Laboratory Tests for the Diagnosis and Evaluation of Leishmaniasis

Mapping linear B-cell epitopes of the Tryparedoxin Peroxidase and its implications in the serological diagnosis of tegumentary leishmaniasis

Diagnosis of tegumentary leishmaniasis (TL) is essential to avoid permanent damage and severe functional sequelae and there is an urgent need to discover new antigens. The present study aimed to comprehensively evaluate the potential use of the Tryparedoxin Peroxidase (TryP) as an antigen for serological tests. The proposal integrates data from immunoproteomics with immunoinformatics, in addition to a precise analysis of protein levels in the evolutionary stages of the parasite by flow cytometry. To evaluate the performance in the diagnosis of TL, Enzyme-Linked Immunosorbent Assay (ELISA) assays were performed using the recombinant protein and the respective B-cell epitope, followed by an analysis of the contribution of this peptide in the recognition of the protein by patients, evaluated by serum depletion assays. We showed that the TryP has a linear B-cell epitope with high divergence compared to orthologs from Trypanosoma cruzi and Homo sapiens. The results also show high expression and positive cells for TryP (TryP⁺) in the infective metacyclic promastigotes (MET) and intracellular (24 and 48 hours) stages. From the depletion assays, it was possible to confirm the contribution of the peptide in the specific recognition of the TryP protein by patients with TL (13.7-15.9%). ELISA using the peptide showed high performance in the diagnosis compared to the recombinant TryP (rTryP), Soluble Leishmania braziliensis Antigen (sLba) and Immunofluorescence Assay (IFA) with accuracy of 94.29, 89.29, 65.00 and 37.14%, respectively). We can conclude that the MNEPAPP peptide is a potential antigen for the diagnosis of TL.

Development of an immunogen containing CD4+/CD8+ T-cell epitopes for the prophylaxis of tegumentary leishmaniasis

Abstract

Tegumentary leishmaniasis (TL) is a disease of high severity and incidence in Brazil, and Leishmania braziliensis is its main etiological agent. The inefficiency of control measures, such as high toxicity and costs of current treatments and the lack of effective immunoprophylactic strategies, makes the development of vaccines indispensable and imminent. In this light, the present work developed a gene encoding multiple T-cell (CD4⁺/CD8⁺) epitope, derived from conserved proteins found in Leishmania species and associated with TL, to generate a chimeric protein (rMEP/TL) and compose a vaccine formulation. For this, six T-cell epitopes were selected by immunoinformatics approaches from proteins present in the amastigote stage and associated with host-parasite interactions. The following formulations were then tested in an L. braziliensis murine infection model: rMEP/TL in saline or associated with MPLA-PHAD^®. Our data revealed that, after immunization (three doses; 14-day intervals) and subsequent challenging, rMEP/TL and rMEP/TL + MPLA-vaccinated mice showed an increased production of key immunological biomarkers of protection, such as IgG_2a, IgG_2a/IgG₁, NO, CD4⁺, and CD8⁺ T-cells with IFN-γ and TNF-α production, associated with a reduction in CD4⁺IL-10⁺ and CD8⁺IL-10⁺ T-cells. Vaccines also induced the development of central (CD44^highCD62L^high) and effector (CD44^highCD62L^low) memory of CD4⁺ and CD8⁺ T-cells. These findings, associated with the observation of lower rates of parasite burdens in the vaccinated groups, when compared to the control groups, suggest that immunization with rMEP/TL and, preferably, associated with an adjuvant, may be considered an effective tool to prevent TL.

Key points

• Rational design approaches for vaccine development.

• Central and effector memory of CD4+ and CD8+ T-cells.

• Vaccine comprised of rMEP/TL plus MPLA as an effective tool to prevent TL.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-022-12033-7.

