Methicillin-sensitive Staphylococcus aureus CC398 in intensive care unit, France

During testing for Staphylococcus aureus in an intensive care unit in France in 2011, we found that methicillin-sensitive S. aureus clonal complex 398 was the most frequent clone (29/125, 23.2%). It was isolated from patients (5/89, 5.6%), health care workers (2/63, 3.2%), and environmental sites (15/864,1.7%). Results indicate emergence of this clone in a hospital setting.

Complete mitochondrial genome of Lutzomyia (Nyssomyia) umbratilis (Diptera: Psychodidae), the main vector of Leishmania guyanensis

The nearly complete mitochondrial genome of Lutzomyia umbratilis Ward & Fraiha, 1977 (Psychodidae: Phlebotominae), considered as the main vector of Leishmania guyanensis, is presented. The sequencing has been performed on an Illumina Hiseq 2500 platform, with a genome skimming strategy. The full nuclear ribosomal RNA segment was also assembled. The mitogenome of L. umbratilis was determined to be at least 15,717 bp-long and presents an architecture found in many mitogenomes of insect (13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and one non-coding region also referred as the control region). The control region contains a large repeated element of c. 370 bp and a poly-AT region of unknown length. This is the first mitogenome of Psychodidae to be described.

Multilocus microsatellite typing of Leishmania and clinical applications: a review

Microsatellite markers have been used for Leishmania genetic studies worldwide, giving useful insight into leishmaniasis epidemiology. Understanding the geographic distribution, dynamics of Leishmania populations, and disease epidemiology improved markedly with this tool. In endemic foci, the origins of antimony-resistant strains and multidrug treatment failures were explored with multilocus microsatellite typing (MLMT). High genetic variability was detected but no association between parasite genotypes and drug resistance was established. An association between MLMT profiles and clinical disease manifestations was highlighted in only three studies and this data needs further confirmation. At the individual level, MLMT provided information on relapse and reinfection when multiple leishmaniasis episodes occurred. This information could improve knowledge of epidemiology and guide therapeutic choices for active chronic visceral leishmaniasis, the disease form in some HIV-positive patients.

Genetic evolution of Mycobacterium bovis causing tuberculosis in livestock and wildlife in France since 1978

To study the dynamics of bovine tuberculosis (bTB) in France, 4,654 M. bovis strains isolated mainly from livestock and wildlife since 1978 were characterized by spoligotyping and MLVA based on MIRU-VNTR. In our study spoligotyping allowed the discrimination of 176 types although 3 spoligotypes are predominant and account for more than half of the total strain population: SB0120 (26%), SB0134 (11%) and SB0121 (6%). In addition, 11% of the isolates, principally from Southern France, showing close spoligotypes and MIRU-VNTR types have been gathered in a family designated as the "F4-family". MLVA typing allowed extensive discrimination, particularly for strains with predominant spoligotypes, with a total of 498 genotypes, several of which were highly regionalized. The similarity of the strains' genetic relationships based on spoligotyping and MIRU-VNTR markers supports the co-existence of different clonal populations within the French M. bovis population. A genetic evolution of the strains was observed both geographically and in time. Indeed, as a result of the reduction of bTB due to the national control campaigns, a large reduction of the strains' genetic variability took place in the last ten years. However, in the regions were bTB is highly prevalent at present, cases in both livestock and in wildlife are due to the spread of unique local genotype profiles. Our results show that the highly discriminating genotyping tools used in this study for molecular studies of bTB are useful for addressing pending questions, which would lead to a better insight into the epidemiology of the disease, and for finding proper solutions for its sustainable control in France.

New microsatellite markers for multi-scale genetic studies on Phlebotomus ariasi Tonnoir, vector of Leishmania infantum in the Mediterranean area

The population structure of Phlebotomus ariasi, a proven vector of Leishmania infantum in the Mediterranean area, is still poorly understood. Previously, only two microsatellite loci had been developed to study the population genetics of this species. Herein we use these loci and determined fourteen novel microsatellite loci, useful for the characterization of P. ariasi populations. These loci were tested on three populations of P. ariasi, two from France and one from Portugal. In addition, the usefulness of these markers was also evaluated on seven other sandfly species. We show, that for P. ariasi, 15 of the 16 loci selected were polymorphic, with a mean of 4.25 alleles and an observed heterozygosity of 0.299. Within the P. ariasi population of France, 11 loci were polymorphic, with an average of 2.44 alleles and an observed heterozygosity of 0.2177. The fixation index was moderate among the French populations but high between French and Portuguese populations. In addition, eight loci were also found to be amplifiable in six other Phlebotomus species. These results demonstrate the usefulness of this new set of microsatellite loci for population structure and molecular ecology studies of P. ariasi at various spatial scales, but also of other sandfly species.

