Diversity, Equity, and Inclusion: Advancing Curricular Development and Recruitment.

PURPOSE OF REVIEW: Currently, the increasing diversity of our society is poorly reflected in the urology workforce. In this review, we sought to address this disparity by highlighting key components involved in forming an academic urology department and training program that is focused on diversity, equity, and inclusion (DEI) as well as recruitment and retention of underrepresented in medicine (URiM) trainees and faculty. RECENT FINDINGS: We identified obstacles and provided approaches to enhance the ability of a department in creating a DEI-based curriculum and recruitment strategy with a key focus on understanding and addressing unconscious biases and microaggressions in the workplace. Substantive changes in the level of diversity within the urologic community can be made through the organization of a structured approach to increasing DEI. It starts with a commitment from each department to form achievable goals surrounding early mentorship of URiM students and trainees, an inclusive curriculum that is rooted in DEI, and targeted benchmarks for recruitment and retention of diverse staff.

Towards an in situ non-lethal rapid test to accurately detect the presence of the nematode parasite, Anguillicoloides crassus, in European eel, Anguilla anguilla.

Anguillicoloides crassus is an invasive nematode parasite of the critically endangered European eel, Anguilla anguilla, and possibly one of the primary drivers of eel population collapse, impacting many features of eel physiology and life history. Early detection of the parasite is vital to limit the spread of A. crassus, to assess its potential impact on spawning biomass. However accurate diagnosis of infection could only be achieved via necropsy. To support eel fisheries management we developed a rapid, non-lethal, minimally invasive and in situ DNA-based method to infer the presence of the parasite in the swim bladder. Screening of 131 wild eels was undertaken between 2017 and 2019 in Ireland and UK to validate the procedure. DNA extractions and PCR were conducted using both a Qiagen Stool kit and in situ using Whatman qualitative filter paper No1 and a miniPCR DNA Discovery-System™. Primers were specifically designed to target the cytochrome oxidase mtDNA gene region and in situ extraction and amplification takes approximately 3 h for up to 16 individuals. Our in-situ diagnostic procedure demonstrated positive predictive values at 96% and negative predictive values at 87% by comparison to necropsy data. Our method could be a valuable tool in the hands of fisheries managers to enable infection control and help protect this iconic but critically endangered species.

Genome erosion and evidence for an intracellular niche - exploring the biology of mycoplasmas in Atlantic salmon.

Mycoplasmas are the smallest autonomously self-replicating life form on the planet. Members of this bacterial genus are known to parasitise a wide array of metazoans including vertebrates. Whilst much research has been significant targeted at parasitic mammalian mycoplasmas, very little is known about their role in other vertebrates. In the current study, we aim to explore the biology of mycoplasmas in Atlantic Salmon, a species of major significance for aquaculture, including cellular niche, genome size structure and gene content. Using fluorescent in-situ hybridisation (FISH), mycoplasmas were targeted in epithelial tissues across the digestive tract (stomach, pyloric caecum and midgut) from different development stages (eggs, parr, subadult) of farmed Atlantic salmon (Salmo salar), and we present evidence for an intracellular niche for some of the microbes visualised. Via shotgun metagenomic sequencing, a nearly complete, albeit small, genome (~0.57 MB) as assembled from a farmed Atlantic salmon subadult. Phylogenetic analysis of the recovered genome revealed taxonomic proximity to other salmon derived mycoplasmas, as well as to the human pathogen Mycoplasma penetrans (~1.36 Mb). We annotated coding sequences and identified riboflavin pathway encoding genes and sugar transporters, the former potentially consistent with micronutrient provisioning in salmonid development. Our study provides insights into mucosal adherence, the cellular niche and gene catalog of Mycoplasma in the gut ecosystem of the Atlantic salmon, suggesting a high dependency of this minimalist bacterium on its host. Further study is required to explore and functional role of Mycoplasma in the nutrition and development of its salmonid host.

Determinants of adequate lymph node dissection following neoadjuvant chemotherapy in patients with urothelial muscle-invasive bladder cancer: results from the National Cancer Database.