Development of a chimeric protein based on a proteomic approach for the serological diagnosis of human tegumentary leishmaniasis

Leishmania braziliensis is responsible for most cases of human tegumentary leishmaniasis (HTL) and has caused a wide range of clinical manifestations, including cutaneous (CL) and mucosal leishmaniasis (ML). The diagnosis is based on criteria that consider epidemiological data, clinical findings, and laboratory tests and is hard to establish. For laboratory tests, none of the assays available can be considered gold standards for disease detection. In addition, the Montenegro skin test, essential to supporting infectologists in the clinical management of the disease, is no longer available in Brazil. Thus, the aim of this study was to develop new targets to be used in diagnostic tests for HTL. In the first step, we carried out two-dimensional gel electrophoresis, followed by mass spectrometry, combined with heat map analysis and immunoproteomics approach, and disclosed eight proteins expressed in the amastigote stage specifically recognized by serum from CL and ML patients. A chimeric protein was designed based on the combination of thirteen linear B-cell epitopes, identified by immunoinformatics analysis, from L. braziliensis proteins. Our results showed that the strategy used in this work was successful in developing an antigen to be used in immunological assays (100.0% sensitivity and specificity) in the detection of HTL cases and in comparison with results obtained from an ELISA using soluble L. braziliensis antigen (SLb-Antigen) and immunofluorescence assay (Bio-Manguinhos/FIOCRUZ). The present technology opens the door for its use in field exams by means of an immunochromatographic test, which will be even more helpful in regions without laboratory structures.Key points• Rational strategy to develop antigens.• Integration between immunoproteomic and immunoinformatics analysis.• Chimeric protein shows high performance in HTL diagnosis.

Anti-Leishmania IgG is a marker of disseminated leishmaniasis caused by Leishmania braziliensis

BACKGROUND

In this study, we determined the accuracy of anti-Leishmania IgG and IgG subclasses to distinguish clinical forms of American tegumentary leishmaniasis (ATL) and and determined the relationship between antibodies levels with cytokine production and severity of ATL.

METHODS

Participants were 40 patients with cutaneous leishmaniasis (CL), 20 patients with mucosal leishmaniasis (ML), 20 patients with disseminated leishmaniasis (DL), and 20 individuals with subclinical Leishmania braziliensis infection (SC). Diagnosis was performed by DNA of L. braziliensis or IFN-γ production in SC. IgG and subclasses of IgG to soluble Leishmania antigen and cytokine levels in supernatants of mononuclear cells were detected by ELISA.

RESULTS

IgG was detected in 95%, 95%, and 100% of patients with CL, ML, and DL, respectively. Higher levels of anti-Leishmania IgG and IgG2 were seen in DL compared to CL, ML, and SC. ROC analysis confirmed the ability of IgG to distinguish DL from the other clinical forms. A direct correlation was observed between IgG titers and levels of IFN-γ and CXCL10 in CL and DL, and IgG2 antibodies were correlated with the number of lesions in DL.

CONCLUSIONS

High anti-Leishmania IgG and IgG2 levels are characteristic of DL, and while IgG was correlated with pro-inflammatory cytokines, IgG2 was direct correlated with the number of lesions.

Cutaneous and mucocutaneous leishmaniasis: Differential diagnosis, diagnosis, histopathology, and management

The diagnosis of leishmaniasis can be challenging because it mimics both infectious and malignant conditions. A misdiagnosis may lead to an unfavorable outcome. Using culture, histologic, and/or polymerase chain reaction study results, a diagnosis of leishmaniasis can be established and treatment initiated. Appropriate management requires an accurate diagnosis, which often includes identification of the specific etiologic species. Different endemic areas have varying sensitivities to the same medication, even within individual species. Species identification may be of practical value, because infections with select species have a substantial risk of visceral involvement. In addition, HIV and otherwise immunocompromised patients with leishmaniasis have a propensity for diffuse cutaneous leishmaniasis. For most New World Leishmania species, parenteral antimonial drugs remain the first line of therapy, while Old World species are easily treated with physical modalities. Historically, live organism vaccination has been used and is effective in preventing leishmaniasis, but results in an inoculation scar and an incubation period that may last for years. A more effective method of vaccination would be welcome.

Diffuse cutaneous leishmaniasis in coexistence with leprosy

Cutaneous leishmaniasis and leprosy are diseases both caused by intracellular pathogens that represent a major health predicament even today. Both these diseases have some characteristics in common, such as the involvement of mucocutaneous tissue, a course with a chronic granulomatous response, a broad clinical spectrum in relation to the host's immunity, and they often affect the poor population in tropical countries. Co-infection of the two diseases, although known to occur, is rarely encountered and reported. Even though new cases of leprosy are diagnosed in the region of coastal Karnataka of India, cutaneous leishmaniasis is rarely reported. We hereby describe a patient who presented with concurrent leprosy and diffuse cutaneous leishmaniasis.

