Post kala-azar dermal leishmaniasis in the Sudan: clinical features, pathology and treatment

Post-kala-azar dermal leishmaniasis (PKDL) drug efficacy study landscape: A systematic scoping review of clinical trials and observational studies to assess the feasibility of establishing an individual participant-level data (IPD) platform

BACKGROUND

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis which can occur after successful treatment of visceral leishmaniasis (VL) and is a public health problem in VL endemic areas. We conducted a systematic scoping review to assess the characteristics of published PKDL clinical studies, understand the scope of research and explore the feasibility and value of developing a PKDL individual patient data (IPD) platform.

METHODS

A systematic review of published literature was conducted to identify PKDL clinical studies by searching the following databases: PubMed, Scopus, Ovid Embase, Web of Science Core Collection, WHO Global Index Medicus, PASCAL, Clinicaltrials.gov, Ovid Global Health, Cochrane Database and CENTRAL, and the WHO International Clinical Trials Registry Platform. Only prospective studies in humans with PKDL diagnosis, treatment, and follow-up measurements between January 1973 and March 2023 were included. Extracted data includes variables on patient characteristics, treatment regimens, diagnostic methods, geographical locations, efficacy endpoints, adverse events and statistical methodology.

RESULTS

A total of 3,418 records were screened, of which 56 unique studies (n = 2,486 patients) were included in this review. Out of the 56 studies, 36 (64.3%) were from India (1983-2022), 12 (21.4%) from Sudan (1992-2021), 6 (10.7%) were from Bangladesh (1991-2019), and 2 (3.6%) from Nepal (2001-2007). Five (8.9%) studies were published between 1981-1990 (n = 193 patients), 10 (17.9%) between 1991-2000 (n = 230 patients), 10 (17.9%) between 2001-2010 (n = 198 patients), and 31 (55.4%) from 2011 onwards (n = 1,865 patients). Eight (14.3%) were randomised clinical trials, and 48 (85.7%) were non-randomised studies. The median post-treatment follow-up duration was 365 days (range: 90-540 days) in 8 RCTs and 360 days (range: 28-2,373 days) in 48 non-randomised studies. Disease diagnosis was based on clinical criterion in 3 (5.4%) studies, a mixture of clinical and parasitological methods in 47 (83.9%) and was unclear in 6 (10.7%) studies. Major drugs used for treatment were miltefosine (n = 636 patients), liposomal amphotericin B (L-AmB) (n = 508 patients), and antinomy regimens (n = 454 patients). Ten other drug regimens were tested in 270 patients with less than 60 patients per regimen.

CONCLUSIONS

Our review identified studies with very limited sample size for the three major drugs (miltefosine, L-AmB, and pentavalent antimony), while the number of patients combined across studies suggest that the IPD platform would be valuable. With the support of relevant stakeholders, the global PKDL community and sufficient financing, a PKDL IPD platform can be realised. This will allow for exploration of different aspects of treatment safety and efficacy, which can potentially guide future healthcare decisions and clinical practices.

Unusual Observations in Leishmaniasis-An Overview

Leishmaniasis significantly affects the population of the tropics and subtropics. Clinical features and infective species of Leishmania are the primary factors driving the direction of diagnosis. The rise in incidences of atypical presentations present a challenge in patient treatment. Knowledge of unusual/rare presentations can aid in having a broader perspective for including the different aspects during the examination and thus avoid misdiagnosis. A comprehensive literature survey was performed to present the array of atypical presentations confounding clinicians which have been seen in leishmaniasis. Case reports of unusual findings based on the localizations and morphology of lesions and infective species and the predominant geographical sites over almost five decades highlight such presentations in the population. Information regarding the clinical features recorded in the patient and the chosen treatment was extracted to put forward the preferred drug regimen in such cases. This comprehensive review presents various unusual observations seen in visceral leishmaniasis, post-kala-azar dermal leishmaniasis, cutaneous leishmaniasis, and mucocutaneous leishmaniasis. It highlights the need to consider such features in association with differential diagnosis to facilitate proper treatment of the patient.

Para Kala-Azar Dermal Leishmaniasis: A Case Report

Rarely, post-kala-azar dermal leishmaniasis (PKDL) may coexist with visceral leishmaniasis (VL). The concomitant PKDL and VL are referred to as Para-kala-azar dermal Leishmaniasis. We report a case of Para kala-azar dermal leishmaniasis in a chronic Hepatitis-B virus-infected patient who presented with an abdominal lump and multiple maculopapular skin lesions and is resistant to sodium stibogluconate but successfully treated with liposomal Amphotericin-B.

Histopathology of Post Kala-azar Dermal Leishmaniasis

The various lesions seen in the clinical presentation of post kala-azar dermal leishmaniasis (PKDL) are reflected in the histopathology of the type of lesion biopsied. The cells that form the dermal infiltrate include lymphocytes, histiocytes, and plasma cells in varying proportions. The infiltrate, which is mild and confined to the superficial dermis in macular lesion becomes denser with the increasing severity of the lesion. Leishman–Donovan bodies (LDB) in general are rarely demonstrable in macules and somewhat infrequently in the rest, though at times they may be numerous; mucosal lesions offer a greater chance of visualizing LDB than biopsies from the skin. A characteristic histomorphology in nodules is prominent follicular plugging with a dense plasma cell-rich lymphohistiocytic dermal infiltrate that shows an abrupt cut-off in the lower dermis, an appearance highly suggestive of PKDL even in the absence of LDB. Russell bodies within plasma cells, vascular changes, and xanthoma-like hue have been seen in plaques from chronic PKDL. The histopathologic picture in some may also mimic that seen in tuberculoid and lepromatous leprosy, and other granulomatous dermatoses. In contrast to Indian PKDL, epithelioid cell granulomas with giant cells are more common in African PKDL, and vascular changes are rare though neuritis showing LDB has been described.

Epidemiology of Post-Kala-azar Dermal Leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is a cutaneous sequel of visceral leishmaniasis (VL) or kala-azar and has become an entity of epidemiological significance by virtue of its ability to maintain the disease in circulation during inter-epidemic periods. PKDL has been identified as one of the epidemiological marker of “kala-azar elimination programme.” Data obtained in 2018 showed PKDL distribution primarily concentrated in 6 countries, which includes India, Sudan, south Sudan, Bangladesh, Ethiopia, and Nepal in decreasing order of case-burden. In India, PKDL cases are mainly found in 54 districts, of which 33 are in Bihar, 11 in West Bengal, 4 in Jharkhand, and 6 in Uttar Pradesh. In West Bengal the districts reporting cases of PKDL cases include Darjeeling, Uttar Dinajpur, Dakshin Dinajpur, Malda, and Murshidabad. The vulnerability on the young age is documented in various studies. The studies also highlights a male predominance of the disease but recent active surveillance suggested that macular form of PKDL shows female-predominance. It is recommended that along with passive case detection, active survey helps in early identification of cases, thus reducing disease transmission in the community. The Accelerated plan for Kala-azar elimination in 2017 introduced by Government of India with the goal to eliminate Kala-azar as a public health problem, targets to reduceing annual incidence <1/10,000. Leishmania donovani is the established causative agent, but others like L. tropica or L. infantum may occasionally lead to the disease, especially with HIV-co-infection. Dermal tropism of the parasite has been attributed to overexpression of parasite surface receptors (like gp 63, gp46). Various host factors are also identified to contribute to the development of the disease, including high pretreatment IL 10 and parasite level, inadequate dose and duration of treatment, malnutrition, immuno-suppression, decreased interferon-gamma receptor 1 gene, etc. PKDL is mostly concentrated in the plains below an altitude of 600 mts which is attributed to the environment conducive for the vector sand fly (Phlebotumus). Risk factors are also linked to the habitat of the sand fly. Keeping these things in mind “Integrated vector control” is adopted under National vector borne disease control programme as one of the strategies to bring down the disease burden.

