Francine Pratlong

Evolutionary and geographical history of the Leishmania donovani complex with a revision of current taxonomy

Leishmaniasis is a geographically widespread severe disease, with an increasing incidence of two million cases per year and 350 million people from 88 countries at risk. The causative agents are species of Leishmania, a protozoan flagellate. Visceral leishmaniasis, the most severe form of the disease, lethal if untreated, is caused by species of the Leishmania donovani complex. These species are morphologically indistinguishable but have been identified by molecular methods, predominantly multilocus enzyme electrophoresis. We have conducted a multifactorial genetic analysis that includes DNA sequences of protein-coding genes as well as noncoding segments, microsatellites, restriction-fragment length polymorphisms, and randomly amplified polymorphic DNAs, for a total of ≈18,000 characters for each of 25 geographically representative strains. Genotype is strongly correlated with geographical (continental) origin, but not with current taxonomy or clinical outcome. We propose a new taxonomy, in which Leishmania infantum and L. donovani are the only recognized species of the L. donovani complex, and we present an evolutionary hypothesis for the origin and dispersal of the species. The genus Leishmania may have originated in South America, but diversified after migration into Asia. L. donovani and L. infantum diverged ≈1 Mya, with further divergence of infraspecific genetic groups between 0.4 and 0.8 Mya. The prevailing mode of reproduction is clonal, but there is evidence of genetic exchange between strains, particularly in Africa.

Visceral leishmaniasis and HIV-1 co-infection in southern France

Between 1986 and 1993 visceral leishmaniasis (VL) was diagnosed in 50 adult patients with human immunodeficiency virus type 1 (HIV-1) infection (8 females, 42 males: 31 intravenous drug users, 11 homosexual or bisexual men, 6 heterosexual individuals, 2 blood recipients) from 5 hospital centres in southern France. Diagnosis of VL was by demonstration of Leishmania and isolation of promastigotes by culture in Novy-McNeal-Nicolle medium. Leishmania isolates were identified by their isoenzyme profile in 28 patients. All the patients were immunocompromised when VL was diagnosed. Their median CD4 cell count was 25 x 10(6) (0-200). However, only 21 patients (42%) fulfilled the 1987 CDC criteria for the acquired immune deficiency syndrome before VL developed. Fever (84%), splenomegaly (56%), hepatomegaly (34%), and pancytopenia (62%) were the most common presenting features. Clinical signs were lacking in 10% of patients. Anti-leishmanial antibodies were detected by indirect immunofluorescence or enzyme-linked immunosorbent assay in 26/47 cases (55%). Combining these techniques with Western blotting (WB) gave a positivity rate of 95%. Amastigotes were demonstrated in bone marrow aspirates in 47 cases (94%). Unusual sites for parasites were found in 17 patients (34%), mainly in the digestive tract but also skin and lung. Viscerotropic L. infantum zymodeme MON-1 was characterized in 86% of cases. Dermotropic zymodemes MON-24, MON-29, MON-33, and a previously undescribed zymodeme MON-183, were isolated from 4 patients. The response rate to pentavalent antimony was 50% and to amphotericin B 100%, but clinical relapses were noted in both groups. In endemic areas, VL should be considered as a possible opportunistic infection in HIV-infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Visceral Leishmaniasis in a German Child Who Had Never Entered a Known Endemic Area: Case Report and Review of the Literature

We describe a case of visceral leishmaniasis in a 15-month-old German child. Diagnosis was significantly delayed because the patient had no history of travel to known endemic areas. Congenital or blood transfusion-associated leishmaniasis was ruled out. Possible modes of transmission (including a potential new autochthonous focus of the disease in central Europe) are discussed.

Outbreak of Cutaneous Leishmaniasis in Northern Israel

This study describes a new focus of cutaneous leishmaniasis (CL) due to Leishmania tropica, in the Galilee region of northern Israel. Thirty-three cases from 4 villages (northern part) and from the city of Tiberias (southern part) have been clinically diagnosed since 1996. Parasites from 13 patients and from 6 sand flies were characterized by isoenzyme electrophoresis, 2 immunological methods, and 3 polymerase chain reaction (PCR)-based methods. Isolates from the northern part were antigenically similar to Leishmania major and were different from other L. tropica isolates, including those from the southern part of the focus. They belonged to a newly reported zymodeme and were separable from all known Israeli L. tropica isolates, by use of 2 different PCR-based methods. Five (5.2%) of 97 Phlebotomus (Adlerius) arabicus and 2 (1.2%) of 162 Phlebotomus (Paraphlebotomus) sergenti females from the northern part of the focus were found to be infected with L. tropica. Three of 29 hyraxes (Procavia capensis) were positive for Leishmania ribosomal DNA. Thus, the northern part of this emerging focus of CL in Israel is distinct from all known L. tropica foci. P. arabicus is the main vector, and it transmits parasites that are different from other L. tropica isolates, with respect to antigenic, molecular, and biochemical parameters.