Towards a more precise serological diagnosis of human tegumentary leishmaniasis using Leishmania recombinant proteins

Background

Exposure to Leishmania induces a humoral immune response that can be used as a marker of parasite exposure.

Methodology/Principal Findings

Herein, ELISA was used to screen sera from patients with Tegumentary Leishmaniasis (TL) against different L. infantum-chagasi-derived recombinant proteins (rHSP70, rH2A, rH2B, rH3, rH4 and rKMP11). Among the recombinant proteins, rHSP70 and rH2A showed the best reactivity against human sera obtained from endemic areas of TL. Receiver-Operator Characteristics (ROC) curve analysis was used to identify the effectiveness of these proteins for serodiagnosis of TL. ROC curves confirmed the superior performance of rHSP70 and rH2A, in comparison to the other tested recombinant proteins. Additionally, we evaluated the specificity of the response to rHSP70 and rH2A by testing sera obtained from patients with Chagas' disease, Tuberculosis, Leprosy or Systemic Lupus Erythematosus. In this case, rHSP70 displayed an increased ability to discriminate diseases, in comparison to SLA.

Conclusion

Our results raise possibility of using rHSP70 for the serodiagnosis of TL

Cutaneous leishmaniasis: cryosurgery using carbon dioxide slush in a resource-poor country

Leishmaniasis is a widespread parasitic disease seen most often in children and young adults, although it may occur at any age. In Yemen, up until now, specific treatment for cutaneous leishmaniasis (CL) has been challenging. Available chemotherapy is expensive and replete with significant side effects. Standard cryosurgery with liquid nitrogen is prohibitively expensive and often unavailable. The objective of this paper is to highlight the importance of cryosurgery with carbon dioxide slush in the treatment of CL in an economically underdeveloped region as a cost-effective, simple, successful, and affordable option.

Panniculitis is an important feature of cutaneous leishmaniasis pathology

Background. Cutaneous leishmaniasis is an inflammatory parasitic infection characterized by superficial and deep perivascular infiltration with or without granuloma formation. Clinical diagnosis usually requires seeing Leishmania bodies. Methods. We report two cases of cutaneous leishmaniasis with unusual histological finding of panniculitis. Case 1: a 36-year-old male presented with multiple ulcerative nodules involving the left leg for two months duration which was greatly responsive to antimony intralesional therapy. Case 2: A 45-year-old woman presented with painless nodules on her upper chest of a 10-week duration which were successfully treated with oral and topical zinc sulphate. Results. Diagnosis of both cases was confirmed by finding the Leishmania bodies with Gimesa stain in addition to the diffuse dermal inflammatory cellular infiltration of the dermis forming granulomatous dermatitis. Mixed cellular infiltration of lymphocytes, histiocytes, and plasma cells of the panniculus caused both septal and lobular panniculitis. Conclusion. Cutaneous leishmaniasis can cause panniculitis and this could be seen more commonly if deep biopsies were taken. So cutaneous leishmaniasis must be considered in evaluating pathology of panniculitis especially in endemic regions.

Cutaneous and mucocutaneous leishmaniasis

Leishmaniasis is a cluster of diseases caused by protozoa in the genus Leishmania. There are three basic clinical forms: cutaneous, mucocutaneous, and visceral leishmaniasis. The present review focuses on the diagnosis and treatment of cutaneous and mucocutaneous leishmaniasis. Characteristics of both the human host and the parasite species influence the clinical disease manifestations that range from asymptomatic exposure, to self-healing skin ulcers, to life-threatening widespread destructive ulcerations. Whether through medical treatment or through spontaneous resolution, skin ulcerations generally result in disfiguring scars with significant social and economic impact. Tests to confirm the diagnosis should be performed on patients who have recently visited endemic areas and have skin or mucosal manifestations consistent with leishmaniasis. Treatment depends on the species of Leishmania and the risk of widespread or disfiguring disease. Because of increasing trends in global travel, educating health care providers to recognize and treat leishmaniasis in both endemic and non-endemic countries is imperative.

