The biochemical and serological taxonomy of visceralizingLeishmania

Molecular identification of an old clinical isolate of Indian Kala-azar

Molecular characterization is an important task for species identification of the isolates belonging to different Leishmania species. Clinical symptoms, tissue tropism, vector preference, reservoir and geographical distribution may act as distinguishing parameters but not always decisive. On the other hand, modern taxonomic tools employed to divulge characteristics of the genome or protein molecules of the parasite would be convincing and for Leishmania sp., they include nuclear and kDNA buoyant density, multi locus enzyme electrophoresis (MLEE), RAPD, RFLP or use of monoclonal antibodies etc. In the present study, we intend to establish the identification of an old clinical isolate of Indian Kala-azar, familiarly known as 'UR6' by MLEE, RAPD, RFLP and species specific monoclonal antibodies. UR6 has been isolated from a confirmed Kala-azar patient admitted in Calcutta School of Tropical Medicine, Kolkata in 1978. From then it is being regularly used for various scientific studies by the Leishmania Research Group of India and abroad. The isozyme profile of UR6 showed similar electrophoretic mobility that of WHO reference strain for Leishmania tropica, K27. Similar findings were obtained in the RAPD and RFLP assays. Screening with species specific monoclonal antibodies showed its strong reactivity towards L. tropica. The Jaccard's Similarity Indices were calculated.

Increased prevalence of human cutaneous leishmaniasis in Israel and the Palestinian Authority caused by the recent emergence of a population of genetically similar strains of Leishmania tropica

Twelve unlinked microsatellite markers were used to determine the microsatellite profiles of 50 newly and 46 previously typed strains of L. tropica from various Israeli and Palestinian foci. Their microsatellite profiles were compared to those of 99 previously typed strains of L. tropica from 15 countries. Israeli and Palestinian strains of L. tropica fell into three different groups, one of which contained 75 of the 96 Israeli and Palestinian strains. This population separated from all the others at the first hierarchical level by Bayesian statistics and formed a distinct monophyletic group on applying genetic distance and allele frequency analyses. The second cluster contained ten Israeli strains from a specific focus north of the Sea of Galilee, which were previously shown to differ from all other strains of L. tropica in their serological, biochemical and molecular biological parameters. This cluster was closely related to clusters comprising strains of L. tropica from Africa. Four Israeli and five Palestinian strains fell into different genetic entities mostly related to strains from Asian foci of CL. Importation during numerous migrations of humans and, perhaps, infected reservoir animals in the past and, now, through modern travel is the most likely explanation for the existence of so many locally encountered genetic variants of L. tropica in the Israeli-Palestinian region. Geographical and ecological variation may play a role in expanding the genetic heterogeneity once given importations had become established in different foci. Currently, one population is expanding in the area comprising almost all of the Palestinian and Israeli strains of L. tropica isolated since 1996 and investigated in this study, which differ clearly from all other strains of whatsoever origin. This population seems to result from the re-emergence of a previously existing genotype owing to environmental changes and human activities.

A real-time ITS1-PCR based method in the diagnosis and species identification of Leishmania parasite from human and dog clinical samples in Turkey

Human visceral leishmaniasis (VL) caused by L. infantum and cutaneous leishmaniasis (CL) caused by L. tropica and L. infantum have been reported in Turkey. L. infantum is also responsible for canine leishmaniasis (CanL) and it is widely common in the country. The main aim of the present study was to design a real-time PCR method based on the internal transcribed spacer 1 (ITS1) region in the diagnosis of all clinical forms of leishmaniasis in Mediterranean, and to identify the species directly from clinical samples. Totally, 315 clinical specimens, human/canine visceral (blood, bone marrow, lymph node) and cutaneous (lesion aspiration) samples, and 51 Turkish Leishmania isolates typed by isoenzymatic method were included in the study. For optimization, DNA samples of the 34 strains were amplified by conventional ITS1-PCR and then sequenced for designing the primers and probes, allowing the species identification. Following the validation with the isolates, the test was applied on clinical samples and melting temperatures were used for genotyping. A group of PCR products were further sequenced for confirmation and assigning the inter- and intraspecies heterogeneity. The diagnosis of leishmaniasis is successfully achieved by the new real-time PCR method, and the test identified 80.43% of human and canine VL samples as L.infantum and 6.52% as L.tropica; 52.46% of CL samples as L. infantum and 26.90% as L. tropica. In 13.04% of visceral and 20.62% of cutaneous samples, two peaks were observed. Hovewer, the higher peak was found to be concordant with the sequencing results in 96.96%, in terms of species identification. The real-time ITS1 PCR assay clearly identified the leishmanial species in 81.58% of all clinical samples. Genotypic variations of Leishmania parasites in Turkey within species and intraspecies were observed, and L. tropica is also found as causative agent of human and canine VL in Turkey.

