Discovered in 1681 by ______________________ in his own stool.
Most common intestinal flagellate of humans and most common water-borne disease.
cosmopolitan (worldwide) distribution; 2 million cases estimated
in U.S. each year - responsible for 5000 hospitalizations/year
endemic in the Midwest - __________ in WI in 1987 (this is an increase from 2.9% in 1976)
children under 5 and mothers with young children have the highest rates of infection
name of disease caused by parasite is ______________________
2 Stages of Giardia lamblia
TROPHOZOITE - actively moving and feeding stage
M ay invade the common bile duct.
Trophozoites may also be found in watery stools associated with _____________________
Shape: rounded anterior end, posterior end pointed
Size: 12 to 15 µm long x 5 to 9 µm wide
Morphology of Giardia lamblia trophozoite Each trophozoite has ____________________ (looks like monkey face) Ventral surface bears _______________________ to adhere to surface of intestinal cell 8 flagella (2 anterior, 2 posterior, 2 ventral, and 2 caudal) - all arise from ________________________ ________________________ occur behind adhesive disk - function is unknown
Morphology of Giardia lamblia trophozoite Scanning EM view of trophozoite surface showing the adhesive disk (text photo on p. 92) ventral dorsal
Morphology of Giardia lamblia trophozoite Light microscope photos of trophozoites
Morphology of Giardia lamblia trophozoite Trophozoite attaches to surface of epithelial cells with its adhesive disk and feeds on _____________________________________________
2 nd Stage is Giardia lamblia cyst
The cyst forms as trophozoites become dehydrated when they pass through the large intestine
ovoid in shape; 8-12 µ m long x 7-10 µ m wide
thin cyst wall
_________________________ present, often concentrated at on end (indicates that a nuclear division occurs during encystment)
Other species of Giardia 5 species of Giardia occur in other birds and mammals; They are not thought to be transmissable to humans Giardia muris Giardia canis Giardia felis Giardia equi
Phylum Retortamonada Chilomastix mesnili
6% prevalence in the world
3.5% prevalence in the U.S.
0.3% in Wisconsin in 1987
Chilomastix mesnili life cycle stages
1. TROPHOZOITE - 6-24 µ m long by 3-20 µ m wide
4 flagella arise from kinetosomes at anterior end; 3 flagella extend anteriorly, 1 extends into the cytostome (flagella are difficult to see in stained trophozoites)
- commonly seen in fecal smears especially from watery stools
Chilomastix mesnili life cycle stages 2. CYST is lemon-shaped; 6 to 10 µm in diameter - anterior end: __________________ - contains single nucleus, cytosome, and retracted flagella - common diagnostic stage in feces
Chilomastix mesnili life cycle 1. Trophozoites live in the human large intestine and multipy by _____________________________ 2. ___________________________ in the large intestine stimulates encystment. Cyst is released in the feces. 3. Cyst survives in water in the external environment. 4. When cyst is ingested, it excysts in the small intestine and moves to the large intestine. Transmission involves ingestion of cysts primarily from _____________________________ contaminated with feces.
Chilomastix mesnili life cycle PATHOLOGY: IMPORTANCE:
Phylum Parabasalia Trichomonas spp.
Common flagellate parasites of many vertebrates.
I will discuss 5 species:
Three species infect humans
One important species infects cattle
A common species in mice in laboratory
Why is Trichomonas unusual?
General Morphology of the Trichomonas trophozoite Shape: Nucleus: 3 to 5 flagella extend anteriorly 1 flagellum extends posteriorly along the cell membrane to form an _______________________________ _______________________________attaches the undulating membrane to the cell membrane and gives the undulating membrane support
General Morphology of the Trichomonas trophozoite Internal support provided by: _______________________________ is a Golgi apparatus located near the nucleus (not generally seen in most specimens)
3 species of Trichomonas occur in humans
Host and habitat:
T rophozoite is small - usually between 5 and 10 µm in length
possesses 4 anterior flagella; undulating membrane is 3/4 the body length
(We do not have any slides of this species to examine in lab, but know of its presence.)
Trichomonas hominis = Pentatrichomonas hominis Host and habitat: Pathology: Food:
Trichomonas hominis = Pentatrichomonas hominis Trophozoite is usually between 8-12 µm in length ID characters: Often is placed in genus Pentatrichomonas due to presence of 5 anterior flagella Undulating membrane and 6th flagellum runs length of parasite but are not seen in most smears
Life Cycle of Trichomonas hominis 1. Trophozoites live in the human large intestine and multipy by binary fission . 2. Dehydration of the feces in the large intestine caused the trophozoite to round up and become dormant. No cyst is formed. 3. Trophozoites are released in the feces and survive in water in the external environment. 4. When trophozoite is ingested, it passes down the digestive tract to the large intestine.