Molecular diagnosis of Old World cutaneous leishmaniasis and species identification by use of a reverse line blot hybridization assay

Reverse line blot hybridization assays (RLB) have been used for the rapid diagnosis and genotyping of many pathogens. The leishmaniases are caused by a large number of species, and rapid, accurate parasite characterization is important in deciding on appropriate therapy. Fourteen oligonucleotide probes, 2 genus specific and 12 species specific (2 specific for Leishmania major, 3 for L. tropica, 1 for L. infantum, 3 for L. donovani, and 3 for L. aethiopica), were prepared by using DNA sequences in the internal transcribed spacer 1 (ITS1) region of the rRNA genes. Probe specificity was evaluated by amplifying DNA from 21 reference strains using biotinylated ITS1 PCR primers and the RLB. The genus-specific probes, PP and PP3', recognized all Leishmania species examined, while the species-specific probes were able to distinguish between all the Old World Leishmania species. Titrations using purified parasite DNA showed that the RLB is 10- to 100-fold more sensitive than ITS1 PCR and can detect <0.1 pg DNA. The RLB was compared to kinetoplast DNA (kDNA) and ITS1 PCR by using 67 samples from suspected cutaneous leishmaniasis (CL) patients in Israel and the West Bank. The RLB accurately identified 58/59 confirmed positive samples as CL, a result similar to that found by kDNA PCR (59/59) and better than that by ITS1 PCR (50/59). The positive predictive value and negative predictive value of the RLB were 95.1% and 83.3%, respectively. L. major or L. tropica was identified by the RLB in 55 of the confirmed positive cases, a level of accuracy better than that of ITS1 PCR with restriction fragment length polymorphism (42/59). Thus, RLB can be used to diagnose and characterize Old World CL.

Imported tropical infectious ulcers in travelers

Skin ulcers are a commonly encountered problem at departments of tropical dermatology in the Western world. Furthermore, the general dermatologist is likely to be consulted more often for imported chronic skin ulcers because of the ever-increasing travel to and from tropical countries. The most common cause of chronic ulceration throughout the world is probably pyoderma. However, in some parts of the world, cutaneous leishmaniasis is one of the most prevalent causes. Mycobacterium ulcerans is an important cause of chronic ulcers in West Africa. Bacterial infections include pyoderma, mycobacterial infections, diphtheria, and anthrax. Pyoderma is caused by Staphylococcus aureus and/or beta-hemolytic streptococci group A. This condition is a common cause of ulcerative skin lesions in tropical countries and is often encountered as a secondary infection in travelers. The diagnosis is often made on clinical grounds. Antibacterial treatment for pyoderma should preferably be based on culture outcome. Floxacillin is generally active against S. aureus and beta-hemolytic streptococci. Infection with Mycobacterium ulcerans, M. marinum, and M. tuberculosis may cause ulcers. Buruli ulcers, which are caused by M. ulcerans, are endemic in foci in West Africa and have been reported as an imported disease in the Western world. Treatment is generally surgical, although a combination of rifampin (rifampicin) and streptomycin may be effective in the early stage. M. marinum causes occasional ulcerating lesions in humans. Treatment regimens consist of combinations containing clarithromycin, rifampin, or ethambutol. Cutaneous tuberculosis is rare in travelers but may be encountered in immigrants from developing countries. Treatment is with multiple drug regimens consisting of isoniazid, ethambutol, pyrazinamide, and rifampin. Cutaneous diphtheria is still endemic in many tropical countries. Cutaneous diphtheria ulcers are nonspecific and erythromycin and penicillin are both effective antibacterials. Antitoxin should be administered intramuscularly in suspected cases. Anthrax is caused by spore-forming Bacillus anthracis. This infection is still endemic in many tropical countries. Eschar formation, which sloughs and leaves behind a shallow ulcer at the site of inoculation, characterizes cutaneous anthrax. Penicillin and doxycycline are effective antibacterials. Cutaneous leishmaniasis is caused by different species belonging to the genus Leishmania. The disorder is one of the ten most frequent causes of skin diseases in travelers returning from (sub)tropical countries. The clinical picture is diverse, ranging from a painless papule or nodule to an ulcer with or without a scab. Treatment depends on the clinical manifestations and the species involved.Sporotrichosis, chromo(blasto)mycosis, and mycetoma are the most common mycoses that may be accompanied by ulceration. Infections are restricted to certain regions and often result from direct penetration of the fungus into the skin. Anti-mycotic treatment depends on the microorganism involved. The most common causes of infectious skin ulceration encountered in patients from tropical countries who present at a department of tropical dermatology are reviewed in this article.