PURPOSE: Recent literature has separately identified multiple determinants of the use of neoadjuvant chemotherapy (NAC) and adherence to pelvic lymph node dissection (PLND) guidelines in the management of non-metastatic bladder cancer. However, such NAC/PLND analyses tend not to account for the other modality, despite the fact that NAC may impact the extent of dissectible lymph nodes. We aimed to determine the predictors of adequate PLND in patients with non-metastatic urothelial muscle-invasive bladder cancer (MIBC) undergoing radical cystectomy (RC) following receipt of NAC. METHODS: We queried the National Cancer Database to identify patients from 2006-2015 with cT2-cT4a/N0M0 urothelial MIBC who underwent RC and were pre-treated with NAC. Multivariate logistic regression analysis was used to identify independent predictors of undergoing an adequate PLND (defined as > 8 nodes). RESULTS: A total of 1518 patients met the criteria for inclusion (74.4% underwent adequate PLND). Adequate PLND was associated with treatment at an academic research facility (OR 2.762 [95% CI 2.119-3.599], p < 0.001). The likelihood of adequate PLND was significantly decreased in patients of older age (0.607 [0.441-0.835], p = 0.002 for age 70-79 years; 0.459 [0.245-0.860], p = 0.015 for age ≥ 80 years), a Charlson-Deyo score of 1 (0.722 [0.537-0.971], p = 0.031), and those who were uninsured (0.530 [0.292-0.964], p = 0.038). CONCLUSIONS: Established predictors of PLND may not necessarily be generalizable to all patients undergoing treatment for bladder cancer. The interplay between PLND and NAC merits further study, particularly in view of recent literature calling into question the survival benefit of PLND in patients pre-treated with NAC.

Neutral Processes Dominate Microbial Community Assembly in Atlantic Salmon, Salmo salar.

In recent years, a wealth of studies has examined the relationships between a host and its microbiome across diverse taxa. Many studies characterize the host microbiome without considering the ecological processes that underpin microbiome assembly. In this study, the intestinal microbiota of Atlantic salmon, Salmo salar, sampled from farmed and wild environments was first characterized using 16S rRNA gene MiSeq sequencing analysis. We used neutral community models to determine the balance of stochastic and deterministic processes that underpin microbial community assembly and transfer across life cycle stage and between gut compartments. Across gut compartments in farmed fish, neutral models suggest that most microbes are transient with no evidence of adaptation to their environment. In wild fish, we found declining taxonomic and functional microbial community richness as fish mature through different life cycle stages. Alongside neutral community models applied to wild fish, we suggest that declining richness demonstrates an increasing role for the host in filtering microbial communities that is correlated with age. We found a limited subset of gut microflora adapted to the farmed and wild host environment among which Mycoplasma spp. are prominent. Our study reveals the ecological drivers underpinning community assembly in both farmed and wild Atlantic salmon and underlines the importance of understanding the role of stochastic processes, such as random drift and small migration rates in microbial community assembly, before considering any functional role of the gut microbes encountered.IMPORTANCE A growing number of studies have examined variation in the microbiome to determine the role in modulating host health, physiology, and ecology. However, the ecology of host microbial colonization is not fully understood and rarely tested. The continued increase in production of farmed Atlantic salmon, coupled with increased farmed-wild salmon interactions, has accentuated the need to unravel the potential adaptive function of the microbiome and to distinguish resident from transient gut microbes. Between gut compartments in a farmed system, we found a majority of operational taxonomic units (OTUs) that fit the neutral model, with Mycoplasma species among the key exceptions. In wild fish, deterministic processes account for more OTU differences across life stages than those observed across gut compartments. Unlike previous studies, our results make detailed comparisons between fish from wild and farmed environments, while also providing insight into the ecological processes underpinning microbial community assembly in this ecologically and economically important species.

Changes observed in prostate biopsy practices in an inner city hospital with a high risk patient population following the 2012 USPSTF PSA screening recommendations

ABSTRACT Introduction: We compared characteristics of patients undergoing prostate biopsy in a high-risk inner city population before and after the 2012 USPSTF recommendation against PSA based prostate cancer screening to determine its effect on prostate biopsy practices. Materials and Methods: This was a retrospective study including patients who received biopsies after an abnormal PSA measurement from October 2008-December 2015. Patients with previously diagnosed prostate cancer were excluded. Chi-square tests of independence, two sample t-tests, Mann-Whitney U tests, and Fisher's exact tests were performed. Results: There were 202 and 208 patients in the pre-USPSTF and post-USPSTF recommendation cohorts, respectively. The post-USPSTF cohort had higher median PSA (7.8 versus 7.1ng/mL, p=0.05), greater proportion of patients who were black (96.6% versus 90.5%, p=0.01), and greater percentage of biopsy cores positive for disease (58% versus 29.5%, p<0.001). Multivariable analysis supported that the increase in PSA was independent of the increase in the proportion of patients who were black. The proportion of patients who were classified as D'Amico intermediate and high-risk disease increased in the post-USPSTF cohort and approached statistical significance (70.1% versus 58.8%, p=0.12). Conclusions: Our study suggests that the USPSTF recommendations may have led to an increase in pre-biopsy PSA as well as greater volume of disease. Also, a greater proportion of patients were being classified with intermediate or high risk disease. While the clinical significance of these findings is unknown, what the data suggests is somewhat troubling. Future research should further examine these changes in a larger cohort as well as resultant long-term outcomes.