Leishmaniasis caused by Leishmania parasites are seen as cutaneous (CL) and visceral (VL) clinical forms in Turkey. Leishmania (L.) tropica and L. infantum were determined as CL agents, while L. infantum was incriminated for VL in the country. Canine leishmaniasis (CanL) is widely common throughout the country and L. infantum is the responsible agent of the disease. Related to Leishmania species diversity and different clinical forms in human and dogs in this geographical area, the identification of the parasite species prefers to be done during the time of diagnosis. Internal transcribed spacer region was chosen as the target area for developing a real-time PCR assay to use as a fast and standardized diagnostic method and species identification simultaneously. Clinical samples from parasitologically/serologically proven cases and isolates were included the study, and high positivity rate in species identification was obtained. The method can also determine the intragenomic heterogeneity in Leishmania tropica and L. infantum. The assay presents a sufficient sensitivity for fast and correct detection of leishmaniasis directly from clinical materials. L. tropica and L. infantum were found as causative agents of human CL, VL and CanL in Turkey. Knowledge about differences in the parasites is useful for future studies in Turkey.

RFLPs of ITS, ITS1 and hsp70 amplicons and sequencing of ITS1 of recent clinical isolates of Kala-azar from India and Bangladesh confirms the association of L. tropica with the disease

Visceral Leishmaniasis or Kala-azar (KA) is a serious health concern in India. In the present study, Restriction Fragment Length Polymorphism (RFLP) of three genetic markers viz., Internal Transcribed Spacer (ITS), ITS1 and heat shock protein 70 (hsp70) have been employed for typing the clinical isolates [n=15] of KA and post Kala-azar Dermal Leishmaniosis (PKDL) collected from India and Bangladesh in the period of 2006-2010. Experimentally, ITS, ITS1 and hsp70 regions of genomes of all the clinical isolates were separately amplified by PCR and then digested with restriction enzymes: ITS with Alu1, EcoR1 and Msp1, ITS1 with Hae III and Rsa1 and hsp70 with Hae III. The resultant fragments were analyzed by agarose gel electrophoresis and the RFLP profiles of the clinical isolates were compared with that of the WHO reference strains for Leishmania donovani (DD8) and Leishmania tropica (K27), respectively. Also, the ITS1 regions of all the clinical isolates along with the two WHO reference strains were sequenced and a phylogram was constructed to ascertain the extent of similarity or dissimilarity. Interestingly, the RFLP profiles of one of the isolates showed a significant homology with K27 and the phylogram revealed its closeness with the same putting credence to our earlier typing of isolates by RAPD method. This observation also supported an earlier report claiming that both the species are responsible for KA in India and thus, emphasizes urgent need for thorough systematic characterization of the clinical isolates of Indian KA as appropriate treatment regime relies primarily on proper diagnosis.

Epidemiological and clinical features of cutaneous leishmaniases in Jenin District, Palestine, including characterisation of the causative agents in clinical samples

During 2002-2009, 466 cases of cutaneous leishmaniasis (CL) were reported from Jenin District, Palestine, affecting both genders. The average annual incidence was 23 cases per 100000 inhabitants, increasing with age in children. Most cases presented a single lesion, generally on the face. Diagnosis and species identification was done by applying internal transcribed spacer 1 (ITS1) RFLP analysis to 47 isolates, of which 44 (93.6%) were Leishmania tropica and 3 (6.4%) were L. major. RFLP analysis was also performed on 256 skin tissue scrapings spotted onto filter papers, showing that 138 (53.9%) were positive, of which 50.7% were infected with L. tropica, 17.4% with L. major and 2.9% with L. donovani s.l., and 29.0% could not be identified. This is the first report from Palestine on human CL caused by L. infantum. Nine of the strains of L. tropica were subjected to multilocus enzyme electrophoresis, six of which belonged to the zymodeme MON-137 and three to a new zymodeme (MON-307). This separation was corroborated by excreted factor serotyping. This observation modifies the classical epidemiological view of CL in Palestine. Jenin District is an active focus of CL caused by L. tropica, where Phlebotomus sergenti, the putative vector, is abundant. These data suggest that CL is a zoonotic infection, but an animal reservoir has not been found.

Characterization of Leishmania (Leishmania) tropica axenic amastigotes

Optimum conditions for generating Leishmania (Leishmania) tropica axenic amastigotes (AxA) in culture were determined, pH 5.5/36 degrees C, and the parasites characterized by different techniques, including light microscopy, macrophage infection, stage specific antigen expression and differential display. AxA were morphologically similar to amastigotes and 15.5-fold more infective than stationary phase promastigotes for mouse peritoneal macrophages. Western blotting with promastigote stage specific monoclonal antibodies to either lipophosphoglycan (T2) or a 60 kDa flagella antigen (F3) showed a dramatic decrease in antigen expression when AxA were compared to promastigotes. Similarly F3 gave strong immune fluorescent staining of the promastigote flagellum, but no fluorescence was detected when AxA were examined. Conversely, Western blotting with the amastigote specific monoclonal antibody (T16) showed that this antigen is more highly expressed in AxA than promastigotes. Differential display-PCR was used to identify several parasite genes showing stage specific expression. One gene selectively expressed by AxA was partially sequenced and identified as Leishmania (L.) tropicaamastin. Amastigote specific expression of this gene was further confirmed by reverse transcriptase-PCR (RT-PCR) using AxA and infected macrophages. No amastin expression was observed with promastigotes. Expression of the cysteine protease B (cpb) and protein kinase A catalytic isoform 1 subunit (pkac1) in promastigotes and AxA was also examined by RT-PCR. Pkac1 was strongly expressed by promastigotes, while cpb expression was only seen with AxA or infected macrophages. L. (L.) tropica AxA will prove useful for further studies on parasite differentiation and gene regulation, as well as for drug screening.