Post kala-azar dermal leishmaniasis: A threat to elimination program

Leishmaniasis remains a public health concern around the world that primarily affects poor folks of the developing world spanning across 98 countries with mortality of 0.2 million to 0.4 million annually. Post kala-azar dermal leishmaniasis (PKDL) is the late skin manifestation of visceral leishmaniasis (VL). It has been reported that about 2.5% to 20% of patients recovered from VL develop PKDL having stilted macular or nodular lesions with parasites. In the Indian subcontinent (ISC), it manifests a few months after recovery from VL, though in Africa it can occur simultaneously with VL or a little later. New cases of PKDL are also observed without prior VL in the ISC. These individuals with PKDL represent an important but largely neglected reservoir of infection that perpetuates anthroponotic Leishmania donovani transmission in the ISC and can jeopardize the VL elimination program as these cases can infect the sand flies and spread the endemic. Therefore, it becomes imperative to eradicate PKDL as a part of the VL elimination program. With the limited treatment options besides little knowledge on PKDL, this review stands out in focusing on different aspects that should be dealt for sustained VL elimination.

Biomarkers in Post-kala-azar Dermal Leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) follows visceral leishmaniasis (VL, kala-azar) in 10–60% of cases. It is characterized by an asymptomatic skin rash, usually starting in the face and consisting of macules, papules, or nodules. Diagnosis is difficult in the field and is often made clinically. There is an extensive differential diagnosis, and parasitological confirmation is preferred particularly when drug treatment is considered. The response to treatment is difficult to assess as this may be slow and lesions take long to heal, thus possibly exposing patients unnecessarily to prolonged drug treatment. Biomarkers are needed; these may be parasitological (from microscopy, PCR), serological (from blood, or from the lesion), immunological (from blood, tissue), pathological (from cytology in a smear, histology in a biopsy), repeated clinical assessment (grading, photography), or combinations. In this paper, we will review evidence for currently used biomarkers and discuss promising developments.

Cytokines: Key Determinants of Resistance or Disease Progression in Visceral Leishmaniasis: Opportunities for Novel Diagnostics and Immunotherapy

Leishmaniasis is a parasitic disease of humans, highly prevalent in parts of the tropics, subtropics, and southern Europe. The disease mainly occurs in three different clinical forms namely cutaneous, mucocutaneous, and visceral leishmaniasis (VL). The VL affects several internal organs and is the deadliest form of the disease. Epidemiology and clinical manifestations of VL are variable based on the vector, parasite (e.g., species, strains, and antigen diversity), host (e.g., genetic background, nutrition, diversity in antigen presentation and immunity) and the environment (e.g., temperature, humidity, and hygiene). Chemotherapy of VL is limited to a few drugs which is expensive and associated with profound toxicity, and could become ineffective due to the parasites developing resistance. Till date, there are no licensed vaccines for humans against leishmaniasis. Recently, immunotherapy has become an attractive strategy as it is cost-effective, causes limited side-effects and do not suffer from the downside of pathogens developing resistance. Among various immunotherapeutic approaches, cytokines (produced by helper T-lymphocytes) based immunotherapy has received great attention especially for drug refractive cases of human VL. Therefore, a comprehensive knowledge on the molecular interactions of immune cells or components and on cytokines interplay in the host defense or pathogenesis is important to determine appropriate immunotherapies for leishmaniasis. Here, we summarized the current understanding of a wide-spectrum of cytokines and their interaction with immune cells that determine the clinical outcome of leishmaniasis. We have also highlighted opportunities for the development of novel diagnostics and intervention therapies for VL.

Visceral Leishmaniasis IgG1 Rapid Monitoring of Cure vs. Relapse, and Potential for Diagnosis of Post Kala-Azar Dermal Leishmaniasis

Background: There is a recognized need for an improved diagnostic test to assess post-chemotherapeutic treatment outcome in visceral leishmaniasis (VL) and to diagnose post kala-azar dermal leishmaniasis (PKDL). We previously demonstrated by ELISA and a prototype novel rapid diagnostic test (RDT), that high anti-Leishmania IgG1 is associated with post-treatment relapse versus cure in VL.

Methodology: Here, we further evaluate this novel, low-cost RDT, named VL Sero K-SeT, and ELISA for monitoring IgG1 levels in VL patients after treatment. IgG1 levels against L. donovani lysate were determined. We applied these assays to Indian sera from cured VL at 6 months post treatment as well as to relapse and PKDL patients. Sudanese sera from pre- and post-treatment and relapse were also tested.

Results: Of 104 paired Indian sera taken before and after treatment for VL, when deemed clinically cured, 81 (77.9%) were positive by VL Sero K-SeT before treatment; by 6 months, 68 of these 81 (84.0%) had a negative or reduced RDT test line intensity. ELISAs differed in positivity rate between pre- and post-treatment (p = 0.0162). Twenty eight of 33 (84.8%) Indian samples taken at diagnosis of relapse were RDT positive. A comparison of Indian VL Sero K-SeT data from patients deemed cured and relapsed confirmed that there was a significant difference (p < 0.0001) in positivity rate for the two groups using this RDT. Ten of 17 (58.8%) Sudanese sera went from positive to negative or decreased VL Sero K-SeT at the end of 11–30 days of treatment. Forty nine of 63 (77.8%) PKDL samples from India were positive by VL Sero K-SeT.

Conclusion: We have further shown the relevance of IgG1 in determining clinical status in VL patients. A positive VL Sero K-SeT may also be helpful in supporting diagnosis of PKDL. With further refinement, such as the use of specific antigens, the VL Sero K-SeT and/or IgG1 ELISA may be adjuncts to current VL control programmes.

Cutaneous Manifestations of Human and Murine Leishmaniasis

The leishmaniases are diseases caused by pathogenic protozoan parasites of the genus Leishmania. Infections are initiated when a sand fly vector inoculates Leishmania parasites into the skin of a mammalian host. Leishmania causes a spectrum of inflammatory cutaneous disease manifestations. The type of cutaneous pathology is determined in part by the infecting Leishmania species, but also by a combination of inflammatory and anti-inflammatory host immune response factors resulting in different clinical outcomes. This review discusses the distinct cutaneous syndromes described in humans, and current knowledge of the inflammatory responses associated with divergent cutaneous pathologic responses to different Leishmania species. The contribution of key hematopoietic cells in experimental cutaneous leishmaniasis in mouse models are also reviewed and compared with those observed during human infection. We hypothesize that local skin events influence the ensuing adaptive immune response to Leishmania spp. infections, and that the balance between inflammatory and regulatory factors induced by infection are critical for determining cutaneous pathology and outcome of infection.

