Visceral leishmaniases
There are three main forms of leishmaniasis of which visceral leishmaniasis (VL) also known as kala-azar is the most serious form because it is fatal if left untreated in the majority of patients. It ranks among the top parasitic tropical diseases which have a high outbreak and mortality potential. An estimated 50 000 to 90 000 new cases of VL occur worldwide annually.
Early detection and appropriate treatment are key strategies in VL control. In visceral leishmaniasis, signs and symptoms are non-specific which requires a diagnostic algorithm of making a diagnosis by combining clinical signs with parasitological or serological tests (such as direct agglutination and VL rapid diagnostic tests). An RDT detects antibodies and is a simple test that can be used at all levels of health care services. A scientific review of published studies estimates that the sensitivity and specificity of RDTs vary with the eco-epidemiological endemic areas specially its low sensitivity in East Africa. Due to the persistence of antibodies for long periods after cure, one of the disadvantages of the serological test is it cannot distinguish between active cases and relapse in previously treated cases. Also, in patients with advanced HIV infection, a negative RDT result cannot rule out the diagnosis of VL. Due to the limitations of parasitological methods and the persistence of specific antibodies for several years after treatment, currently, the cure at the field level is considered a clinical cure.
Thus, there is a need for an in vitro point-of-care test to confirm or exclude active cases for early diagnosis, in order to benefit both patients and communities as untreated cases are reservoirs of infection and therefore put the community at risk of ongoing Leishmania transmission. Similarly, an in vitro laboratory test is needed for confirming or rejecting whether visceral leishmaniasis has been successfully cured post-treatment.
The World Health Organization (WHO) is seeking feedback on the TPP from experts in the industry, product developers, the scientific community, NTD programme personnel and clinicians currently involved in the management and control of visceral leishmaniases.
Details of the TPP may be found in the linked document.
- Target Product Profile (Context and background)
- Draft Target Product Profile
Proposed revisions arising from the public consultation will be considered by the TPP working group before it is finalized. The final TPPs will be used for the development of diagnostics for the treatment of visceral leishmaniases.
If you have any comments, please mention them in the subject line-VL diagnostics TPP feedback, and submit them to Dr. Saurabh Jain (jainsau@who.int).