Laser-capture microdissection: applications in routine molecular dermatopathology

Advances in molecular pathology with the introduction of the Southern blot technique and the polymerase chain reaction (PCR) have emerged as important tools, which are frequently used in routine dermato-histopathology. Applications for PCR-based diagnostics are particularly helpful for the determination of clonality in cutaneous lymphocytic infiltrates and for detection of infectious agents, such as herpes simplex virus (HSV), varicella zoster virus (VZV), Borrelia burgdorferi, Mycobacteria, Leishmania, and Treponema pallidum. As biopsies are always composed of different cells, the cells of interest are often only a minor population. As a consequence, their specific DNA is diluted by the majority of contaminating cells. Another problem is the time- and labor-intensive DNA extraction, because usually only formalin-fixed, paraffin-embedded tissue is available, which makes molecular diagnostics a time and labor consuming, and consequently a cost-intensive procedure. To overcome these shortcomings and to eventually shorten the time to generate a result, we introduce a laser-capture microdissection (LCM)-based method for the detection of infectious agents and clonality. Only the cells of interest for the particular indication are microdissected (e.g. epidermal cells for HSV and VZV and lymphocytes for clonality analysis) and subjected to PCR amplification. Due to an accelerated DNA-extraction procedure which generates DNA in 5 h (compared to 3-4 days using conventional DNA extraction), we are able to generate a result within one working day.

Leishmaniasis cutánea

Leishmaniases are diseases caused by infection by protozoa of the genus Leishmania. Cutaneous leishmaniasis caused by Leishmania infantum is frequent in Spain, especially in certain geographic areas. Diagnosis of cutaneous leishmaniasis is difficult because of the varied symptoms and because making cultures of this parasite is complicated. There are also different therapeutic, medical and surgical options, none of which is fully satisfactory. We review the most significant agents of cutaneous leishmaniasis in Spain.

Leishmania infantum heat shock protein 83 for the serodiagnosis of tegumentary leishmaniasis

The serologic assay is an important tool in the diagnosis of leishmaniasis. One of the most commonly used tests is enzyme-linked immunosorbent assay (ELISA). Since total Leishmania promastigotes are used as antigen in the routine assay, false-positive reactions are frequent due to cross-reaction with sera from other diseases, mainly Chagas' disease. Therefore, an antigen that determines less cross-reactivity has been pursued for the serodiagnosis of leishmaniasis. In the present study we analyzed the use of recombinant Leishmania infantum heat shock protein (Hsp) 83 in ELISA for the serodiagnosis of cutaneous (N = 12) and mucocutaneous leishmaniasis (N = 14) and we observed the presence of anti-L. infantum Hsp 83 antibodies in all samples as well as anti-Leishmania total antigen antibodies. When cross-reactivity was tested, chronic Chagas' disease patients (N = 10) did not show any reactivity. Therefore, we consider this L. infantum Hsp 83 to be a good antigen for routine use for serodiagnosis of tegumentary leishmaniasis.

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.

Validation of the polymerase chain reaction for the diagnosis of human cutaneous leishmaniasis in north-west Colombia

Leishmania species of the subgenus Viannia account for 88% of all cases of leishmaniasis recorded in Colombia. Correct diagnosis is essential as infection with members of this subgenus can produce disfiguring destruction of the mucosa. Several methods are available to diagnose leishmaniasis in clinical samples. More recently, the polymerase chain reaction (PCR) has been used, with varying sensitivities and specificities depending on the primers used. In this paper we report on the sensitivity and specificity of PCR primers B1/B2 used on clinical samples and compare their use to the conventional parasitological methods. PCR alone is more sensitive than any single conventional method used, but a combination of conventional methods produced comparable sensitivity. PCR is well suited for use in selected cases and as a test for mucosal leishmaniasis.