Changes observed in prostate biopsy practices in an inner city hospital with a high risk patient population following the 2012 uspstf psa screening recommendations.

INTRODUCTION: We compared characteristics of patients undergoing prostate biopsy in a high-risk inner city population before and after the 2012 USPSTF recommendation against PSA based prostate cancer screening to determine its effect on prostate biopsy practices. MATERIALS AND METHODS: This was a retrospective study including patients who received biopsies after an abnormal PSA measurement from October 2008-December 2015. Patients with previously diagnosed prostate cancer were excluded. Chi-square tests of independence, two sample t-tests, Mann-Whitney U tests, and Fisher's exact tests were performed. RESULTS: There were 202 and 208 patients in the pre-USPSTF and post-USPSTF recommendation cohorts, respectively. The post-USPSTF cohort had higher median PSA (7.8 versus 7.1ng/mL, p=0.05), greater proportion of patients who were black (96.6% versus 90.5%, p=0.01), and greater percentage of biopsy cores positive for disease (58% versus 29.5%, p<0.001). Multivariable analysis supported that the increase in PSA was independent of the increase in the proportion of patients who were black. The proportion of patients who were classified as D'Amico intermediate and high-risk disease increased in the post-USPSTF cohort and approached statistical significance (70.1% versus 58.8%, p=0.12). CONCLUSIONS: Our study suggests that the USPSTF recommendations may have led to na increase in pre-biopsy PSA as well as greater volume of disease. Also, a greater proportion of patients were being classified with intermediate or high risk disease. While the clinical significance of these findings is unknown, what the data suggests is somewhat troubling. Future research should further examine these changes in a larger cohort as well as resultant long-term outcomes.

Genetic fingerprinting of salmon louse (Lepeophtheirus salmonis) populations in the North-East Atlantic using a random forest classification approach.

Caligid sea lice represent a significant threat to salmonid aquaculture worldwide. Population genetic analyses have consistently shown minimal population genetic structure in North Atlantic Lepeophtheirus salmonis, frustrating efforts to track louse populations and improve targeted control measures. The aim of this study was to test the power of reduced representation library sequencing (IIb-RAD sequencing) coupled with random forest machine learning algorithms to define markers for fine-scale discrimination of louse populations. We identified 1286 robustly supported SNPs among four L. salmonis populations from Ireland, Scotland and Northern Norway. Only weak global structure was observed based on the full SNP dataset. The application of a random forest machine-learning algorithm identified 98 discriminatory SNPs that dramatically improved population assignment, increased global genetic structure and resulted in significant genetic population differentiation. A large proportion of SNPs found to be under directional selection were also identified to be highly discriminatory. Our data suggest that it is possible to discriminate between nearby L. salmonis populations given suitable marker selection approaches, and that such differences might have an adaptive basis. We discuss these data in light of sea lice adaption to anthropogenic and environmental pressures as well as novel approaches to track and predict sea louse dispersal.

Foraging and recruitment hotspot dynamics for the largest Atlantic loggerhead turtle rookery.

Determining patterns of migratory connectivity for highly-mobile, wide-ranging species, such as sea turtles, is challenging. Here, we combined satellite telemetry and stable isotope analysis to estimate foraging locations for 749 individual loggerheads nesting along the east central Florida (USA) coast, the largest rookery for the Northwest Atlantic population. We aggregated individual results by year, identified seven foraging hotspots and tracked these summaries to describe the dynamics of inter-annual contributions of these geographic areas to this rookery over a nine-year period. Using reproductive information for a subset of turtles (n = 513), we estimated hatchling yields associated with each hotspots. We found considerable inter-annual variability in the relative contribution of foraging areas to the nesting adults. Also reproductive success differed among foraging hotspots; females using southern foraging areas laid nests that produced more offspring in all but one year of the study. These analyses identified two high priority areas for future research and conservation efforts: the continental shelf adjacent to east central Florida and the Great Bahama Bank, which support higher numbers of foraging females that provide higher rates of hatchling production. The implementation of the continuous-surface approach to determine geographic origins of unknown migrants is applicable to other migratory species.