Mycobacterium tuberculosis: ecology and evolution of a human bacterium

Some species of the Mycobacterium tuberculosis complex (MTBC), particularly Mycobacterium tuberculosis, which causes human tuberculosis (TB), are the first cause of death linked to a single pathogen worldwide. In the last decades, evolutionary studies have much improved our knowledge on MTBC history and have highlighted its long co-evolution with humans. Its ability to remain latent in humans, the extraordinary proportion of asymptomatic carriers (one-third of the entire human population), the deadly epidemics and the observed increasing level of resistance to antibiotics are proof of its evolutionary success. Many MTBC molecular signatures show not only that these bacteria are a model of adaptation to humans but also that they have influenced human evolution. Owing to the unbalance between the number of asymptomatic carriers and the number of patients with active TB, some authors suggest that infection by MTBC could have a protective role against active TB disease and also against other pathologies. However, it would be inappropriate to consider these infectious pathogens as commensals or symbionts, given the level of morbidity and mortality caused by TB.

Sacroiliitis secondary to catheter-related bacteremia due to Mycobacterium abscessus (sensu stricto)

We describe a case of sacroiliitis secondary to catheter-related bacteremia due to Mycobacterium abscessus (sensu stricto). This case confirms that MultiLocus sequence typing and variable-number tandem-repeat methods are very robust techniques to identify the pathogen species and to validate molecular epidemiological links among complex M. abscessus isolates.

Of parasites and men

The living world has evolved and is evolving through interspecific relationships between organisms. The diversity of these interactions is enormous going from mutualism to parasitism. Humans live with a multitude of microorganisms, essential for their biology. However, interactions are not always advantageous. Indeed, many organisms might become pathogens, such as the Plasmodium species, the causative agents of malaria. Like many other microorganisms, they are «Machiavellian» in their capacity to elaborate a range of reproduction strategies, giving them a huge advantage in terms of adaptation. Here, we discuss the role played by parasites in the ecology and evolution of living organisms and particularly of humans. In the study of infectious diseases, humans are legitimately the focal point, although they represent only one ecosystem among many others and not taking this into account certainly biases our global view of the system. Indeed, we know only a minimal fraction of the microorganisms we live with. However, parasites have shaped and are still shaping the human genome. Several genetic signatures are the proofs of the selection pressures by parasites that humankind has endured during its evolution. But, ultimately, what are the solutionsfor living with pathogens? Should we eradicate them or should we learn how to control and manage them?

Parasitic genotypes appear to differ in leishmaniasis patients compared with asymptomatic related carriers

For numerous infectious diseases affecting humans, clinical manifestations range from asymptomatic forms to severe pathologies. The originality of this study was its focus on asymptomatic carriers of Leishmania infantum in southern France. The fundamental interest in these asymptomatic carriers is that they can be a reservoir of potentially pathogenic microorganisms. It remains to be established whether the parasitic genomes from asymptomatic carriers differ from those of patients. Multilocus microsatellite typing was used to investigate the genetic variation among 36 French strains of L. infantum. Nine Leishmania strains isolated from blood donors (asymptomatic carriers) were compared with 27 strains of L. infantum belonging to zymodemes, MON-1, -33 and -183. These strains were isolated from HIV positive or negative patients with visceral leishmaniasis, cutaneous leishmaniasis, from canine leishmaniasis or from phlebotomine sandflies. Multilocus microsatellite typing data generated using 33 loci were analyzed by a Bayesian model-based clustering algorithm and construction of a phylogenetic tree based on genetic distances. Both analyses structured the MON-1 sample into two main clusters. Furthermore, genetic analysis demonstrated that these nine asymptomatic carrier strains are divided into two clusters grouped with the MON-1 strains. One cluster with seven strains is related to, but different from, human symptomatic strains from the Alpes-Maritimes region whereas the other cluster has the two remaining strains together with canine leishmaniasis strains as well as one strain from a visceral leishmaniasis patient. Genetic diversity among asymptomatic carrier was very weak since the nine Leishmania strains belong to only two genotypes. Genetic differentiations were evidenced between asymptomatic carrier strains and non-asymptomatic carrier strains and especially between asymptomatic carrier and HIV+ populations, although these findings require confirmation with a larger sample size. We believe that our data explore for the first time, the genetic diversity among L. infantum from asymptomatic human carriers and reveal a weak polymorphism compared with Leishmania parasites isolated from human patients.