A Comparison of the Effectiveness of Sodium Stibogluconate Monotherapy to Sodium Stibogluconate and Paromomycin Combination for the Treatment of Severe Post Kala Azar Dermal Leishmaniasis in South Sudan - A Retrospective Cohort Study

Background

Post-kala-azar dermal leishmaniasis (PKDL) is a common dermatological complication following successful treatment of Visceral Leishmaniasis (VL) caused by Leishmania donovani. PKDL presents as macular, papular, nodular or mixed skin rash on sun-exposed body parts. Patients are not ill unless there are complications due to mucosal involvement or ulceration. As PKDL in East Africa is typically self-healing, and treatment is long and with significant adverse events, only severe and complicated cases are treated. Studies to determine optimal treatment of PKDL are rare and based on small cohorts. Since 1989, Médecins Sans Frontières is treating severe PKDL within VL treatment programmes in South Sudan. Treatment was initially with sodium stibogluconate (SSG) monotherapy and since 2002 with a combination of SSG and paromomycin (PM). SSG monotherapy (20 mg/kg/day for a minimum of 30 days) was provided in primary health units, and the combination of PM (15 mg sulphate/kg/day for 17 days) plus SSG (30 mg/kg/day for a minimum of 17 days) was provided in secondary health facilities.

Methodology/Principal Findings

By retrospective analysis of routinely collected programme data we compared the effectiveness (outcome and treatment duration) of both regimens. Between 2002 and 2008, 422 patients with severe PKDL were treated; 343 received SSG and 79 SSG/PM combination. The cure rate was significantly better with combination treatment when compared to monotherapy (97% vs. 90%; odds ratio [OR], 7.6; p = 0.02), treatment duration was shorter (mean 34 days vs. 42 days; p = 0.005), and defaulter rate was lower (3% vs. 9%; OR, 0.3; p = 0.03). There was no significant difference in death rate (0% vs. 1%; p = 0.5).

Conclusions/Significance

We found that SSG/PM combination therapy resulted in more favourable outcomes than SSG monotherapy. An additional advantage is the lower cost of the combination therapy, due to the shorter treatment duration. A combination of SSG and PM is therefore a suitable option for the treatment of PKDL in East Africa.

Clinicopathological and Immunological Changes in Indian Post Kala-Azar Dermal Leishmaniasis (PKDL) Cases in relation to Treatment: A Retrospective Study

Post-kala-azar dermal leishmaniasis (PKDL) is an important factor in kala-azar transmission; hence its early detection and assessment of effective treatment is very important for disease control. In present study on 60 PKDL cases presented with macular, mixed papulonodular, or erythematous lesions, Leishmania parasites were demonstrated microscopically in 91% of papulonodular and 40% of macular lesions. Cellular infiltrates in skin biopsy imprint smears from lesions were mononuclear cells, 25–300/OIF (oil immersion field), predominantly histiocytes with vacuolation, many lymphocytes, some plasma cells, and Leishmania amastigotes 0–20/OIF. Cases with no demonstrable parasites were diagnosed on the basis of past history of VL, lesion's distribution, cytopathological changes, and positive DAT (86.83%). Following antileishmanial treatment with SAG, papulonodular forms of PKDL lesions disappeared clinically but microscopically the mononuclear cells (20–200/OIF) persisted in the dermal lesions. Response observed in macular PKDL lesions was poor which persisted both clinically and cytopathologically. Follow-up of PKDL will assess the effectivity of treatment as either disappearance of lesions or any relapse. Studies on involvement of immunological factors, that is, certain cytokines (IL-10, TGF-β, etc.) and chemokines (macrophage inflammatory protein, MIP 1-α, etc.) in PKDL, may provide insight for any role in the treatment response.

Insights into the possible role of IFNG and IFNGR1 in Kala-azar and Post Kala-azar Dermal Leishmaniasis in Sudanese patients

BACKGROUND

Little is known about the parasite/host factors that lead to Post Kala-azar Dermal Leishmaniasis (PKDL) in some visceral leishmaniasis (VL) patients after drug-cure. Studies in Sudan provide evidence for association between polymorphisms in the gene (IFNGR1) encoding the alpha chain of interferon-γ receptor type I and risk of PKDL. This study aimed to identify putative functional polymorphisms in the IFNGR1 gene, and to determine whether differences in expression of interferon-γ (IFNG) and IFNGR1 at the RNA level are associated with pathogenesis of VL and/or PKDL in Sudan.

METHODS

Sanger sequencing was used to re-sequence 841 bp of upstream, exon1 and intron1 of the IFNGR1 gene in DNA from 30 PKDL patients. LAGAN and SYNPLOT bioinformatics tools were used to compare human, chimpanzee and dog sequences to identify conserved noncoding sequences carrying putative regulatory elements. The relative expression of IFNG and IFNGR1 in paired pre- and post-treatment RNA samples from the lymph nodes of 24 VL patients, and in RNA samples from skin biopsies of 19 PKDL patients, was measured using real time PCR. Pre- versus post-treatment expression was evaluated statistically using the nonparametric Wilcoxon matched pairs signed-rank test.

RESULTS

Ten variants were identified in the 841 bp of sequence, four of which are novel polymorphisms at -77A/G, +10 C/T, +18C/T and +91G/T relative to the IFNGR1 initiation site. A cluster of conserved non-coding sequences with putative regulatory variants was identified in the distal promoter of IFNGR1. Variable expression of IFNG was detected in lymph node aspirates of VL patients before treatment, with a marked reduction (P = 0.006) in expression following treatment. IFNGR1 expression was also variable in lymph node aspirates from VL patients, with no significant reduction in expression with treatment. IFNG expression was undetectable in the skin biopsies of PKDL cases, while IFNGR1 expression was also uniformly low.

CONCLUSIONS

Uniformly low expression of IFN and IFNGR1 in PKDL skin biopsies could explain parasite persistence and is consistent with prior demonstration of genetic association with IFNGR1 polymorphisms. Identification of novel potentially functional rare variants at IFNGR1 makes an important general contribution to knowledge of rare variants of potential relevance in this Sudanese population.

Efficacy of liposomal amphotericin B (AmBisome®) in the treatment of persistent post-kala-azar dermal leishmaniasis (PKDL)

A dermatosis commonly known as post-kala-azar dermal leishmaniasis (PKDL) may develop following the treatment of human visceral leishmaniasis (VL). In about 15% of PKDL cases the disfiguring lesions persist, sometimes for many years. Such persistent lesions currently require daily injections of sodium stibogluconate (SSG) for 2-4 months and even then treatment may not be successful. Alternative, quicker and cheaper treatment options that cause less toxicity are being explored. Immuno-chemotherapeutic regimens (based on leishmaniasis candidate vaccines/BCG with SSG) are still experimental but treatment with liposomal amphotericin B (AmBisome) has already been found effective, albeit in a small number of patients. AmBisome is considered less nephrotoxic than non-liposomal amphotericin B because it specifically targets the macrophages in which the Leishmania parasites develop. The aim of the present study was to evaluate further the usefulness of AmBisome in the treatment of persistent PKDL, in Sudan. The 12 subjects, all of whom gave their informed consent, had each had PKDL lesions for >6 months and shown no improvement after repeated injections of SSG. During the study period, they were hospitalized and regularly screened, haematologically and biochemically, for adverse effects. The AmBisome, given intravenously at 2.5 mg/kg.day for 20 days, completely cleared the skin rash of 10 (83%) of the patients and caused no detectable adverse effects. In the 10 patients who responded well to the treatment, the papular lesions regressed and became flat while the hypopigmented lesions darkened (continuing to do so even after the last AmBisome injections). Treatment outcome appeared to be unaffected by the age or gender of the patient (P = 0.7 for each) but the time taken for the PKDL lesions to heal was correlated with the age of the lesions (P = 0.009). The macular lesions healed more slowly than the papular (P = 0.02). In conclusion, Ambisome appears suitable for the treatment of persistent PKDL lesions in Sudan. Once certain favourable clinical signs (the regression and/or darkening of the PKDL lesions) have been noted, the lesions will probably continue to clear without the need for more injections.