Parasitism perturbs the mucosal microbiome of Atlantic Salmon.

Interactions between parasite, host and host-associated microbiota are increasingly understood as important determinants of disease progression and morbidity. Salmon lice, including the parasitic copepod Lepeophtheirus salmonis and related species, are perhaps the most important problem facing Atlantic Salmon aquaculture after feed sustainability. Salmon lice parasitize the surface of the fish, feeding off mucus, scales and underlying tissue. Secondary bacterial infections are a major source of associated morbidity. In this study we tracked the diversity and composition of Salmo salar skin surface microbiota throughout a complete L. salmonis infection cycle among 800 post-smolts as compared to healthy controls. Among infected fish we observed a significant reduction in microbial richness (Chao1, P = 0.0136), raised diversity (Shannon, P < 7.86e-06) as well as highly significant destabilisation of microbial community composition (Pairwise Unifrac, beta-diversity, P < 1.86e-05; P = 0.0132) by comparison to controls. While undetectable on an individual level, network analysis of microbial taxa on infected fish revealed the association of multiple pathogenic genera (Vibrio, Flavobacterium, Tenacibaculum, Pseudomonas) with high louse burdens. We discuss our findings in the context of ecological theory and colonisation resistance, in addition to the role microbiota in driving primary and secondary pathology in the host.

Contemporary evaluation and management of renal trauma.

INTRODUCTION: Renal trauma occurs in approximately 1%-5% of all trauma cases. Improvements in imaging and management over the last two decades have caused a shift in the treatment of this clinical condition. MATERIALS AND METHODS: A systematic search of PubMed was performed to identify relevant and contemporary articles that referred to the management and evaluation of renal trauma. RESULTS: Computed tomography remains a mainstay of radiological evaluation in hemodynamically stable patients. There is a growing body of literature showing that conservative, non-operative management of renal trauma is safe, even for Grade IV-V renal injuries. If surgical exploration is planned due to other injuries, a conservative approach to the kidney can often be utilized. Follow up imaging may be warranted in certain circumstances. Urinoma, delayed bleeding, and hypertension are complications that require follow up. CONCLUSION: Appropriate imaging and conservative approaches are a mainstay of current renal trauma management.

Response to Tibayrenc and Ayala: Reproductive clonality in protozoan pathogens--truth or artefact?

Tibayrenc and Ayala raised several interesting objections to an opinion piece we recently published in Molecular Ecology (Ramirez & Llewellyn 2014). Our piece examined the value of an alternative perspective to their theory of predominant clonal evolution (PCE) on the prevalence and importance of genetic exchange in parasitic protozoa. In particular, our aim was to establish whether population genetic signatures of clonality in parasites were representative of true biological/evolutionary processes or artefacts of inadequate tools and inappropriate or inadequate sampling. We address Tibayrenc and Ayala's criticisms and make a detailed response. In doing so, we deny the consensus that Tibayrenc and Ayala claim around their views and dismiss much of the language which Tibayrenc and Ayala have introduced to this debate as either arbitrary or inaccurate. We strongly reject accusations that we misunderstood and misquoted the work of others. We do not think the PCE provides a useful framework for understanding existing parasite population structures. Furthermore, on the eve of the population genomic era, we strongly urge Tibayrenc and Ayala to wait for the forthcoming wealth of high-resolution data before considering whether it is appropriate to refine or re-iterate their PCE hypothesis.

Relating fibropapilloma tumor severity to blood parameters in green turtles Chelonia mydas.

Fibropapillomatosis is a neoplastic disease that is commonly found in the green turtles Chelonia mydas in tropical and subtropical regions of the world. In the current project, juvenile green turtles were captured with large-mesh tangle nets in the Indian River Lagoon and on nearshore reefs of Indian River County, Florida, USA, in 1998 and 1999. The purpose of the study was to determine the relationship between the severity of the disease and the general health of green turtles as indicated by blood parameters. All turtles were measured and examined, and the overall severity of the disease was rated by the size, number, and location of external fibropapilloma tumors. Hematocrit, total protein, and hemoglobin concentration were measured and compared with tumor scores (tumor severity appraisal). As the tumor score increased, the blood parameters of turtles decreased; for instance, the percentage of decrease in hematocrit for mildly afflicted, moderately afflicted, and severely afflicted groups were 2.6, 18.3, and 45.5%, respectively. Severely afflicted turtles suffered from anemia, while individuals with mild affliction did not.

