Page 138 - Medical Parasitology_ A Textbook ( PDFDrive )

Cyclophyllidean Tapeworms 131

Fig. 11.10 Hymenolepis nana egg

i = Infective Stage
d = Diagnostic Stage

Oncosphere hatches.
5
Humans and rodents Cysticercoid develops in
3 are infected when they intestinal villus
ingest cysticercoid-infected
arthropods.
6
Cysticercoid i
develops in insect Autoinfection can occur if
9 eggs remain in the intestine.
4 The eggs then release the Scolex
Embryonated egg hexacanth embryo, which
penetrates the intestinal villus
ingested by humans continuing the cycle.
from contaminated
food, water, or hands
Adult in ileal
Egg ingested portion of 7
by insect small intestine
2

Eggs can be released through the
8
genital atrium of the gravid proglottids.
d i Gravid proglottids can also disintegrate
1 Embryonated egg in faeces releasing eggs that are passed in stools.
Fig. 11.11 Life cycle of Hymenolepis nana (Reproduced from https://www.cdc.gov/dpdx/hyme-
nolepiasis/index.html)