Leishmaniases are caused by a protozoan Leishmania parasites, transmitted by the bites of infected female phlebotomine sandfly.

 

There are three main clinical forms of leishmaniases: i) cutaneous, the most common form of the disease (CL);

ii) visceral, also known as kala-azar and the most fatal (VL); and iii) mucocutaneous. Whereas cutaneous and mucocutaneous leishmaniases are chronic, non-life-threatening but highly stigmatising, visceral leishmaniasis is fatal if left untreated in over 95% of cases.

 

Post kala-azar dermal leishmaniasis (PKDL) is a sequel of VL which develops in 5-10% of cases but more commonly after completing treatment for VL. It is mainly observed in Sudan and India and play a central role in VL transmssion as people with PKDL are reservoir of Leishmania parasites.

 

Leishmaniasis is classified as one of the “most neglected diseases” due to the limited resources invested in diagnosis, treatment, and control, and its strong association with poverty. It represents a severe barrier to socio-economic development.

To date, there are no vaccines approved for human use against leishmaniases, and control measures rely on chemotherapy to alleviate disease as well as on vector control to reduce transmission. The development of vaccines has been hampered by significant antigenic diversity and the fact that the parasites have a digenetic life cycle in at least two hosts (sandfly vector and human, but also an animal reservoirs).

 

An equally important consideration for the design and implementation of anti-parasite vaccines in general is the contribution of the genetics of the target host population and their susceptibility to infection and disease, i.e. the severity of disease manifestations.