Life Cycle of Trichomonas hominis PATHOLOGY: IMPORTANCE:
Trichomonas vaginalis Host and habitat: Food: Common in 30-49 year old women; a recent study in California indicated a prevalence of 30% in childbearing women
Trichomonas vaginalis Morphology: Size: ID characters: - all structures show in stained specimens
Life Cycle of Trichomonas vaginalis 1. Trophozoites occur in the urogenital system. 2. Trophozoites multiply by binary fission. 3. Trophozoites are transmitted from one person to another by ____________________________________________________________________________________ (washcloths, towels, etc.). Fomites
Pathology of Trichomonas vaginalis infections Pathology in men: ________________________________ _______________________________________________ Pathology in women – causes _________________ infection: (1) (2) (3) These symptoms disappear in women as the infection becomes chronic; she becomes asymptomatic. Parasite is often sexually transmitted from an asymptomatic person to his/her partner.
culturing techniques increase diagnostic frequency in asymptomatic cases as numbers of trophozoites are usually low in these cases
Two non-human species of Trichomonas Trichomonas (=Tritrichomonas) foetus Parasite of veterinary importance in _____________________________ Habitat: PATHOLOGY in cows: PATHOLOGY in bulls: Treatment is expensive and not always effective
Two non-human species of Trichomonas Trichomonas muris - common parasite in _____________________________________ - nonpathogenic - occur in uncountable numbers
Dientamoeba fragilis Parasite was originally thought to be an ameba but recent EM and immunological studies indicate it is more closely related to Trichomonas HABITAT - ___________________________________________________ - it is cosmopolitan and infects 4% of the world's population
Dientamoeba fragilis MORPHOLOGY - Trophozoite is round in shape - 6 to 12 µm in diameter - nucleus: cyst?
Dientamoeba fragilis LIFE CYCLE - parasite does not form cysts and trophozoites cannot survive passage through the small intestine TRANSMISSION: Transmission through eggs of pinworm and whipworm
Considered to be nonpathogenic and infections are asymptomatic
Some infections have been reported as causing diarrhea but most parasitologists now believe that other parasites were the cause, as Dientamoeba fragilis is usually never found alone
Cosmopolitan parasite of _________________________________
Causes a severe and often fatal disease called _________________
Only a trophozoite stage present; no cyst:
trophozoite is irregular in shape
may appear as an ameboid form with pseudopodia or a flagellated form with a single flagellum
Histomonas meleagridis life cycle Transmission is within the egg of the cecal nematode of chickens and turkeys ( Heterakis gallinarum ) - trophozoites from the cecum of an infected bird are ingested by the nematode and invade the eggs - infected eggs of the nematode are released onto the soil where they are eaten by young birds during pecking activities - as nematode eggs hatch in small intestine, Histomonas trophozoites are released to invade cecum and liver
Histomonas meleagridis pathology Habitat of trophozoites: Pathology: Young turkeys are more susceptible to the infection than are chickens Mortality can reach 100% in young turkeys - millions of dollars worth of turkeys are lost to this parasite
Termite Flagellates Trichonympha and Holomastigotes are common genera inhabiting the intestine of termites. This is an example of ___________________________ Trichonympha Holomastigotes
CILIATES (Chapter 10 – p. 175-179) The Phylum Ciliophora contains a single species of medical importance. Balantidium coli
Hosts and habitat:
Prevalence in humans is ______; in pigs _____________
Pigs appear to be the source of most human cases; thus, this is a _________________________________
See case report in lab that describes a fatal infection in a Venezuelan pig farmer.
Cosmopolitan in distribution but more common in the tropics
Balantidium coli – Morphology of 2 stages
1. TROPHOZOITE - large ovoid ciliate; 30 to 150 µm in length (largest protozoan parasite of humans)
Balantidium coli – Morphology of 2 stages
2. CYST - formed as feces dehydrate in the rectum
round shape; 40 – 60 µm in diameter; cyst wall is transparent
cyst is the diagnostic stage in a fecal smear
Balantidium coli life cycle 1. Trophozoites live in the human large intestine and multipy by binary fission . Conjugation may occur but it is rare. 2. Dehydration of the feces in the large intestine stimulates encystment. Cyst is released in the feces. 3. Cyst survives in water in the external environment. 4. When cyst is ingested, it excysts in the small intestine and trophozoite moves to the large intestine.
Balantidium coli Pathology Trophozoites are tissue invaders. They secrete proteolytic enzymes which digest the epithelium of the large intestine. __________________________________ are formed in the mucosa of the large intestine and extend into the submucosa. Ulceration results in bleeding and secondary bacterial infection. Perforation of the large intestine has occurred in some fatal cases. Disease is primarily _________________ _________________________________ Secondary infections in other organs such as liver and lungs are rare.
Balantidium coli TREATMENT: PREVENTION:
This ciliate causes a problem called _________________________ in aquarium and wild freshwater fish
Trophozoites attack the epidermis, cornea, and gill filaments of fish
grayish pustules occur in the skin
destruction of ___________________________causes death by asphyxiation
Ichthyopthirius multifiliis Trophozoites are released into water when skin pustules rupture Cysts are formed and _____________________________occurs within the cyst Trophozoites are formed and are infective to a new fish when it comes into contact