|
Knowledge of the life
cycle and transmission is still under investigation, therefore this is a
proposed life cycle for B. hominis. The classic form found in human
stools is the cyst, which varies tremendously in size from 6 to 40 μm
.
The thick-walled cyst present in the stools
is believed to be responsible for external transmission, possibly by the
fecal-oral route through ingestion of contaminated water or food
. The
cysts infect epithelial cells of the digestive tract and multiply asexually
( ,
).
Vacuolar forms of the parasite give origin to multi vacuolar
and
ameboid
forms. The multi-vacuolar develops into a pre-cyst
that
gives origin to a thin-walled cyst
,
thought to be responsible for autoinfection. The ameboid form gives origin
to a pre-cyst
, which
develops into thick-walled cyst by schizogony
. The
thick-walled cyst is excreted in feces
. |
|