Identification of the agent causing visceral leishmaniasis in Uzbeki and Tajiki foci by analysing parasite DNA extracted from patients' Giemsa-stained tissue preparations

Our present study is the first attempt to characterize Leishmania parasites from foci in Uzbekistan and Tajikistan endemic for visceral leishmaniasis (VL). PCR-sequencing of the ribosomal internal transcribed spacer 1 and multilocus microsatellite typing (MLMT) were applied to DNA extracted from preparations of Giemsa-stained bone marrow aspirates from 13 cases of VL. L. infantum was shown to cause VL currently occurring in this area. MLMT applying 14 microsatellite markers, previously shown to be polymorphic for strains of the L. donovani complex, revealed that microsatellite profiles of parasites causing human VL in the Namangan and Jizzakh regions in Uzbekistan, and Penjikent region in Tajikistan, basically coincide with those of strains of L. infantum MON-1. Furthermore, these parasites were assigned to a distinct cluster genetically clearly separated from the populations of L. infantum MON-1 from Europe, the Middle East and North Africa. The existence of a genetically homogeneous but distinct group of L. infantum MON-1 indicates that the parasites circulating in the Uzbeki and Tajiki foci studied have been restricted there for a long time rather than having been recently introduced from elsewhere by human or animal reservoir migration.

Microsatellite analysis reveals genetic structure of Leishmania tropica

The current rapid spread of leishmaniases caused by Leishmania tropica and the complexity of its clinical spectrum call for this parasite's epidemiological and evolutionary investigation. Evaluation of its population structure by isoenzyme electrophoresis and previous molecular biological analysis has proved difficult. In this study, we used 21 microsatellite loci to type 117 strains from different African and Asian locations. Eighty-one different genotypes were found. A genetic bottleneck supported by a gradient in the number of alleles and consistent with the geographical structure of the Middle East suggests an African origin of this species. A Bayesian approach identified 10 genetic clusters that correlated predominantly with geographical origin. The strains in the 'Asia' cluster form a very heterogeneous sub-population, with a varied but inter-related genotype that is geographically very widely dispersed and consistent with anthroponotic transmission of the parasite. The other nine clusters were more homogenous. The propagation of L. tropica appears to be predominantly clonal. In Africa and the Middle East, anthroponotic and zoonotic systems of distribution may contribute to the development of overlapping, genetically distinct populations of L. tropica.

Leishmania priming of human dendritic cells for CD40 ligand-induced interleukin-12p70 secretion is strain and species dependent

A major question in the study of leishmaniasis is what dictates clinical disease expression produced by different Leishmania species, i.e., cutaneous versus systemic and healing versus nonhealing. Animal models using a Leishmania species associated with self-limiting cutaneous disease (L. major) have revealed that protective immunity requires CD40/CD40 ligand (CD40L)-dependent, interleukin-12 (IL-12)-driven Th1 responses. We recently showed that L. major can prime human dendritic cells (DCs) for CD40L-triggered IL-12p70 secretion and that these cells can drive a Th1 response in autologous T cells from sensitized individuals. Here we show that in contrast to L. major, Leishmania species responsible for visceral disease (L. donovani), as well as species associated with persistent, cutaneous lesions and occasional systemic disease (L. tropica), did not induce CD40L-dependent IL-12p70 production, despite comparable levels of uptake by DCs. Up-regulated surface expression of CD40 did not correlate with IL-12p70 production, and appreciable CD40L-induced IL-12p40 secretion was observed in uninfected as well as infected DCs, regardless of species. Reverse transcription-PCR analysis confirmed that the production of heterodimeric IL-12 was limited by expression of IL-12p35 mRNA, which was dependent on both a microbial priming signal and CD40 engagement for its high-level induction. The intrinsic differences in the ability of Leishmania species to prime DCs for CD40L-dependent IL-12p70 secretion may account, at least in part, for the evolution of healing and nonhealing forms of leishmanial disease.

