MICROBIOLOGY

• Protozoan parasite, HIV increases the risk of visceral (hepatosplenic and bone marrow) disease but not cutaneous or mucocutaneous disease.
  • Second most common tissue protozoan OI in HIV after Toxoplasma gondii worldwide.
• Transmitted by sand fly vectors [Fig 1]. Also may be acquired through shared needles among IDUs, primarily in endemic urban settings.
  • Zoonosis: reservoirs
    • Canine: L. infantum, L. chagasi
    • Anthroponotic: L. donovani
• Forms:
  • Visceral leishmaniasis: L. donovani (Asia), L. infantum (southern Europe, Mediterranean), L. chagasi (Brazil).
  • Cutaneous leishmaniasis: L. major and L. tropica (Old World), L. mexicana, L. amazonensis, L. peruviana, L. guyanensis (New World), L. (viania) braziliensis (cutaneous and mucocutaneous)
• Amastigote forms are seen within macrophages; flagellated promastigote forms seen in cultures, transmitted from insect vector.
• Leishmania and HIV co-localize in similar cells (macrophages, dendritic cells) resulting in additive immune dysfunction, especially in macrophages leading to increased immune activation.