Comparative Immunology, Microbiology and Infectious Diseases
Leishmaniasis: current situation and new perspectives
Introduction
The leishmaniases remain a severe public health problem. The burden is increasing [1]. The perspectives of control are still highly dependent on research progresses to obtain better tools and a more cost-effective strategy for case management and vector control. With valuable field tools, a step by step elimination should become feasible specially in anthroponotic foci where man is the sole reservoir.
Section snippets
Disease manifestations
Clinical forms of leishmaniasis are particularly diverse representing a complex of diseases: visceral leishmaniasis (VL) is usually fatal when untreated, muco-cutaneous (MCL) is a mutilating disease, diffuse cutaneous leishmaniasis (DCL) is a long-lasting disease due to a deficient cellular-mediated immune response and cutaneous leishmaniasis (CL) is disabling when lesions are multiple.
The disease is caused by a parasite belonging to the genus Leishmania. It is spread by the bite of the female
DALYs
The burden of leishmaniasis expressed in disability-adjusted life years (DALYs) is estimated at: 2,357,000 (946,000 for males and 1,410,000 for females) [8].
Morbidity
The leishmaniases cause considerable morbidity and mortality. In man, the disease occurs in at least 4 major forms: cutaneous, diffuse cutaneous, mucocutaneous and visceral.
Current management and control strategies
The main control strategy includes: case finding and treatment, vector control, when feasible and, in zoonotic foci, animal reservoir control. For VL, serological diagnosis is classically based on ELISA, IFAT and Direct agglutination test (DAT), parasitological diagnosis relies on spleen, bone marrow or lymph nodes aspirate. Treatment consists of first-line drugs: the pentavalent antimonials, and second line drugs amphotericin B and amphotericin B in liposomes, the latest restricted to
Persistence of VL burden and lack of attention
The burden is still increasing due to technical and managerial constraints. Currently there is not a real cost-effective control package. There is a clear need to reinforce the screening and the diagnosis of VL in peripheral health structures where patients are treated on the base of clinical suspicion. Usually, there are no facilities to perform and read bone marrow or spleen aspiration in most of the districts hospitals. Screening and diagnosis in such settings should rely on simple tests.
Up
Previous successes in China, Turkmenistan, Uzbekistan
In the past, some eradication programmes were successfully completed when supported by a strong political and financial commitment. For example:
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Foci of anthroponotic cutaneous leishmaniasis (ACL) of Turkmenistan and Uzbekistan were put under control in 1957 and 1960, respectively, The strategy applied was a combination of early diagnosis through active case detection, systematic treatment, large-scale vector control based on insecticide spraying and intensive urban sanitation including improved
Diagnosis
The new field tests, recently made available, are more accessible than the traditional ones (IFAT and ELISA): rapid strip, dipstick k39 (US$ 1), DAT freeze dried antigen (US$ 3), latex agglutination test for antigen detection in urine(US$ 1,5). It is a great progress but currently the case management strategy depends more on the cost of treatment than on that of testing.
Treatment
Some cost reduction has been obtained during the last 5 years, particularly with the availability on the market of the generic
R&D Agenda
As leishmaniasis mainly affects poor countries, research and development of new diagnostic tools and drugs have been dramatically neglected.
There is a clear need for more investment in field oriented research, to continue improving case management (better use of existing tools and validation of new tools). Simultaneously to the availability of the first oral drug for VL, it is of prime importance to have accurate and practical diagnostic methods available in endemic areas.
Conclusions
The main challenge is to translate new knowledge into cost-effective and affordable control tools (better reagents for diagnosis, new drugs and vaccines) and to improve the patient's accessibility to them. Progress obtained through basic research should be transformed into field achievements.
Increased research and funds are needed for neglected diseases such as leishmaniasis. WHO, together with several other institutions, should approach donors from public and private sectors to convince them
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