Protozoology Theory lec.4

College of Health Sciences
Dep. of Medical Laboratories
Parasitology Theory
3rd stage
Lecture 4
Dr.: Shameeran S. Ismael
BVM & S, M.Sc Medical Microbiology(Parasitology),
PhD Molecular Parasitology
11/28/2020
Shameeran S. Ismael Medical protozology
theory, Medical Laboratories 2020

2. Acanthamoebae produces granulomatous
amoebic encephalitis (GAE)
• There are several pathogenic species of
Acanthamoeba that infect human and the
important species is Acanthamoeba culbertsoni.
• They are present in nature and are therefore
widely distributed across the environment (fresh
water, soil, etc)
• It typically causes a chronic granulomatous
amoebic encephalitis and death
11/28/2020

Keys
Kingdome: Protista
Phylum: Protozoa
Sub-phylum: Sarcomastigophora
Class: Sarcodina
Order: Centramoebadia
Family:Acanthamoebidae
Genus: Acanthamoeba
Species: culbertsoni
11/28/2020

Disease: Chronic Granulomatous Amoebic Encephalitis
(GAE)
Final host: Man
Site of infection: brain
Infective stage: Trophozoite
Diagnostic stage: Trophozite and cyst
Infection: by inhalation of trophozoites, ingestion of
trophozoites or trophozoites penetrate the broken skin or
through eyes
Life cycle: Direct
11/28/2020

Morphology
There are two morphological stages: Trophozoite and cyst
stage.
• Trophozoite - A trophozoite is 20-50µm in size - Rough
exterior with several spine like projections(acanthopoda).
This trophozoite stage is the vegetative and motile phase
that occurs during favorable conditions (neutral pH,
availability of sources of nutrition, optimal temperature-
about 30 degrees etc)
• Cyst - Spherical and 15µm in diameter.
• Both forms can be the source of infection
11/28/2020

11/28/2020

Life cycle
• Acanthamoeba has two stages in its life cycle, a
vegetative trophozoite stage and cyst
• Infection with Acanthamoeba spp occur by inhalation
of trophozoites, ingestion of trophozoites or
trophozoites penetrate the broken skin or through
eyes
• After enter of trophozoites the body and trophozoite
reach the brain by blood stream, most likely from the
lower respiratory tract or through the ulcers of skin or
mucosa and replicated by binary fission.
11/28/2020

• When trophozoites are void of nutrition or in hostile
environments (high and low temperatures, lack of
moisture, etc), the trophozoite does not die but
simply transfer into cyst. This process is called
‘encystation.
• Acanthamoeba will remain a cyst until the
environment becomes more favorable for growth
and the trophozoite will re-emerge in a process
called ‘excystation
11/28/2020

Life cycle
11/28/2020

Pathogenesis
• Granulomatous Amebic Encephalitis (GAE) and
disseminated infection primarily affect people with
compromised immune systems. Commonly seen in
immunocompromised patients, including those with
neoplasia, systemic lupus erythematosus, human
immunodeficiency virus and tuberculosis.
11/28/2020

• Acanthamoeba causes single or multiple focal
granulomatous space-occupying lesions in the brain
• The gross pathology of the autopsied brains show
severe edema and haemorrhagic necrosis
11/28/2020

Clinical signs
• GAE starts slowly, with symptoms like headache,
nausea, dizziness, irritability and a low-grade fever.
• The CNS symptoms depend on the part of the brain
that is infected. Changes in behavior are an important
sign. Other CNS signs may include seizures, focal
neurologic signs, diplopia (double vision), cranial
nerve palsies, ataxia, confusion, and personality
changes
11/28/2020

Diagnosis
• Specimens should never be refrigerated, to preserve
the trophozoites.
• Acanthamoeba trophozoites or cysts can be
demonstrated with corneal scrapings or a biopsy
sample via wet mount, stains, histopathologic
examination.
• Smears stained with Giemsa or Wright's stain.
• Granulomatous amebic encephalitis: _ This condition
is diagnosed via brain biopsy. (cyst and trophozoit)
11/28/2020

Prevention
• Wear Nose-Clips for Swimming.
• Do not wear contact lenses while swimming
• Take good care of lenses
• Do not use home-made saline for cleaning lenses
• Avoidance of swimming in contaminated water
• Proper chlorination of water
11/28/2020

