[Mediterranean visceral leishmaniasis: physiopathology]

INFANTILE LEISHMANIASIS: The protozoan parasites of the genus Leishmania are the causal agent of various diseases ranging from cutaneous lesions to fatal systemic diseases. In southern France, Leishmania infantum is an endemic species recognized as the causal agent of infantile leishmaniasis (Mediterranean visceral leishmaniasis). Little is known about the pathophysiology of the disease in humans, but models in mice may provide a new approach. INSECT VECTOR: Leishmania infantum are carried by sand flies. Antigenic modifications of the promastigote forms occur in these insects modifying lipophyosphoglycan (LPG) or glyocprotein gp63. Salivary gland lysates from the sand flies also enhance Leishmania infectivity. HUMAN INFESTATION: In humans, LPG and gp63 play a role in complement fixation, cell adhesion and resistance to complement-mediated lysis. Macrophage expression of class I and II major histocompatibility complex antigens is suppressed. T cells and interferon gamma are very important keys in the control of the parasite infection.