Page 42 - Medical Parasitology_ A Textbook ( PDFDrive )

34 5 Hemoflagellates

Sandfly Stages Human Stages
1 Sandfly takes a blood meal Promastigotes are
(injects promastigotes stage 2 phagocytized by
into the skin) macrophages
8 Divide in the gut and or other types
migrate to proboscis of mononuclear
phagocytic cells
i
3
Promastigotes transform
into amastigotes
d
Amastigotes transform into
7 promastigotes in the gut

4
Amastigotes multiply in cells
of various tissues and infect
other cells
d
Ingestion of
6
parasitized cells
5 Sandfly takes a blood meal
(ingests macrophages infected
with amastigotes)
i = Infective Stage
d = Diagnostic Stage
Fig. 5.6 Life cycle of Leishmania donovani (Reproduced from https://www.cdc.gov/dpdx/leish-
maniasis/index.html)
Some patients with visceral leishmaniasis in endemic areas may develop post
kala azar dermal leishmaniasis (PKDL), about a year or 2 after recovery from the
systemic illness. PKDL is seen mainly in India and East Africa and is a non ulcerative
skin lesion.
Visceral leishmaniasis has emerged as an important opportunistic infection asso-
ciated with HIV.

Immunity

Recovery from visceral leishmaniasis and cutaneous leishmaniasis will give lasting
immunity to the respective disease but may not provide cross-protection.

Diagnosis

1. Microscopic examination
Demonstration of amastigotes in blood smears and tissue aspirates (bone
marrow, spleen, lymph nodes) is the gold standard for diagnosis. Fixed smears
can be stained with Giemsa to demonstrate amastigotes.