Leishmaniasis diagnostics

Visceral leishmaniasis
Visceral leishmaniasis (VL) is the most severe form of leishmaniasis. The disease is fatal if left untreated. The diagnosis of human VL is difficult. The principal signs of VL are an enlarged spleen and a prolonged irregular fever; other signs and symptoms are loss of weight, pallor, enlarged liver, enlarged lymph nodes, anaemia, cough and diarrhoea. These signs and symptoms may mimic those of malaria, typhoid, tuberculosis, schistosomiasis and a number of other diseases. The clinical suspicion may be confirmed directly by the detection of parasites in patient material or by culture. However, sample collection is inconvenient for the patient and parasite isolation by culture is time-consuming, expensive and difficult. Because of the mentioned limitations of the direct diagnostic methods, a number of indirect immunological methods, such as indirect immunofluorescent-antibody tests (IFAT), enzyme-linked immunosorbent assays (ELISA) and a direct agglutination test (DAT), have been developed .

Cutaneous leishmaniasis
In the case of cutaneous leishmaniasis (CL), a systemic serum response is often absent, rendering serology insufficient as a diagnostic tool. Also in the case of HIV co-infection it is often impossible to use a sero-diagnostic test. Detection of the parasite in a skin smear or skin biopsy with microscopy or demonstrating the parasite in culture are in general the standard diagnostic procedures for CL. However, even when these assays are combined, they are not sensitive enough to confirm all CL cases. Therefore, a molecular technique (direct detection of parasite specific DNA or RNA) is needed as an additional diagnostic tool. These techniques are not only ideal for the detection of low numbers of parasites, but also for quantification of the parasite load. Finally, treatment choices depend on the correct identification of the infecting parasite. In particular for New World infections, in which some species can cause more damage to the patient than others and have to be treated differently. In this case, molecular techniques are also helpful tools.

 

Approach

KIT Biomedical Research develops diagnostic methods for the diagnosis of visceral and (muco)cutaneous leishmaniasis and is involved in their evaluation and application in the field. The work is conducted in close collaboration with research institutes in disease endemic countries. Emphasis is on development of diagnostic tests that can be used under harsh field conditions, for example the direct agglutination test (DAT) based on freeze dried antigen. Test production is performed in collaboration with industry.

Up-to-date molecular technology is also being applied for diagnostic test development and for studies towards species identification. Improving the diagnosis of HIV/leishmaniasis co-infected patients are becoming an important part of our work.

Tests for the diagnosis of animal leishmaniosis are also subject of our studies.

KIT Biomedical Research can provide training (via workshops) in the use of a number of molecular biological and serological tools.

 

Focal points

  • Development, evaluation and implementation of sero-diagnostic tests for leishmaniasis
  • Development, evaluation and implementation of molecular tests for the diagnosis of leishmaniasis and Leishmania (sub-)species identification.
  • Test production
  • Studies on the improvement of the diagnosis of leishmaniasis in HIV co-infected patients

Example

Over the years we have developed a number of molecular biological tools, which are used for diagnosis, epidemiology and strain identification. A PCR has been developed which employs Leishmania specific primers. These primers are directed against a part of the 18S rRNA gene, which contains Leishmania-specific sequences. Using a combination of PCR and restriction enzyme analysis, it is possible to differentiate between different Leishmania spp. or complexes.
The performance of the PCR and its value for the diagnosis of leishmaniasis has been extensively evaluated, both in The Netherlands as in endemic countries. During a study in Sudan, it was proved that the PCR is more sensitive than traditional microscopic methods and is especially useful for the confirmation of:

  1. the diagnosis of visceral leishmaniasis in those cases where microscopy was negative;
  2. the diagnosis of post kala-azar dermal leishmaniasis (PKDL).

Moreover, we showed that a positive PCR after treatment of visceral leishmaniasis is a strong indicator for the future development of either PKDL or a relapse. People who had a negative PCR after treatment remained free of complications.

Using a combination of PCR and restriction enzyme analysis, it is possible to differentiate between Old World species causing visceral leishmaniasis on the one hand and cutaneous leishmaniasis on the other hand.

 

Projects


Publications


Team members


Contact

For more information please contact Dr. Henk Schallig

Tags

disease control | diagnostics | infectious diseases | leishmaniasis | research |

Royal Tropical Institute