This document summarizes several medically important protozoans that infect the Philippines, including their lifecycles and modes of transmission. It describes the trophozoite and cyst stages of Naegleria fowleri and Acanthamoeba, and notes they can infect through broken skin or nasal passages. Balantidium coli, Giardia lamblia, and Trichomonas vaginalis are described as having cyst infective stages transmitted through fecal-oral routes. Cryptosporidium parvum and Cyclospora cayetanensis are sporozoan parasites transmitted through contaminated food or water via oocysts. Toxoplasma gondii can infect

1. Notes on Philippine Medically Important Protozoans Part 2 (Coccidian and Sporozoan)
Meccar Moniem Elino, BSBio IV , Davao Doctors College
Instructor: Mrs. Chalee Sienes-Reyes, RMT, MSMT, Ph.D
Reference: Philippine textbook of Medical Parasitology 2nd ed.(2004) UP. Edited by Vicente Y. Belizario, Jr. and Winifreda U. de Leon
Infective
Trophozoite Cyst Transmission
Stage
Trophozoite with broad penetration in
pseudopods Single-walled cyst broken skin or
Naegleria fowleri Actively motile Cyst
Does not encyst in tissues entry thru
Forms the flagellate stage olfactory
Trophozoite with filamentous
penetration
pseudopods
Double-walled cyst through
Acanthamoeba Sluggishly motile Cyst
May encyst in tissues ulcerated or
Does not form flagellate stage
broken skin
Double-walled cyst
May encyst in tissues
ingestion of
contaminated
an actively motile ciliate; highly a latent survival stage is significant in
food or drink
Balantidium coli specialized for reproduction and transmission; infective stage with one cysts
with
food intake (cytostome) large nucleus
contaminated
water; fecal/oral
ingestion of
flagellate protozoan( 10 x 10 um) contaminated
having two large nuclei, a large slightly smaller the trophozoite with four food or drink
Giardia lamblia cyst
sucking disc, and many flagella; face nuclei and parabasal body with
- like appearance contaminated
water; fecal/oral
only a flagellate trophozoite with
Trichomonas vaginalis four flagella and undulating x Trophozoite sexual contact
membrane
Sporozoan(coccidian) parasite exhibits both asexual(schizogony) and
sporulated
Cryptosporidium parvum sexual(gametogony) in the brush border of the intestinal epithelium fecal/oral
oocysts
Oocyts are released from the cells and transmitted
ingestion of
contaminated
a sporozoan(coccidian) parasite of the small intestine sporulated food or drink
Cyclospora cayetanensis
asexual and sexual cycle similar to Cryptosporidium but oocysts are larger oocysts with
contaminated
water; fecal/oral
intracellular coccidian(sporozoan) parasite infecting various tissues(systemic) but
confined to intestines in felines
infected tissues release pseudocysts containing bradyozoites Eat of infected
Toxoplasma gondii feline intestines release oocyts containing tachyzoites undercooked/raw
meat
Pathogenesis : cellular death due to intracellular muliplication of trophozoites
especially severe in fetal and cerebral tissues
The organisms resemble P.falciparum
Bite/Skin
Babesia microti they vary more in shape and in size; and they do not produce pigment
Penetration
evidence of Maltese cross formation