Showing papers on "Visceral leishmaniasis published in 1997"

Human leishmaniasis: clinical, diagnostic, and chemotherapeutic developments in the last 10 years.

Abstract: The current interest in leishmaniasis stems from the importance of this disease with respect to travel medicine, veterans of Operation Desert Storm, humanitarian concerns, and infection with human immunodeficiency virus. Herein, I review aspects of leishmaniasis that are of practical value to practitioners, including presentation, diagnosis, and chemotherapy; I will emphasize advances in chemotherapy over the last 10 years. Amphotericin B and its new lipid formulations are now competitive with pentavalent antimony as primary therapy for visceral leishmaniasis. Pentamidine, paromomycin, and adjunctive therapy with interferon-gamma are secondary regimens for the treatment of this condition. High-dose long-term regimens of antimony have been shown to be highly effective for the treatment of cutaneous leishmaniasis. Preliminary evidence of efficacy has been observed with short courses of pentamidine for the treatment of Leishmania braziliensis complex disease and topical paromomycin/methylbenzethonium chloride for the treatment of Leishmania major disease.

Leishmania and human immunodeficiency virus coinfection: the first 10 years.

Abstract: 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.

Axenically cultured amastigote forms as an in vitro model for investigation of antileishmanial agents.

Abstract: Using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide microassay, previously described as a means of quantifying Leishmania amazonensis in vitro at the amastigote stage (D. Sereno and J. L. Lemesre, Parisitol. Res., in press), we have compared the activities of seven drugs, including those currently used to treat leishmaniasis, against axenically grown amastigote and promastigote forms of three Leishmania species (L. amazonensis, L. mexicana, and L. infantum, responsible for diffuse cutaneous, cutaneous, and visceral leishmaniasis, respectively). The ability of axenically cultured amastigote organisms to be used in an investigation of antileishmanial agents was first evaluated. We have confirmed the toxicities of sodium stibogluconate (Pentostam), pentamidine, and amphotericin B to active and dividing populations of axenically cultured amastigotes. The toxicity of potassium antimonyl tartrate trihydrate, which is generally higher than that of Pentostam, seemed to indicate that pentavalent antimony can be metabolized in vivo to compounds, possibly trivalent in nature, which are more active against the amastigote organisms. When the drug susceptibilities of parasites at both stages were compared, great variations were found for all the drugs studied. These major differences, which show the specific chemosusceptibility of the parasite at the mammalian stage, demonstrate the potential of using cultured amastigotes instead of promastigotes in a drug-screening procedure for early detection. This in vitro model may help in the isolation of active compounds, particularly those with low-grade activities, against the mammalian stage of the parasite.

In vitro and in vivo resistance of Leishmania infantum to meglumine antimoniate: a study of 37 strains collected from patients with visceral leishmaniasis.

Abstract: Primary and secondary unresponsiveness to meglumine has long been described in human visceral leishmaniasis. However, no studies have been performed to elucidate if these therapeutic failures were due to strain variability in meglumine sensitivity or were related to host factors. We have studied the in vitro sensitivity of 37 strains of Leishmania infantum isolated from 23 patients (11 human immunodeficiency virus-infected and 12 immunocompetent patients) with visceral leishmaniasis. Sensitivity tests were performed by infecting murine macrophages with Leishmania parasites and culturing them in medium containing different concentrations of meglumine. For each test we calculated a 50% effective dose (ED50) corresponding to the meglumine concentration at which 50% of the Leishmania parasites survived. In vitro results were strongly correlated to immediate clinical outcome. All strains requiring an ED50 of >70 microg/ml were related to therapeutic failures, whereas all strains requiring an ED50 of <40 microg/ml corresponded to an initial efficiency of meglumine. Among those patients who were initially improved, relapses occurred in all immunocompromised patients and in most immunocompetent patients who had a short duration of treatment (15 days). Finally, we found that in vitro sensitivity of strains decreased progressively in relapsing patients treated with meglumine. Consequently, the physician may be encouraged to alternate meglumine with other treatments such as amphotericin B or pentamidine, especially in the case of relapsing patients.