DNAGear--a free software for spa type identification in Staphylococcus aureus

Background

Staphylococcus aureus is both human commensal and an important human pathogen, responsible for community-acquired and nosocomial infections ranging from superficial wound infections to invasive infections, such as osteomyelitis, bacteremia and endocarditis, pneumonia or toxin shock syndrome with a mortality rate up to 40%. S. aureus reveals a high genetic polymorphism and detecting the genotypes is extremely useful to manage and prevent possible outbreaks and to understand the route of infection. One of current and expanded typing method is based on the X region of the spa gene composed of a succession of repeats of 21 to 27 bp. More than 10000 types are known. Extracting the repeats is impossible by hand and needs a dedicated software. Unfortunately the only software on the market is a commercial program from Ridom.

Findings

This article presents DNAGear, a free and open source software with a user friendly interface written all in Java on top of NetBeans Platform to perform spa typing, detecting new repeats and new spa types and synchronizing automatically the files with the open access database. The installation is easy and the application is platform independent. In fact, the SPA identification is a formal regular expression matching problem and the results are 100% exact. As the program is using Java embedded modules written over string manipulation of well established algorithms, the exactitude of the solution is perfectly established.

Conclusions

DNAGear is able to identify the types of the S. aureus sequences and detect both new types and repeats. Comparing to manual processing, which is time consuming and error prone, this application saves a lot of time and effort and gives very reliable results. Additionally, the users do not need to prepare the forward-reverse sequences manually, or even by using additional tools. They can simply create them in DNAGear and perform the typing task. In short, researchers who do not have commercial software will benefit a lot from this application.

High prevalence of Beijing and EAI4-VNM genotypes among M. tuberculosis isolates in northern Vietnam: sampling effect, rural and urban disparities

A total of 221 isolates of M. tuberculosis were sampled from hospitals and the general population in the northern plain of Vietnam, one of the most populated region of the country. Genotypic composition and diversity were characterized, and we investigated how they are affected by sampling (hospital vs. general population), correcting for potential confounding effects (location, age and gender of the patients). Spoligotyping and 12 MIRU-VNTR typing were used as first line. Then 15 MIRU-VNTR standard set was used, making 21 MIRU-VNTR typing for the clustered isolates. Result showed that 8 lineages and 13 sub-lineages were circulating in the region. The most predominant lineages were Beijing (38.5%) and EAI (38.5%). Others appeared with small proportions H (1.4%), LAM (1.8%), T (8.1%), X (0.9%), MANU (2.3%), and Zero (0.4%). Higher clustering rate was found in the hospital samples (17.9% in urban and 19.2% in rural areas) compared to the population ones (0%). The typical Vietnamese EAI4-VNM sub-lineage of EAI lineage accounted for 67% of EAI strains and was associated with older ages. Beijing genotypes were associated with younger, urban population and were characterized by high clustering rates. These characteristics strongly suggest that Beijing strains are invading the population, replacing the local EAI-VNM4, thus predicting a more serious tuberculosis situation in the future in the absence of more effective control strategies.

Wing size and shape variation of Phlebotomus papatasi (Diptera: Psychodidae) populations from the south and north slopes of the Atlas Mountains in Morocco

The wing shape and size morphology of populations of the medically important phlebotomine sand fly, Phlebotomus papatasi, were examined in two endemic (south of the Atlas Mountains) and nonendemic (north of the Atlas Mountains) foci of cutaneous leishmaniasis by using geometric morphometrics in Morocco. Although it is present in all of Morocco, P. papatasi is the main vector of Leishmania major in only southern part of the Atlas Mountains. There are four major mountain ranges that serve as geographical barriers for species distribution in the study area and at least four gaps were recognized among these barriers. We found statistically significant differences in wing shape morphology between southern and northern populations. Analysis clearly recognized two main groups of populations on both sides of the mountains. The graphical depiction of Principal Component Analysis (PCA) and Canonical Variates Analysis (CVA) confirmed our morphometric study suggesting that the difference in wing morphology between the populations indicates that the population of P. papatasi shows phenotypic plasticity in the study area. According to centroid size analyses, which were used as measures of wing size differences among different sites, the north population of P. papatasi had relatively larger wings than the south population.

