Leishmaniasis Quiz

Study Notes

Species causing cutaneous lesions cannot grow at core body temperature, but visceral species can

Endemic in Mediterranean region, Turkey, North and West Africa, Middle and South Asia
Confined to skin, especially face and limbs
Occasionally extends to mucous membrane of mouth, producing mucocutaneous lesions

Promastigotes change to amastigotes, which are rapidly phagocytosed by macrophages
Parasites replicate, cells rupture, and then invade other cells
Granulomatous reaction leads to formation of:
- Nodule at site of inoculation, which crusts and then ulcerates
- Chronic ulcer with elevated, indurated edges
- Healing gradually in 2-10 months, leaving a depigmented scar with small nodules at the edge
- Secondary bacterial infection

Includes L. tropica, L. major, and L. aethiopica
L. tropica:
- Geographically distributed in Mediterranean region, Middle East, South Russia, and India
- Clinically, it causes a painless ulcer with raised margins, usually affecting face and exposed parts of the body

Amastigotes in vertebrate host (man and animal)
Promastigote in arthropode vector (sandfly in old world and Lutzomyia in new world)
Reservoir hosts: rodents, foxes, and dogs

Immunity is mainly cellular (not entirely beneficial, can cause granulomas and tissue destruction)
According to immune system, one of three events occurs:
- Parasites are killed by immune response, and person becomes immune to reinfection
- Local infection is established, which persists until immune response eradicates it or is overwhelmed, permitting dissemination
- Infection metastasizes through blood to viscera (viscerotropic species), oronasal mucosa (mucocutaneous species), or skin

Leishmanin (Montenegro) I.D. test:
- Antigen: washed promastigotes solution in 5% phenol on saline
- Method: intradermal injection of 0.1 ml antigen in forearm à induration after 48 hours
Identification of species of Leishmania:
- Isoenzyme analysis
- PCR

Local (for simple sores):
- Excision for small facial lesions
- Curettage under local anesthesia
- Heat for 39-41°C for many hours for several days
- Cryotherapy using liquid nitrogen or carbon dioxide snow
- Drugs: aminosidine (Paromomycin) ointment or Pentavalent antimony (Pentostam) injections in the edge of the ulcer
Systemic:
- Pentavalent antimony (Pentostam): 10 mg/Kg I.M. daily for 10 days
- Amphotericine B (Fungizone)