Parasite detection in patients with post kala-azar dermal leishmaniasis in India: a comparison between molecular and immunological methods

Abstract

Aims: To evaluate the sensitivity and specificity of serological, immunohistochemical, and molecular methods in the diagnosis of post kala-azar dermal leishmaniasis (PKDL). Methods: Twenty five patients with confirmed PKDL and 25 controls were included in the study. G2D10, a monoclonal antibody against Leishmania, was used for the immunohistochemical (IHC) staining of lesion sections to visualise anti-Leishmania donovani antibodies. The diagnostic usefulness of IHC was compared with enzyme linked immunosorbent assay (ELISA) with a recombinant (rk39) antigen, and a species specific polymerase chain reaction (PCR) assay, amplifying a kinetoplast minicircle DNA sequence. Results: IHC detected 22 of 25 PKDL cases, giving a sensitivity of 88%. The diagnostic sensitivity of both the ELISA and PCR tests was higher (96%). All of the 25 controls examined were negative in PCR, indicating 100% specificity of the test, whereas ELISA showed 96% specificity. Conclusions: IHC with G2D10 significantly enhances the sensitivity of detection of PKDL over routine haematoxylin and eosin staining. ELISA with a recombinant antigen is an economical and practical assay. PCR is the most sensitive and specific diagnostic method for PKDL. The tests described would facilitate the recognition of patients with PKDL, enabling timely treatment, which would contribute greatly to the control of kala-azar.

PCR-Based Detection of Leishmania DNA in Skin Samples of Post Kala-Azar Dermal Leishmaniasis Patients from an Endemic Area of Bangladesh

“…Such variable detection rates were considered to be caused because the diagnostic results of skin smear microscopy vary from person to person, and because it is prone to be influenced by the distribution of parasites throughout the skin tissue from which the skin biopsy was taken. Our results are in accordance with other authors who reported higher positive rates for PCR than for other detection methods (12,15). Although high detection rates of Leishmania DNA by PCR in suspected PKDL patients have been reported, lower rates were described when slit skin specimens were used for PCR; 42.9z in Bangladesh (12/28) (15), 82.7z in Sudan (19/23) (10).…”

“…Although high detection rates of Leishmania DNA by PCR in suspected PKDL patients have been reported, lower rates were described when slit skin specimens were used for PCR; 42.9z in Bangladesh (12/28) (15), 82.7z in Sudan (19/23) (10). In contrast, in only two studies conducted in India, higher positivity rates, 93z (27/29) and 96z (24/25) were recorded by using skin biopsy specimens for PCR (12,13). However, the number of samples in these studies was too small to confirm the efficacy of PCR diagnosis.…”

Canine visceral leishmaniasis due to Leishmania (L.) infantum chagasi in Amazonian Brazil: comparison of the parasite density from the skin, lymph node and visceral tissues between symptomatic and asymptomatic, seropositive dogs

“…By this method parasites were readily detected in sections of tissues from 10 randomly selected seropositive dogs, whereas in Giemsa-stained sections it was possible to detect the parasites in only 70-80% of these animals. Using the same immunohistochemical staining, TAFURI et al 34 detected small numbers of amastigotes in the tissue of dogs with CVL in Minas Gerais State, south-eastern Brazil, and the same method has been used to detect other parasites such as Trypanosoma cruzi 6,26 , Toxoplasma gondii 7,22 and Leishmania (L.) donovani 27 .…”

Herramientas no invasivas en Venezuela: comparación entre las pruebas inmunoserológicas DAT, rK26 y rK39 en el diagnóstico de leishmaniasis visceral

“…Dichos parámetros se calcularon aplicando las correcciones para la evaluación de pruebas diagnósticas con patrones de referencia imperfectos (16). Como patrón de referencia, en el estudio se usó la prueba ELISA rK39, cuya especificidad y sensibilidad han sido reportadas alrededor de 97% (17)(18)(19)(20)(21)(22)(23). Se determinaron los parámetros de sensibilidad, especificidad, valor diagnóstico positivo y negativo y razón de verosimilitud.…”