Effect of Eliminating Seropositive Canines on the Transmission of Visceral Leishmaniasis in Brazil

Abstract: In Brazil, where Leishmania chagasi causes endemic American visceral leishmaniasis (AVL), the spread and maintenance of human disease are attributed to canine reservoirs. However, despite measures directed toward the elimination of infected canines, the incidence of human disease continues to increase. To evaluate the role of infected canines in the acquisition of AVL by humans, we undertook a controlled intervention study in three similar, but isolated, valleys of Pancas, Espirito Santo, Brazil. In the two experimental (intervention) valleys, infected dogs were eliminated whereas in the control valley, seropositive canines remained untouched. During the 12-month study period, human seropositivity rates, as measured by dot enzyme-linked immunosorbent assay, increased from 15% to 54% in the intervention valleys and from 14% to 54% in the control valley. The elimination of infected canines in the intervention valleys did not result in a statistically significant difference between the incidences of human serological conversion in the intervention and control valleys at either 6 (20% and 22%, respectively; P = .5961) or 12 months (26% and 27%, respectively; P = .9442). The role of humans as a significant reservoir for AVL is proposed as an explanation for the study results.

Loss of virulence in Leishmania donovani deficient in an amastigote-specific protein, A2

Abstract: Leishmania donovani is the etiologic agent of fatal visceral leishmaniasis in man. During their life cycle, Leishmania exist as flagellated promastigotes within the sandfly vector and as nonflagellated amastigotes in the macrophage phagolysosomal compartment of the mammalian host. The transformation from promastigotes to amastigotes is a critical step for the establishment of infection, and the molecular basis for this transformation is poorly understood. To define the molecular basis for amastigote survival in the mammalian host, we previously identified an amastigote stage-specific gene family termed “A2.” In the present study, we have inhibited the expression of A2 mRNA and A2 protein in amastigotes using antisense RNA and show that the resulting A2-deficient amastigotes are severely compromised with respect to virulence in mice. Amastigotes that did survive in the mice had restored A2 protein expression. These data demonstrate that A2 protein is required for L. donovani survival in a mammalian host, and this represents the first identified amastigote-specific virulence factor identified in Leishmania. This study also reveals that it is possible to study gene function in Leishmania through the expression of antisense RNA.

Evaluation of PCR for diagnosis of visceral leishmaniasis.

Abstract: An evaluation of Leishmania PCR was performed with bone marrow, lymph node, and blood samples from 492 patients, 60 positive controls, and 90 negative controls. Results were compared with microscopy results for Giemsa-stained smears. PCR and microscopy of lymph node and bone marrow aspirates from patients with microscopically confirmed visceral leishmaniasis (VL) were equally sensitive. However, in patients clinically suspected of having VL and in whom parasites could not be demonstrated by microscopy, PCR was positive for 12 of 23 (52.2%) lymph node aspirates and 8 of 12 (66.7%) bone marrow aspirates, thus confirming the clinical diagnosis of VL. With PCR on filter paper, Leishmania DNA was detected in the blood of 33 of 47 (70%) patients with confirmed VL and in 2 of 11 (19%) patients suspected of having VL. Positive PCR results were more frequently found for blood samples on filter paper than for samples stored in EDTA. In conclusion, PCR is a more sensitive method than microscopy for the detection of Leishmania in lymph node and bone marrow aspirates, being especially useful for the confirmation of cases of suspected VL. Blood from a finger prick may be used for the initial PCR screening of people suspected of having VL. If the PCR of blood is negative, one should perform PCR with lymph node and/or bone marrow material, because PCR with these materials is more often positive.

Destruction of follicular dendritic cells during chronic visceral leishmaniasis.

Abstract: Follicular dendritic cells (FDCs) play a pivotal role in the germinal center (GC) response and in the development and regulation of B lymphocytes. Pathologic changes in GCs and a loss of FDCs have previously been noted in various viral infections, notably HIV-1. However, such changes have not been formally described in a chronic parasitic infection. In BALB/c mice infected with Leishmania donovani, parasites persist in the spleen for long periods, with associated splenomegaly. To examine the fate of FDC during the course of this chronic infection, we used 1) immunohistology, with FDC-specific mAbs; and 2) passive immunization with immune complexes, followed by light and electron microscopy. This study demonstrates that destruction of FDCs and a concomitant loss of GCs are associated with chronic visceral leishmaniasis. These pathologic effects are notable from 4 wk postinfection. At 8 wk postinfection and beyond, FDC are almost undetectable by both immunohistology and functional immune complex trapping. The loss of FDCs is associated with the infiltration of heavily parasitized macrophages into the GC, and reduction in parasite burden by chemotherapy is able to retard the process of FDC destruction. These data directly demonstrate for the first time the loss of FDCs during a chronic parasite infection and suggest a mechanism underlying the aberrant regulation of B cell function in murine visceral leishmaniasis.