A 10-year analysis of metastatic prostate cancer as an initial presentation in an underserved population.

OBJECTIVE: To analyze patients from an underserved area who presented initially with metastatic prostate cancer in order to identify patients in our population who would suffer greatly if PSA screening was eliminated. MATERIALS AND METHODS: A prospectively maintained androgen deprivation therapy database from an inner city municipal hospital was queried to identify patients who presented with metastatic prostate cancer. We identified 129 individuals from 1999 to 2009 eligible for study. Those who underwent previous treatment for prostate cancer were excluded. We examined metastatic distribution and analyzed survival using Kaplan Meier probability curves. RESULTS: The median age of presentation was 68 with a median Gleason sum of 8 per prostate biopsy. Thirty-two patients presented with hydronephrosis with a median creatinine of 1.79, two of whom required emergent dialysis. Of those patients who underwent radiographic imaging at presentation, 35.5% (33/93) had lymphadenopathy suspicious for metastasis, 16.1% (15/93) had masses suspicious for visceral metastases. Of the patients who underwent a bone scan 93% (118/127) had positive findings with 7.9% (10/127) exhibiting signs of cord compression. The 2 and 5- year cancer specific survival was 92.1% and 65.6%, respectively. CONCLUSIONS: In this study we have highlighted a group of men in an underserved community who presented with aggressive and morbid PCa despite widespread acceptance of PSA screening.

A 10-year analysis of metastatic prostate cancer as an initial presentation in an underserved population

Objective To analyze patients from an underserved area who presented initially with metastatic prostate cancer in order to identify patients in our population who would suffer greatly if PSA screening was eliminated. Materials and Methods A prospectively maintained androgen deprivation therapy database from an inner city municipal hospital was queried to identify patients who presented with metastatic prostate cancer. We identified 129 individuals from 1999 to 2009 eligible for study. Those who underwent previous treatment for prostate cancer were excluded. We examined metastatic distribution and analyzed survival using Kaplan Meier probability curves. Results The median age of presentation was 68 with a median Gleason sum of 8 per prostate biopsy. Thirty-two patients presented with hydronephrosis with a median creatinine of 1.79, two of whom required emergent dialysis. Of those patients who underwent radiographic imaging at presentation, 35.5% (33/93) had lymphadenopathy suspicious for metastasis, 16.1% (15/93) had masses suspicious for visceral metastases. Of the patients who underwent a bone scan 93% (118/127) had positive findings with 7.9% (10/127) exhibiting signs of cord compression. The 2 and 5- year cancer specific survival was 92.1% and 65.6%, respectively. Conclusions In this study we have highlighted a group of men in an underserved community who presented with aggressive and morbid PCa despite widespread acceptance of PSA screening. .

Inferring foraging areas of nesting loggerhead turtles using satellite telemetry and stable isotopes.

In recent years, the use of intrinsic markers such as stable isotopes to link breeding and foraging grounds of migratory species has increased. Nevertheless, several assumptions still must be tested to interpret isotopic patterns found in the marine realm. We used a combination of satellite telemetry and stable isotope analysis to (i) identify key foraging grounds used by female loggerheads nesting in Florida and (ii) examine the relationship between stable isotope ratios and post-nesting migration destinations. We collected tissue samples for stable isotope analysis from 14 females equipped with satellite tags and an additional 57 untracked nesting females. Telemetry identified three post-nesting migratory pathways and associated non-breeding foraging grounds: (1) a seasonal continental shelf-constrained migratory pattern along the northeast U.S. coastline, (2) a non-breeding residency in southern foraging areas and (3) a residency in the waters adjacent to the breeding area. Isotopic variability in both δ(13)C and δ(15)N among individuals allowed identification of three distinct foraging aggregations. We used discriminant function analysis to examine how well δ(13)C and δ(15)N predict female post-nesting migration destination. The discriminant analysis classified correctly the foraging ground used for all but one individual and was used to predict putative feeding areas of untracked turtles. We provide the first documentation that the continental shelf of the Mid- and South Atlantic Bights are prime foraging areas for a large number (61%) of adult female loggerheads from the largest loggerhead nesting population in the western hemisphere and the second largest in the world. Our findings offer insights for future management efforts and suggest that this technique can be used to infer foraging strategies and residence areas in lieu of more expensive satellite telemetry, enabling sample sizes that are more representative at the population level.