Leishmaniasis in Sudan. Visceral leishmaniasis

From the early 1900s, visceral leishmaniasis (VL; kala-azar) has been among the most important health problems in Sudan, particularly in the main endemic area in the eastern and central regions. Several major epidemics have occurred, the most recent--in Western Upper Nile province in southern Sudan, detected in 1988--claiming over 100,000 lives. The disease spread to other areas that were previously not known to be endemic for VL. A major upsurge in the number of cases was noted in the endemic area. These events triggered renewed interest in the disease. Epidemiological and entomological studies confirmed Phlebotomus orientalis as the vector in several parts of the country, typically associated with Acacia seyal and Balanites aegyptiaca vegetation. Infection rates with Leishmania were high, but subject to seasonal variation, as were the numbers of sand flies. Parasites isolated from humans and sand flies belonged to three zymodemes (MON-18, MON-30 and MON-82), which all belong to the L. donovani sensu lato cluster. Transmission dynamics have not been elucidated fully; heavy transmission in relatively scarcely populated areas such as Dinder national park suggested zoonotic transmission whereas the large numbers of patients with post kala-azar dermal leishmaniasis (PKDL) in heavily affected villages may indicate a human reservoir and anthroponotic transmission. Clinical presentation in adults and in children did not differ significantly, except that children were more anaemic. Fever, weight loss, hepato-splenomegaly and lymphadenopathy were the most common findings. PKDL was much more common than expected (56% of patients with VL developed PKDL), but other post-VL manifestations were also found affecting the eyes (uveitis, conjunctivitis, blepharitis), nasal and/or oral mucosa. Evaluation of diagnostic methods showed that parasitological diagnosis should still be the mainstay in diagnosis, with sensitivities for lymph node, bone marrow and spleen aspirates of 58%, 70% and 96%, respectively. Simple, cheap serological tests are needed. The direct agglutination test (DAT) had a sensitivity of 72%, specificity of 94%, positive predictive value of 78% and negative predictive value of 92%. As with other serological tests, the DAT cannot distinguish between active disease, subclinical infection or past infection. The introduction of freeze-dried antigen and control sera greatly improved the practicality and accuracy of the DAT in the field. An enzyme-linked immunosorbent assay using recombinant K39 antigen had higher sensitivity than DAT (93%). The polymerase chain reaction using peripheral blood gave a sensitivity of 70-93% and was more sensitive than microscopy of lymph node or bone marrow aspirates in patients with suspected VL. The leishmanin skin test (LST) was typically negative during active VL and converted to positive in c. 80% of patients 6 months after treatment. Immunological studies showed that both Th1 and Th2 cell responses could be demonstrated in lymph nodes from VL patients as evidenced by the presence of messenger ribonucleic acid for interleukin (IL)-10, interferon gamma and IL-2. Treatment of peripheral blood mononuclear cells from VL patients with IL-12 was found to drive the immune response toward a Th1 type response with the production of interferon gamma, indicating a potential therapeutic role for IL-12. VL responded well to treatment with sodium stibogluconate, which is still the first line drug at a dose of 20 mg/kg intravenously or intramuscularly per day for 15-30 d. Side effects and resistance were rare. Liposomal amphotericin B was effective, with few side effects. Control measures have not been implemented. Based on observations that VL does not occur in individuals who have a positive LST, probably because of previous cutaneous leishmaniasis, a vaccine containing heat-killed L. major promastigotes is currently undergoing a phase III trial.

Sudan: the possible original focus of visceral leishmaniasis

Fifty-two Leishmania strains, obtained from human patients and dogs in a visceral leishmaniasis focus in Sudan, were characterized by isoenzyme electrophoresis (15 enzymes). The phylogenetic analysis showed that the 7 Leishmania zymodemes obtained hold ancestral positions on the phylogenetic tree, supporting the hypothesis of an East African origin of visceral leishmaniasis.

Genetic heterogeneity in the species Leishmania tropica revealed by different PCR-based methods

A PCR fingerprinting approach, using single non-specific primers, as well as restriction and single-strand conformation polymorphism (SSCP) analyses of the amplified ribosomal internal transcribed spacer, were used to investigate genetic variability in the species Leishmania tropica. Twenty-nine strains of the 'L. tropica complex' from different Old World geographical areas were studied including 4 from Namibia, and 1 strain of L. killicki. All techniques revealed a high degree of genetic heterogeneity among the strains of L. tropica. The PCR fingerprinting displayed the highest discriminatory power, but can be applied only to cultured parasites. The internal transcribed spacer (ITS) region can be amplified directly from infected clinical samples and analysed subsequently. No strict correlation was discerned between the genetic variants and either the geographical origin of the strains or the clinical manifestations associated with human disease, except for the Namibian strains. Also, genetic variation did not correlate well with characterization by enzyme variant electrophoretic analysis. The strain of L. killicki always clustered together with the strains of L. tropica, suggesting it, probably, should not be considered a separate species of Leishmania. However, the 4 Namibian strains formed a distinct, statistically well-supported group closely related to but different from the other strains of L. tropica.

Characterisation of Bangladeshi Leishmania isolated from kala-azar patients by isoenzyme electrophoresis

To identify the prevalent Leishmania species in Bangladesh, a total of nine patients aged 4-35 years, were studied; six (66.7%) of them were below 20 years of age. All the patients were clinically diagnosed to have visceral leishmaniasis; their haematological profile was in accordance with leishmaniasis and all were improved after treatment with sodium stibogluconate. All the aspirated materials (eight bone marrows and one splenic aspirate) yielded growth of Leishmania parasite in NNN media; Leishman-Donovan bodies were found in seven (77.8%) of them in a Giemsa stained smear. Aldehyde test (AT) was positive in all the nine cases examined, whereas, complement fixation test (CFT) was positive in seven (77.8%) and indirect fluorescent antibody test (IFAT) in eight (88.9%) cases. In this study, five of the nine isolates from kala-azar patients were characterised by isoenzyme analysis comparing with five WHO reference strains viz., Leishmania (Leishmania) donovani (DD8), L.(L.) donovani (HU3), L.(L.) infantum (IPT-1), L.(L.) tropica (K-27) and L.(L.) major (5-ASKH) using cellulose acetate electrophoresis. By analysing 11 soluble isoenzymes it was found that all five WHO reference strains had distinct electrophoretic mobility of the isoenzymes studied. No interspecies difference was observed amongst the five isolates from kala-azar patients examined and their isoenzyme profiles were consistent with WHO reference strain of L.(L.) donovani (DD8) but different from L.(L.) donovani (HU3).