Activity of liposomal amphotericin B against experimental cutaneous leishmaniasis.

Abstract: The polyene antibiotic amphotericin B is currently a second-line treatment for visceral leishmaniasis (VL) and mucocutaneous leishmaniasis. Lipid-amphotericin B formulations with lower toxicity than the parent drug that were developed for the treatment of systemic mycoses have proved to be an effective treatment for VL, especially AmBisome, a small unilamellar negatively charged liposome. In vitro, free amphotericin B was three to six times more active than the liposomal formulation AmBisome against both Leishmania major promastigotes in culture and amastigotes in murine macrophages. In a BALB/c L. major model of cutaneous infection, liposomal amphotericin B administered once a day on six alternate days by the intravenous route produced a dose-response effect between 6.25 and 50 mg/kg. Liposomal amphotericin B administered subcutaneously close to a lesion had no significant activity. Free drug was ineffective at nontoxic doses. The results suggest that liposomal amphotericin B may be useful in the treatment of cutaneous leishmaniasis.

Rapid identification of causative species in patients with Old World leishmaniasis.

Abstract: Conventional methods for the identification of species of Leishmania parasite causing infections have limitations. By using a DNA-based alternative, the present study tries to develop a new tool for this purpose. Thirty-three patients living in Marseilles (in the south of France) were suffering from visceral or cutaneous leishmaniasis. DNA of the parasite in clinical samples (bone marrow, peripheral blood, or skin) from these patients were amplified by PCR and were directly sequenced. The sequences observed were compared to these of 30 strains of the genus causing Old World leishmaniasis collected in Europe, Africa, or Asia. In the analysis of the sequences of the strains, two different sequence patterns for Leishmania infantum, one sequence for Leishmania donovani, one sequence for Leishmania major, two sequences for Leishmania tropica, and one sequence for Leishmania aethiopica were obtained. Four sequences were observed among the strains from the patients: one was similar to the sequence for the L. major strains, two were identical to the sequences for the L. infantum strains, and the last sequence was not observed within the strains but had a high degree of homology with the sequences of the L. infantum and L. donovani strains. The L. infantum strains from all immunocompetent patients had the same sequence. The L. infantum strains from immunodeficient patients suffering from visceral leishmaniasis had three different sequences. This fact might signify that some variants of L. infantum acquire pathogenicity exclusively in immunocompromised patients. To dispense with the sequencing step, a restriction assay with HaeIII was used. Some restriction patterns might support genetic exchanges in members of the genus Leishmania.

Short-course, low-dose amphotericin B lipid complex therapy for visceral leishmaniasis unresponsive to antimony.

Abstract: Background: Visceral leishmaniasis (kala-azar) is a world-wide, disseminated intracellular protozoal infection for which prolonged, conventional therapy with pentavalent antimony has become increas...

Antibody Response against a Leishmania donovani Amastigote-Stage-Specific Protein in Patients with Visceral Leishmaniasis

Abstract: The antibody response against an amastigote-specific protein (A2) from Leishmania donovani was investigated. Sera from patients with trypanosomiasis and various forms of leishmaniasis were screened for anti-A2 antibodies. Sera from patients infected only with L. donovani or Leishmania mexicana specifically recognized the A2 recombinant protein. These results were consistent with karyotype analyses which revealed that the A2 gene is conserved in L. donovani and L. mexicana strains. The potential of this antigen in diagnosis was further explored by screening a series of sera obtained from patients in regions of the Sudan and India where L. donovani is endemic. The prevalence of anti-A2 antibodies was determined by Western blotting for all samples. Enzyme-linked immunosorbent assay (ELISA) and an immunoprecipitation assay were also performed on some of the samples. Anti-A2 antibodies were detected by ELISA in 82 and 60% of the samples from individuals with active visceral leishmaniasis (kala-azar) from the Sudan and India, respectively, while the immunoprecipitation assay detected the antibodies in 92% of the samples from India. These data suggest that the A2 protein may be a useful diagnostic antigen for visceral leishmaniasis.

Short report: Leishmania tropica: etiologic agent of a case of canine visceral leishmaniasis in northern Morocco.