Report of the Post Kala-azar Dermal Leishmaniasis (PKDL) Consortium Meeting, New Delhi, India, 27-29 June 2012

Post kala-azar dermal leishmaniasis (PKDL) is a neglected complication of visceral leishmaniasis (VL)―a deadly, infectious disease that claims approximately 20,000 to 40,000 lives every year. PKDL is thought to be a reservoir for transmission of VL, thus, adequate control of PKDL plays a key role in the ongoing effort to eliminate VL. Over the past few years, several expert meetings have recommended that a greater focus on PKDL was needed, especially in South Asia. This report summarizes the Post Kala-Azar Dermal Leishmaniasis Consortium Meeting held in New Delhi, India, 27–29 June 2012. The PKDL Consortium is committed to promote and facilitate activities that lead to better understanding of all aspects of PKDL that are needed for improved clinical management and to achieve control of PKDL and VL. Fifty clinicians, scientists, policy makers, and advocates came together to discuss issues relating to PKDL epidemiology, diagnosis, pathogenesis, clinical presentation, treatment, and control. Colleagues who were unable to attend participated during drafting of the consortium meeting report.

Treatment-based strategy for the management of post-kala-azar dermal leishmaniasis patients in the Sudan

Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis that affects more than 50% of successfully treated visceral leishmaniasis (VL) patients in Sudan. PKDL is considered an important reservoir for the parasite and its treatment may help in the control of VL. Currently, treatment is mainly with sodium stibogluconate (SSG), an expensive and fairly toxic drug and without universally in treatment protocols used. A literature review, a consensus of a panel of experts, and unpublished data formed the basis for the development of guidelines for the treatment of PKDL in the Sudan. Six treatment modalities were evaluated. Experts were asked to justify their choices based on their experience regarding of drug safety, efficacy, availability, and cost. The consensus was defined by assigning a categorical rank (first line, second line, third line) to each option. Regarding the use of AmBisome the presence of the drug in the skin was confirmed in smears from PKDL lesions. Recommendations: AmBisome at 2.5 mg/kg/day/20 days or SSG at 20 mg/kg/day/40 days plus four/weekly intradermal injection of alum-precipitated autoclave L. major vaccine are suggested as first- and second-treatment options for PKDL in the Sudan, respectively. SSG at 20 mg/Kg/day/60 or more days can be used if other options are not available.

Misdiagnosis and mistreatment of post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is a known complication of visceral leishmaniasis (VL) caused by L. donovani. It is rare in VL caused by L. infantum and L. chagasi. In Sudan, it occurs with a frequency of 58% among successfully treated VL patients. In the majority of cases, PKDL can be diagnosed on the basis of clinical appearance, distribution of the lesions, and past history of treated VL. The ideal diagnostic method is to demonstrate the parasite in smears, by culture or PCR. Diagnosis is particularly difficult in patients who develop PKDL in the absence of previous history of visceral leishmaniasis. We describe a case of cutaneous leishmaniasis misdiagnosed as PKDL and 3 cases of PKDL who were either misdiagnosed or mistreated as other dermatoses. This caused exacerbation of their disease leading to high parasite loads in the lesions and dissemination to internal organs in one of the patients, who was also diabetic. The latter patient had L. major infection. A fourth patient with papulonodular lesions on the face and arms of 17-year duration and who was misdiagnosed as having PKDL is also described. He turned out to have cutaneous leishmaniasis due to L. major. Fortunately, he was not treated with steroids. He was cured with intravenous sodium stibogluconate.

Disseminated cutaneous leishmaniasis resembling post-kala-azar dermal leishmaniasis caused by Leishmania donovani in three patients co-infected with visceral leishmaniasis and human immunodeficiency virus/acquired immunodeficiency syndrome in Ethiopia

We report paired strains of Leishmania parasites, one from the viscera and the other from skin lesions that were isolated from three patients with visceral leishmaniasis and disseminated cutaneous leishmaniasis that were co-infected with human immunodeficiency virus. The causative parasites were characterized by polymerase chain reaction-restriction length polymorphism of the ribosomal DNA internal transcribed spacer 1 and by a panel of multilocus microsatellite markers. We demonstrated that the causative agent was Leishmania donovani in all cases, irrespective of the phenotype of the disease. The paired strains from viscera and skin lesions of the same patients showed genetic identity across the 14 microsatellite markers investigated. These findings demonstrate that the skin lesions in these human immunodeficiency virus-positive patients with visceral leishmaniasis were caused by dissemination of viscerotropic L. donovani parasites as a consequence of severe immunosuppression. However, in all three patients, rapid clearance of the skin lesions was observed after antimonial therapy.

Interleukin 10 gene polymorphisms and development of post kala-azar dermal leishmaniasis in a selected sudanese population

Background

Post kala-azar dermal leishmaniasis (PKDL) is a cutaneous form of disease that develops at variable times after individuals have received treatment for clinical visceral leishmaniasis (VL). The study aimed to investigate the possible role of interleukin 10 (IL−10) and development of PKDL.

Methods

77 families composed of 41 complete case-parent trios and 36 case-parent pairs from the Masalit ethnic group were genotyped for 3 IL10 promoter polymorphisms: −1082A/G, −819C/T and −592C/A.

Results

Single point analysis using the transmission disequilibrium test showed no evidence of association between any of these IL10 promoter single nucleotide polymorphisms (SNPs) and development of PKDL. Haplotype analysis performed using TRANSMIT showed borderline significance between PKDL and the haplotype AA across −592C/A and −1082A/G (p = 0.053). Haplotypes GCC (0.33) and ATA (0.30) were the common haplotypes in this Sudanese population. Allele frequencies for the 3 SNPs differed significantly in Sudan compared to other African (Gambian, Malawian, YRI) populations.

Conclusion

There is no evidence for an association between 3 SNPs in the IL10 gene promoter and susceptibility to PKDL in the Masalit ethnic group in Sudan, although some evidence for haplotype association was observed.

