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 Ϸ18,000 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 Ϸ1 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.Leishmania infantum ͉ Leishmaniasis ͉ parasitic protozoa ͉ phylogeny ͉ population genetics

The objectives of this study were to compare the sensitivities and reliabilities of different PCR methods for the diagnosis and epidemiological study of canine visceral leishmaniasis (CVL) using dog blood. We chose to work with peripheral blood, as this type of sampling is noninvasive, straightforward, and easy to repeat. Six PCR methods were compared: three primer pairs target genomic DNA, and the other three target kinetoplast (mitochondrial) DNA. Sensitivity, specificity, reproducibility, and ease of interpretation without hybridization were evaluated for each method. The assessment was first performed using artificial samples. All methods could detect less than one parasite per reaction tube. However, the sensitivities varied among the different methods by a factor of 500 on purified cultivated parasites and by a factor of 10,000 on seeded dog blood samples (i.e., from 10 to 10 ؊3 parasite per ml of blood for the latter). Only four methods were found sufficiently reliable for the diagnosis of CVL. They were tested on 37 dogs living in an area of endemicity and grouped according to clinical status and specific serology. Only the two methods targeting kinetoplast DNA (K13A-K13B and RV1-RV2) could detect the parasite in 100% of symptomatic infected dogs. Similarly, all seropositive dogs were found PCR positive by these methods versus 62% by the genomic-DNA-based methods. Finally, these kinetoplast-based methods proved clearly superior to the others in the detection of Leishmania in asymptomatic dogs. Our data allow the discussion of the advantages and drawbacks of highly sensitive versus moderately sensitive PCR methods in diagnosis and prevalence studies of CVL.

Sri Lankan cutaneous leishmaniasis (CL), once considered sporadic, is fairly widespread in some parts of the country. Identification of 5 isolates from 4 CL patients by enzyme analysis during 2002 showed that they were all Leishmania donovani zymodeme MON-37, the parasite which also causes visceral leishmaniasis in India and East Africa.

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Abstract. In Cyprus, leishmaniasis has been considered exclusively a veterinary problem. It was prevalent before 1945, and until its recent reemergence, it was nearly eradicated by 1996 as a consequence of the destruction of reservoir hosts and vectors. A survey carried out to provide an unbiased estimate of current transmission rates in dogs and humans showed a 9-fold increase in dog seroprevalence (reaching 14.9%) compared with 10 years ago. However, no human cases caused by Leishmania infantum were detected, although L. donovani cases were reported recently. The 62 strains isolated from dogs were typed as L. infantum MON-1 (98.4%), which is the predominating zymodeme in the Mediterranean region, and MON-98 (1.6%). The Phlebotomus species P. tobbi (vector of L. infantum in Cyprus), P. galilaeus , and P. papatasi were the predominant species captured. Two transmission cycles seem to run in parallel in Cyprus: in dogs with L. infantum and in humans with L. donovani .

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).

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In French Guiana, cutaneous leishmaniasis in moderately immunosuppressed HIV-infected subjects (> 200 CD4+ T cells mm(-3)) is characterized by a higher rate of recurrence or reinfection and is more difficult to treat than that in HIV- subjects.