Cell biology of Leishmania

Leishmania are digenetic protozoa which inhabit two highly specific hosts, the sandfly, where they grow as motile flagellated promastigotes in the gut, and the mammalian macrophage, where they survive and grow intracellularly as non-flagellated amastigotes in the phagolysosome. Leishmaniasis is the outcome of an evolutionary 'arms race' between the host's immune system and the parasite's evasion mechanisms, which ensure survival and transmission in the population. The diverse spectrum of patterns and severity of disease reflect the varying contributions of parasite virulence factors and host responses, some of which act in a host protective manner while others exacerbate disease. This chapter describes the interaction of the Leishmania with their hosts, with emphasis on the molecules and mechanisms evolved by the parasites to avoid, subvert or exploit the environments in the sandfly and the macrophage, and to move from one to the other.

Leishmania donovani invasion of the blood in a child with dermal leishmaniasis

Cutaneous leishmaniasis is highly endemic in eastern Mediterranean countries. The causative organisms are Leishmania tropica or Leishmania major but, further west, variants of Leishmania infantum frequently cause cutaneous leishmaniasis. We report a young girl from Beirut with an acute cutaneous leishmaniasis in whom the causative organism was cultured from both the skin lesion and the blood in the absence of any signs or symptoms typical of systemic involvement. The parasite was found to have a zymodeme typical of organisms belonging to the L. donovani complex. With the negative past history and in the absence of anti-Leishmania antibodies in her serum, post-kala-azar dermal leishmaniasis is an unlikely possibility, especially in view of the rarity of the complication in this part of the world. The infection was probably acquired during a recent visit to Aleppo, where cutaneous leishmaniasis is hyperendemic as similar cases have not been reported in Beirut. This case indicates the need to consider L. infantum strains in addition to L. tropica in cutaneous disease in Aleppo. This case also demonstrates that L. infantum can spread by the haematogenous route, even in a child without evidence of the immunosuppression, which usually predisposes to such spread.

Leishmania tropica: the identification and purification of metacyclic promastigotes and use in establishing mouse and hamster models of cutaneous and visceral disease

Few experimental studies on Leishmania tropica have been undertaken despite the importance of this parasite as the cause of cutaneous leishmaniasis, and now visceral disease, in the Old World. In part, this is due to the absence of convenient animals models, especially mice, for L. tropica infections. An anti-lipophosphoglycan (LPG) monoclonal antibody XCIV 1H2-A8 (T11), specific for L. tropica, was found to distinguish between culture-derived procyclic and metacyclic promastigotes. The antibody was used to negatively select for nonagglutinated metacyclic forms in stationary cultures, and the exceptional virulence of the purified metacyclics was verified by their infectivity for mouse macrophages in vitro and by their ability to produce cutaneous lesions in footpads of BALB/c mice. The lesions produced by three cutaneous isolates of L. tropica were nonulcerative and nonprogressive. Nonetheless, the lesions failed to heal, and high numbers of parasites could be recovered from footpads and draining lymph nodes up to 9 months after infection. Infections using L. tropica metacyclics purified from cutaneous, visceral and viscerotropic (Desert Storm) isolates of L. tropica were compared in both mouse and hamster models. Differences in disease progression were found that may reflect the parasite tissue tropism and virulence displayed by these strains in their human hosts. These findings suggest a role for parasite-related determinants in the clinical spectrum of disease.

Development of a slide ELISA for canine leishmaniasis and comparison with four serological tests

A slide ELISA for canine leishmaniasis was developed by using promastigotes of Leishmania infantum, and compared with microimmunodiffusion, immunoelectrophoresis, direct agglutination and indirect immunofluorescence assays. The sensitivity of all the tests was 100 per cent. The specificity of the direct agglutination test was 95 per cent but it was 100 per cent for the three other tests. There was also a positive correlation and a high level of concordance between the titres measured by the different tests.

Leishmania tropica in Egypt: an undesirable import

Cutaneous as well as visceral leishmaniasis has been previously reported in Egypt. The former clinical manifestation is attributed to Leishmania major, the latter to L. infantum. In this study, L. tropica was isolated from an Egyptian labourer returning from Saudi Arabia. Amastigotes were detected by both Giemsa staining and indirect immunofluorescence using rabbit anti-gp63. Promastigotes from Schneider's medium were typed isoenzymatically as L. tropica. In view of the emerging threat of visceralization of L. tropica, the potential risk for its transmission in Egypt is discussed.

The characterization of Leishmania from patients with lymphadenopathy in Shiraz, Iran

Leishmania were cultured from enlarged lymph nodes of 6 of 18 patients with localized lymphadenitis and no other sign or symptom of leishmaniasis in Shiraz, Iran. The organisms failed to produce visible lesions when injected intradermally or intraperitoneally into Swiss outbred white or Balb/c mice. Golden hamsters similarly injected appeared well 16 weeks later, but histological examination of their spleens and livers revealed a few amastigotes in sections of the liver of one. Lectin agglutination profiles of promastigotes cultured from 2 of the patients were identical with those obtained with the World Health Organization reference strain of L. tropica (MHOM/SU/74/K27). Isoenzyme characterization of one of the isolates showed it to be L. tropica zymodeme LON18.

