Revisiting the role of the slit-skin smear in the diagnosis of Indian post-kala-azar dermal leishmaniasis

Background: Post kala azar dermal leishmaniasis (PKDL) is a neglected dermatosis that develops as a sequel to kala azar after apparent complete treatment. Being a non life threatening condition, patients often delay treatment thereby maintaining a reservoir of infection. The diagnosis of PKDL rests on the demonstration of the parasite in tissue smears, immune diagnosis by detection of parasite antigen or antibody in blood, or detection and quantitation of parasite DNA in tissue specimens. Sophisticated molecular tests are not only expensive but also need skilled hands and expensive equipment. To be useful, diagnostic methods must be accurate, simple and affordable for the population for which they are intended. Aims: This study was designed to assess functionality and operational feasibility of slit-skin smear examination. Methods: Sensitivity and specificity was evaluated by performing slit-skin smear and histo-pathological examination in 46 PKDL patients and the results were compared with the parasite load in both the slit aspirate and tissue biopsy specimens by performing quantitative Real-time PCR (Q-PCR). Results: The slit-skin smear examination was more sensitive than tissue biopsy microscopy. The parasite loads significantly differed among various types of clinical lesions (P < 0.05). The threshold of parasite load for detection by SSS microscopy was 4 parasites/μl in slit aspirate and 60 parasites/μg tissue DNA in tissue biopsy while that for tissue microscopy was 63 parasites/μl and 502 parasites/μg tissue DNA respectively. As detection of Leishmania donovani bodies may be challenging in inexperienced hands, the microscopic structure of these has been detailed along with a comprehensive discussion of pre analytical, analytical and post analytical variables affecting its identification. To facilitate the diagnosis of PKDL, some scenarios have been suggested taking into consideration the clinical, epidemiological, immunological and microscopic aspects. Conclusion: Such evidence based medicine helps minimize intuition, systematize clinical experience and provides a diagnostic rationale as sufficient grounds for a clinical decision.

Unresponsive cutaneous leishmaniasis and HIV co-infection: Report of three cases.

Cutaneous leishmaniasis (CL) is a vector borne disease caused by various species of Leishmania parasite. CL is endemic in the Thar desert of Rajasthan state and Himachal Pradesh in India. Immune suppression caused by human immunodeficiency virus (HIV) infection is associated with atypical clinical presentation of CL which responds poorly to the standard treatment and causes frequent relapses. We are reporting three cases of localized and disseminated CL due to Leishmania tropica which failed to respond to conventional intralesional/intramuscular sodium stibogluconate (SSG) injections. Initially, we did not think of HIV infection because CL is endemic in this region. When patients did not respond to SSG injections, we performed enzyme-linked immunosorbent assay (ELISA) tests for HIV and they turned out to be HIV positive. Our report showed that CL is emerging as an opportunistic infection associated with HIV/AIDS and may be the first manifestation in HIV positive patients in an endemic area.

A retrospective study of intravenous sodium stibogluconate alone and in combinations with allopurinol, rifampicin, and an immunomodulator in the treatment of Indian post-kala-azar dermal leishmaniasis.

Background and Aims: A retrospective analysis of treatment outcome using recommended dose of sodium stibogluconate (SSG) alone and in combination with other antileishmanial drugs in adults with post-kala-azar dermal leishmaniasis (PKDL) attending as outpatients. Methods: A total of 61 patients seen over ten years were included in the report. All had polymorphic lesions. Diagnosis was based on clinical picture, hailing from kala-azar (KA) endemic area, exclusion of other dermatoses, histopathology, and therapeutic response. Patients were distributed into two groups: Group I (n = 32), where SSG was given intravenously; in Group II (n = 29), they were allocated to one of four categories using SSG in combination with other drugs. In the first category, SSG was given along with allopurinol (n = 10); in second with rifampicin (n = 6); and in third with both allopurinol and rifampicin (n = 5). In the fourth category, SSG was administered with an immunomodulator (n = 8), Mw vaccine, known to enhance host Th1 response. Results: Only 12 out of 61 patients completed treatment till histopathologic evidence of cure, five in Group I and seven in Group II, no patient being from third category. None had taken SSG without interruptions. Time taken for papulonodules to subside was similar in both groups, but erythema and induration subsided earlier in Group II. Group I patients attained cure after 120 injections while in Group II it took 95 injections in SSG + allopurinol and Mw vaccine categories respectively, and 110 with SSG + rifampicin. Nevertheless this was insufficient to facilitate compliance. Poor performance and high dropouts related to long duration of therapy, thrombophlebitis, difficulty in accessing veins, disabling rheumatic side-effects and practical problems. Liver, renal and pancreatic functions and ECG remained normal. Conclusion: No major advantage was obtained using allopurinol, rifampicin or Mw vaccine along with SSG as compared to SSG alone.

Genetically modified live attenuated parasites as vaccines for leishmaniasis.

Leishmaniasis causes significant morbidity and mortality worldwide and is an important public health problem. Even though it is endemic in developing countries in tropical regions of the world,in recent years economic globalization and increased travel has extended its reach to people in developed countries. Leishmania is usually spread by the bite of the female sandfly. In addition, naïve populations can be exposed to Leishmania infection through transfusion of blood and blood products from infected asymptomatic individuals. There are several clinical forms of leishmaniasis caused by different species of the parasite. In some cases, the only possible cure for this disease is drug treatment. However, prolonged use of such drugs has led to parasite drug resistance. At present there are no effective vaccines against Leishmania. Many vaccine strategies have been pursued, including the use of whole cell lysate, killed, avirulent or irradiated parasites. Additionally, DNA vaccines and purified or recombinant parasite antigens have also been tested. Most of these strategies have shown some degree of effectiveness in animal models but little or no protection in humans. There is now a general consensus among Leishmania vaccine researchers that parasite persistence may be important for effective protective response and could be achieved by live attenuated parasite immunization. In this article we reviewed the efforts in developing genetically defined live attenuated Leishmania parasites as vaccine candidates with the goal of achieving a low level of parasite persistence without being virulent in the host and inducing protective immunity.

Challenges in the diagnosis of post kala-azar dermal leishmaniasis.

Post kala-azar dermal leishmaniasis (PKDL) is a dermatosis that occurs as a sequel of visceral leishmaniasis (VL). Elimination of VL requires detection and treatment of PKDL, necessarily because of its capacity to serve as a reservoir for the causative parasite, Leishmania donovani. Diagnosis of PKDL presents a challenge due to low parasite burden in the lesions. In this article we have reviewed the recent advances in the development of immunological and molecular methods for diagnosis of PKDL.