excreted in the feces of infected people. It is the causative agent of amebic
dysentery.- Naegleria fowleri: This ameba causes primary amebic meningoenceph-
alitis (PAM) that results in headache, fever, vomiting, stiff neck, and loss
of bodily control. N. fowlerienters the body through the mucous mem-
branes (when the person swims in warm water) and travels to the brain and
spinal cord. - Acanthamoeba polyphaga: This ameba lives in water (including tap water)
and infects the cornea of the eye leading to blindness. It can also cause
ulcerations of the eye and the skin. A. polyphagais also known to invade
the central nervous system, resulting in death.
Flagellates move by structures called flagella. They have two or more spindle-
shaped flagella in the front of the cell that they use to pull themselves through
their environment. Food enters flagellates through a mouth-like grove called a
cytosome.
Here are common flagellates:- Trichomonas vaginalis: Commonly known as T. vaginalis, this flagellate
is the cause of trichomoniasis, which is a sexually transmitted disease.
T. vaginalisis found in the male urinary tract and the vagina of females. - Giardia lamblia:This flagellate is commonly known as G. lambliaand
causes giardiasis. Giardiasiscauses nausea, cramping, and diarrhea when
food or water contaminated by fecal material is ingested. G. lamblialives
in the small intestines of humans and other mammals.
(^176) CHAPTER 11 The Eukar yotes
Fig. 11-2. A common type of ameba is the
Amoeba proteus.