Short term treatment of visceral leishmaniasis of the Old World with low dose interferon gamma and pentavalent antimony

Eight adult patients with visceral leishmaniasis acquired in mediterranean countries were treated in a prospective study with a combined immunomodulating and antiparasitic regimen consisting of low-dose interferon-gamma (IFN-gamma) and pentavalent antimony. The clinical outcome, hematological and parasitological parameters, the duration of treatment and number of treatment cycles as well as the cumulative dose of pentavalent antimony applied, have been evaluated. The combined treatment led to complete resolution of symptoms and parasitological cure in all cases of visceral leishmaniasis without major side effects. Combined treatment resulted in a significant reduction of duration of treatment (19 vs. 31 days, p < 0.02) and cumulative dose of pentavalent antimony (11.67 vs. 19.30 g, p < 0.02) compared to historical controls (n = 6). No relapses occurred after a median follow-up of 9 months (range: 2-28 months). We conclude that combination therapy is tolerated well and is highly effective in patients with visceral leishmaniasis. The addition of IFN-gamma to standard therapy with pentavalent antimony may reduce the cumulative dose of antimonial drugs, shortens the treatment period and probably reduces the number of relapses.

Visceral infection caused by Leishmania tropica in veterans of Operation Desert Storm

BACKGROUND

Visceral leishmaniasis, usually caused by Leishmania donovani, has rarely been reported from eastern Saudi Arabia, so it was not expected to affect the soldiers of Operation Desert Storm.

METHODS

We evaluated eight soldiers with visceral leishmanial infection, examining their serum with an immunofluorescent-antibody assay, examining their marrow or biopsy tissue for amastigotes with an indirect immunofluorescent-monoclonal-antibody assay, and culturing the parasites. Cultured promastigotes were isolated and characterized by isoenzyme analysis.

RESULTS

None of the eight soldiers had classic signs or symptoms of visceral leishmaniasis (kala-azar). Seven soldiers had unexplained fever, chronic fatigue, malaise, cough, intermittent diarrhea, or abdominal pain that began up to seven months after they returned to the United States; one had no symptoms. Five had adenopathy or mild, transient hepatosplenomegaly. None had cutaneous manifestations. Diagnoses were made by bone marrow aspiration (seven patients) or lymph-node biopsy (one patient). Six isolates have been identified as L. tropica, which usually causes only cutaneous disease. Of the six patients treated with sodium stibogluconate, five improved and one remained symptomatic.

CONCLUSIONS

L. tropica can produce visceral infection that can cause unexplained systemic illness in persons returning from areas where this organism is endemic.

Chronic cutaneous leishmaniasis: Leishmania parasites in blood

Two patients with chronic cutaneous leishmaniasis had positive blood cultures. The diagnosis was established by the clinical picture, skin biopsy, and culture for Leishmania major and tropica.

A new rural focus of cutaneous leishmaniasis caused by Leishmania tropica in Kenya

We have identified a new rural focus of cutaneous leishmaniasis caused by Leishmania tropica in Muruku sublocation, Salama location, Laikipia district, Rift Valley province, Kenya. Based on a few available case histories, previous reports of L. tropica in Kenya indicated a tentative geographical distribution. Recently 6 indigenous Kenyans from the new focus, who had never travelled outside Kenya, developed cutaneous lesions on the face and/or extremities found to contain Leishmania by culture and smear. Most of the patients manifested the typical 'urban' dry sore which grew slowly into a nodule measuring 2 x 1 cm to 9.5 x 3 cm, and after some months formed a central crust surrounded by small satellite papules. After treatment with Pentostam (sodium stibogluconate), about 40% of the sores failed to heal completely, either scarring centrally with fulminating papules at the edges and spreading peripherally, or healing but then recrudescing at the edge of the scar. Stationary-phase promastigotes from culture isolates were analysed by cellulose acetate electrophoresis. Isoenzyme profiles of 6 isolates were compared with those of World Health Organization reference strains using 12 enzyme loci; they were indistinguishable from those of 2 L. tropica reference strains. All 6 case sites lay within a radius of 4 km. Several other suspected cases from the same area are being investigated.

Studies on the leishmaniases in the Sudan. 3. Clinical and parasitological studies on visceral and mucosal leishmaniasis

The epidemiological, clinical and laboratory findings of 27 patients with visceral leishmaniasis (VL) and six with mucosal leishmaniasis (ML) in Sudan are described. The diagnosis was confirmed by the demonstration of amastigotes in bone-marrow in 20 cases with VL (80%) and impression smears in 2 cases with ML. The enzyme-linked immunosorbent assay and direct agglutination test were positive in all the sera tested. The leishmanin test was positive in all patients with ML, the diameter of the reaction ranging from 18 to 28 mm (mean 23 mm). Only one isolate (from a patient with VL) grew sufficiently well in culture to be typed and this was characterized by isoenzyme electrophoresis as Leishmania donovani zymodeme LON-46. The possibility that the ML isolate could have been L. major zymodeme LON-1 is discussed. The importance of further research to isolate and identify by biochemical procedures a more representative range of isolates of Leishmania from different clinical types in the Sudan, in order to elucidate questions such as the relationship between the vectors and possible animal reservoirs, is emphasized.