Treatment
• Antifungaldrugs including ketoconazole, miconaz
ole, 5-flucytosine and pentamidine have been
shown to be effective against Acanthamoeba
11/28/2020

Acanthamoeba keratitis AK
• Acanthamoeba keratitis is a rare but serious infection
of the eye that can result in permanent visual
impairment or blindness. This infection is caused
by Acanthamoeba. Acanthamoeba causes Acanthamo
eba keratitis when it infects the transparent outer
covering of the eye called the
cornea. Acanthamoeba amebas are very common in
nature and can be found in bodies of water (for
example, lakes and oceans), soil, and air.
11/28/2020

• Is a progressive disease of the cornea, which is sight-
threatening. Commonly seen in immunocompetent
patients.
• Risk factors: poor contact lens hygiene, corneal
abrasion, or exposure of the eye to contaminated
water
11/28/2020

• The symptoms of Acanthamoeba keratitis can be very
similar to the symptoms of other eye infections.
These symptoms, which can last for several weeks or
months, may include:
• Eye pain
• Eye redness
• Blurred vision
• Sensitivity to light
• Sensation of something in the eye
• Excessive tearing
11/28/2020

II Class: Flagellates
1. Intestinal flagellate:
Giardia lamblia
11/28/2020

Giardia lamblia
• Giardiasis is caused by Giardia lamblia, a protozoal
parasite. This organism is also called Giardia
intestinalis,Lamblia intestinalis and Giardia
duodenalis. The organisms isolated from humans,
domestic animals
• Giardiasis usually represents a zoonosis with cross-
infectivity between animals and humans. Giardia
intestinalis has been isolated from the stools of
beavers, dogs, cats, and primates
11/28/2020

• Giardia lamblia is a flagellated protozoan parasite
that colonizes and reproduces in the small intestines
causing Giardiasis.
• The Giardia parasite attaches to the epithelium of
small intestine by a ventral adhesive disc.
• Reproduces via Binary fission.
• Does not spread via bloodstream nor does it spread
to other parts of the Gastrointestinal tract, but remains
confined to the lumen of the small intestines
11/28/2020

Key
Kingdome: Protista
Phylum: Protozoa
Class: Masticophora
Family: Hexamitidae
Genus: Giardia
Species: lamblia
Synonyme: Giardia intestinalis, G. duodenalis &
Lamblia lamblia
11/28/2020

Disease: Giardiasis
Final host: Man
Site of infection: Small intestine (Jejunum & duodenum)
Infective stage: cyst
Life cycle: Direct
Infection: Occur by ingestion of the contaminated food &
water with cyst
11/28/2020

Transmission
• Giardiasis is passed via the face- oral route.
• Primary routes are personal contact and
contaminated water and food.
• People who have contact with individuals already
infected.
• It is a particular danger to people hiking or
backpacking in wilderness areas worldwide,
especially if they have no immediate access to
medical supplies
11/28/2020

Morphology
• There are two morphological stages including:
Trophozoite or active feeding stage and cyst stage:
1. Trophozoite:
• Anterior end is rounded & the post. end is tapers to
a point
• Dorsal surface is convex & the ventral surface is
concave
• An ovoid adhesive disc at anterior ventral surface
11/28/2020

• It is bilaterally symmetrical (there are 2 axostyles, 2 nuclei
& 4 pairs of flagella.
• The parasite give a typical monkey-face appearance on
microscopic examination
11/28/2020

2. Cyst:
• Oval in shape
• Surrounded by thick hyaline cyst wall
• Have 4 nuclei, usually located near one end or lie
in pairs at opposite poles
• There are No. of fibrils which represented the
retracted flagellae
11/28/2020

Life Cycle
• Giardia has one of the simplest life cycles of all
human parasite. The life cycle is composed of 2
stages: first is trophozoite which exists freely in the
human small intestine and the second is the cyst,
which is passed into the environment and is the
infective stage
• The final host infected by ingestion of cysts by
consuming contaminated food or water, or fecal-
orally. They can survive outside the body for several
months, and are also relatively resistant to
chlorination, UV exposure and freezing.
11/28/2020

• After ingestion of the cysts, the low pH of the
stomach acid produces excystation, in which the
activated flagella breaks through the cyst wall. This
occurs in the small intestine (duodenum), and
trophozoites released, with each cyst producing two
trophozoites.
• Within the small intestine, the trophozoites
reproduce asexually (longitudinal binary fission)
and either float free or are attached to the mucosa of
the lumen
11/28/2020