Geographical distribution and epidemiological features of Old World cutaneous leishmaniasis foci, based on the isoenzyme analysis of 1048 strains

A series of 1048 Leishmania strains from Old World cutaneous leishmaniasis foci, isolated between 1981 and 2005, were studied by isoenzyme analysis. The strains were obtained from humans, rodents, dogs and sandflies from 33 countries. The four typically dermotropic species, Leishmania major, L. tropica, L. aethiopica and L. killicki, were found. The viscerotropic species L. donovani and L. infantum, which can occasionally be responsible for cutaneous leishmaniasis, are not considered in this paper. Leishmania major was the least polymorphic species (12 zymodemes, 638 strains). Leishmania tropica was characterized by a complex polymorphism varying according to focus (35 zymodemes, 329 strains). Leishmania aethiopica, a species restricted to East Africa, showed a high polymorphism, in spite of a limited number of strains (23 zymodemes, 40 strains). Leishmania killicki, mainly restricted to Tunisia had a single zymodeme for 39 strains. Recently a parasite close to L. killicki (one zymodeme, two strains) was isolated in Algeria, which lead us to revise the taxonomic status of this taxon.

Genetic variability within the species Leishmania aethiopica does not correlate with clinical variations of cutaneous leishmaniasis.

Leishmania aethiopica infections in man result in a spectrum of diseases from LCL to DCL. These clinical manifestations have been attributed to genetic differences within the host or the parasites. In this study two different PCR-based methods were used to elucidate genetic variation within the species L. aethiopica. Inter- and intra-specific variations were detected in the ITS of the ribosomal operon in different strains and species of Leishmania, using a PCR-RFLP approach, and by a PCR fingerprinting technique that used single non-specific primers to amplify polymorphic regions of the genomic DNA. Both methods revealed genetic heterogeneity among ten L. aethiopica isolates examined. Unrooted distance trees separated the ten strains into two different genetic groups. This subdivision was correlated to the geographical origin of the isolates rather than to the clinical manifestation of the disease.

Leishmania infantum and L. major in Algeria

Since 1980, the development of leishmaniasis in Algeria has been marked by a considerable increase in the number of cases of both visceral leishmaniasis (1121 cases recorded) and cutaneous leishmaniasis (more than 2000 cases per year). New Leishmania infantum and L. major foci have appeared in the north and south of the country. During this period, 100 strains of Leishmania isolated from humans, other mammals and sandflies have been identified. The presence of L. major MON-25 in Psammomys obesus and Phlebotomus papatasi had identified these species as the main reservoir and vector, respectively, of zoonotic cutaneous leishmaniasis. Similarly, the presence of L. infantum MON-1 in Ph. perniciosus and dogs has implicated them as the vector and reservoir of visceral leishmaniasis. The isolation of the dermotropic zymodeme MON-24 of L. infantum from Ph. perfiliewi suggested that it was one of the main vectors of cutaneous leishmaniasis in the north of the country; the reservoir has not been identified. In addition, other zymodemes of Leishmania have been identified in visceral leishmaniasis patients, frequently associated with human immunodeficiency virus (MON-24, MON-33, MON-34 and MON-78), in patients with cutaneous leishmaniasis (MON-80), and in dogs with leishmaniasis (MON-34 and MON-77).

Disseminated feline leishmaniosis due to Leishmania infantum in Southern France

A fortuitously discovered case of feline leishmaniosis is reported. The parasites were found in the skin and the bone marrow of a domestic female cat that spontaneously died after a few weeks of evolution. Serological tests for FeLV, FIV and PIF virus detection gave negative results. By using Western blot serology, a characteristic pattern of leishmaniosis was obtained and by performing an isoenzyme electrophoresis, a Leishmania infantum MON-1 strain was identified. The same zymodeme is implicated in most of the canine and human leishmaniosis in Southern Europe. A study on the prevalence of asymptomatic feline leismaniosis is foreseen.

Global Distribution Maps of the Leishmaniases

The leishmaniases are vector-borne diseases that have a broad global distribution throughout much of the Americas, Africa, and Asia. Despite representing a significant public health burden, our understanding of the global distribution of the leishmaniases remains vague, reliant upon expert opinion and limited to poor spatial resolution. A global assessment of the consensus of evidence for leishmaniasis was performed at a sub-national level by aggregating information from a variety of sources. A database of records of cutaneous and visceral leishmaniasis occurrence was compiled from published literature, online reports, strain archives, and GenBank accessions. These, with a suite of biologically relevant environmental covariates, were used in a boosted regression tree modelling framework to generate global environmental risk maps for the leishmaniases. These high-resolution evidence-based maps can help direct future surveillance activities, identify areas to target for disease control and inform future burden estimation efforts. DOI: http://dx.doi.org/10.7554/eLife.02851.001

Epidemic visceral leishmaniasis in southern Sudan: identity and systematic position of the parasites from patients and vectors.

Twenty-five strains of Leishmania donovani isolated from humans and Phlebotomus orientalis in an epidemic area of southern Sudan were shown to belong to 3 very similar zymodemes: MON 18 (11 strains), MON 30 (1 strain) and MON 82 (13 strains). The 3 zymodemes are very closely related and seem to behave as a single population.