Genetic fingerprinting and identification of differentially expressed genes in isolates of Leishmania donovani from Indian patients of post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is an unusual dermatosis that develops as a sequel in 5-15% of cured cases of kala-azar (KA) after months or years of treatment in India. Molecular differences are reported to exist between the KA and PKDL isolates which may underlie the diversity in clinical manifestations of the disease. Here, arbitrary primed-PCR (AP-PCR) has been used for genetic fingerprinting of parasite isolates from dermal lesions of PKDL patients (n=14) and compared with bone-marrow derived parasites from KA patients (n=3). All isolates showed an identical AP-PCR pattern with 4 arbitrary primers. Further, AP-PCR was exploited to identify the stage regulated genes of the parasite. Six polymorphic fragments were identified in PKDL in comparison with KA isolates, and were subjected to Northern blot analysis. Five polymorphic fragments represented transcribed sequences; 4 out of 5 drew differential expression in pro- and amastigote stages, although the expression was comparable between PKDL and KA isolates. The study led to the identification of genes, which exhibit stage-regulated expression in Leishmania donovani derived from PKDL or KA patients, including a putative phosphodiesterase, DEAD box RNA helicase, iron superoxide dismutase b (fesodb) and a hypothetical protein. Demonstration of transcripts of DEAD box RNA helicase in PKDL and KA diseased tissues implicates its role in disease pathogenesis.

Short communication: Post-kala-azar dermal leishmaniasis - an appraisal

This short descriptive paper assesses diagnostics, clinical characteristics and therapy of both Indian and African post-kala-azar dermal leishmaniasis.

Pathology of post-kala-azar dermal leishmaniasis: a light microscopical, immunohistochemical, and ultrastructural study of skin lesions and draining lymph nodes

BACKGROUND

Whereas the clinical manifestations and treatment of post-kala-azar dermal leishmaniasis (PKDL) have been adequately described before, the pathology received little attention, particularly the African form of PKDL which shows some clinical differences from the disease in India. Therefore, our aim was to characterize the pathology and the immunohistopathology in PKDL lesions and correlate the histopathological findings with the clinical features of the disease.

METHODS

Biopsies of skin lesions were examined for histopathological changes in formalin-fixed tissues and for cell phenotypes and adhesion molecules by immunohistochemistry.

RESULTS

The epidermis showed various changes in different combinations. The dermis was infiltrated by lymphocytes and macrophages, but plasma cells were scanty or absent. The majority of cells were CD3 T cells, with a preponderance of CD4 over CD8 cells. Degenerating basal keratinocytes expressed HLA-DR, ICAM-1 and Leishmania antigen and closely interacted with CD4 T cells. Regional lymph nodes showed hyperplasia of the B- and T-cell zones.

CONCLUSIONS

The inflammatory reaction in PKDL lesions is in response to Leishmania parasites and/or antigen. The majority of cells are CD4 T cells. Degeneration of the basal keratinocytes is probably due to the action of cytotoxic CD4 T cells interacting with leishmania-expressing epidermal cells. Ismail A, Gadir AFA, Theander TG, Kharazmi A, El Hassan AM. Pathology of post-kala-azar dermal leishmaniasis: a light microscopical, immunohistochemical, and ultrastructural study of skin lesions and draining lymph nodes.

Upregulation of surface proteins in Leishmania donovani isolated from patients of post kala-azar dermal leishmaniasis

Five to fifteen percent of visceral leishmaniasis (VL) patients in India develop post kala-azar dermal leishmaniasis (PKDL), usually 1-2 years after apparent clinical cure. There is evidence pointing to a role played by the host immune responses in the disease pathogenesis, however, the contribution of changes in parasite gene expression has not been explored. Highly sensitive gene expression microarray technology was employed to identify genes that are differentially expressed in Leishmania parasites isolated from PKDL patients in comparison with those from VL. Hybridization on Leishmania donovani genomic microarray comprised of unique clones allowed us to identify 46/2268 (2%) clones that showed statistically significant (P<0.05) changes in expression (1.5-3.5-fold) in parasites of PKDL origin compared to those of VL origin. Sequence analysis of six genomic clones, consistently showing approximately 2-fold higher expression in PKDL parasites, revealed significant homology with gp63, gp46, putative amastin, a putative reductase and a possible calpain-like protein. The gene products showing upregulated expression in PKDL isolates may be candidates playing a role in the altered clinical manifestation in PKDL. Such differentially expressed genes hold the key to understanding the parasite genetic factors that contribute to the persistence after clinical cure of VL.

The pathogenesis of post kala-azar dermal leishmaniasis from the field to the molecule: Does ultraviolet light (UVB) radiation play a role?

Post kala-azar dermal leishmaniasis (PKDL) is a dermatosis caused by persistence of Leishmania donovani parasites in the skin following apparently successful treatment of visceral leishmaniasis. The distribution of PKDL lesions in Sudanese patients often mirrors the clothing habits of those affected. It is most severe in or confined to the sun-exposed parts of the skin. It is well established that elimination of Leishmania parasites requires activation of parasitised macrophages by a Th1 immune response and that the latter is depressed by ultraviolet light (UVB). In this paper, we hypothesized that UVB light might be a key player in the pathogenesis of PKDL. This paper links observations made in the field with immunological data that are compatible with this hypothesis. We therefore investigated patients with PKDL immunologically for a possible role of UVB exposure in the pathogenesis of this condition. We marshal evidence that the changes in the tissues are compatible with the effects of UVB light and it is probable that UVB appears to be a key factor in the pathogenesis of PKDL. Immunopathologically the lesions were characterized by an influx of various inflammatory cells. The number of CD1a (Langerhans' cells) was decreased, they lost their dendrites, their HLA-DR and B7-1 expression was down regulated while B7-2 was expressed. Others have shown that Langerhans' cells with these features result from UVB exposure and that such cells are unable to present antigen to Th1 cells while retaining the capacity to present antigen to Th2 cells. Various cytokines known to be induced by UVB radiation could be demonstrated in PKDL lesions. Of these IL-10, TGF-beta, IL-12, IL-4 and TNF-alpha were found in different quantities. The Th-1 cytokine IFN-gamma was constantly present. The tissue origin of the Th-1 cells in PKDL is unknown. We believe that the antagonistic action of the different cytokines is the cause of the inflammation and chronicity of PKDL.

Leishmania promastigote membrane antigen-based enzyme-linked immunosorbent assay and immunoblotting for differential diagnosis of Indian post-kala-azar dermal leishmaniasis

Diagnosis of post-kala-azar dermal leishmaniasis (PKDL), caused by Leishmania donovani, is difficult, as the dermal lesions are of several types and resemble those caused by other skin diseases, especially leprosy. Since the disease generally appears very late after the clinical cure of kala-azar in India, it is also difficult to correlate PKDL with a previous exposure to L. donovani. Very few attempts have been made so far to diagnose PKDL serologically, and the diagnostic methods vary in their sensitivities and specificities. Diagnosis of PKDL through sophisticated PCR methods, although highly sensitive, has limited practical use. We have developed a serodiagnostic method using an enzyme-linked immunosorbent assay to detect specific immunoglobulin (Ig) isotypes and IgG subclass antibodies in the sera of Indian PKDL patients. Our assay, which uses L. donovani promastigote membrane antigens, was 100% sensitive for the detection of IgG and 96.7% specific for the detection of IgG and IgG1. Optical density values for individual patients, however, demonstrated wide variations. Western blot analysis based on IgG reactivity could differentiate patients with PKDL from control subjects, which included patients with leprosy, patients from areas where kala-azar is endemic, and healthy subjects, by the detection of polypeptides of 67, 72, and 120 kDa. The recognition patterns of the majority of serum samples from patients with PKDL were also distinct from those of the serum samples from patients with visceral leishmaniasis (VL), at least for a 31-kDa polypeptide. To further differentiate patients with PKDL from those with active and cured VL, we analyzed the specific titers of the Ig isotypes and IgG subclasses. High levels of IgG, IgG1, IgG2, and IgG3 antibodies significantly differentiated patients with PKDL from patients cured of VL. The absence of antileishmanial IgE and IgG4 in patients with PKDL differentiated these patients from those with active VL. These results imply intrinsic differences in the antibodies generated in the sera from patients with PKDL and VL.

