New Leishmania (Leishmania) infantum zymodemes responsible for visceral leishmaniasis in patients co-infected with HIV in Spain

Genetic Diversity and Population Structure of Leishmania infantum in Morocco as Revealed by Multilocus Sequence Typing (MLST) Approach

Leishmania infantum is endemic in Morocco, and it causes both visceral (VL) and cutaneous leishmaniasis (CL). In this study, the multilocus sequence typing (MLST) approach was used to investigate the phylogeny and population structure of Leishmania infantum strains isolated from CL and VL patients and the canine reservoir in different leishmaniasis endemic foci in Morocco. For this purpose, eight loci (pgm, alat, me, fh, g6pd, pgd, gpi and cytb) were amplified in 40 samples, out of which 31 were successfully sequenced. The genetic diversity analysis detected a high degree of intraspecific genetic variability among the studied strains. The phylogenetic and the haplotype analyses showed that most of the strains from the same geographical areas clustered together. The recombination among Leishmania infantum strains was revealed through a splits tree analysis and the number of recombination events. Moreover, the assessment of the gene flow between Leishmania infantum and Leishmania tropica through phylogenetic analysis and haplotype diversity in two endemic foci where the two species were sympatric showed no genetic exchange between the two species.

Geographical distribution updating of Tunisian leishmaniasis foci: about the isoenzymatic analysis of 694 strains

Over a period of ten years, a series of 694 Leishmania strains from Tunisian leishmaniasis foci were isolated and identified by isoenzymatic analysis. Strains were obtained from human cutaneous and visceral leishmaniasis in immunocompetent subjects, visceral leishmaniasis in imunocompromised individuals and from dogs with visceral leishmaniasis. Two classically dermotropic species, Leishmania (L.) major and Leishmania killicki were found. L. major with the single zymodeme MON-25 was the most isolated in cutaneous leishmaniasis foci of the Centre and South of Tunisia with a recent northern extension. L. killicki zymodeme MON-8 was sporadically found both in its classical microfocus of Tataouine in southeastern Tunisia as well as in some new foci in Southwestern, Central and Northern Tunisia. Leishmania infantum with its three zymodemes MON-1, MON-24 and MON-80 was isolated from both visceral and cutaneous human cases. The majority of L. infantum strains were found in the Northern part of the country; however, some strains were reported for the first time in the Southern part. L. infantum MON-1 was the only zymodeme isolated from canine leishmaniasis.

Differentiation and gene flow among European populations of Leishmania infantum MON-1

BACKGROUND

Leishmania infantum is the causative agent of visceral and cutaneous leishmaniasis in the Mediterranean region, South America, and China. MON-1 L. infantum is the predominating zymodeme in all endemic regions, both in humans and dogs, the reservoir host. In order to answer important epidemiological questions it is essential to discriminate strains of MON-1.

METHODOLOGY/PRINCIPAL FINDINGS

We have used a set of 14 microsatellite markers to analyse 141 strains of L. infantum mainly from Spain, Portugal, and Greece of which 107 strains were typed by MLEE as MON-1. The highly variable microsatellites have the potential to discriminate MON-1 strains from other L. infantum zymodemes and even within MON-1 strains. Model- and distance-based analysis detected a considerable amount of structure within European L. infantum. Two major monophyletic groups-MON-1 and non-MON-1-could be distinguished, with non-MON-1 being more polymorphic. Strains of MON-98, 77, and 108 were always part of the MON-1 group. Among MON-1, three geographically determined and genetically differentiated populations could be identified: (1) Greece; (2) Spain islands-Majorca/Ibiza; (3) mainland Portugal/Spain. All four populations showed a predominantly clonal structure; however, there are indications of occasional recombination events and gene flow even between MON-1 and non-MON-1. Sand fly vectors seem to play an important role in sustaining genetic diversity. No correlation was observed between Leishmania genotypes, host specificity, and clinical manifestation. In the case of relapse/re-infection, only re-infections by a strain with a different MLMT profile can be unequivocally identified, since not all strains have individual MLMT profiles.

CONCLUSION

In the present study for the first time several key epidemiological questions could be addressed for the MON-1 zymodeme, because of the high discriminatory power of microsatellite markers, thus creating a basis for further epidemiological investigations.