Rhesus monkey model for Leishmania major transmitted by Phlebotomus papatasi sandfly bites

Leishmaniasis research needs a near-human model for investigations of natural infection processes, immunological responses and evaluation of treatments. Therefore, we developed a reproducible system using Leishmania major Yakimoff & Schokhor (Trypanosomatidae: Kinetoplastida), the cause of Old World zoonotic cutaneous leishmaniasis (ZCL), transmitted to rhesus monkeys Macaca mulatta (Zimmerman) (Primates: Cercopithecidae) by sandfly bites of experimentally infected Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae). Eight monkeys of presumed Indian origin (Leishmania naive) were exposed to bites of female sandflies that had been infected with L. major by membrane-feeding on human blood seeded with amastigotes isolated from hamster footpad lesions. Infection rates of membrane-fed sandflies averaged > 85% seven days after the infective feed, with uniformly high numbers of promastigotes in the stomodaeal valve region of the sandfly gut. Nodules and ulcerating dermal lesions developed on 7/8 monkeys 2-4 weeks post-bite and persisted for 3-7 months. Monkeys also developed satellite lesions beyond the area of sandfly bites on the head, but not on the chest. Three re-challenged monkeys developed lesions that healed faster than lesions from their primary challenges. After infection, monkeys developed delayed type hypersensitivity (DTH) responses to a panel of Leishmania skin test antigens (LSTA) and, when tested by ELISA and IFA, showed significant post-infection antibody titres which typically rose for approximately 170 days and then gradually receded during the next 100 days following the first challenge. After the second challenge, antibody titres spiked higher within approximately 50 days and receded more rapidly. In contrast, four rhesus macaques of Chinese origin developed no lesions following infected sandfly bites, although they raised antibodies and LSTA reactions, indicating subclinical infection.

Diagnosis of cutaneous leishmaniasis in Colombia: the sampling site within lesions influences the sensitivity of parasitologic diagnosis

Parasitologic confirmation of cutaneous leishmaniasis is obligatory before chemotherapy can be considered. Direct microscopic examination of scrapings taken from indurated borders of ulcers has been routinely used as primary method of diagnosis. In this report we compared the sensitivity of examination of dermal scrapings taken from the bottoms of ulcers (BDS) with that of dermal scrapings taken from indurated active margins of lesions (MDS) in a total of 115 patients. The sensitivities of the microscopic examination were 90.4 and 78.3% for BDS and MDS samples, respectively. When the PCR method was used with a group of 40 patients, we also observed a higher sensitivity when BDS samples were examined (80.8% in BDS samples versus 57.7% in MDS samples). The improvement of the diagnostic sensitivity in the BDS samples appears to be related to the higher parasite load and more easily detectable morphology of amastigotes in the centers of the ulcers. Other parasitologic diagnostic methods, such as culture and histopathologic examination of biopsies, are less sensitive (67.5 and 64.3%, respectively). Aspirate culture, however, was shown to be the most sensitive method for the diagnosis of patients with chronic ulcers. When microscopic examinations of both MDS and BDS samples are combined, the sensitivity of diagnosis may rise up to 94%. We therefore recommend this method as a primary routine procedure for diagnosis of cutaneous leishmaniasis.

Reactivation of cutaneous leishmaniasis after surgery

Cutaneous leishmaniasis (CL) is caused by a parasite from the genus Leishmania. Infection is transmitted to humans from the bite of sandflies. We describe an 85-year-old man who developed CL on his face after recent cutaneous surgery in that site. The case is also unusual because the most likely source of exposure to the infection occurred over 50 years previously. Polymerase chain reaction, slit-skin smear, serology and the leishmanin test were not helpful in diagnosis, which was confirmed by histopathological demonstration of the parasite.

Leishmaniasis

In 1903, Leishman and Donovan separately described the protozoan now called Leishmania donovani in splenic tissue from patients in India with the life-threatening disease now called visceral leishmaniasis. Almost a century later, many features of leishmaniasis and its major syndromes (ie, visceral, cutaneous, and mucosal) have remained the same; but also much has changed. As before, epidemics of this sandfly-borne disease occur periodically in India and elsewhere; but leishmaniasis has also emerged in new regions and settings, for example, as an AIDS-associated opportunistic infection. Diagnosis still typically relies on classic microbiological methods, but molecular-based approaches are being tested. Pentavalent antimony compounds have been the mainstay of antileishmanial therapy for half a century, but lipid formulations of amphotericin B (though expensive and administered parenterally) represent a major advance for treating visceral leishmaniasis. A pressing need is for the technological advances in the understanding of the immune response to leishmania and the pathogenesis of leishmaniasis to be translated into field-applicable and affordable methods for diagnosis, treatment, and prevention of this disease.