Infection rates with Leishmania donovani and Mycobacterium tuberculosis in a village in eastern Sudan

BACKGROUND

Leishmania-tuberculosis co-infection is not uncommon in clinical practice in East Africa, but little is known about the epidemiology of this problem at population level. A cross-sectional household survey was carried out in an active visceral leishmaniasis (VL) focus in Eastern Sudan in February 2002.

METHODS

All inhabitants of Marbata village in Atbara River Area, Gedarif State, who gave informed consent, underwent both a leishmanin skin test (LST) and a tuberculin test for infection with L. donovani and Mycobacterium tuberculosis. All subjects were clinically screened for VL and tuberculosis (TB).

RESULTS

About 66% (252 of 382) were LST-positive, 26% (100 of 382) were tuberculin-positive and 20% (77 of 382) were positive for both tests. By the age of 15, more than 60% of inhabitants were LST-positive, but <20% were tuberculin-positive. By the age of 30, these percentages increased to 100 and 50%. No association was found at the individual level between leishmanial and tuberculous infection after controlling for age.

CONCLUSION

In this community study, we found no association between the risk of infection with L. donovani and M. tuberculosis. However, the progression to active VL disease might be different in M. tuberculosis-infected than in non-infected persons and vice versa. Prospective studies are needed to document the prognosis of TB/VL co-infection.

Role for CD4(+) CD25(+) regulatory T cells in reactivation of persistent leishmaniasis and control of concomitant immunity

Reactivation of dormant infections causes an immense burden of morbidity and mortality in the world at large. Reactivation can occur as a result of immunosuppression, environmental insult, or aging; however, the cause of reactivation of such infections is often not clear. We have previously shown that persistence of the parasite Leishmania major is controlled by endogenous CD4(+) CD25(+) regulatory T (T reg) cells. In this report, we show that despite efficient parasite clearance at secondary sites of infection, Leishmania superinfection can cause disease reactivation at the primary site. Our results strongly suggest that T reg cells, whose numbers increase in sites of reactivation, are directly responsible for such reactivation. Depletion of CD25(+) cells at the time of secondary challenge prevented disease reactivation at the site of persistent infection while strengthening the expression of immunity at the site of secondary challenge. Finally, transfer of T reg cells purified from infected mice into chronically infected mice was sufficient to trigger disease reactivation and prevent the expression of an effector memory response. Our results demonstrate that after persistence is achieved, an equilibrium between T reg cells and effector lymphocytes, which can be disturbed by superinfection, controls the efficiency of recall immune responses and disease reactivation.

Identification of parasite antigen, correlation of parasite density and inflammation in skin lesions of post kala-azar dermal leishmaniasis

BACKGROUND

Post kala-azar dermal leishmaniasis (PKDL) is an unusual dermatosis following kala-azar (KA). Demonstration of the amastigotes in lesions plays an important role in the diagnosis of PKDL. It was aimed to evaluate the utility of an antibody G2D10 in detecting leishmania parasite antigen, to correlate the parasite number/percentage of parasites with the inflammation, and to assess the epidemiological significance associated with the location of the parasites.

MATERIAL AND METHODS

The study was conducted on 50 cases. Hematoxylin and eosin (H & E) stains and immunohistochemical (IHC) stains, using G2D10 antibody, was performed on the skin biopsies. The number of parasites and density of inflammation were semiquantitatively assessed.

RESULTS

Leishmania donovan bodies (LDBs) were identified in 50% of cases with the H & E compared to 80% positivity with the IHC. All 50 cases showed inflammation in the superficial dermis (SD). About 44% showed dense inflammation compared to 16% sparse and 40% moderate inflammation. Parasite percentage was maximum in the SD (100%) compared to 75 and 42% in the mid and deep dermis, respectively.

CONCLUSIONS

The IHC showed a higher percentage of LDB localization (80 vs. 50%). Density of inflammation was maximum in the SD. The parasite percentage was correlated with the inflammation. Location of parasites could have an epidemiological significance.

Post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is a complication of visceral leishmaniasis (VL); it is characterised by a macular, maculopapular, and nodular rash in a patient who has recovered from VL and who is otherwise well. The rash usually starts around the mouth from where it spreads to other parts of the body depending on severity. It is mainly seen in Sudan and India where it follows treated VL in 50% and 5-10% of cases, respectively. Thus, it is largely restricted to areas where Leishmania donovani is the causative parasite. The interval at which PKDL follows VL is 0-6 months in Sudan and 2-3 years in India. PKDL probably has an important role in interepidemic periods of VL, acting as a reservoir for parasites. There is increasing evidence that the pathogenesis is largely immunologically mediated; high concentrations of interleukin 10 in the peripheral blood of VL patients predict the development of PKDL. During VL, interferon gamma is not produced by peripheral blood mononuclear cells (PBMC). After treatment of VL, PBMC start producing interferon gamma, which coincides with the appearance of PKDL lesions due to interferon-gamma-producing cells causing skin inflammation as a reaction to persisting parasites in the skin. Diagnosis is mainly clinical, but parasites can be seen by microscopy in smears with limited sensitivity. PCR and monoclonal antibodies may detect parasites in more than 80% of cases. Serological tests and the leishmanin skin test are of limited value. Treatment is always needed in Indian PKDL; in Sudan most cases will self cure but severe and chronic cases are treated. Sodium stibogluconate is given at 20 mg/kg for 2 months in Sudan and for 4 months in India. Liposomal amphotericine B seems effective; newer compounds such as miltefosine that can be administered orally or topically are of major potential interest. Although research has brought many new insights in pathogenesis and management of PKDL, several issues in particular in relation to control remain unsolved and deserve urgent attention.

CD4+CD25+ regulatory T cells control Leishmania major persistence and immunity

The long-term persistence of pathogens in a host that is also able to maintain strong resistance to reinfection, referred to as concomitant immunity, is a hallmark of certain infectious diseases, including tuberculosis and leishmaniasis. The ability of pathogens to establish latency in immune individuals often has severe consequences for disease reactivation. Here we show that the persistence of Leishmania major in the skin after healing in resistant C57BL/6 mice is controlled by an endogenous population of CD4+CD25+ regulatory T cells. These cells constitute 5-10% of peripheral CD4+ T cells in naive mice and humans, and suppress several potentially pathogenic responses in vivo, particularly T-cell responses directed against self-antigens. During infection by L. major, CD4+CD25+ T cells accumulate in the dermis, where they suppress-by both interleukin-10-dependent and interleukin-10-independent mechanisms-the ability of CD4+CD25- effector T cells to eliminate the parasite from the site. The sterilizing immunity achieved in mice with impaired IL-10 activity is followed by the loss of immunity to reinfection, indicating that the equilibrium established between effector and regulatory T cells in sites of chronic infection might reflect both parasite and host survival strategies.