Abstract: The domestic dog has been previously demonstrated to be the reservoir of Leishmania infantum, the etiologic agent of human visceral leishmaniasis around the Mediterranean Basin. It can also be infected with L. tropica, the etiologic agent of anthroponotic cutaneous leishmaniasis in Morocco. We report a canine L. tropica visceral infection for the first time in Morocco.

Asymptomatic leishmania chagasi infection in relatives and neighbors of patients with visceral leishmaniasis

Abstract: The frequency of asymptomatic infection among relatives and neighbors of cases of visceral leishmaniasis (VL) was compared and characterization of the immunological response in these subjects was performed. Cases were from a new endemic area close to the beach and near Salvador capital of the State of Bahia, Brazil. The characterization of asymptomatic infection was made using a skin reaction test and detection of antibody to Leishmania chagasi by the ELISA test. To characterize the immunological response of these subjects with asymptomatic L. chagasi infection the cytokines profile and the lymphoproliferative response were determined after stimulation of lymphocytes by L. chagasi antigen. There was no difference in the frequency of L. chagasi infection in relatives (45%) and in neighbors (27%) of cases of VL (P > 0.05). The immunological response from these subjects was characterized by high production of IFN-gamma and a low production of IL-10 and a good lymphoproliferative response to L. chagasi antigen.

Bone marrow biopsy in the diagnosis of fever of unknown origin in patients with acquired immunodeficiency syndrome.

Abstract: Background: Fever is commonly observed in patients with human immunodeficiency virus (HIV) disease and frequently eludes diagnosis. The role of bone marrow biopsy in the diagnosis of fever of unknown origin in patients infected with HIV remains controversial. Patients and Methods: One hundred twenty-three consecutive patients with 137 episodes of fever lasting 10 or more days without diagnosis after 1 week of hospitalization were evaluated by bone marrow biopsy. Results: Overall, a specific diagnosis was achieved in 52 episodes by means of culture and histopathological examination (diagnostic yield, 37.9%). Three types of disease were found: mycobacterial infections (n=36, 69% of documented episodes), including 18 patients with disseminated tuberculosis and 14 withMycobacterium avium-intracellulare complexinfections; non-Hodgkin lymphomas (n=12, 23%); and visceral leishmaniasis (n=4, 8%). Although bone marrow cultures were more sensitive than microscopic examination with special stains for the diagnosis of mycobacterial infections, the pathological examination of bone marrow led to a more rapid diagnosis of disease. In addition, the histopathological examination of bone marrow alone led to the diagnosis of a specific condition in 43 episodes (31.3% of all episodes). Conclusions: Bone marrow biopsy is a useful procedure for the diagnosis of fever in patients with advanced HIV disease, particularly in areas where tuberculosis and leishmaniasis are prevalent. Involvement of the marrow may be the first indication of the existence of extranodal non-Hodgkin lymphoma. ForMycobacterium avium-intracellulare complexinfection, blood cultures were more sensitive than bone marrow biopsy. Arch Intern Med. 1997;157:1577-1580

Diagnosis of visceral leishmaniasis by the polymerase chain reaction using blood, bone marrow and lymph node samples from patients from the Sudan

Abstract: We have evaluated the sensitivity of the polymerase chain reaction (PCR) as a diagnostic tool for Leishmania donovani using blood, bone marrow and lymph node samples from Sudanese patients with a confirmed infection. Forty patients were diagnosed by microscopic examination of bone marrow or lymph node samples. The PCR was able to detect parasite DNA in 37 out of 40 blood samples. In bone marrow and lymph node samples, the PCR was able to detect parasite DNA in all 7 and 6 samples, respectively. We suggest that the PCR should be considered as a valuable and sensitive tool for the diagnosis of L. donovani infection. However, if PCR diagnosis is to supplement or even replace microscopic diagnosis in developing countries, a large number of patients with no apparent signs of infection and patients with other diseases have to be tested in order to evaluate its true potential.