• Some trophozoites are encysted in the small intestine,
encystation occurs most likely as a result of exposure
to bile salts and fatty acids, and a more alkaline
environment. Both cysts and trophozoites are then
passed with the feces.
11/28/2020

Pathogenesis
• Attachment of the trophozoite to the mucosal surface by
means of its adhesive disc causes shortening of the villi
of the small intestine, causing inflammation of the crypts
and lamina propria, and lesions on mucosal cells.
• The troph. attached to the mucosa of intestine & forming
pavement like membrane that prevent the absorption of
food & water ( specially fatty material) such as carotene,
vitamin B12, and folate
• There may also be a reduction in the secretion of a
number of small intestinal digestive enzymes.
11/28/2020

Clinical Signs:
• Infections cause severe intestinal disorders, most
commonly:
1. Fatty diarrhea
2. GIT disturbance
3. Weakness
11/28/2020

Diagnosis
• Symptoms(fatty diarrhea)
• Fecal examination for detection of cyst or troph.
• Duodenal aspiration, is a technique that is used to
detect the presence of trophozoites.
• Serological tests, Stool enzyme immunoassay (EIA)
or direct fluorescent antibody tests are more sensitive
11/28/2020

Treatment
• Metronidazole is the most commonly prescribed
antibiotic for this condition
• Appropriate fluid and electrolyte management is
critical, particularly in patients with large-volume
diarrheal losses
11/28/2020

Prevention
• Careful hand washing; Infected persons and persons
at risk should carefully wash their hands after they
have any contact with feces
• Avoid food that might be contaminated
• Avoid eating uncooked foods
11/28/2020

2. Urogenital flagellate:
Trichomonis vaginalis
11/28/2020

Trichomoniasis in human
• Trichomoniasis (or “trich”) is a very common
sexually (venereal) transmitted disease (STD). It is
caused by infection with a protozoan parasite
called Trichomonas vaginalis.
• The primary habitat of this organism is vagina
and prostate
11/28/2020

Key
Kingdome: Protista
Phylum: Protozoa
Class: Masticophora
Family: Trichomonadidae
Genus: Trichomonas
Species: vaginalis
11/28/2020

Disease: Trichomoniasis
Final host: Man
Site of infection: Vagina & urethra
Infective stage: Trophozoite
Diagnostic stage: Trophozoite
Life cycle: Direct
Infection:
•Sexual intercourse
• Mutual masturbation
• Mother to child during vaginal delivery
11/28/2020

Morphology of Trophozoite
Only have one stage is Trophozoite stage:
• Trophozoite is pear shaped organism with a central
nucleus
• Have 5 flagella are arise from the anterior end, 4 of
them are free anterior Flagella, while the 5th is extend
backward forming short undulating membrane. Have
short undulating membrane which reaches back only
just beyond the middle of the cell
• A prominent axostyle & project posteriorly like needle
11/28/2020

Life cycle:
11/28/2020

• It is not an invasive parasite. It remains adherent to
the squamous epithelium but not columnar epithelium
and causing intracellular edema and “ chicken like
epithelium” is the most characteristic feature.
Virulence Factors:
• Protein liquids & proteases –help in adherence.
• Lactic acid and Acetic acid which lowers the vaginal
ph low ph is cytotoxic to vaginal epithelial cells.
11/28/2020
Pathogenesis

Clinical Signs
o Inflammation of the vaginal canal
o Vulvar itching leading to edema
o Tenderness and chaffing
o Redness
o yellow and green foul smelling discharge
o Painful urination-dysuria
o Dyspareunia
11/28/2020

Diagnosis:
11/28/2020
For detection of Trophozoite

• Treatment : Single dose of Metronidazole 2
gm once or Metronidazole PO 500 mg TDS
for 7 days
• Treat the male sexual partner
• Tinidazole is an alternate drug
11/28/2020
Treatment

Prevention
• Personal hygiene
• Barrier precautions
• Avoidance of sexual contact with infected
partners.
• Detection & Treatment of cases either
males/females.
11/28/2020

Thanks for attention
11/28/2020

Protozoology Theory lec.4

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Protozoology Theory lec.4

Similar to Protozoology Theory lec.4 (20)

More from Dr. Shameeran Bamarni

More from Dr. Shameeran Bamarni (20)

Recently uploaded

Recently uploaded (20)

Protozoology Theory lec.4