Genetic barcoding of marine leeches (Ozobranchus spp.) from Florida sea turtles and their divergence in host specificity.

Ozobranchus margoi and Ozobranchus branchiatus are the only two species of marine turtle leeches (Ozobranchus spp.) known to inhabit the Atlantic coast of the United States and the Gulf of Mexico. In early reports of fibropapillomatosis (FP) in green turtles (Chelonia mydas), O. branchiatus was implicated as a vector in the transmission of Fibropapilloma-associated turtle herpesvirus (FPTHV). It is imperative that the leech species be identified to elucidate the role Ozobranchus spp. may play in disease transmission. In this study, Ozobranchus branchiatus has been identified for the first time on a loggerhead (Caretta caretta) turtle, and the molecular data for this species is now available for the first time in GenBank. Both species of leeches were also found infecting a single C. mydas. Using morphological taxonomy combined with distance- and character-based genetic sequence analyses, this study has established a DNA barcode for both species of Ozobranchus spp. leech and has shown it can be applied successfully to the identification of leeches at earlier stages of development when morphological taxonomy cannot be employed. The results suggest a different haplotype may exist for O. branchiatus leeches found on C. caretta versus C. mydas. Leech cocoon residue collected from a C. mydas was identified using the new method.

Identification and lineage genotyping of South American trypanosomes using fluorescent fragment length barcoding.

Trypanosoma cruzi and Trypanosoma rangeli are human-infective blood parasites, largely restricted to Central and South America. They also infect a wide range of wild and domestic mammals and are transmitted by a numerous species of triatomine bugs. There are significant overlaps in the host and geographical ranges of both species. The two species consist of a number of distinct phylogenetic lineages. A range of PCR-based techniques have been developed to differentiate between these species and to assign their isolates into lineages. However, the existence of at least six and five lineages within T. cruzi and T. rangeli, respectively, makes identification of the full range of isolates difficult and time consuming. Here we have applied fluorescent fragment length barcoding (FFLB) to the problem of identifying and genotyping T. cruzi, T. rangeli and other South American trypanosomes. This technique discriminates species on the basis of length polymorphism of regions of the rDNA locus. FFLB was able to differentiate many trypanosome species known from South American mammals: T. cruzi cruzi, T. cruzi marinkellei, T. dionisii-like, T. evansi, T. lewisi, T. rangeli, T. theileri and T. vivax. Furthermore, all five T. rangeli lineages and many T. cruzi lineages could be identified, except the hybrid lineages TcV and TcVI that could not be distinguished from lineages III and II respectively. This method also allowed identification of mixed infections of T. cruzi and T. rangeli lineages in naturally infected triatomine bugs. The ability of FFLB to genotype multiple lineages of T. cruzi and T. rangeli together with other trypanosome species, using the same primer sets is an advantage over other currently available techniques. Overall, these results demonstrate that FFLB is a useful method for species diagnosis, genotyping and understanding the epidemiology of American trypanosomes.

The molecular epidemiology and phylogeography of Trypanosoma cruzi and parallel research on Leishmania: looking back and to the future.

Trypanosoma cruzi is the protozoan agent of Chagas disease, and the most important parasitic disease in Latin America. Protozoa of the genus Leishmania are global agents of visceral and cutaneous leishmaniasis, fatal and disfiguring diseases. In the 1970s multilocus enzyme electrophoresis demonstrated that T. cruzi is a heterogeneous complex. Six zymodemes were described, corresponding with currently recognized lineages, TcI and TcIIa-e--now defined by multiple genetic markers. Molecular epidemiology has substantially resolved the phylogeography and ecological niches of the T. cruzi lineages. Genetic hybridization has fundamentally influenced T. cruzi evolution and epidemiology of Chagas disease. Genetic exchange of T. cruzi in vitro involves fusion of diploids and genome erosion, producing aneuploid hybrids. Transgenic fluorescent clones are new tools to elucidate molecular genetics and phenotypic variation. We speculate that pericardial sequestration plays a role in pathogenesis. Multilocus sequence typing, microsatellites and, ultimately, comparative genomics are improving understanding of T. cruzi population genetics. Similarly, in Leishmania, genetic groups have been defined, including epidemiologically important hybrids; genetic exchange can occur in the sand fly vector. We describe the profound impact of this parallel research on genetic diversity of T. cruzi and Leishmania, in the context of epidemiology, taxonomy and disease control.