Protozoa causing diarrhea

1. Benha Faculty of Medicine
Department of Parasitology
Under Supervision of
Dr. Azza ElHamshary
Head of Parasitology Department
Done by
Sarah ElSayed Ahmed Gobba ( Giardia lamblia ,
Microsporidia & Isospora)
Asmaa Mohamed ElShamy (Cryptosporidium parvum)
Mina Attallah Iskandar (Cyclospora Cyetanensis)
Doha Saber Abdelbaky (Sarcocystis)
Protozoa causing
diarrhea

2. Giardia lamblia
Giardia lamblia exists in two forms , an active form called a trophozoite
and an inactive formcalled a cyst. the active trophozoite attaches to
the linig of the intestine with a sucker and is responsiblefor causing
the signs and symptoms of giardiasis . When ingested the cystis
activated by the stomach acid into trophozoite.Later on , the
trophozoiteforms the cyst that exits the in feces to spread infection to
others .
The most common way to get giardiasis is to drink water that contain
G. lamblia . Contaminated water can be in swimming pools , spas and
lakes.Sources of infection include animal feces , diapers and
agricultural runoff.

3. Some people are carriers of giardiasis withoutany symptoms
.Symptoms generally show up after two weeks .Acute symptoms
include diarrhea , stomach or abdominak cramps , nausea , vomiting
and dehydration that results from diarrhea.
Giardia can be diagnosed by examination of stool under the
microscopefor cysts .The best bestfor diagnosing giardiasis is antigen
testing of stool .Other tests include examination of fluid from the
duodenum or biopsy.
Giardiasis is treated by metronidazolefor 5-10 days .Tinidazole is also
added.
Microsporidia
The microsporidia are a group of obligate intracellular parasitic
They are characterized by the production of resistantspores thati.fung
Becausethe microsporidiandepending on the species.vary in size,
species are so greatly numbered and their hosts so varied, these
parasites can be found in many types of ecosystems.

4. Humans acquiremicrosporidiosis through ingestion or inhalation of
microsporidia sp'ores Microsporidiosis is believed to be a zoonosis.
Evidence suggests that microsporidia may be water-bornepathogens
and may be transmitted from human to human.[9]
Most cases of microsporidiosis in patients with HIV infection occur in
those with severeimmunodeficiency.
Cases of microsporidiosis havebeen reported in individuals who are
HIV negativeand who areimmunocompromised secondary to
transplantsurgery or prolonged steroid use.
Self-limited diarrhea due to microsporidiosis has been reported in
immunocompetent travelers; waterbornetransmission may play a role
in these cases.
History fromthe patient is taken as the following:
Intestinalor biliary microsporidiosis
 Chronic diarrhea (loose, watery, nonbloody)
 Weight loss
 Abdominal pain
 Nausea
 Vomiting
Disseminated microsporidiosis

5.  Symptoms of cholecystitis, renal failure, and respiratory tract
infections occur.
 Patients with respiratory tractinvolvement may present with
persistentcough, dyspnea, and wheezing.
 Headache, nasalcongestion or discharge, ocular pain, and loss of
taste may indicate sinus involvement.
 Patients with urinary tract involvementare frequently
asymptomatic.
Ocular microsporidiosis
 Foreign body sensation, eye pain, or both
 Light sensitivity
 Ocular redness
 Excessivetearing
 Blurred or decreased vision
Musculoskeletal microsporidiosis: Myalgia, generalized muscle
weakness, and fever are common in patients with myositis and severe
cellular immunodeficiency.
Dermatologic microsporidiosis: Microsporidia havebeen associated
with a nodular cutaneous lesion in patients with HIV infection.
CNS microsporidiosis: Patients with microsporidiosis of the brain may
experience seizures and headache.
There are severalmethods for diagnosis of microsporidia;Light
microscopic examination of the stained clinical smears, especially the
fecal samples, is an inexpensive method of diagnosing microsporidial
infections even though it does not allow identification of microsporidia
to the species level.Immunoflorescenseessaysand PCRis also used.
Albendazole and fumagillin are used for the treatment of
microsporidiasis.

6. Isospora belli
It is worldwide distributed , especially in tropical and subtropical areas. Infection occurs
in immunodepressed individuals, and outbreaks have been reported in institutionalized
groups in the United States.
The mode of transmission of isosporiasis is fecal-oral, ie, through
food or water contaminated with human feces. In immunocompetent
hosts, C belli infection causes a self-limited diarrheal illness. In
individuals with immunocompromise, it may cause chronic life-
threatening diarrhea and dehydration.
C belli infection is most commonly observed in
immunocompromised individuals or in individuals who have recently
traveled to tropical areas, in people who are institutionalized, or in
persons who live in poor sanitary conditions. The incubation period
ranges from 3 to 14 days. Symptoms begin approximately 1 week
after ingestion of the oocysts and last 2-3 weeks, with gradual
improvement. Infection in people who are immunocompromised
may continue indefinitely.