The role of interleukin (IL)-10 in the persistence of Leishmania major in the skin after healing and the therapeutic potential of anti-IL-10 receptor antibody for sterile cure

Some pathogens (e.g., Mycobacterium tuberculosis, Toxoplasma gondii, Leishmania spp) have been shown to persist in their host after clinical cure, establishing the risk of disease reactivation. We analyzed the conditions necessary for the long term maintenance of Leishmania major in genetically resistant C57BL/6 mice after spontaneous healing of their dermal lesions. Interleukin (IL)-10 was found to play an essential role in parasite persistence as sterile cure was achieved in IL-10-deficient and IL-4/IL-10 double-deficient mice. The requirement for IL-10 in establishing latency associated with natural infection was confirmed in IL-10-deficient mice challenged by bite of infected sand flies. The host-parasite equilibrium was maintained by CD4+ and CD8+ T cells which were each able to release IL-10 or interferon (IFN)-gamma, and were found to accumulate in chronic sites of infection, including the skin and draining lymph node. A high frequency of the dermal CD4+ T cells released both IL-10 and IFN-gamma. Wild-type mice treated transiently during the chronic phase with anti-IL-10 receptor antibodies achieved sterile cure, suggesting a novel therapeutic approach to eliminate latency, infection reservoirs, and the risk of reactivation disease.

Treatment of visceral leishmaniasis (kala-azar): a decade of progress and future approaches

In 1990, there was essentially one treatment regimen in use for visceral leishmaniasis (kala-azar) around the world: 20 to 28 days of daily injections of pentavalent antimony (Sb). During the past 10 years, however, new agents have been tested alone or in combination, in more than 50 studies carried out worldwide. This renewed clinical effort was spurred by a variety of factors, including the emergence of large-scale Sb unresponsiveness in India, where up to one-half of the world's cases of kala-azar now are found. As this new decade opens, the success of this clinical research effort is tangible: three additional, highly effective parenteral regimens now are available (amphotericin B, lipid formulations of amphotericin B, aminosidine), and an active oral agent, a long sought after objective in kala-azar, has been identified (miltefosine). This report reviews the evolution of treatment of visceral leishmaniasis, considers the interaction of the immune response and chemotherapy, highlights therapeutic successes and failures, examines advantages and disadvantages of current treatments, and looks at future therapeutic approaches to the management of this disseminated intracellular protozoal infection.

4. Post kala-azar dermal leishmaniasis

Post kala-azar dermal leishmaniasis (PKDL) is increasingly recognized in Sudan as a complication of visceral leishmaniasis (VL), occurring in c. 55% of patients after, or during treatment of, VL. The development of PKDL seems to be restricted to parasites of the Leishmania donovani sensu stricto cluster; no particular zymodeme has been found to be associated with it. In contrast to PKDL in India, PKDL in Sudan occurs within 0-6 months after treatment for VL. The rash may be macular, maculo-papular or nodular, and spreads from the perioral area to other parts of the body, depending on grade of severity. Young children are particularly at risk of developing more severe disease. In 16% of PKDL patients, parasites can be demonstrated by microscopy in lymph node or bone marrow aspirates and, with the aid of the polymerase chain reaction (PCR), in lymph nodes of 81% of patients, possibly indicating persistent visceralized infection. Diagnosis can be made by demonstration of parasites in skin smears or biopsies in 20-30% of cases; newer techniques, using PCR with skin smears, have higher sensitivity (83%). Monoclonal antibodies against L. donovani can detect parasites in 88% of biopsies. Serological tests are of limited value. The leishmanin skin test is positive in 50-60% of cases; there is an inverse relationship between the skin test result and severity of PKDL. In differential diagnosis, miliaria rubra is the most common problem; differentiation from leprosy is the most difficult. In biopsies, hyperkeratosis, parakeratosis, acanthosis, follicular plugging and liquefaction degeneration of the basal layer may be found in the epidermis; in the dermis there are varying intensities of inflammation with scanty parasites and mainly lymphocytes; macrophages and epithelioid cells may also be found. In 20% of cases discrete granulomas may be found. After VL, the immune response shifts from a Th2-type to a mixed Th1/Th2-type. High levels of interleukin-10 in skin biopsies as well as in peripheral blood mononuclear cells and plasma in patients with VL predict the development of PKDL. Treatment is needed only for those who have severe and prolonged disease; sodium stibogluconate (20 mg/kg/d for 2 months) is usually sufficient. (Liposomal) amphotericin B is effective, whereas ketoconazole, terbinafine and itraconazole are not.

2. Mucosal leishmaniasis

Sudanese mucosal leishmaniasis is a chronic infection of the upper respiratory tract and/or oral mucosa caused mainly by Leishmania donovani. The disease occurs in areas of the country endemic for visceral leishmaniasis, particularly among Masalit and other closely related tribes in western Sudan. The condition may develop during or after an attack of visceral leishmaniasis, but in most cases it is a primary mucosal disease. Unlike South American mucocutaneous leishmaniasis, mucosal leishmaniasis in Sudan is not preceded or accompanied by a cutaneous lesion. Pathologically, the lesions show a mixture of macrophages, plasma cells and lymphocytes. An epithelioid granuloma may also be found. Parasites are scanty. Diagnosis is established by demonstration of parasites in smears or biopsies, by culture or animal inoculation, or with the aid of the polymerase chain reaction. Most patients give positive results in the direct agglutination test and leishmanin skin test. Patients respond well to treatment with pentavalent antimony compounds.

Post-kala-azar dermal leishmaniasis in Nepal

BACKGROUND

Post-kala-azar dermal leishmaniasis (PKDL) manifests as a skin eruption after healing of visceral leishmaniasis (VL), either spontaneously or as a result of treatment. This study was undertaken to describe the demographic, clinical, and histopathologic features of PKDL in Nepal.

METHODS

Demographic, clinical, microbiologic, and histopathologic features and response to treatment were studied in 22 patients with PKDL from April 1998 to March 2000.

RESULTS

PKDL accounted for 0.13% of all new dermatologic cases. There were 13 (59.1%) males and nine (40.9%) females. A past history of kala-azar was present in all but one patient. A family history of kala-azar was noted in eight (36.4%) patients. All patients presented with multiple types of lesion, except for two in whom only macular lesions were seen. Oral lesions in the form of nodules and plaques were seen in four patients. Generalized lymphadenopathy was present in five patients. Slit skin smears revealed Leishman-Donovan bodies (LDBs) in nine (40.9%) patients. In macular lesions, there was a sparse infiltrate of plasma cells, lymphocytes, or histiocytes in the upper dermis. There was a dense chronic inflammatory infiltrate comprising plasma cells, lymphocytes, histiocytes, and epithelioid cells in the entire dermis from papules, plaques, or nodules. Giemsa staining of biopsy specimens revealed LDBs in seven (38.9%) patients only. Fine needle aspiration from epitrochlear lymph nodes in two patients demonstrated LDBs. All patients responded well to treatment with minimal side-effects.