Genetic diversity, population structure and drug resistance of Mycobacterium tuberculosis in Peru

This paper presents the first evaluation of the molecular epidemiology of Mycobacterium tuberculosis in Peru. We characterised 323 isolates using spoligotyping and mycobacterial interspersed repetitive units variable number tandem repeats (MIRU-VNTR) typing. We aimed to determine the levels of genetic diversity and genetic differentiation among and within Peruvian isolates and the epidemiological factors which may be driving patterns of population structure and evolution of M. tuberculosis in Peru. Our results compared to the fourth international spoligotyping database (SpolDB4) and MIRU-VNTRplus, show that the main M. tuberculosis families present are Latin American-Mediterranean, Haarlem, T, and Beijing. Bayesian clustering recovered 15 groups in the Peruvian M. tuberculosis isolates, among which two were composed mainly of orphans, implying the presence of native "Peruvian" strains not previously reported. Variable levels of association with drug resistance were observed, with Beijing genotypes not showing any association with multidrug resistance, while in other groups MIRU-VNTR loci 2, 23, 31, and 40 were found to be associated with the multidrug-resistant tuberculosis (MDR-TB) phenotype, suggesting that a linkage disequibrium between these MIRU and drug resistance loci may be present. Genetic differentiation was present among drug resistant and sensitive strains. Ethambutol appeared to be the main driver of differentiation, suggesting that strong selection pressure could have been exerted by drug treatment in Peru over recent years.

Clinical pleiomorphism in human leishmaniases, with special mention of asymptomatic infection

This review gives an update of current knowledge on the clinical pleiomorphism of Leishmania, with a special emphasis on the case of asymptomatic carriage. The first part describes the numerous unusual expressions of the disease that occur besides the classic (visceral, cutaneous, and mucocutaneous) forms of leishmaniases. The second part deals with progress in the understanding of disease outcome in humans, and the possible future approaches to improve our knowledge in the field. The third part highlights the role of the too often neglected asymptomatic carrier compartment. This group could be key to understanding infraspecific differences in virulence and pathogenicity of the parasite, as well as identifying the genetic determinants involved in the expression of the disease.

Reproductive strategies and population structure in Leishmania: substantial amount of sex in Leishmania Viannia guyanensis

Leishmania species of the subgenus Viannia and especially Leishmania Viannia guyanensis are responsible for a large proportion of New World leishmaniasis cases. Since a recent publication on Leishmania Viannia braziliensis, the debate on the mode of reproduction of Leishmania parasites has been reopened. A predominant endogamic reproductive mode (mating with relatives), together with strong Wahlund effects (sampling of strains from heterogeneous subpopulations), was indeed evidenced. To determine whether this hypothesis can be generalized to other Leishmania Viannia species, we performed a population genetic study on 153 human strains of L. (V.) guyanensis from French Guiana based on 12 microsatellite loci. The results revealed important homozygosity and very modest linkage disequilibrium, which is in agreement with a high level of sexual recombination and substantial endogamy. These results also revealed a significant isolation by distance with relatively small neighbourhoods and hence substantial viscosity of Leishmania populations in French Guiana. These results are of epidemiological relevance and suggest a major role for natural hosts and/or vectors in parasite strain diffusion across the country as compared to human hosts.

Ecology of phlebotomine sand flies in the rural community of Mont Rolland (Thiès region, Senegal): area of transmission of canine leishmaniasis

Background

Different epidemiological studies previously indicated that canine leishmaniasis is present in the region of Thiès (Senegal). However, the risks to human health, the transmission cycle and particularly the implicated vectors are unknown.