Isoenzymatic variability of Leishmania infantum in Tunisia concerning 254 human strains

The different clinical forms of leishmaniasis are the result of both the immunological status of individuals and the species of the parasite causing the infection. In Mediterranean countries, the Leishmania infantum complex groups zymodemes which are responsible for visceral, cutaneous and exceptionally cutaneomucosal or mucosal leishmaniasis. We report in this study a synthesis concerning 254 cases of L. infantum that have been characterized at the "Laboratoire de Parasitologie" of the Rabta Hospital. The strains were isolated from human cases of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) by culture on NNN medium: 156 VL cases and 98 CL cases. The isoenzymatic characterization revealed three zymodemes of L. infantum. * L. infantum MON 1, a common zymodeme of VL,occurred in 154 cases (61%): 147 VL (95%) and 7 CL (5%). All CL cases were from the northern provinces, six of them occurring during an epidemic disease in 2001. * L. infantum MON 24, a common zymodeme of CL in the north, occurred in 98 cases (38.5%): 91 CL (93%) and 7 VL (7%). The seven VL cases were immunocompetent children aged from 8 months to 9 years and native of northern Tunisia. Two of the CL cases were from central regions of the country. This is the first time that cases from these regions are reported. * L. infantum MON 80, an uncommon zymodeme in Tunisia, occurred in two VL cases (0.5%): two children aged 7 and 5. The small number of strains of this zymodeme does not allow understanding of its epidemiological role. The results of this study indicate a low enzymatic variability of L. infantum in the country. However, our study includes only human strains and should be extended to animal ones (dogs, rodents and sand flies). This would lead to a better understanding of the epidemiology of leishmaniasis in Tunisia.

Sepsisähnliches Krankheitsbild bei Immunsuppression nach früherem Mallorcaurlaub

In immunosuppressed patients, a high rate of complications due to opportunistic infection is known. We report the case of a 36 year old patient with ulcerative colitis and a septic complication with ongoing pancytopenia. Due to colonic perforation, colectomy had to be performed. Despite this intervention, the septic constellation persisted. The pancytopenia in peripheral blood counts also persisted with the necessity of repetitive transfusions. A bone marrow biopsy showed an infiltration with Leishmania bodies in macrophages. Tissue culture allowed for typing of the parasites as belonging to the L. donovani/infantum complex, DNA sequencing confirmed infection with L. infantum. This infection must have been contracted during a vacation on Mallorca about 1.5 years earlier. Administration of liposomal amphotericin B cured the patient. Surprisingly, histological examination of the resected colon reveiled the presence of an immunoblastic B-cell lymphoma. In this case, immunosuppression was a prerequisite for the manifestation of leishmaniosis.

Isoenzymatic polymorphism of Leishmania infantum in southern Spain

Over a period of more than 10 years we have isolated and classified 161 Leishmania strains from cases of human visceral, cutaneous and mucosal leishmaniasis in immunocompetent subjects, from cases of visceral leishmaniasis in immunocompromised individuals with HIV, from dogs with leishmaniasis (visceral and cutaneous), from Rattus rattus and from sandflies. The strains were all L. infantum, the only species endemic in Spain, and corresponded to 20 different zymodemes. We describe the life cycle of these zymodemes for which, in most cases, we only partially know the hosts involved. We also discuss possible reasons for the greater polymorphism of L. infantum in southern Spain.

The identification and variability of the parasites causing leishmaniasis in HIV-positive patients in Italy

Between 1988 and 1998, 258 Leishmania strains from patients infected with HIV were characterized by iso-enzyme electrophoresis at the Istituto Superiore di Sanità (ISS) in Rome. Most (227) of the isolates came from 80 Italian patients with visceral leishmaniasis (VL), the rest from cases of Leishmania/HIV co-infection in other Mediterranean countries. Every strain was found to be Leishmania infantum. In Italy, 19 zymodemes of L. infantum were identified, broadly divided into three groups. Over 50% of the Italian patients were infected by the commonest agent of Mediterranean VL in HIV-negative individuals (zymodeme MON-1) whereas the remaining patients were infected by two distinct groups of zymodemes: one usually causing simple, self-resolving cutaneous leishmaniasis in HIV-negative patients, the other consisting of agents detected, so far, only in HIV-positive subjects. This last group, consisting of seven zymodemes, showed re-assortment patterns within electromorphs frequently observed in dermotropic L. infantum zymodemes. A similar grouping was also observed in the isolates from other Mediterranean countries. Basing on general data recorded at the ISS over the last 20 years, accurate identification of the geographical origin of the zymodemes was attempted by careful analysis of the patients' histories, using the iso-enzyme electromorphs as geographical markers. Furthermore, a polymorphism index (no. of zymodemes/no. of patients) was defined for each Leishmania species and geographical region, and used to assess the level of L. infantum zymodeme heterogeneity in Italy, before and after stratification by HIV status. The greatest zymodeme heterogeneity was found in Sicily (southern Italy), with nine zymodemes identified among only 30 HIV-positive patients.