A cloned kinetoplast DNA mini-circle fragment from a Leishmania spp. specific for post-kala-azar dermal leishmaniasis strains

DNA-DNA hybridization techniques have been found to be very useful in the classification and identification of Leishmania parasites. We report here the cloning of a mini-circle from Leishmania strain UR6 in a plasmid and subcloning of the mini-circle fragments in M13 mp9. Clone MLURk32, containing a 560 bp fragment of mini-circle, has been found to have unique specificity. Application of this specific probe in identifying different Leishmania isolates reveals that the probe reacted only with strains of post-kala-azar dermal leishmaniasis but not with strains or isolates of visceral leishmaniasis.

Biochemical characterization of Leishmania spp. isolated from man and wild animals in Kenya

Isoelectrofocusing in agarose was used to characterize Leishmania spp. isolated from a kala-azar patient, a lizard, genet cat and elephant shrew. Isoenzyme profiles of 12 enzymes and general protein patterns were examined. Both methods were found to be useful for distinguishing between the isolates. The wild animal Leishmania spp. were shown to be indistinguishable from a reference strain of L. major, but the isolate from man was distinctly different from L. donovani sensu stricto. The unique finding that the lizard isolate was similar to L. major and its significance are discussed in some detail. The use of the isoelectrofocusing technique for separation of enzymes and general proteins for characterization purposes is emphasized.

Cloning of a polymorphic DNA fragment from the genome of Leishmania donovani

Recombinant DNA clones, containing highly repetitive DNA sequences, have been isolated from a Leishmania donovani genomic DNA library prepared in the replacement vector lambda gt.WES.lambda B. Two clones, probably telomeric in location, have been characterised and show a restriction fragment size polymorphism. Evidence is presented which suggests that L. donovani is diploid for this cloned genomic locus.

Acid phosphatase isoenzyme mapping in Leishmania

The profiles of acid phosphatase isoenzymes of several well defined species of the genus Leishmania were compared. The profiles were generated after isoelectric focusing of parasite extracts in polyacrylamide and incubation of the gels with an appropriate substrate coupled to an azo dye. Analysis of the zymograms showed that there is species-specificity of the acid phosphatase isoenzyme maps in Leishmania. It was also demonstrated that different strains of the same species present identical pattern of enzyme activity. The method even enabled the differentiation of closely related species which were previously difficult to identify. Some technical aspects of the isoelectric focusing procedure are discussed. The method described here can be used as an aid for species identification of Leishmania.

Numerical taxonomy of some Old World Leishmania species

Iraqi Leishmania stocks originating from human cutaneous and visceral infections, others from the sandfly Sergentomyia baghdadis, and one visceral stock from a dog, were compared among themselves and with Old World reference stocks, by electrophoresis of 11 enzymes. 79 unit characters emerged. Paired comparison technique and complete-linkage cluster analysis revealed heterogeneity within the L. donovani complex. The Iraqi L. donovani stocks appear to be more closely related to an Ethiopian reference L. donovani than to an L. donovani infantum. Two Indian visceral stocks were linked to the L. donovani complex and the L. tropica complex by similarity indices of the same range. The results show a marginally closer association between L. tropica and L. donovani complexes than between L. tropica and L. major.

Chromosome size polymorphisms of Leishmania donovani

A minimum of 22 chromosomes were found in all Leishmania donovani stocks examined by orthogonal field alternation gel electrophoresis (OFAGE). Chromosome sizes ranged from approximately 270 to 4000 kb. Certain chromosomes were polymorphic in size between stocks and chromosomes present in some stocks had no apparent equivalent in others. Specific polymorphisms were useful in distinguishing the subspecies L. d. donovani, L. d. infantum and L. d. chagasi and African L. donovani stocks but there were karotypic differences within these taxa. Radiolabelled DNA derived from whole chromosomes was hybridised to OFAGE Southern blots. Chromosome 1 of L. d. donovani was homologous to two larger chromosomes in all stocks. Chromosome 2 of certain L. d. chagasi and L. d. infantum stocks was homologous to both chromosomes 2 and 3 of L. d. donovani: this suggested that translocation between chromosomes may have contributed to the size polymorphisms. The smallest chromosome seen (270 kb) was unique to the African stock HU3. It was not homologous to small chromosomes in L. d. donovani, L. d. infantum or L. d. chagasi. The small chromosome did hybridise to two small chromosomes in another African stock, Khartoum, and to a large chromosome present in all stocks. The beta-tubulin gene was mapped to chromosomes 21/22, 13 and 7 with strongest hybridisation to 21/22. alpha-Tubulin was mapped to chromosomes 9. The alpha- and beta-tubulin arrangement was highly conserved.

Histopathological patterns of the liver involvement in visceral leishmaniasis

The hepatic changes observed in liver specimen from either biopsy or necropsy of 47 patients with visceral leishmaniasis permited us to define three different histopathological patterns of involvement: typical, nodular, and fibrogenic. These patterns seem to be representative of different evolutive stages of the hepatic involvement in the disease either towards a more benign evolution or to more chronic stage with fibrosis and "cirrhosis". These histopathological evolutive stages are related to the prognosis of the disease.