Methodology/Principal Findings

To improve our knowledge on the population of phlebotomine sand flies and the potential vectors of canine leishmaniasis, sand flies were collected using sticky traps, light traps and indoor spraying method using pyrethroid insecticides in 16 villages of the rural community of Mont Rolland (Thiès region) between March and July 2005. The 3788 phlebotomine sand flies we collected (2044 males, 1744 females) were distributed among 9 species of which 2 belonged to the genus Phlebotomus: P. duboscqi (vector of cutaneous leishmaniasis in Senegal) and P. rodhaini. The other species belonged to the genus Sergentomyia: S. adleri, S. clydei, S. antennata, S. buxtoni, S. dubia, S. schwetzi and S. magna. The number of individuals and the species composition differed according to the type of trap, suggesting variable, species-related degrees of endophily or exophily. The two species of the genus Phlebotomus were markedly under-represented in comparison to the species of the genus Sergentomyia. This study also shows a heterogeneous spatial distribution within the rural community that could be explained by the different ecosystems and particularly the soil characteristics of this community. Finally, the presence of the S. dubia species appeared to be significantly associated with canine leishmaniasis seroprevalence in dogs.

Conclusions/Significance

Our data allow us to hypothesize that the species of the genus Sergentomyia and particularly the species S. dubia and S. schwetzi might be capable of transmitting canine leishmaniasis. These results challenge the dogma that leishmaniasis is exclusively transmitted by species of the genus Phlebotomus in the Old World. This hypothesis should be more thoroughly evaluated.

Additional haplogroups of Toxoplasma gondii out of Africa: population structure and mouse-virulence of strains from Gabon

BACKGROUND

Toxoplasma gondii is found worldwide, but distribution of its genotypes as well as clinical expression of human toxoplasmosis varies across the continents. Several studies in Europe, North America and South America argued for a role of genotypes in the clinical expression of human toxoplasmosis. Genetic data concerning T. gondii isolates from Africa are scarce and not sufficient to investigate the population structure, a fundamental analysis for a better understanding of distribution, circulation, and transmission.

METHODOLOGY/PRINCIPAL FINDINGS

Seropositive animals originating from urban and rural areas in Gabon were analyzed for T. gondii isolation and genotyping. Sixty-eight isolates, including one mixed infection (69 strains), were obtained by bioassay in mice. Genotyping was performed using length polymorphism of 13 microsatellite markers located on 10 different chromosomes. Results were analyzed in terms of population structure by Bayesian statistical modeling, Neighbor-joining trees reconstruction based on genetic distances, F(ST) and linkage disequilibrium. A moderate genetic diversity was detected. Three haplogroups and one single genotype clustered 27 genotypes. The majority of strains belonged to one haplogroup corresponding to the worldwide Type III. The remaining strains were distributed into two haplogroups (Africa 1 and 3) and one single genotype. Mouse virulence at isolation was significantly different between haplogroups. Africa 1 haplogroup was the most virulent.

CONCLUSION

Africa 1 and 3 haplogroups were proposed as being new major haplogroups of T. gondii circulating in Africa. A possible link with strains circulating in South and Central America is discussed. Analysis of population structure demonstrated a local spread within a rural area and strain circulation between the main cities of the country. This circulation, favored by human activity could lead to genetic exchanges. For the first time, key epidemiological questions were addressed for the West African T. gondii population, using the high discriminatory power of microsatellite markers, thus creating a basis for further epidemiological and clinical investigations.

Pulmonary tuberculosis due to Mycobacterium microti: a study of six recent cases in France

Human tuberculosis caused by Mycobacterium microti is rare, but its prevalence and clinical significance may have been underestimated. To the best of our knowledge, 21 cases have been reported in the literature in the last decade. We report six recent pulmonary cases caused by M. microti over a period of 5 years detected in French clinical mycobacteriology laboratories of the hospital network. Our data confirm the potential of M. microti to cause clinical illness in immunocompetent patients. M. microti grew slowly from specimens, delaying the final microbiological diagnosis. Therefore, patients with tuberculosis caused by M. microti could benefit from the use of rapid diagnostic molecular techniques directly on clinical samples. From a review of the literature and this study, a classical antituberculous therapy seems effective in treating patients with M. microti disease.