Immunohistochemistry to identify Leishmania parasites in fixed tissues

The definitive diagnosis of leishmaniasis currently depends on the identification of characteristic amastigote morphology in tissue, or isolation of promastigotes by culture. Histopathological identification can be difficult, and is variably sensitive; culture is considered "the gold standard", but is not uniformly diagnostic or available. In this study, we compared light microscopic immunohistochemistry (IHC) using a monoclonal anti-Leishmania antibody (G2D10) to standard hematoxylin and eosin (H&E) stain in the diagnosis of Leishmania on skin. Sixty-one archived specimens from patients suspected of being infected with Leishmania were used; 41 of these had leishmaniasis confirmed by culture. Although not statistically significant, both sensitivity and specificity were higher for IHC compared to H&E: 51% (95% CI: 35-67%) compared to 42% (CI: 26-58%; 2p=0.29) for sensitivity, and 100% (CI: 83-100%) compared to 85% (CI: 62-97%, 2p=0.25) for specificity, respectively. Furthermore, because organisms could be diagnosed by IHC at low power (x20-40), this assay was more rapid than H&E, in which parasite morphology could best be identified at oil immersion power. The G2D10 antibody has broad Leishmania species recognition, and offers promise as a simple, rapid diagnostic screen for leishmaniasis. Further study is underway to better characterize this antibody.

The United States military and leishmaniasis

Leishmaniasis occurs not only in American travelers and military personnel alike but infects a significant portion of the world's population. The US military has made major contributions to the understanding of the complicated epidemiology of this parasite, the development of rapid reliable diagnostic tests, and to the development of safe, more efficient, and more effective treatment of leishmaniasis.

New World cutaneous leishmaniasis imported into Australia

A case of cutaneous leishmaniasis in a traveller from Belize, Central America is reported. Leishmaniasis presents rarely in Australia and delays in diagnosis and treatment often occur. A high index of suspicion in a patient who has returned from an endemic region is required. Subsequent confirmation of a diagnosis of cutaneous leishmaniasis is best achieved by demonstration of the organism on skin biopsy, aspiration or smear. The histology is variable and depends on geographic, parasite species and host factors. Speciation of New World disease as either Leishmania braziliensis or Leishmania mexicana is important to determine the risk of later development of mucosal disease, which normally only occurs with L. braziliensis infection, and for optimal treatment. Several different modes of treatment have been suggested, but antimonials, such as sodium stibogluconate, remain the treatment of choice in New World cutaneous leishmaniasis.

Imported mucocutaneous leishmaniasis

We report a case of mucocutaneous leishmaniasis in a otherwise fit Caucasian man who had traveled in an endemic area. Initial tissue microscopy failed to identify the causative organism, which was only determined by subsequent culture as Leishmania braziliensis. This case illustrates the variability in the presence of Leishman-Donovan (LD) bodies in histopathological studies and emphasizes the need for culture in suspected cases of leishmaniasis, particularly given the ability of certain Leishmania species such as L. braziliensis to cause recalcitrant and destructive infections of the nose and mouth.

Treatment of cutaneous leishmaniasis

The World Health Organization estimates that approximately 400,000 new cases of leishmaniasis occur worldwide each year. Cutaneous leishmaniasis is being encountered more frequently in the United States because of increasing travel and immigration from endemic areas. The indications for treatment and recommended treatment regimens reported in the infectious disease and dermatology literature vary widely. We examine both classic and newly developed therapeutic agents and modalities for cutaneous leishmaniasis. Proper therapy depends on species identification. New World leishmaniasis, in general, requires more aggressive therapy; parenteral antimonials are the drugs of choice. Physical modalities may suffice in most cases of Old World leishmaniasis because of its strong tendency toward spontaneous resolution.