Iso-enzymatic variability of Leishmania infantum in Spain

In many areas of the Mediterranean basin, leishmaniasis can now be found in HIV-positive individuals. Such cases of Leishmania/HIV co-infection are relatively common in southern Europe, Spain being the country that has reported the greatest number. Since 1984, 359 Spanish isolates of Leishmania infantum have been characterized at the Instituto de Salud Carlos III in Madrid. Most (94.6%) of the isolates came from HIV-positive patients. The results of iso-enzymatic analysis indicated a high level of variability among the isolates, the visceralization in HIV-positive individuals of variants considered to be dermotropic in the immunocompetent, and the appearance of new zymodemes among the HIV-positive human population.

Molecular epidemiology of Leishmania infantum on the island of Majorca: a comparison of phenotypic and genotypic tools

In the Mediterranean basin, Leishmania infantum is the causative agent of both visceral and cutaneous leishmaniasis, and is an important opportunistic parasite in patients infected with human immunodeficiency virus (HIV). The commonest method used to study the variability of Leishmania spp. is isoenzyme analysis. In addition to this, we employed 3 assays based on the polymerase chain reaction (PCR): random amplified polymorphic deoxyribonucleic acid (RAPD), intergenic region typing (IRT), based on the amplification of ribosomal ribonucleic acid internal transcribed spacers and restriction fragment length polymorphism (PCR-RFLP). We used 54 L. infantum stocks isolated from HIV co-infected patients, 38 isolated from dogs, 3 isolated from immunocompetent patients and 3 isolated from 1826 sand files in the island of Majorca (Spain), a closed ecological niche. Zymodemes MON-1 (70%), MON-24 (11%) and MON-34 (18%) were found among the human isolates, and MON-1 (95%) and MON-108 (5%) among those from dogs. RAPD and IRT could not discriminate among the strains as they all gave the same pattern, even when different zymodemes were examined. In contrast, PCR-RFLP was able to distinguish the strains and, furthermore, a dendrogram (unweighted pair group method with arithmetic average [UPGMA]) was constructed from the genetic distances derived from RFLP data. The Leishmania isolates from HIV-infected subjects formed a single cluster, supporting the existence of an artificial anthroponotic cycle previously proposed by our group, in which syringes have been substituted for sand flies, and in which certain clones have been spread among intravenous drug users. This contrasts with the clusters representing a zoonotic cycle, involving dogs, sand flies and both immunocompetent and immunocompromised humans.

Visceral leishmaniasis in human immunodeficiency virus (HIV)-infected and non-HIV-infected patients. A comparative study

Visceral leishmaniasis is an endemic infection in Mediterranean countries, where it has become a frequent complication of acquired immunodeficiency syndrome (AIDS). The incidence of visceral leishmaniasis is increasing in Spain due to human immunodeficiency virus (HIV)-related cases, but some aspects of its epidemiology, clinical features, and management remain unknown. In addition, no comparative clinical studies about the disease in HIV-infected and non-HIV-infected patients have been reported. During a 24-year period, 120 cases of visceral leishmaniasis were diagnosed at our institution and 80 (66%) were associated with HIV infection. The mean age at diagnosis was higher in HIV-infected that in non-HIV-infected patients (33.2 versus 23.2 yr; p = 0.002), but the male/female ratio was similar in both groups. The main risk factor for HIV infection was intravenous drug abuse (78.7%). The clinical presentation of leishmaniasis was similar in both groups, but HIV-infected patients had a lower frequency of splenomegaly than HIV-negative individuals (80.8% versus 97.4%; p = 0.02). HIV-infected patients had a greater frequency and degree of leukopenia, lymphocytopenia, and thrombocytopenia. Most of them were profoundly immunosuppressed (mean CD4+ lymphocyte count, 90 cells/mm3) at the time of diagnosis of leishmaniasis, and 53.7% had AIDS. The sensitivity of serologic studies for Leishmania was significantly lower in HIV-infected than in non-HIV-infected patients (50% versus 80%; p < 0.001), but the diagnostic yield of bone marrow aspirate (67.1% versus 79.4%) and bone marrow culture (62.9% versus 66.6%) was similar in both groups. After initial treatment, the response rate was significantly lower in HIV-infected than in non-HIV-infected individuals (54.8% versus 89.7%; p = 0.001). The relapse rate was 46.2% and 7.5%, respectively (p < 0.001). Secondary prophylaxis with antimonial compounds or amphotericin B seems to be useful in preventing relapses in HIV-infected patients. The mortality rate was higher (53.7% versus 7.5%; p < 0.001) and the median survival time shorter (25 versus > 160 mo; p < 0.001) in AIDS patients than in HIV-negative individuals. Although leishmaniasis could contribute to death in a significant number of HIV-infected patients, it was the main cause of death in only a few of them. The CD4+ lymphocyte count and the use of highly active antiretroviral therapy and secondary prophylaxis for leishmaniasis were the most significant prognostic factors for survival in AIDS patients. Visceral leishmaniasis behaves as an opportunistic infection in HIV-infected individuals and should be considered as an AIDS-defining disease.