CONCLUSIONS

This study emphasizes the need to be aware of the possibility of cases of PKDL in endemic regions of leprosy, as the conditions may be difficult to distinguish clinically and histopathologically.

Leishmaniasis in the Sudan: a literature review with emphasis on clinical aspects

The literature on the leishmaniases in the Sudan is reviewed with an emphasis on clinical aspects and on literature related to the recent outbreaks in the south and east of the country. The numbers of cases of subclinical infection and post-kala azar dermal leishmaniasis in the recent outbreaks are remarkable. New diagnostic techniques have been introduced and evaluated, notably the direct agglutination test and polymerase chain reaction technology. The latter gives very promising results and further research into application of the technique is warranted. Treatment with pentavalent antimony is still satisfactory. The reservoir host has not been identified definitely.

Post-kala-azar dermal leishmaniasis in the Sudan: clinical presentation and differential diagnosis

Post-kala-azar dermal leishmaniasis (PKDL) is a common complication following kala-azar (visceral leishmaniasis). In a prospective study in a village in the endemic area for kala-azar in the Sudan, 105 of 183 (57%) kala-azar patients developed PKDL. There was a significantly higher PKDL rate (69%) in those who received inadequate and irregular treatment of kala-azar than in those who were treated with stibogluconate 20 mg kg-1 daily for 15 days (35%). The group of patients who developed PKDL did not differ from those who did not develop PKDL with regard to age and sex distribution, reduction in spleen size, and conversion in the leishmanin skin test (LST). In a clinical study, 416 PKDL patients were analysed and divided according to grade of severity. Severe PKDL was more frequent in younger age groups (P < 0.001); there was an inverse correlation between grade and conversion in the LST (P < 0.01). In 16% of patients tested, parasites were demonstrated in inguinal lymph node or bone marrow aspirates, indicating still visceral disease (para-kala-azar dermal leishmaniasis); there was no correlation between the presence of parasites and grade of severity. Conversion rates in the LST were lower than in those who did not have demonstrable parasites (11% and 37%, respectively; P < 0.01). In the absence of reliable and practical diagnostic tests, PKDL may be diagnosed on clinical grounds and differentiated from other conditions, of which miliaria rubra was the most common. Differentiation from leprosy was most difficult.

The development of post-kala-azar dermal leishmaniasis (PKDL) is associated with acquisition of Leishmania reactivity by peripheral blood mononuclear cells (PBMC)

PKDL develops in about 50% of Sudanese patients treated for visceral leishmaniasis (kala-azar). Patients with kala-azar were entered into this study and followed for a period of up to 2 years. During follow up 12 patients developed PKDL and eight did not. Proliferative responses and cytokine production to Leishmania donovani and control antigens were measured in vitro using PBMC isolated at the time of diagnosis of kala-azar, after treatment of visceral leishmaniasis, during follow up, and at the time of diagnosis of PKDL. Proliferative responses and interferon-gamma (IFN-gamma) production were low at diagnosis and increased after treatment of kala-azar in both patients who developed (group 1) and those who did not develop PKDL later (group 2). In group 1, development of PKDL was always associated by an increased PBMC response to Leishmania antigen in proliferation and IFN-gamma production assays. There were no differences in Leishmania antigen-induced production of IL-4, IL-5 and IL-10 between or within the two groups. We have previously shown that Leishmania parasites spread to the skin during visceral leishmaniasis and proposed that PKDL was the result of an immunological attack on parasites, which have survived in the skin despite the drug treatment. The finding that PKDL develops after treatment of kala-azar as Leishmania-reactive T cells start to circulate in peripheral blood in sufficient numbers to be detected in in vitro assays supports this hypothesis.

High levels of C-reactive protein in the peripheral blood during visceral leishmaniasis predict subsequent development of post kala-azar dermal leishmaniasis

Post kala-azar dermal leishmaniasis (PKDL) is a known sequel to visceral leishmaniasis in India and East Africa, and in Sudan about 50% of the kala-azar patients develop PKDL. In this study we followed kala-azar patients from diagnosis and up to 2 years after initiation of treatment. During the first 6 months some developed PKDL (group 1), while some did not develop PKDL (group 2). We measured the plasma levels of C-reactive protein (CRP) at diagnosis of kala-azar (day 0), during treatment (day 15), after treatment (day 30) and later during the follow up period. At day 0, plasma CRP levels were higher in patients who later developed PKDL (group 1) than in patients who did not develop PKDL subsequently (group 2) (P = 0.008). At days 15 and 30, the CRP levels were comparable in the two groups, and lower than at day 0. We have previously shown that high plasma levels of IL 10 and in keratinocytes during visceral leishmaniasis predict subsequent development of PKDL. The method however requires expensive equipment and reagents. The results of the present study indicate that kala-azar patients, who have a high risk of developing PKDL after treatment can be identified by measuring plasma CRP.

Immunopathology of post kala-azar dermal leishmaniasis (PKDL): T-cell phenotypes and cytokine profile

In Sudan, post kala-azar dermal leishmaniasis (PKDL) caused by Leishmania donovani develops in half of the patients treated for visceral leishmaniasis (kala-azar). In most patients lesions heal spontaneously, but in others symptoms are severe and persist for years. This study examined the immunological response in lesions of PKDL patients by immunohistochemistry and compared the findings with results obtained using peripheral blood mononuclear cells (PBMCs). In all lesions, parasites or parasite antigen were present and provoked the formation of an inflammatory infiltrate consisting of a mixture of macrophages, lymphocytes, and plasma cells. In patients who had high interferon-gamma (IFNgamma) responses to Leishmania antigen in vitro, compact epithelioid granulomas were formed. The inflammatory cells were mainly CD3(+) and interleukin-10 (IL10) was the most prominent cytokine in the lesions. However, IFNgamma was found in all and IL4 in most lesions, in varying amounts. PBMCs from all patients responded to Leishmania antigen by IFNgamma production or proliferation. The results indicate that PKDL develops as a result of an influx of immunocompetent cells into skin, which harbours parasites. The inflammatory response to the parasites is complex. It involves several cell types and cytokines, of which some are antagonistic. It is conceivable that the balance between these cytokines determines the outcome of the disease.

A clinical and histopathological study of macular type of post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is an uncommon sequel seen in patients with a previous attack of kala-azar (KA). It is characterized by hypopigmented macules and erythematous eruptions leading to the formation of papules, plaques and nodules. Little attention has been paid to the rare group of patients who present with only hypopigmented macules. The present study has described the distribution of lesions in macular PKDL and their histopathology.

T-cell response in human leishmaniasis

In the present communication we provide evidence for the existence of a Th1/Th2 dichotomy in the T-cell response to Leishmania antigens in human leishmaniasis. Our data suggest that the pattern of IL-4 and IFN-gamma response is polarised in these patients. Lymphocytes from individuals recovered from cutaneous leishmaniasis (CL) responded by IFN-gamma production following stimulation with Leishmania antigens whereas cells from patients recovered from visceral leishmaniasis (VL) showed a mixed pattern of IFN-gamma and IL-4 responses. The cells producing these cytokines were predominantly CD4+. Furthermore, IL-10 plays an important role in the development of post kala azar dermal leishmaniasis (PKDL) from VL. The balance between the parasitic-specific T-cell response plays an important regulatory role in determining the outcome of Leishmania infections in humans.