Detection and characterization of Leishmania species and strains from mammals and vectors by hybridization and restriction endonuclease digestion of kinetoplast DNA

Leishmania parasites from animals, man or insect vectors were characterized by the gel electrophoresis of restriction endonuclease enzyme-produced mitochondrial (kinetoplast) DNA (kDNA) fragments and/or by DNA-DNA hybridization with 32P-labelled cloned, or uncloned, kDNA fragment probes from type isolates. The electrophoretic separation of kDNA fragments is a sensitive method for detecting genetic similarities and differences among Leishmania. Parasites with similar kDNA restriction fragment patterns belong to the same schizodeme and schizodeme analysis is useful for studying Leishmania populations. Cloned, species-specific kDNA probes detected Leishmania in sandflies and in liver, spleen or blood preparations from infected animals. Cloned DNA probes also hybridized to immobilized kDNA from in vitro cultivated promastigotes and detected as few as 100 parasites in a species-specific manner. Sensitive DNA hybridization probes should be useful in research on the immunology, chemotherapy or epidemiology of animal and human leishmaniasis.

Sex-influenced response in the pathogenesis of cutaneous leishmaniasis in mice

Male B10 X 129 (10M) ScSn mice were relatively resistant to cutaneous leishmaniasis, while females frequently developed non-healing expanding ulcers, leading to loss of infected extremities, metastasis to distal skin sites, and in some animals, death. Anti-leishmanial antibody titers were higher, and delayed-type hypersensitivity responses to parasite antigens, lower, in infected females than in males. Sex differences in response to cutaneous infection were not marked in BALB/cJ mice, a highly susceptible strain, and both males and females ultimately lost infected extremities, developed metastases, and died.

Leishmania in the Old World: 2. Heterogeneity among L. tropica zymodemes

Isoenzyme profiles of 27 stocks of Leishmania tropica from widely separated geographical areas were compared with those of reference strains of L. tropica and L. major using starch-gel electrophoresis of 13 enzymes (GPI, GD, ES, PGM, PEPD, NH, ASAT, ALAT, PK, MPI, 6PGD, SOD, MDH). 18 zymodemes were seen. L. tropica showed considerable intraspecific variation which did not correlate with its epidemiological uniformity. Isolates from cases of cutaneous and visceral leishmaniasis and leishmaniasis recidivans were identified as L. tropica. Only one isoenzyme band was held in common with the enzyme profile of the L. major reference strain thus supporting the status of L. tropica as a separate species.

Leishmania in the Old World: 5. Numerical analysis of isoenzyme data

Numerical analysis of 59 zymodemes of Old World Leishmania, based on the enzyme profiles of 280 stocks, revealed several distinct clusters. Some of these clusters corresponded with traditional taxonomic groupings: L. major, L. tropica, L. aethiopica and L. donovani sensu lato, but hitherto unrecognized groups were also indicated. The analysis provided an overview of the interrelationships between the Leishmania zymodemes.

Leishmaniasis in Greece I. Isolation and identification of the parasite causing human and canine visceral leishmaniasis

Three human and 19 canine leishmanial stocks were typed according to their excreted factor serotype and the electrophoretic mobility of their MDH, GPI, G6PDH and 6PGDH and shown to be identical with regard to these characters and, thus with Leishmania donovani infantum. This verifies the opinion of earlier researchers, who suggested that the parasites which cause human and canine visceral leishmaniasis in Greece are the same organism and that dogs are the reservoir for the human infection. The complexities raised by the co-existence of human cutaneous leishmaniasis in Greece caused by L. tropica (formerly L. t. minor) are stressed. A comparison was made of the clinical symptomatology, serological diagnosis by IFA and ELISA tests and parasitological diagnosis of the human cases and canine infections.

Leishmaniasis in Greece II. Isolation and identification of the parasite causing cutaneous leishmaniasis in man

The serological and biochemical identity of four Greek leishmanial strains isolated from cases of cutaneous leishmaniasis was determined. All four strains were identical and shown to be Leishmania tropica (formerly L. t. minor). The cases are described; two came from the Greek mainland and two from Greek islands, one of the latter being a case of leishmaniasis recidivans. The significance of the results is discussed, in particular the co-existence in Greece of strains of L. tropica and L. donovani infantum.

Identification of species, strains and clones of Leishmania by characterization of kinetoplast DNA minicircles

Molecular analysis of kinetoplast deoxyribonucleic acid (kDNA) minicircles has permitted the genotypic characterization of pathogenic isolates of Leishmania species. The apparent size in agarose gels of unit-length minicircles released by EcoRI digestion of kDNA networks is not conserved during speciation in this genus since the minicircles of strains and clones of L. major are smaller (710 base pairs, bp) than those found in certain strains of L. mexicana subspecies (820 bp), L. donovani (825, 865 bp) or L. tropica (900, 930 bp). EcoRI-cut minicircles within any one species of Leishmania are heterogeneous in mobility during electrophoresis in acrylamide gels. Schizodeme analysis of minicircles reveals a high degree of sequence divergence in kDNA with the degree of microheterogeneity varying between species. This sequence divergence allows the discrimination of closely related clones and strains within a given species. Southern blot hybridization reveals that overall minicircle sequence homology is conserved among clones and strains of one species (L. major or L. tropica) but not between different species. This property of minicircle DNA permits the use of kDNA probes as a species-specific diagnostic test for the identification of Leishmania isolates. The analysis of kDNA from two L. tropica strains isolated at 14 year intervals from a patient with leishmaniasis recidivans has shown that the two strains are closely related, suggesting that the individual suffered the cutaneous disease as a result of a resurgence of the same parasite which caused the initial infection. The differences in the properties of kDNA from the L. tropica and L. major strains studied support the taxonomic separation of L. tropica and L. major into distinct species.