Intestinal Flagellates

Intestinal Flagellates

Old Taxonomy: Phylum Sarcomastigophora Subphylum Mastigophora

New Taxonomy: Flagellates are placed in 4 PHYLA

2 groups of parasites:

• intestinal flagellates (Chapter 6)

• blood and tissue-dwelling flagellates (Chap. 5)

Phylum Retortamonada Giardia lamblia = Giardia duodenalis

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

• Habitat:________________________________

• May 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 trophozoiteEach 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


Light microscope photos of trophozoites


Trophozoite attaches to surface of epithelial cells with its adhesive disk and feeds on _____________________________________________

2nd Stage is Giardia lamblia cystThe cyst forms as trophozoites become dehydrated when they pass through the large intestine Morphology:

• ovoid in shape; 8-12 µm long x 7-10 µm wide• thin cyst wall• _________________________ present, often concentrated at on end (indicates that a nuclear division occurs during encystment)• flagella shorten and are retracted within cyst• ________________________ provide internal support

Cyst may remain viable in the external environment usually water) for many months.

When ingested: ____________________________

2nd Stage is Giardia lamblia cyst

Giardia lamblia life cycle

DIAGNOSIS ?

INFECTIVE STAGE?

PRIMARY DIAGNOSTIC STAGE?

Pathology of Giardia lamblia infections

1. ___________________________________ accompanied by nausea, flatulence, and weight loss occurs in most cases

• Diarrhea caused by the production of a watery mucus in response to the trophozoites

2. Numerous trophozoites cover and shorten microvilli of intestinal cells causing ______________________________________________

3. Numerous trophozoites may ______________________________

interferes with ______________________________

Epidemiology of Giardia lamblia infections

4 general methods of infection:

1. _____________________________________________________

• many cases in hikers, fishermen, and canoeists in Wisconsin

• recent problems with giardiasis in Boundary Water Canoe Area of Minnesota

Textbook suggests that beavers may be an important source of Giardia for transmission to humans - A ZOONOSIS.

Recent studies at the University of Minnesota suggest that giardiasis is of human origin - thus, it is an ANTHROPONOSIS.

Epidemiology of Giardia lamblia infections

2. _______________________________________________________

_______________________________________________________

3. _______________________________________________________

• mothers changing diapers and contaminating fingers

• use of wading pools by diaper-age children

4. _______________________________________________________

• about 5% of giardiasis is food-borne; thus, 95% is water-borne

Prevention and Treatment of Giardia lamblia

PREVENTION:

• filtration of water (be sure filter is fine enough to trap the cysts)

• boiling water from stream or lake

• addition of a tincture of iodine are effective in killing cysts (chlorination of water does not effect the cysts)

• avoid use of wading/swimming pools by diaper-age children

TREATMENT: ___________________________________________

_______________________________________________________

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

Habitat: __________________________________

Hosts: ___________________________________

Cosmopolitan distribution:

• 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 µm long by 3-20 µm wide

-shape: __________________________

________________________________

-nucleus: ________________________

________________________________

- 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

Trichomonas tenaxHost and habitat:

Pathology:

Food:

Trophozoite is small - usually between 5 and 10 µm in length

• possesses 4 anterior flagella; undulating membrane is 3/4 the body length

Transmission:

(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.

Diagnosis & Treatment of Trichomonas vaginalis

DIAGNOSIS:

• ___________________________________________________

• culturing techniques increase diagnostic frequency in asymptomatic cases as numbers of trophozoites are usually low in these cases

TREATMENT:

Two non-human species of Trichomonas

Trichomonas (=Tritrichomonas) foetusParasite 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


MORPHOLOGY - Trophozoite is round in shape

- 6 to 12 µm in diameter

- nucleus:

cyst?


LIFE CYCLE - parasite does not form cysts and trophozoites cannot survive passage through the small intestine

TRANSMISSION:

Transmission through eggs of pinworm and whipworm


PATHOLOGY

• Food:

• 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

Histomonas meleagridis

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)

• ID characters:

• Reproduction:

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

• transmission:

• 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:

Ichthyopthirius multifiliis

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


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


Treatment:

Intestinal Flagellates

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