Highly structured genetic diversity of the Mycobacterium tuberculosis population in Djibouti

Djibouti is an East African country with a high tuberculosis incidence. This study was conducted over a 2-month period in Djibouti, during which 62 consecutive patients with pulmonary tuberculosis (TB) were included. Genetic characterization of Mycobacterium tuberculosis, using mycobacterial interspersed repetitive-unit variable-number tandem-repeat typing and spoligotyping, was performed. The genetic and phylogenetic analysis revealed only three major families (Central Asian, East African Indian and T). The high diversity and linkage disequilibrium within each family suggest a long period of clonal evolution. A Bayesian approach shows that the phylogenetic structure observed in our sample of 62 isolates is very likely to be representative of the phylogenetic structure of the M. tuberculosis population in the total number of TB cases.

Identification of Old World Leishmania spp. by specific polymerase chain reaction amplification of cysteine proteinase B genes and rapid dipstick detection

We used the cysteine proteinase B (cpb) gene family of the trypanosomatid genus Leishmania as a target to develop rapid, specific, and easy-to-use polymerase chain reaction (PCR) tests to discriminate Leishmania infantum, Leishmania donovani, Leishmania tropica, Leishmania aethiopica, and Leishmania major. Identification of all 5 Old World species and validation of intraspecies variability are features lacking in other species-specific PCRs. Amplicon analysis was done on agarose gels and was further simplified by using an oligochromatography dipstick to detect L. infantum and L. donovani products. Because the analytical sensitivity is lower than that of certain other species- and genus-specific PCRs, our assays are especially valuable for use on cultured isolates or directly on cryostabilates. As such, they can be implemented by research and health centers having access to culturing, DNA isolation, and PCR.

The promastigote surface antigen gene family of the Leishmania parasite: differential evolution by positive selection and recombination

Background

PSA (promastigote surface antigen) is one of the major classes of membrane proteins present at the surface of the parasitic protozoan Leishmania. While it harbours leucine rich repeats, which are suggestive of its involvement in parasite-to-host physical interactions, its exact role is largely unknown. Furthermore, the extent of diversity of this gene family, both in copy number and sequence has not been established.

Results

From the newly available complete genome sequences of L. major, L. infantum and L. braziliensis, we have established the complete list of PSA genes, based on the conservation of specific domain architecture. The latter includes an array of leucine rich repeats of unique signature flanked by conserved cysteine-rich domains. All PSA genes code either for secreted or membrane-anchored surface proteins. Besides the few previously identified PSA genes, which are shown here to be part of a relatively large subclass of PSA genes located on chromosome 12, this study identifies seven other PSA subtypes. The latter, whose genes lie on chromosomes 5, 9, 21 and 31 in all three species, form single gene (two genes in one instance) subfamilies, which phylogenetically cluster as highly related orthologs. On the other hand, genes found on chromosome 12 generally show high diversification, as reflected in greater sequence divergence between species, and in an extended set of divergent paralogs. Moreover, we show that the latter genes are submitted to strong positive selection. We also provide evidence that evolution of these genes is driven by intra- and intergenic recombination, thereby modulating the number of LRRs in protein and generating chimeric genes.

Conclusion

PSA is a Leishmania family of membrane-bound or secreted proteins, whose main signature consists in a specific LRR sequence. All PSA genes found in the genomes of three sequenced Leishmania species unambiguously distribute into eight subfamilies of orthologs. Seven of these are evolving relatively slowly and could correspond to basic functions related to parasite/host interactions. On the opposite, the other PSA gene class, which include all so far experimentally studied PSA genes, could be involved in more specialised adaptative functions.

Leishmania and the leishmaniases: a parasite genetic update and advances in taxonomy, epidemiology and pathogenicity in humans

Leishmaniases remain a major public health problem today despite the vast amount of research conducted on Leishmania pathogens. The biological model is genetically and ecologically complex. This paper explores the advances in Leishmania genetics and reviews population structure, taxonomy, epidemiology and pathogenicity. Current knowledge of Leishmania genetics is placed in the context of natural populations. Various studies have described a clonal structure for Leishmania but recombination, pseudo-recombination and other genetic processes have also been reported. The impact of these different models on epidemiology and the medical aspects of leishmaniases is considered from an evolutionary point of view. The role of these parasites in the expression of pathogenicity in humans is also explored. It is important to ascertain whether genetic variability of the parasites is related to the different clinical expressions of leishmaniasis. The review aims to put current knowledge of Leishmania and the leishmaniases in perspective and to underline priority questions which 'leishmaniacs' must answer in various domains: epidemiology, population genetics, taxonomy and pathogenicity. It concludes by presenting a number of feasible ways of responding to these questions.