Visceral leishmaniasis in patients infected with the human immunodeficiency virus

Abstract: The experience with 52 episodes of visceral leishmaniasis diagnosed in 43 patients is reported. The most common symptoms were fever (81%), splenomegaly (65%), hepatomegaly (63%), and pancytopenia (73%). In 79% of the patients, CD4+ cell counts were <100 cells/mm3. Prior or simultaneous diagnosis of AIDS was made in 29 (67%) patients. Diagnosis was considered fortuitous in 19% of the episodes. In 27% of the episodes, the diagnosis was made on the basis of demonstration of parasites outside the reticuloendothelial system, chiefly blood (7 cases) and gastrointestinal mucosa (5 cases). Parasites were frequently observed or cultured from blood (22/37 episodes) or the digestive tract (8/9 episodes). High antimony doses were more effective than low doses in achieving clinical or parasitological cure (rate of cure, 80% vs. 40%, p=0.11). Severe toxicity was observed in six (11.7%) of the 51 treated episodes. Severe AIDS-related diseases [odds ratio (OR) 10, p<0.05] and CD4+ counts (OR 12, p<0.05) were independent factors for early death. Prophylaxis with monthly pentamidine was not useful in reducing relapses of visceral leishmaniasis.

Epidemiologic surveillance of visceral leishmaniasis in Sicily, Italy.

Abstract: Visceral leishmaniasis (VL) is endemic in Sicily. Although it is a notifiable disease, there is evidence that the actual number of cases is higher than that reported. In 1987, a regional reference center for active surveillance of VL was established and it recorded a total of 284 cases through 1995, a mean of 31.5 cases/year and about four-fold more than previously reported. Of the 284 cases, 150 (53%) were children (≤ 14 years of age), and of the 134 adults, 39 (29%) were coinfected with human immunodeficiency virus (HIV). The commonest viscerotropic zymodeme of Leishmania infantum, MON 1, was identified in 40 (93%) of 43 HIV-negative and eight (57%) of 14 HIV-positive patients. Among 280 patients evaluated (i.e., all HIV-negative and 35 of 39 HIV-positive subjects), 254 (91%) were treated with meglumine antimoniate alone or in combination with other drugs; 23 (8%) received allopurinol or amphotericin B, either conventional or in liposomal form; and three terminally ill patients were not treated. Among the 245 HIV-negative patients, 236 (96%) were successfully cured, while nine (4%) (seven adults) died during the course of antimonial treatment. None of the 35 HIV-positive patients was definitively cured, although mortality was apparently associated with other opportunistic infections.

Experimental pathogenicity of viscerotropic and dermotropic isolates of Leishmania infantum from immunocompromised and immunocompetent patients in a murine model

Abstract: The pathogenicity of 22 strains of Leishmania infantum from 11 HIV-infected and 11 immunocompetent patients with visceral (VL, n=16) or cutaneous (CL, n=6) leishmaniasis, belonging to 3 zymodemes (MON-1, n=14; MON-29, n=5; MON-33, n=3), was studied using a murine model. For each strain 16–20 BALB/c mice were infected at day 0 (d0) by i.v. injection of 107 stationary-phase promastigotes. Parasite burdens were quantified in the spleen and liver of 4–5 mice of each strain at d7, d20, d60 and d90 or d100, using a sensitive culture microtitration technique. A great variability of infection profiles between strains was observed: (i) six strains showed a progressive infection, with a predominance of hepatic parasites at d7 or d20 (104–106 g−1), then a continuous rise of splenic parasites reaching 105–107 g−1 at d90 or d100 contrasting with a stagnation or decrease in the liver; (ii) ten strains gave a controlled infection with hepatic parasite burden reaching 104–105 g−1 at d7 or d20, followed by a more or less rapid decline leading frequently to no detectable parasites; (iii) six strains resulted in other profiles, i.e., undetectable infection (n=1) or low parasite loads (n=4), or late occurrence of parasites in the spleen (n=1). No relationship was observed between profile and growth characteristics in vitro or zymodeme of the strain. Strains originating from CL never gave a visceralizing pattern in mice, but belonged more frequently to the avirulent type compared to VL strains. Strains from HIV-infected patients were not less virulent than those from immunocompetent individuals. These results showed that the course of L. infantum infection varies markedly with intrinsic parasite factors that display striking intraspecific variability.

A case of autochthonous canine leishmaniasis in The Netherlands.

Abstract: Summary The transmission of visceral leishmaniasis (VL) in the absence of its natural vector, the sandfly, is considered exceptional. This report describes VL in a 12‐month‐old dog which had never been in an area in which VL is endemic but was born in the Netherlands from a bitch that had been infected in Spain. Although the mode of transmission, via the placenta or otherwise, is unknown, it can be concluded that bitches with VL can be a source of infection for their pups, even in a sandfly‐free non‐endemic area. The dog was successfully treated with allopurinol.

