomys laurentius demonstrated to be an eclectic species and a competent reservoir of T. cruzi, being infected in all study areas. Small wild mammals infected with the TCII genotype of T. cruzi were localized only in the buffer zone of PARNA while TCI infected specimens were found in both areas, inside the PARNA and its buffer zone. The impact of biodiversity loss on the transmission cycle of T. cruzi in the wild environment was discussed.

Efficacy of Soybean's Event DAS-81419-2 Expressing Cry1F and Cry1Ac to Manage Key Tropical Lepidopteran Pests Under Field Conditions in Brazil.

Bacillus thuringiensis (Bt) event DAS-81419-2 (Conkesta technology) in soybean, Glycine max (L.) Merrill, expresses Cry1F and Cry1Ac proteins to provide protection from feeding by several lepidopteran pests. A total of 27 field experiments across nine locations were conducted from 2011 to 2015 in southern and central Brazil to characterize the efficacy of DAS-81419-2 soybean infested with Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), Heliothis virescens (F.) (Lepidoptera: Noctuidae), and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) during vegetative (V4) and reproductive (R2 and R4) crop developmental stages. The efficacy of DAS-81419-2 was compared to that of a non-Bt isogenic variety managed with or without applications of commercial foliar insecticides for lepidopteran control. DAS-81419-2 soybean consistently experienced defoliation levels of 0.5% or less (compared with 20.05-56.74% in the non-Bt, nonsprayed treatment) and larval survival of < 0.1% in all four species across the vegetative and reproductive plant stages evaluated. The efficacy of DAS-81419-2 was significantly higher than commercial foliar insecticides applied to the non-Bt variety. DAS-81419-2 soybeans containing two highly effective Bt proteins are expected to be a more robust IRM tool compared to single-trait Bt technologies. The consistent efficacy of DAS-81419-2 soybeans across years, locations, and crop stages suggests that it will be a valuable product for management of hard-to-control key lepidopteran pests in South American soybean production.

Trypanosoma cruzi infection in wild mammals of the National Park 'Serra da Capivara' and its surroundings (Piaui, Brazil), an area endemic for Chagas disease.

We studied the prevalence of Trypanosoma cruzi infection among eight species of wild small mammals (n=289) in an area where human cases of infection/disease have occurred. Dogs (n=52) and goats (n=56) were also surveyed. The study was carried out inside a biological reserve, the National Park 'Serra da Capivara' and its surroundings in Piaui State, Brazil. The marsupial Didelphis albiventris and the caviomorph rodent Trichomys apereoides were found to be the most important reservoirs in the study area. Trichomys apereoides was the most abundant species (80%) and D. albiventris the most frequently infected (61%). Both T. cruzi I and T. cruzi II genotypes were isolated from these species. One specimen of Tr. apereoides displayed a mixed T. cruzi I/zymodeme 3 infection. Serum prevalence among dogs suggests that they may be involved in the maintenance of the parasite in the peridomestic environment, in contrast to goats, which are not apparently of any epidemiological importance. The distinct distribution and patterns of infection observed in the study areas suggest that even in the same biome, epidemiological studies or determination of control measures must take into account ecological peculiarities.

On organic emissions testing from indoor consumer products' use.

A wide range of consumer and personal care products may, during their use, release significant amounts of volatile organic compounds (VOC) into the air. The identification and quantification of the emissions from such sources is typically performed in emission test chambers. A major question is to what degree the obtained emissions are reproducible and directly applicable to real situations. The present work attempts partly to address this question by comparison of selected VOC emissions in specific consumer products tested in chambers of various dimensions. The measurements were performed in three test chambers of different volumes (0.26-20 m(3)). The analytic performance of the laboratories was rigorously assessed prior to chamber testing. The results show emission variation for major VOC (terpenes); however, it remains in general, within the same order of magnitude for all tests. This variability does not seem to correlate with the chamber volume. It rather depends on the overall testing conditions. The present work is undertaken in the frame of EPHECT European Project.

Mini-exon gene variation in human pathogenic Leishmania species.

We have used polymerase chain reaction to amplify the mini-exon gene repeat from 18 Leishmania strains. DNA sequence analysis of the cloned products reveals high conservation of both the exon and intron (i.e. transcribed region). In contrast, variation is evident in both the length and primary sequence of the non-transcribed spacers. Dermotropic species of the New World subgenus Leishmania possess a 0.3-kb gene that differs from the 0.25-kb gene of New World dermotropic species of the subgenus Viannia. The Old/New World viscerotropic species and Old World dermotropic species possess a 0.4-kb mini-exon gene. However, the genes from the viscerotropic and dermotropic groups may be distinguished on the basis of sequence differences in the non-transcribed spacer. Comparative analysis of the -86 to -1 region from all species has been used to measure relatedness within the genus. In general, all the observed differences correlate with the four major groups of Leishmania (New World dermotropic Leishmania, New World dermotropic Viannia, Old World dermotropic Leishmania and viscerotropic Leishmania). Two of the three repeats cloned from L. donovani show short deletions. The missing sequence is flanked by direct, 7-bp repeats suggesting that the sequences may have been deleted by homologous recombination. Such rearrangements could account for the diversity detected in the non-transcribed spacers of the mini-exon genes.

DNA markers define two major phylogenetic lineages of Trypanosoma cruzi.

Parasitic protozoa within the taxon Trypanosoma cruzi are considered to be derived from multiple clonal lineages, and show broad genetic diversity as a result of propagation with little or no genetic exchange. We have analyzed a wide sample of T. cruzi isolates from vertebrate and invertebrate hosts by PCR amplification of a ribosomal RNA gene sequence, a mini-exon gene sequence and random amplified polymorphic DNA (RAPD). Amplification of the distinct rDNA and mini-exon gene sequences indicated a dimorphism within both of the tandemly-repeated genes: 125 or 110 bp products for rDNA and 300 or 350 bp products for the mini-exon. Within individual isolates, one of three associations was observed: the 125 bp rDNA product with the 300 bp mini-exon product (defined as group 1), the 110 bp rDNA product with the 350 bp mini-exon product (defined as group 2) and the presence of both rDNA amplification products with the mini-exon group 1 product (group 1/2). The RAPD analysis showed variability between individual isolates, however, tree analysis clearly indicated the presence of two major branches. Interestingly, the rDNA/mini-exon group 2 isolates correlated precisely with one branch of the RAPD-derived tree; group 1 and group 1/2 isolates correlated with the other branch. Our studies show a clear division of T. cruzi into two major lineages presenting a high phylogenetic divergence. Hypotheses are discussed to explain the origin of the two lineages as well as isolates that are hybrid for group 1 and 2 rDNA markers.