7. Symptoms and signs may include the following:
 Profuse, watery, nonbloody, offensive-smelling diarrhea, which
may contain mucus
 Foul-smelling flatus
 Cramping abdominal pain, vomiting (nausea and vomiting are
uncommon)
 Malaise, anorexia, weight loss
 Low-grade fever
 Steatorrhea in protracted cases
 Myalgias (rare)
 Headache (rare)
In immunocompromised individuals with severe or long-lasting
disease, dehydration may be evident. Otherwise, minimal
abdominal tenderness may be present. Severe dehydration is the
most common complication and almost always occurs in patients
who are very young or immunocompromised. Acalculous
cholecystitis has been reported in patients with AIDS. Tissue
invasion and dissemination have been reported on autopsy findings
in a few patients with AIDS. Colitis in patients with AIDS has been
rarely reported. Reactive arthritis is rare but has been reported in
immunocompromised patients.
Microscopic demonstration of the large, typically shaped oocysts, is the basis for
diagnosis. Because the oocysts may be passed in small amounts and intermittently,
repeated stool examinations and concentration procedures are recommended. If stool
examinations are negative, examination of duodenal specimens by biopsy or string test
(Enterotest®) may be needed. The oocysts can be visualized on wet mounts by
microscopy with bright-field, differential interference contrast (DIC), and
epifluorescence. They can also be stained by modified acid-fast stain.

8. Cryptosporidium parvum
Cryptosporidium parvum Cryptosporidium parvum is a protozoan and
an obligate intracellular parasite (a parasite that cannotsurvive
without a host) that commonly causes an opportunistic infection in
immunocompromised hosts. Distribution: Cosmopolitian ,
immunocompromised peole are more susceptible.
Life cycle: Oocyst→trophozoite→aporogony Epidemology : Fecal-
oral route is the most common mode of transmission of the disease.
The parasite can survivein food, water, soil or in vertebratehosts.
INCUBATIONPERIOD : Notprecisely known; 1-12 days is the likely
range with a mean of 7 days.
Pathology & manifestation : Cryptosporidiasis, a diarrhealdiseaseis
characterized by watery diarrhea, nausea and vomiting, dehydration,

9. abdominal cramps and fever. Symptoms usually resolvein 2-4 weeks in
immunocompetent hosts. Cryptosporidiosiscan also manifest as
pulmonary or tracheal disease, causing cough and fever. However,
these patients also manifest with the intestinal component of the
disease. Diagnosis: Identification of cysts in fecal smears or by
intestinal biopsy. Treatment: Symptomatic treatment of the diarrhea
by administering plenty of fluids to preventdehydration is the primary
management. A new drug, Nitazoxanide has been approved for the
treatment of cryptosporidiosis.

10. ospora cyatenansisCycl
Geographic distribution: Cyclosporiasis has been reported in many
countries , but most common in tropical and subtropicalareas.
Lifecycle & transmition:

11. lifecycle intracellularly within the host's epithelial cells and
gastrointestinal tract. Infection is transmitted through the fecal-oral
route, and begins when a person ingests oocysts in fecally
contaminated food or water. Various chemicals in the host's
gastrointestinal tract cause the oocysts to excyst and release
sporozoites; generally, two are observed per oocyst. After these
sporozoites invade the epithelial cells, they undergo merogony, a form
of asexual reproduction that results in many daughter merozoites.
These daughter cells may either infect new host cells and initiate yet
another round of merogony or take on a sexual track via gametogony:
Daughter merozoites become male macrogamonts—which form many
microgametes—and female macrogamonts. After fertilization has
occurred via male microgamete fusion with female macrogamont, the
zygote matures into an oocyst and ruptures the host cell, from which
point it is passed with the stool. The oocysts that are passed are not,
however, immediately infectious. Sporulation can take from one to
several weeks, meaning person-to-person transmission is not a likely
problem. This differentiates C. cayentanensis from Cryptosporidium
parvum—a closely related organism that causes a similar disease—
since C. parvum oocysts are immediately infectious upon release from
the host.
symptoms
C. cayentanensis causes gastroenteritis, with the extent of the illness
varying based on age, condition of the host, and size of the infectious
dose. Symptoms include "watery diarrhea, loss of appetite, weight loss,
abdominal bloating and cramping, increased flatulence, nausea,
fatigue, and low-grade fever", though this can be augmented in more
severe cases by vomiting, substantial weight loss, excessive diarrhea,
and muscle aches. Typically, patients with a persistent watery diarrhea
lasting over several days may be suspected of harboring the disease,
especially if they have traveled to a region where the protozoan is
endemic. The incubation period in the host is typically around a week,
and illness can last six weeks before self-limiting. Unless treated, illness

12. may relapse. The more severe forms of the disease can occur in
immunocompromised patients, such as those with AIDS.
Treatment
The specific drug treatment for disease caused by Cyclospora
cayetanensis is the combination of two antibiotics—trimethoprim and
sulfamethoxazole (co-trimaxazole).
Sarcocystis
Itis a protozoan genus of parasites , the majority of species infect
mammals and some infect reptiles and birds.
Disribution:In wild Africa , Europe, China , India
Life cycle:There are two hostspecies , definitive host and its predator ,
intermediate host is its prey . The parasite reproduces sexually in the gut of
the definitive host , then passes with and is ingested by intermediate host ,
there it enters the muscle tissue . When intermediate hostis eaten by the
definitive host, the cycle is completed.

13. Mode of infection: Eating raw meat from cattle and pig
Clinical picture: Symptoms appear 3-6 hours after eating . These
include anorexia , nausea , abdominal pain , distension , diarrhea ,
dyspnea and tachycardia.
Diagnosis:Enteric Sarcocystis is diagnosed by finding mature sporocysts
in stool using concentration techniques.For musclesarcocystitis muscle
biopsy of infected muscle is taken . Sarcocysts areidentifiable by the
hematoxylin and eosin stain. Inflammatory cells can be found in cases
of myositis and vasculitis.
Treatment: Albendazole,Metronidazole and coatrimoxozolefor
myositis.Corticosteroids areused for symptomatic relief.Amprolium
and selinomycin is effective in preventing severe illness and death.