Protection of mice against visceral leishmaniasis by immunization with promastigote antigen incorporated in liposomes.

Abstract: Leishmanial antigens (LAg) were used as a vaccine against Leishmania donovani, the causative agent of visceral leishmaniasis. BALB/c mice, immunized intraperitoneally with 20 micrograms of the antigen in phosphate-buffered saline (PBS) or entrapped in liposomes, were infected intravenously with 2 x 10(7) L. donovani promastigotes. Mice immunized with PBS and empty liposomes showed similar levels of parasite burdens in the liver and spleen. Injection of the antigen alone or entrapped in liposomes, followed with infection, induced significant levels of protection against the disease. After 2 and 4 mo of infection, mice immunized with free antigen induced 7.4% and 50.7% reduction in the liver parasite burden, respectively, compared to control (PBS) mice. With antigen encapsulated in liposome, the liver parasite burden was further reduced by 30.4% and 73% at 2 and 4 mo by infection, respectively. Splenic parasite burden was very low at 2 mo of infection. At 4 mo, the parasite level was reduced by 54.2% with free antigen and 69.3% with antigen entrapped in liposomes. Whereas the protection induced by the free antigen is mainly cell mediated, stimulation of an antibody response together with a strong delayed-type hypersensitivity may be responsible for the better protection with liposomal antigen.

Progression of visceral leishmaniasis due to Leishmania infantum in BALB/c mice is markedly slowed by prior infection with Trichinella spiralis.

Abstract: We investigated in BALB/c mice the influence of the immunological environment created by the nematode Trichinella spiralis on the course of visceral leishmaniasis due to Leishmania infantum. On the day of Leishmania inoculation (day 0), mice, T. spiralis infected 7 days earlier, presented increased gamma interferon (IFN-gamma), interleukin-4 (IL-4), and IL-5 mRNA levels locally and systemically and increased the potential of spleen cells to synthesize IFN-gamma and IL-4 after activation in vitro. Eighteen days after Leishmania inoculation (day 18), corresponding to the acute phase of leishmaniasis, the hepatic amastigote burden in mice coinfected with L. infantum and T. spiralis (LT mice) was significantly lower (P < 0.001) than that in mice infected with L. infantum only (L mice). IFN-gamma and IL-4 mRNAs were overexpressed in livers of LT and L mice. On day 70, corresponding to the chronic phase, the splenic amastigote load was significantly lower (P = 0.004) in LT mice than it was in L mice. Splenic IFN-gamma transcripts were overexpressed in both L and LT mice. After Leishmania-specific in vitro stimulation, cytokine production was enhanced in both groups, but spleen cells from L mice produced significantly more IFN-gamma than did spleen cells from LT mice. Our data (i) generalize previous results indicating the lack of a clear-cut correlation between the outcome of murine visceral leishmaniasis and the type of cytokine pattern and (ii) demonstrate that in LT mice, leishmaniasis takes a markedly milder course than it does in L mice, providing information on the potential consequences of coinfection in a mammalian host.

Use of PCR on lymph-node samples as test of cure of visceral leishmaniasis

Abstract: When the polymerase chain reaction (PCR) was used to test lymph-node aspirates from 35 patients from eastern Sudan, who had had visceral leishmaniasis but were believed cured, leishmanial DNA was detected in samples from 14 of the patients. There were no signi® cant differences between the PCR-positives and -negatives in terms of age, sex, spleen size, malaria status or presence of anti- Leishmania antibodies. However, PCR was more often positive in the patients who tested negative by the leishmanin skin test (LST) than in those who gave positive skin tests. Moreover, patients with a positive PCR and a negative LST converted more often to LST positivity than those with a negative PCR and a negative LST. The most important ® nding was that, during follow-up, eight (57%) of the PCR-positives, but none of the 21 negatives, developed post-kala-azar dermal leishmaniasis (PKDL). In conclusion, PCR-based testing of lymph-node aspirates after treatment may be used as a prognostic marker for the future development of PKDL and may be useful in the follow-up of patients. Visceral leishmaniasis (VL) is caused by protozoan parasites of the Leishmania donovani s.l. complex. During the active disease, parasites may be detected in spleen, bone-marrow or lymph-node aspirates (Zijlstra et al., 1992). Although the leishmanin skin test (LST) is characteristically negative at this stage of the disease (Manson-Bahr, 1961), serological assays, such as direct agglutination tests (DAT), may demonstrate anti- Leishmania antibodies in serum samples from . 95% of all HIVnegative VL patients (Meredith et al., 1995). After successful treatment, . 80% of ex

Activity of a new liposomal formulation of amphotericin B against two strains of Leishmania infantum in a murine model.

