Page 57 - Medical Parasitology_ A Textbook ( PDFDrive )

Babesia 49

Distribution

Most human cases were reported from the USA and are mainly caused by Babesia
microti.

Habitat

In human, the parasites are found in the erythrocytes.

Morphology

Trophozoites are 2–5 μm in diameter found inside the red cells. The shape may be
pyriform, amoeboid, or spindle-like, usually in pairs and are often mistaken as ring
form of Plasmodium.

Life Cycle (Fig. 6.3)

The definitive host is Ixodid ticks. Humans and rodents are the intermediate hosts.
Modes of transmission to human are through bite of Ixodid ticks and via blood
transfusion.

B
i d 8 Transmitted from
6 Tick takes a human-to-human
blood meal (sporozoites trophozoite via blood transfusion
introduced into host)
7
merozoite

i = Infective Stage
d = Diagnostic Stage
Tick takes
sporozoites i 1 a blood meal
(sporozotes introduced
into host)
sporogony
Mouse trophozoite
Tick
5
Ookinete enters 4 Tick takes 2
salivary gland A a blood meal
(ingests gametes) merozoite

fertilization
in gut
3
gamete
Fig. 6.3 Life cycle of Babesia (Reproduced from https://www.cdc.gov/dpdx/babesiosis/index.html)