Mediterranean leishmaniasis in HIV-infected patients: epidemiological, clinical, and diagnostic features of 22 cases

Twenty-two Italian HIV-infected patients developed leishmaniasis, clinically manifested as visceral (13 cases), cutaneous (2 cases) and disseminated disease (7 cases). Twenty were males and two females (mean age: 32.8 years) with a mean CD4+ cell count of 46.8/microliter at diagnosis; risk factors were intravenous drug use (17 patients) and sexual behaviour (two bisexual, two homosexual, one heterosexual). All but one patient lived or travelled in hypoendemic Italian regions and other Mediterranean countries. Apart from the two patients with cutaneous leishmaniasis, the clinico-pathological and biological spectrum of the infection was often atypical, especially in patients with disseminated disease. The diagnosis was routinely made by direct recovery of parasites in biological specimens, mainly in bone marrow aspirate, whereas serology was negative or borderline in most of the patients. Among 17 in vitro isolates, Leishmania infantum was the only species involved with previously undescribed isoenzyme patterns in two cases. Treatment with antimonials and other drugs showed only temporary clinical improvement in some patients. Relapses were the rule. Leishmaniasis confirms itself as an opportunistic infection in HIV-positive persons. Secondary chemoprophylaxis should be considered in cases of relapsing disease.

Leishmania and human immunodeficiency virus coinfection: the first 10 years

Over 850 Leishmania-human immunodeficiency virus (HIV) coinfection cases have been recorded, the majority in Europe, where 7 to 17% of HIV-positive individuals with fever have amastigotes, suggesting that Leishmania-infected individuals without symptoms will express symptoms of leishmaniasis if they become immunosuppressed. However, there are indirect reasons and statistical data demonstrating that intravenous drug addiction plays a specific role in Leishmania infantum transmission: an anthroponotic cycle complementary to the zoonotic one has been suggested. Due to anergy in patients with coinfection, L. infantum dermotropic zymodemes are isolated from patient viscera and a higher L. infantum phenotypic variability is seen. Moreover, insect trypanosomatids that are currently considered nonpathogenic have been isolated from coinfected patients. HIV infection and Leishmania infection each induce important analogous immunological changes whose effects are multiplied if they occur concomitantly, such as a Th1-to-Th2 response switch; however, the consequences of the viral infection predominate. In fact, a large proportion of coinfected patients have no detectable anti-Leishmania antibodies. The microorganisms share target cells, and it has been demonstrated in vitro how L. infantum induces the expression of latent HIV-1. Bone marrow culture is the most useful diagnostic technique, but it is invasive. Blood smears and culture are good alternatives. PCR, xenodiagnosis, and circulating-antigen detection are available only in specialized laboratories. The relationship with low levels of CD4+ cells conditions the clinical presentation and evolution of disease. Most patients have visceral leishmaniasis, but asymptomatic, cutaneous, mucocutaneous, diffuse cutaneous, and post-kala-azar dermal leishmaniasis can be produced by L. infantum. The digestive and respiratory tracts are frequently parasitized. The course of coinfection is marked by a high relapse rate. There is a lack of randomized prospective treatment trials; therefore, coinfected patients are treated by conventional regimens. Prophylactic therapy is suggested to be helpful in preventing relapses.

Leishmania infantum is clonal in AIDS patients too: epidemiological implications

OBJECTIVE

To test, in AIDS patients, a previously proposed hypothesis of clonal population structure in Leishmania infantum, the agent of visceral leishmaniasis.

DESIGN

Forty-three stocks of L. infantum isolated from AIDS patients in Spain were analysed by multilocus enzyme electrophoresis.

METHODS

The results were analysed in terms of population genetics according to previously described statistical methods. Departures from panmixia were examined by linkage disequilibrium analysis.

RESULTS

As previously shown in HIV-negative patients, classical manifestations of clonality were shown, namely strong linkage disequilibrium, over-representation of genotypes and overall lack of genotype diversity. The same dominant clonal genotype (MON1) was recorded in both HIV-positive and HIV-negative patients. Frequency of this dominant genotype was not statistically different in HIV-positive and HIV-negative patients.

CONCLUSIONS

The parasite population under survey appears to be clonal; parasite genotypes can therefore be equated to natural clones, stable in space and time, which can be used as multilocus epidemiological markers. Nevertheless, additional studies are required to better estimate the long-term stability of these clonal genotypes and the possible interference of gene exchange at an evolutionary scale.