Abstract: The efficacy of a new liposomal formulation of amphotericin B was compared to that of amphotericin B deoxycholate (Fungizone) in a murine model of visceral leishmaniasis induced by Leishmania infantum. Median effective doses (ED50) were determined with two different strains: strain 1 was obtained from an untreated patient, and strain 2 was obtained from a patient who had received 12.5 g of amphotericin B over 3 years. BALB/c mice were infected intravenously on day 0 with promastigotes and then treated on days 14, 16, and 18 (strain 1) or on days 21, 23, and 25 (strain 2) with the liposomal formulation of amphotericin B (five doses were tested for each strain: 0.05, 0.1, 0.5, 0.8, and 3 mg/kg of body weight) or with conventional amphotericin B (four doses were tested for each strain: 0.05, 0.1, 0.5, and 0.8 mg/kg). Mice in the control group received normal saline solution. The liposomal amphotericin B formulation was about three times more active than the conventional drug against both strains. ED50 of the liposomal formulation were 0.054 (strain 1) and 0.194 (strain 2) mg/kg. ED50 of conventional amphotericin B were 0.171 (strain 1) and 0.406 (strain 2) mg/kg. Determination of drug tissular levels, 3 days after the last drug administration, showed a drug accumulation in hepatic and splenic tissues much higher after administration of liposomal amphotericin B than after conventional amphotericin B. A lack of toxicity was noted in all groups treated with the liposomal formulation. Leishmania is a pathogenic protozoan that causes a wide spectrum of infectious diseases in mammalian hosts, ranging from self-healing cutaneous ulceration to progressive and lethal visceral infection. The estimated prevalence in the world is 12 million cases, with 400,000 to 2,000,000 new cases reported per year (11). In the Mediterranean basin, where Leishmania infantum is endemic, Leishmania-human immunodeficiency virus (HIV) coinfections, occurring in about 2 to 7% of AIDS patients, are regarded as emerging diseases (10, 24, 30). Today, 25 to 70% of adult visceral leishmaniasis (VL) cases are related to HIV infection in southern Europe (2, 19). In LeishmaniaHIV-coinfected patients, the first course of antimonial pentavalent compounds is successful in 46 to 75% of cases, with apparent clinical recovery (1, 24). This treatment is initially unsuccessful, totally (with 10% of the patients dying during the course) or partly, in 15 to 19% of cases (1, 14). Relapses after apparent clinical recovery occur after a mean of 4.5 months (28). Relapses following antimonial treatments can be the direct cause of mortality. Therefore, the use of amphotericin B (AmB), an antifungal agent which proved to be also active against Leishmania, was promoted as an alternative first-line treatment. AmB was first used with the deoxycholate formulation (Fungizone). Acute and chronic side effects have limited

Leishmaniasis in Malta and the Mediterranean basin.

Abstract: Leishmaniasis is a public-health problem in most countries bordering the Mediterranean littoral. In Malta, where the disease has been recognized for many years, Phlebotomus perniciosus is the established vector and dogs act as reservoir hosts. Visceral leishmaniasis (VL) was the only form of the disease recorded in Malta until the early 1980s, when cutaneous leishmaniasis (CL) was recognized. Although the incidence of CL has recently increased, the overall numbers of cases of leishmaniasis have markedly decreased since the 1960s. Prior to 1963, almost all cases were aged < 10 years. Although leishmaniasis in Malta is still mainly a disease of children, adult cases are increasingly being recognized. HIV-VL co-infection is being seen more and more frequently in the Mediterranean basin, especially in Spain, France and Italy. During diagnosis, leishmaniasis should be suspected on the basis of the clinical picture in endemic areas and on the travel history of those patients from non-endemic areas. In Malta, VL and CL are generally confirmed by detection of the parasites in smears, of bone-marrow or, rarely, splenic aspirates and of lesions, respectively. Antimonials are the standard therapeutic agents for VL, although liposomal amphotericin B is a very effective but expensive alternative, with no significant adverse effects. In Malta, the treatment of choice for CL is cryotherapy.