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| Keywords: Giardia 1.jpg This digitally-colorized scanning electron micrograph SEM depicted the dorsal upper surface of a Giardia protozoan that had been isolated from a rat ™s intestine Some of the identifying morphologic characteristics include pairs of thread-like flagella that facilitate motility and a ventolateral flange that appears as a ruffle around the anterior portion of the organism Pairs of flagella seen here include an anterior posterior-lateral and caudal pairs The protozoan Giardia causes the diarrheal disease called giardiasis Giardia species exist as free-swimming by means of flagella trophozoites and as egg-shaped cysts It is the cystic stage which facilitates the survival of these organisms under harsh environmental conditions The cyst is considered the infective form and disease is often transmitted by drinking contaminated water As depicted in these SEMs in the intestine cysts are stimulated to liberate trophozoites Cysts can be shed in fecal material and can thereafter remain viable for several months in appropriate environmental conditions Cysts can also be transferred directly from person-to-person as a result of poor hygiene Dr Stan Erlandsen; Dr Dennis Feely http //phil cdc gov/PHIL_Images/11649/11649_lores jpg Dr Stan Erlandsen; Dr Dennis Feely Center for Disease Control 1982 Giardia PD-USGov | ||||
